Screw thread cutter

  • US 10,940,553 B2
  • Filed: 01/04/2017
  • Issued: 03/09/2021
  • Est. Priority Date: 01/13/2016
  • Status: Active Grant
First Claim
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1. A screw thread cutter comprising,a cutter body which is rotated around an axis,a cutting edge portion which is formed on a tip portion of the cutter body,an end cutting edge which is formed on a tip surface of the cutting edge portion, andat least three screw thread-cutting edges which are formed on an outer circumference of the cutting edge portion, and configured to be helically fed relative to a workpiece to form a screw portion workpiece,wherein at least three screw thread-cutting edges protrudes toward an outer peripheral side of the cutter body, and formed to be arranged in an axial direction,wherein among the at least three screw thread-cutting edges, the screw thread-cutting edge positioned on a tip side in the axial direction is a preceding edge, a portion of which intersects with the end cutting edge,wherein among the at least three 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 at least three 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,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, andwherein 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.

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