SCREW THREAD CUTTER

• US 20190009352A1
• Filed: 01/04/2017
• Published: 01/10/2019
• Est. Priority Date: 01/13/2016
• Status: Active Grant

• Current Assignee: Mitsubishi Hitachi Tool Engineering,Ltd. (Mitsubishi Materials Corporation)
• Original Assignee: Mitsubishi Hitachi Tool Engineering,Ltd. (Mitsubishi Materials Corporation)
• Inventors: Iharada, Yuuki, Yokokawa, Mitsuhiro
• Granted Patent: US 10,940,553 B2
• Time in Patent Office: Days
• CPC Class Codes: B23C 5/10 Shank-type cutters, i.e. with an integral shaft
• CPC Class Codes: B23G 2200/44 Taps with more than one threading section, the threading sections being axially spaced from one another
• CPC Class Codes: B23G 5/18 Milling cutters

Abstract

In a screw thread cutter, a screw thread-cutting edge is formed on an outer periphery of a tip portion of a cutter body. Finishing edge-thread ridge height from a tangent line passing through valley bottoms of second and third valley portions to outer peripheral ends of first and second finishing edges are equal to each other. A preceding edge-thread ridge height from the tangent line to an outer peripheral end of a preceding edge is lower than each of the finishing edge-thread ridge height. A first valley portion-depth from the outer peripheral end of the first finishing edge to the valley bottom of the first valley portion is deeper than a second valley portion-depth from the outer peripheral end of the second finishing edge to the valley bottom of the second valley portion.

Claims

1. A screw thread cutter,

wherein at least three screw thread-cutting edges which protrude toward an outer peripheral side of a cutter body rotated around an axis are formed on an outer periphery of a tip portion of the cutter body to be arranged in an axial direction,

wherein among the plurality of screw thread-cutting edges, the screw thread-cutting edge positioned on a tip side in the axial direction is a preceding edge,

wherein among the plurality of screw thread-cutting edges, the screw thread-cutting edge positioned on a posterior end side in the axial direction with respect to the preceding edge is a first finishing edge,

wherein among the plurality of screw thread-cutting edges, the screw thread-cutting edge positioned on a posterior end side in the axial direction with respect to the first finishing edge is a second finishing edge,

wherein a first valley portion which is recessed toward an inner peripheral side of the cutter body is formed between the preceding edge and the first finishing edge,

wherein a second valley portion which is recessed toward the inner peripheral side of the cutter body is formed between the first finishing edge and the second finishing edge,

wherein a third valley portion which is recessed toward the inner peripheral side of the cutter body is formed on a posterior end side in the axial direction with respect to of the second finishing edge,

wherein finishing edge-thread ridge heights in a radial direction with respect to the axis from a tangent line passing through valley bottoms of the second and third valley portions to outer peripheral ends of the first and second finishing edges are equal to each other,

wherein a preceding edge-thread ridge height in the radial direction with respect to the axis from the tangent line passing through the valley bottoms of the second and third valley portions to an outer peripheral end of the preceding edge is lower than the finishing edge-thread ridge heights, and

wherein a first valley portion-depth in the radial direction with respect to the axis from the outer peripheral end of the first finishing edge to the valley bottom of the first valley portion is deeper than a second valley portion-depth in the radial direction with respect to the axis from the outer peripheral end of the second finishing edge to the valley bottom of the second valley portion.

3. The screw thread cutter according to claim 1,

wherein a ratio between the first valley portion-depth and the second valley portion-depth is within a range of 1.03 to 1.15.

4. The screw thread cutter according to claim 1,

wherein an interval in the axial direction from the valley bottom of the first valley portion to the outer peripheral end of the first finishing edge is larger than an interval in the axial direction from the valley bottom of the second valley portion to the outer peripheral end of the second finishing edge.

5. The screw thread cutter according to claim 1,

wherein when the second finishing edge is moved parallel to the tangent line toward the tip side in the axial direction by an interval between the outer peripheral end of the first finishing edge and the outer peripheral end of the second finishing edges in a direction of the tangent line passing through the valley bottoms of the second and third valley portions, a rotation locus of the second finishing edge around the axis overlaps with a rotation locus of the first finishing edge around the axis except for the first and second valley portions.

6. The screw thread cutter according to claim 1,

wherein when a rotation locus of the preceding edge around the axis is moved toward the posterior end side in the axial direction to be parallel to the tangent line passing through the valley bottoms of the second and third valley portions by an interval between the outer peripheral end of the first finishing edge and the outer peripheral end of the second finishing edges in a direction of the tangent line, the rotation locus of the preceding edge is included in a rotation locus of the first finishing edge around the axis.

7. The screw thread cutter according to claim 1,

wherein each of the first and second finishing edges includes a cutting edge facing the tip side in the axial direction, a cutting edge facing the posterior end side in the axial direction, and a linear outer peripheral cutting edge, and

wherein in each of the first and second finishing edges, the outer peripheral cutting edge and the cutting edge facing the tip side in the axial direction are connected to each other via a plurality of linear cutting edges, and the cutting edge facing the posterior end side in the axial direction and the outer peripheral cutting edge are connected to each other via a plurality of linear cutting edges.

