JP4903378B2 - Milling tools - Google Patents

Description

  The present invention relates to a milling tool that is used with a cutting insert attached to the tip of a holder.

  In recent years, demands for high precision and high efficiency of milling tools have increased, and various shapes of cutting inserts used for them have been developed and used in various fields such as die machining.

  For example, in Patent Document 1, in a tool for tilting the cutting insert with respect to the rotation axis of the holder, that is, mounting with a rake angle in the axial direction, scooping the cutting insert into a shape in which the central portion of the outer peripheral cutting edge is expanded toward the outer peripheral side. It is described that the outer peripheral surface can be machined vertically even if the cutting insert is mounted with a constant angle and clearance angle and an axial rake angle. In the same document, the flank is constituted by a simple plane.

  Further, in Patent Document 2, the outer peripheral cutting edge is divided into three sections, and the cutting insert is mounted with an axial rake angle by adjusting the outer peripheral cutting edge shape, rake angle and clearance angle of each of the three sections. However, it is described that the outer peripheral surface can be processed vertically, and chips can be divided to reduce cutting resistance. The flank in the cutting insert is a second flank (flat lower part) from the first flank (upper part) through the intermediate surface (joint part) from the front end to the rear end on the corner cutting edge side. (See FIGS. 9 to 11 of Patent Document 2).

Furthermore, Patent Document 3 describes a spiral cutting insert in which the outer peripheral cutting edge is twisted in the height direction, and in this cutting insert, the wavy long edge cutting edge forming the outer peripheral cutting edge is compared to the short edge cutting edge. It is described that shoulder processing of 90 degrees is possible at right angles. In addition, the flank in the above-mentioned cutting insert also has a complicated shape from the corrugated first flank (main flank) through the stepped flank (intermediate surface) from the leading edge to the rear edge on the corner cutting edge side. It consists of a structure connected to the 2nd flank which becomes a holder restraint surface (refer FIG. 9, 10 of patent document 3).
JP-A-2-298414 JP-A-11-333616 Japanese National Patent Publication No. 10-506582

  However, if the flank face is a simple flat surface as in the cutting insert of Patent Document 1, if the rake angle in the axial direction is increased, the flank angle of the outer peripheral cutting edge is inevitably increased in design, and the cutting edge strength is reduced. There was a problem of being easily lost.

  Therefore, as in Patent Document 2 and Patent Document 3, when the first flank and the second flank are provided over the entire length of the outer peripheral cutting edge and the intermediate surface is connected between them, the first flank adjacent to the outer peripheral cutting edge However, since the thickness of the outer peripheral cutting edge portion is thin, the impact applied to the cutting edge is weak and the cutting edge defect is not improved. In addition, if the intermediate flank is not provided between the first flank and the second flank following the outer peripheral cutting edge, the first flank has an appropriate clearance angle at the center that is geometrically swollen to the outer peripheral side. There is a problem that it becomes impossible to form.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a milling tool capable of processing the outer peripheral surface vertically and reducing the occurrence of chipping of a cutting edge.

  According to the present invention, since the bulge of the outer peripheral cutting edge toward the outer peripheral side is negligibly small at the tip of the outer peripheral cutting edge on the corner cutting edge side, the flank is located in the first clearance existing directly below the outer peripheral cutting edge. It is possible to increase the cutting edge strength at the tip of the outer peripheral cutting edge with the largest cutting load by directly connecting the surface and the second flank that is located on the bottom side and that serves as the holder restraining surface. In addition, the central portion of the outer peripheral cutting edge that swells to the outer peripheral side has a shape in which the first flank and the second flank are connected via an intermediate surface. Since it becomes small to some extent, it is possible to maintain the cutting edge strength to such an extent that no chipping occurs even in the three-surface configuration of the first flank, intermediate surface, and second flank. As a result, the chipping resistance of the entire cutting insert can be improved.

  That is, the milling tool of the present invention is a milling tool in which at least one cutting insert is attached to the tip of a holder. An upper surface, a side surface that forms a flank surface, an outer peripheral cutting edge that is formed on a cross ridge line portion between the rake surface and the flank surface, and is positioned on the outer periphery of the holder; A corner cutting edge connected to the blade, and the outer peripheral cutting edge has a shape in which a central portion swells outward in a top view of the insert, and a flank face continuing from the outer peripheral cutting edge is adjacent to the outer peripheral cutting edge A first flank and a second flank that is positioned on the bottom side of the first flank and serves as a restraint when mounted on the holder, and at the central portion of the outer peripheral cutting edge, The first flank and the second flank Surface and is connected via an intermediate surface, said at corners of the cutting edge side tip portion, characterized in that said second flank and the first flank is directly connected.

