Thread milling cutter and internal pipe thread machining method using the same

Patent metadata

Field	Value
Publication number	US-11045889-B2
Application number	US-201615764551-A
Country	US
Kind code	B2
Filing date	Sep 28, 2016
Priority date	Sep 30, 2015
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

In order to form an internal thread having a concave surface having the same shape as that obtained by using a thread cutting blade having a convex surface without using such a thread cutting blade in formation of an internal thread hole in a mold component or the like using a thread milling cutter, a trimming blade has a leading-side flank surface extending from an axial tip side of a tool body to the rear side, a top surface formed continuously to the leading-side flank surface in the axial direction, and a trailing-side flank surface formed continuously to the top surface in the axial direction. Two or more chamfered surfaces are formed between the leading-side flank surface and the top surface and between the top surface and the trailing-side flank surface in the trimming blade.

First claim

The invention claimed is:

1. A thread milling cutter helically fed, comprising
a tool body having a cutting blade portion at an axial tip side of the tool body, a shank portion and a rotation axis defining an axial tip side direction and an axial shank portion direction, the cutting blade portion having a plurality of cutting blades separated in a circumferential direction by chip discharge grooves, each cutting blade having a plurality of trimming blades for forming an internal thread in a workpiece, the plurality of trimming blades being separated from each other by a respective concave valley;
the plurality of trimming blades being formed in an outer circumference of the axial tip side, protruding in an external, radial direction away from the rotation axis;
wherein in a plan view of a rake surface of each trimming blade, each trimming blade has, sequentially in the axial shank portion direction, an inclined leading cutting edge, a first chamfered cutting edge, a second chamfered cutting edge, a top cutting edge, a third chamfered cutting edge, a fourth chamfered cutting edge, and a declined trailing cutting edge, a non-zero angle being formed between each cutting edge of each trimming blade;
wherein in the plan view, each chamfered cutting edge has a width respectively smaller than the width of the top cutting edge, and the width of the top cutting edge being smaller than a width of each of the inclined leading cutting edge and the declined trailing cutting edge;
wherein each trimming blade has, sequentially in the axial shank portion direction, an inclined leading clearance surface intersecting the inclined leading cutting edge, a first chamfered clearance surface intersecting the first chamfered cutting edge, a second chamfered clearance surface intersecting the second chamfered cutting edge, a top clearance surface intersecting the top cutting edge, a third chamfered clearance surface intersecting the third chamfered cutting edge, a fourth chamfered clearance surface intersecting the fourth chamfered cutting edge, and a declined trailing clearance surface intersecting the declined trailing cutting edge, a non-zero angle being formed between each clearance surface of each trimming blade; and
an axial width v, being measured parallel to the rotation axis, of the respective concave valley separating each trimming blade, an axial width u of a respective trimming blade of the plurality of trimming blades, being measured parallel to the rotation axis, between an intersection point of the inclined leading cutting edge and the first chamfered cutting edge and an intersection point of the fourth chamfered cutting edge and the declined trailing cutting edge, the axial width v being larger than the axial width u.

2. The thread milling cutter according to claim 1 , wherein each cutting blade has a preceding blade in addition to the plurality of trimming blades placed in the axial tip side direction relative to the plurality of trimming blades, the plurality of trimming blades protruding further in the external, radial direction away from the rotation axis than the preceding blade.

3. The thread milling cutter according to claim 1 , wherein an angle α between a straight line passing through a respective vertex of neighboring trimming blades and the rotation axis being within a range of 0° to 5.0°.

4. The thread milling cutter according to claim 3 , wherein the angle α angle between the straight line passing through the vertex of the trimming blade placed in the being larger than 0°.

5. An internal pipe thread machining method comprising:
providing the thread milling according to claim 1 ,
rotating the thread milling cutter with respect to the rotation axis of the tool body,
revolving the thread milling cutter with respect to a revolution axis O RE decentered from the rotation axis, the revolution axis O RE being placed in parallel with the rotation axis, and

feeding the thread milling cutter into a workpiece in the axial tip side direction to form roots and crests of internal threads in the workpiece.

Assignees

• Mitsubishi Hitachi Tool Eng Ltd
• Molding Tool Eng Ltd

Inventors

• YOKOKAWA Mitsuhiro
• Iharada Yuuki

Classifications

• B23G2210/04

  Internal threads · CPC title

• B23G1/34 Primary

  with a cutting bit moving in a closed path arranged eccentrically with respect to the axis of the rotating workpieces · CPC title

• B23G5/18

  Milling cutters · CPC title