Machining method, method for manufacturing planetary carrier, and planetary carrier

Patent metadata

Field	Value
Publication number	US-11511360-B2
Application number	US-201816640438-A
Country	US
Kind code	B2
Filing date	Aug 24, 2018
Priority date	Sep 20, 2017
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

Abstract

A machining method for forming an opening through a workpiece, serving as a green compact, by moving a milling tool in a radial direction relative to the workpiece is provided. The milling tool includes a first milling tool and a second milling tool. The method includes a pre-machining step of using the first milling tool, and forming the first sidewall surface by rotating the first milling tool so as to cause cutting edges of the first milling tool to cut the workpiece from the acute angle corner to the obtuse angle corner, while leaving a cutting allowance on the second sidewall surface; and a post-machining step of using the second milling tool whose cutting edges are reversed from the cutting edges of the first milling tool, and forming the second sidewall surface by rotating the second milling tool so as to cause the cutting edges of the second milling tool to cut the cutting allowance from the acute angle corner to the obtuse angle corner.

First claim

The invention claimed is:

1. A machining method for forming an opening through a workpiece being a green compact, by moving a milling tool in a radial direction relative to the workpiece, wherein among inner wall surfaces defining the opening, respective cut surfaces are defined as a first sidewall surface and a second sidewall surface, the respective cut surfaces being cut by cutting edges on an outer periphery of the milling tool and the second sidewall surface being opposite the first sidewall surface, a side from which the milling tool enters is defined as an outer circumferential surface of the workpiece, a surface opposite to the outer circumferential surface is defined as an inner circumferential surface of the workpiece, a corner where the first sidewall surface and the outer circumferential surface meet is defined as a first obtuse angle corner, a corner where the second sidewall surface and the outer circumferential surface meet is defined as a second obtuse angle corner, a corner where the first sidewall surface and the inner circumferential surface meet is defined as a first acute angle corner, a corner where the second sidewall surface and the inner circumferential surface meet is defined as a second acute angle corner, and the milling tool includes a first milling tool and a second milling tool, the method comprising:
using the first milling tool, and forming the first sidewall surface by rotating the first milling tool so as to cause cutting edges of the first milling tool to cut the workpiece from the first acute angle corner to the first obtuse angle corner, while leaving a cutting allowance on the second sidewall surface; and
using the second milling tool whose cutting edges are reversed from the cutting edges of the first milling tool, and forming the second sidewall surface by rotating the second milling tool so as to cause the cutting edges of the second milling tool to cut the cutting allowance from the second acute angle corner to the second obtuse angle corner, a rotation direction of the second milling tool being opposite to a rotation direction of the first milling tool, a direction in which the first milling tool moves to cut the workpiece being a same as a direction in which the second milling tool moves to cut the workpiece.

2. The machining method according to claim 1 , wherein the first milling tool and the second milling tool are staggered tooth side milling cutters.

3. The machining method according to claim 1 , wherein the workpiece is the green compact for a planetary carrier.

4. The machining method according to claim 1 , wherein, in the forming of the first sidewall surface, a center of rotation of the first milling tool is located on a side closer to the first sidewall surface relative to a centerline that passes through a center in a circumferential direction of the opening and a center of the outer circumferential surface, and
in the forming of the second sidewall surface, a center of rotation of the second milling tool is located on a side closer to the second sidewall surface relative to the centerline.

5. The machining method according to claim 1 , wherein the cutting allowance is determined by a shift amount of a center of rotation of the first milling tool, the shift amount being 1 mm or more and 6 mm or less.

6. A method for manufacturing a planetary carrier that has a plurality of column portions and plate portions, the plate portions being formed on both ends of the column portions and openings being formed between the column portions, the method comprising:
preparing a green compact by integrally forming the plate portions on both ends of a body portion having a circular tubular shape;
forming the openings through the body portion by using a milling tool to cut the body portion of the green compact, so as to form the column portions between the openings; and
sintering the machined green compact,
wherein, in the forming of the openings, among inner wall surfaces defining a first one of the openings, respective cut surfaces are defined as a first sidewall surface and a second sidewall surface, the respective cut surfaces being cut by cutting edges on an outer periphery of the milling tool and the second sidewall surface being opposite the first sidewall surface, a side from which the milling tool enters is defined as an outer circumferential surface of the body portion, a surface opposite to the outer circumferential surface is defined as an inner circumferential surface of the body portion, a corner where the first sidewall surface and the outer circumferential surface meet is defined as a first obtuse angle corner, a corner where the second sidewall surface and the outer circumferential surface meet is defined as a second obtuse angle corner, a corner where the first sidewall surface and the inner circumferential surface meet is defined as a first acute angle corner, a corner where the second sidewall surface and the inner circumferential surface meet is defined as a second acute angle corner, and the milling tool includes a first milling tool and a second milling tool, and
wherein the forming of the openings includes
using the first milling tool, and forming the first sidewall surface by rotating the first milling tool so as to cause cutting edges of the first milling tool to cut the body portion from the first acute angle corner to the first obtuse angle corner, while leaving a cutting allowance on the second sidewall surface; and
using the second milling tool whose cutting edges are reversed from the cutting edges of the first milling tool, and forming the second sidewall surface by rotating the second milling tool so as to cause the cutting edges of the second milling tool to cut the cutting allowance from the second acute angle corner to the second obtuse angle corner, a rotation direction of the second milling tool being opposite to a rotation direction of the first milling tool, a direction in which the first milling tool moves to cut the workpiece being a same as a direction in which the second milling tool moves to cut the workpiece.

7. The method for manufacturing the planetary carrier according to claim 6 , wherein, in the forming of the first sidewall surface, a center of rotation of the first milling tool is located on a side closer to the first sidewall surface relative to a centerline that passes through a center in a circumferential direction of the opening and a center of the outer circumferential surface, and
in the forming of the second sidewall surface, a center of rotation of the second milling tool is located on a side closer to the second sidewall surface relative to the centerline.

8. The method for manufacturing the planetary carrier according to claim 6 , wherein the cutting allowance is determined by a shift amount of a center of rotation of the first milling tool, the shift amount being 1 mm or more and 6 mm or less.

Assignees

• Sumitomo Electric Sintered Alloy Ltd

Inventors

• KIGUCHI Hirofumi
• Harimoto Daisuke

Classifications

• F16H57/08

  of gearings with members having orbital motion · CPC title

• B22F3/24 Primary

  After-treatment of workpieces or articles {(B22F3/1146 takes precedence)} · CPC title

• B23F1/06 Primary

  by milling · CPC title

• F16H57/082

  Planet carriers · CPC title

• B22F2003/247

  Removing material: carving, cleaning, grinding, hobbing, honing, lapping, polishing, milling, shaving, skiving, turning the surface · CPC title