Here, the outer peripheral cutting edge has a front end flat section having the same height on the corner cutting edge side, an inclined section in which the height gradually decreases from the front end to the rear end at an intermediate portion of the rear end, and a rear end portion. Having the rear end flat section of the same height can increase the cutting edge strength at the outer peripheral cutting edge tip and can prevent the cutting resistance from increasing at the center toward the outer cutting edge rear end, In addition, the strength required when handling the cutting insert at the rear edge of the outer peripheral cutting edge is secured, the restraint area of the flank holder to the holder is secured, and the inclination angle at the central portion of the outer peripheral cutting edge is tightened to reduce the cutting resistance. Further reduction is desirable in that the occurrence of defects, boundary damage, and the like can be suppressed.
The outer peripheral cutting edge has a shape in which the tip portion does not bulge outward when the insert is viewed from above, and the first flank and the second flank are directly connected in the tip flat section and intermediate in the inclined section. It is desirable to be connected through a surface.

Further, the clearance angle of the cutting insert at the first flank gradually increases from the front end portion toward the rear end portion on the corner cutting edge side, and the rake angle of the outer peripheral cutting edge is the corner cutting edge. By being constant from the front end to the rear end on the side, the cutting resistance does not increase excessively even in cutting conditions where the vertical cutting is large such that the outer peripheral cutting edge is used in a wide range, and the outer peripheral cutting edge Since the rake angle is constant from the front end portion to the rear end portion on the corner cutting edge side, manufacturing quality control is easy, and the substantial rake angle when the cutting insert 3 is attached to the holder 2 is The corner cutting edge can be set to gradually increase from the front end to the rear end, and can be set to a rake angle corresponding to the magnitude of impact at each part of the outer peripheral cutting edge 12 Cutting edge 12 as a whole fracture resistance is improved.
A virtual crossing straight line L of the cutting insert and a straight line PQ connecting a point P that is a joint between the outer peripheral cutting edge and the corner cutting edge and a point Q that is a joint between the rear end side corner R of the outer peripheral cutting edge. The angle θ1 between the first flank and the second flank at the end of the corner cutting edge is longer than the intermediate surface. It is desirable to improve the chipping resistance on the corner cutting edge side.
A straight line PQ connecting a point P that is a joint between the outer peripheral cutting edge and the corner cutting edge and a point Q that is a joint between the outer peripheral cutting edge and the corner R on the rear end side, and a virtual transverse direction of the cutting insert.
When an angle θ1 is formed with the line L, an angle θ2 formed by the second flank and the virtual transverse line L of the cutting insert is θ1-1 ° ≦ θ2 ≦ θ1 + 1 ° with respect to the angle θ1. This is desirable in taking a long portion where the first flank and the second flank at the tip of the corner cutting edge are directly connected without an intermediate surface.
A virtual crossing straight line L of the cutting insert and a straight line PQ connecting a point P that is a joint between the outer peripheral cutting edge and the corner cutting edge and a point Q that is a joint between the rear end side corner R of the outer peripheral cutting edge. The angle θ2 formed by the second flank and the virtual transverse straight line L of the cutting insert is 0 <θ1-θ2 ≦ 1 ° with respect to the angle θ1, This is desirable in taking a long portion where the first flank and the second flank at the tip of the corner cutting edge are directly connected without an intermediate surface.