8. The screw thread cutter according to claim 4,

wherein a ratio between the interval in the axial direction from the valley bottom of the first valley portion to the outer peripheral end of the first finishing edge and the interval in the axial direction from the valley bottom of the second valley portion to the outer peripheral end of the second finishing edge is within a range of 1.01 to 1.09.

9. The screw thread cutter according to claim 1,

wherein the outer peripheral end of the second finishing edge is positioned outside the outer peripheral end of the first finishing edge in the radial direction with respect to the axis.

10. The screw thread cutter according to claim 1,

wherein an outer peripheral cutting edge of each of the first and second finishing edges has a convex arc shape.

11. The screw thread cutter according to claim 1,

wherein each of the first and second valley portions has a concave arc shape.

14. The screw thread cutter according to claim 3,

wherein an interval in the axial direction from the valley bottom of the first valley portion to the outer peripheral end of the first finishing edge is larger than an interval in the axial direction from the valley bottom of the second valley portion to the outer peripheral end of the second finishing edge.

16. The screw thread cutter according to claim 3,

wherein when the second finishing edge is moved parallel to the tangent line toward the tip side in the axial direction by an interval between the outer peripheral end of the first finishing edge and the outer peripheral end of the second finishing edges in a direction of the tangent line passing through the valley bottoms of the second and third valley portions, a rotation locus of the second finishing edge around the axis overlaps with a rotation locus of the first finishing edge around the axis except for the first and second valley portions.

2. A screw thread cutter,

wherein at least three screw thread-cutting edges which protrude toward an outer peripheral side of a cutter body rotated around an axis are formed on an outer periphery of a tip portion of the cutter body to be arranged in an axial direction,

wherein among the plurality of screw thread-cutting edges, the screw thread-cutting edge positioned on a tip side in the axial direction is a preceding edge,

wherein among the plurality of screw thread-cutting edges, the screw thread-cutting edge positioned on a posterior end side in the axial direction with respect to the preceding edge is a first finishing edge,

wherein among the plurality of screw thread-cutting edges, the screw thread-cutting edge positioned on a posterior end side in the axial direction with respect to the first finishing edge is a second finishing edge,

wherein a first valley portion which is recessed toward an inner peripheral side of the cutter body is formed between the preceding edge and the first finishing edge,

wherein a second valley portion which is recessed toward the inner peripheral side of the cutter body is formed between the first finishing edge and the second finishing edge,

wherein a third valley portion which is recessed toward the inner peripheral side of the cutter body is formed on a posterior end side in the axial direction with respect to of the second finishing edge,

wherein an outer peripheral end of the second finishing edge is positioned outside an outer peripheral end of the first finishing edge in a radial direction with respect to the axis,

wherein a preceding edge-thread ridge height in the radial direction with respect to the axis from a tangent line passing through valley bottoms of the second and third valley portions to an outer peripheral end of the preceding edge is lower than finishing edge-thread ridge heights in the radial direction from the tangent line to the outer peripheral ends of the first and second finishing edges, and

wherein a first valley portion-depth in the radial direction with respect to the axis from the outer peripheral end of the first finishing edge to the valley bottom of the first valley portion is deeper than a second valley portion-depth in the radial direction with respect to the axis from the outer peripheral end of the second finishing edge to the valley bottom of the second valley portion.

12. The screw thread cutter according to claim 2,

wherein a ratio between the first valley portion-depth and the second valley portion-depth is within a range of 1.03 to 1.15.

13. The screw thread cutter according to claim 2,

wherein an interval in the axial direction from the valley bottom of the first valley portion to the outer peripheral end of the first finishing edge is larger than an interval in the axial direction from the valley bottom of the second valley portion to the outer peripheral end of the second finishing edge.

15. The screw thread cutter according to claim 2,

wherein when the second finishing edge is moved parallel to the tangent line toward the tip side in the axial direction by an interval between the outer peripheral end of the first finishing edge and the outer peripheral end of the second finishing edges in a direction of the tangent line passing through the valley bottoms of the second and third valley portions, a rotation locus of the second finishing edge around the axis overlaps with a rotation locus of the first finishing edge around the axis except for the first and second valley portions.

17. The screw thread cutter according to claim 2,

wherein when a rotation locus of the preceding edge around the axis is moved toward the posterior end side in the axial direction to be parallel to the tangent line passing through the valley bottoms of the second and third valley portions by an interval between the outer peripheral end of the first finishing edge and the outer peripheral end of the second finishing edges in a direction of the tangent line, the rotation locus of the preceding edge is included in a rotation locus of the first finishing edge around the axis.

18. The screw thread cutter according to claim 2,

wherein each of the first and second finishing edges includes a cutting edge facing the tip side in the axial direction, a cutting edge facing the posterior end side in the axial direction, and a linear outer peripheral cutting edge, and

wherein in each of the first and second finishing edges, the outer peripheral cutting edge and the cutting edge facing the tip side in the axial direction are connected to each other via a plurality of linear cutting edges, and the cutting edge facing the posterior end side in the axial direction and the outer peripheral cutting edge are connected to each other via a plurality of linear cutting edges.

19. The screw thread cutter according to claim 2,

wherein an outer peripheral cutting edge of each of the first and second finishing edges has a convex arc shape.

20. The screw thread cutter according to claim 2,

wherein each of the first and second valley portions has a concave arc shape.