  The milling tool of the present invention has almost no bulge to the outer peripheral side of the outer peripheral cutting edge at the tip of the outer peripheral cutting edge. The second flank which is positioned and serves as the holder restraint surface can be directly connected, and the cutting edge strength at the tip of the outer peripheral cutting edge with the largest cutting load can be increased. Moreover, the cutting load on the central part of the outer peripheral cutting edge bulging to the outer peripheral side is somewhat smaller than that of the outer peripheral cutting edge tip part by connecting the first flank and the second flank through an intermediate surface. Together, the first flank and the second flank are directly connected to maintain the cutting edge strength so as not to cause chipping rather than unduly increasing the flank angle of the first flank. It can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing an example of an embodiment of a milling tool (hereinafter abbreviated as a tool) 1 of the present invention, and FIG. 2 is a cutting insert (hereinafter referred to as an insert) used in the tool 1 of FIG. 3 is a schematic perspective view of FIG. 3, FIG. 3 is a top view of the insert 3 in FIG. 2, FIG. 4 is a schematic diagram for explaining the outer peripheral cutting edge shape of the insert 3, and FIG. FIG. 6 is a cross-sectional view showing the (a) AA cross section, (b) BB cross section, and (c) CC cross section of FIG.

  In FIG. 1, a tool 1 is formed by attaching at least one insert 3 to the tip of a substantially cylindrical holder 2, and the holder 2 rotates around the central axis of the holder 2 to cut by the cutting insert 3. Processing is performed. According to the embodiment shown in FIG. 1, the insert pockets 4 are formed at three locations on the tip of the holder 2, the inserts 3 are fitted into the respective insert pockets 4 and pass through the screw holes 5 of the cutting insert 3. A fixing screw 6 is screwed onto 2 and fixed to the holder 2.

  On the other hand, the insert 3 has a parallelogram shape as a basic shape as shown in FIG. 3, and a bottom seating surface 8, a top rake surface 9, and a side relief surface 10 as shown in FIGS. The outer peripheral cutting edge 12 formed on the long side portion at the crossing ridge between the rake face 9 and the flank 10 and positioned on the outer periphery of the holder 2 and the corner cutting edge 14 extending from the outer peripheral cutting edge 12 to the tip end portion are diagonally arranged. Are provided at two corners facing each other. Furthermore, in the insert 3 of the present embodiment, a bottom cutting edge 15 is formed on the short side portion following the corner cutting edge 14, and the outer peripheral cutting edge 12 and the bottom cutting edge 15 are substantially perpendicular. With this configuration, it is possible to perform cutting with high processing accuracy in shoulder processing in which the processing bottom surface of the work material and the processing side wall surface perpendicular thereto are simultaneously cut. The radius of curvature of the corner cutting edge 14 is 0.2 to 6.4 mm in view of the balance between the cutting edge strength and the processed shape.

  Further, the shape of the outer peripheral cutting edge 12 of the insert 3 is a curved shape with the central portion bulging outward as viewed from above as shown in FIG. 3, and strictly speaking, the holder 2 is formed with an axial rake angle on the insert 3. When the rotation trajectory of the outer peripheral cutting edge 12 is drawn in a state where the outer peripheral cutting edge 12 is mounted, as shown in FIG. 4, the central portion of the outer peripheral cutting edge 12 swells so that the rotation trajectory of the outer peripheral cutting edge 12 draws a cylinder. ing. That is, when processing is performed with the tool 1 having this configuration, a processed side wall surface with excellent right-angle accuracy can be obtained. This bulge amount is designed based on geometric calculation.

  Here, according to the present invention, as shown in FIG. 2, the flank 10 </ b> A continuing from the outer peripheral cutting edge 12 is positioned below the first flank 17 adjacent to the outer peripheral cutting edge 12 and the first flank 17. And a flat second flank 18 serving as a restraint surface when mounted on the holder 2, and the first flank 17 and the second flank 18 are intermediate surfaces at the center of the outer peripheral cutting edge 12. The first flank 17 and the second flank 18 are directly connected to each other at the tip of the corner cutting edge 14 side.

  With this configuration, the tip of the outer peripheral cutting edge 12 does not bulge to the outside of the outer peripheral cutting edge 12. Therefore, the flank is positioned on the first flank 17 directly below the outer peripheral cutting edge and below it and is flat. The second flank 18 which is a surface can be directly connected, and the cutting edge strength at the tip of the outer peripheral cutting edge 17 having the largest cutting load can be increased. On the other hand, in the central part of the outer peripheral cutting edge 12 swelled to the outer peripheral side, the first flank 17 and the second flank 18 are connected to each other via the intermediate surface 20 so that the tip part of the outer peripheral cutting edge 12 can be obtained. Since the cutting load is small to some extent, it is possible to maintain a cutting edge strength that does not cause chipping. As a result, the chipping resistance of the entire cutting insert 3 can be improved.

  According to the present invention, the rear end portion of the outer peripheral cutting edge 12 may have a shape in which the first flank 17 and the second flank 18 are directly connected as shown in FIG. The shape which connected the 1st flank 17 and the 2nd flank 18 via the intermediate surface 20 similarly to the center part of the cutting blade 12 may be sufficient. In order to increase the fracture resistance of the outer peripheral cutting edge 12, it is desirable that the first flank 17 and the second flank be directly connected.

Further, as shown in FIG. 3, a straight line connecting a point P which is a joint between the outer peripheral cutting edge 12 and the corner cutting edge 14 and a point Q which is a joint between the outer peripheral cutting edge 12 and the corner R on the rear end side. The angle θ ₁ formed by PQ and the imaginary transverse line L of the cutting insert 3 is 89 ° ≦ θ ₁ <90 °, so that the first flank and the second flank at the tip portion on the corner cutting edge 14 side However, it is desirable to increase the fracture resistance on the corner cutting edge 14 side because the portion directly connected without the intermediate surface 20 can be made long. In addition, as a method of lengthening a portion where the first flank 17 and the second flank 18 at the tip portion on the corner cutting edge 14 side are directly connected without passing through the intermediate surface, the second flank 18 and the cutting are used. An angle θ ₂ (not shown) formed by the virtual transverse line L of the insert 3 is designed to be within a range of θ ₁ −1 ° ≦ θ ₂ ≦ θ ₁ + 1 ° with respect to the angle θ ₁ . Examples include a method of designing so that 0 <θ ₁ −θ ₂ ≦ 1 °, and a combination of these methods is also possible.

  Here, as shown in FIG. 5, the outer peripheral cutting edge 12 has a tip flat section 12A having the same height on the corner cutting edge 14 side, and an inclined section in which the height gradually decreases from the front end to the rear end at the rear end portion. 12B and the rear end flat section 12C having the same height at the rear end portion can increase the cutting edge strength at the front end portion of the outer peripheral cutting edge 12, and the center toward the rear end portion of the outer peripheral cutting edge 12. Further, it is possible to prevent the cutting resistance from increasing at the portion, and to secure the strength necessary for handling the cutting insert 3 at the rear end portion of the outer peripheral cutting edge 12 and to secure the restraining area of the flank 10A to the holder and It is desirable in that generation of defects, boundary damage, flash, etc. can be suppressed by further reducing the cutting resistance by tightening the inclination angle at the center of the outer peripheral cutting edge 12.

Further, as shown in FIG. 6, the clearance angle β of the outer peripheral cutting edge 12 is gradually increased from the front end portion on the corner cutting blade 14 side toward the rear end portion with the insert 3 alone (β ₁ <β ₂ <β ₃ ) and the rake angle α of the outer peripheral cutting edge 12 is constant from the front end to the rear end on the corner cutting edge 14 side (α ₁ = α ₂ = α ₃ ), so that the outer peripheral cutting edge 12 can be used in a wide range. Even under cutting conditions where the vertical cutting is large, the cutting force does not increase excessively, and the rake angle α of the outer peripheral cutting edge 12 is constant from the front end to the rear end on the corner cutting edge side, The quality control in manufacturing is easy, and the design is such that the substantial rake angle when the insert 3 is attached to the holder 2 gradually increases from the front end on the corner cutting edge 14 side toward the rear end. The outer peripheral cutting edge 12 There is an advantage that chipping resistance as the body is improved.

  Further, a land portion and a honing portion 30 are formed on the outer peripheral cutting edge 12 to prevent the chipping.

  In FIG. 2, the chip breaker is formed so as to have a raised portion 31 after being lowered from the corner cutting edge 14 and the outer peripheral cutting edge 12 toward the center in the longitudinal direction of the rake face 9, and the chips are curled. It is designed to be well divided and discharged.

  Furthermore, although the bottom surface 8 is a flat surface in FIG. 5, the present invention is not limited to this. For example, so-called serrations, which are elongated and unevenly arranged in parallel with each other, are repeated to form a longitudinal section or a transverse section. A wavy configuration may be used.

  Furthermore, in this embodiment, the bottom cutting edge 15 is formed. However, the present invention is not limited to this. For example, it is added to the rear end portion of the insert 3 of the holder 2 in FIG. The present invention can also be applied to an insert without a bottom cutting edge additionally provided in a so-called helical milling tool provided with an insert.

It is a schematic perspective view which shows an example of the milling tool of this invention. It is a schematic perspective view of the cutting insert used for the milling tool of FIG. It is a top view of the cutting insert of FIG. It is a schematic diagram for demonstrating the shape of the outer periphery cutting blade of the cutting insert of FIG. It is the side view which looked at the cutting insert of FIG. 2 from the X direction. It is a schematic sectional drawing which shows the (a) AA cross section, (b) BB cross section, and (c) CC cross section of the cutting insert of FIG.

Explanation of symbols

1 Milling tool (tool)
2 Holder 3 Cutting insert (insert)
4 Insert pocket 5 Screw hole 6 Fixing screw 8 Seating surface (bottom surface)
9 Rake face (upper surface)
10 Flank (side)
10A Flank 12 continuing from outer peripheral cutting edge 12 Peripheral cutting edge 12A Tip flat section 12B Inclined section 12C Flat rear section 14 Corner cutting edge 15 Bottom cutting edge 17 First flank 18 Second flank 20 Intermediate face 30 Honing portion 31 Part

Claims (7)

In a milling tool formed by attaching at least one cutting insert to the tip of the holder,
The holder is formed by forming a polygonal shape as a basic shape on a bottom surface forming a seating surface, a top surface forming a rake surface, a side surface forming a flank surface, and a cross ridge line portion between the rake surface and the flank surface. An outer peripheral cutting edge located at the outer periphery of the cutting insert, and a corner cutting edge at a corner of the cutting insert and connected to the outer peripheral cutting edge,
The outer peripheral cutting edge has a shape in which the central portion swells outward in the top view of the insert,
The flank that continues from the outer peripheral cutting edge includes a first flank adjacent to the outer peripheral cutting edge, and a second flank that serves as a restraint surface when the holder is mounted on the bottom side of the first flank. And having a surface,
The first flank and the second flank are connected via an intermediate surface at the center of the outer peripheral cutting edge, and the first flank and the second flank are connected at the tip of the corner cutting edge. A milling tool that is directly connected.   The outer peripheral cutting edge has the same height on the corner cutting edge side, the tip flat section having the same height, the inclined section in which the height gradually decreases from the front end to the rear end in the middle part of the rear end, and the same height on the rear end part. The milling tool according to claim 1, further comprising a rear end flat section. The outer peripheral cutting edge has a shape in which the tip portion does not bulge outward in an insert top view,
The milling tool according to claim 2, wherein the first flank and the second flank are directly connected in the tip flat section and are connected via an intermediate surface in the inclined section.   The cutting insert has a clearance angle at the first flank that gradually increases from the leading edge on the corner cutting edge side toward the trailing edge, and the rake angle of the outer peripheral cutting edge is on the corner cutting edge side. The milling tool according to claim 1, which is constant from the front end portion to the rear end portion.   A virtual crossing straight line L of the cutting insert and a straight line PQ connecting a point P that is a joint between the outer peripheral cutting edge and the corner cutting edge and a point Q that is a joint between the rear end side corner R of the outer peripheral cutting edge. The milling tool according to any one of claims 1 to 4, wherein an angle θ1 formed by the following is 89 ° ≦ θ1 <90 °. A virtual crossing straight line L of the cutting insert and a straight line PQ connecting a point P that is a joint between the outer peripheral cutting edge and the corner cutting edge and a point Q that is a joint between the rear end side corner R of the outer peripheral cutting edge. When the angle θ1 is the angle θ1,
The angle θ2 formed by the second flank and the virtual transverse line L of the cutting insert is θ1-1 ° ≦ θ2 ≦ θ1 + 1 ° with respect to the angle θ1. Milling tool. A virtual crossing straight line L of the cutting insert and a straight line PQ connecting a point P that is a joint between the outer peripheral cutting edge and the corner cutting edge and a point Q that is a joint between the rear end side corner R of the outer peripheral cutting edge. When the angle θ1 is the angle θ1,
6. The milling cutter according to claim 1, wherein an angle θ <b> 2 formed by the second flank and the virtual transverse line L of the cutting insert satisfies 0 <θ1−θ2 ≦ 1 ° with respect to the angle θ <b> 1. tool.

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