Zero lead generative cutting tool

Patent metadata

Field	Value
Publication number	US-9764401-B2
Application number	US-201514705211-A
Country	US
Kind code	B2
Filing date	May 6, 2015
Priority date	May 6, 2015
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A hobbing or gear cutting machine uses a rotary tool to rotate a cutting tool around a central axis of the cutting tool. The cutting tool has zero lead cutters, that is, the cutting tool is non-helical. A head holds the rotary tool and moves the cutting tool longitudinally along the central axis of the cutting tool. A workpiece holder holds a workpiece to be machined into a gear proximate the cutting tool. The workpiece holder selectively rotates the workpiece in conjunction with the longitudinal movement of the cutting tool via the head to cut both straight and helical gears from the workpiece.

First claim

What is claimed is:

1. A gear cutting tool, comprising:
a head that is programmably moveable in three axes;
a rotary tool mounted to the head;
a cutting tool with cutters having a zero lead angle, the cutting tool attached to the rotary tool so that as the rotary tool spins the cutting tool about a cutting tool central axis, the cutting tool and the rotary tool are moveable in three dimensions;
a workpiece holder that holds a workpiece proximate to the cutting tool, the workpiece holder configured to rotate the workpiece about a workpiece axis in conjunction with at least one dimension of movement of the cutting tool;
a head rotator that reorients the cutting tool central axis radially about an axis of rotation of the head rotator;
a controller that coordinates independent motion of the head, the head rotator, and the workpiece holder according to a desired gear profile; and
wherein a cutting motion sequence of the cutting tool with respect to the workpiece is repeated at one of a deeper cut or an offset to make a higher tolerance gear tooth.

2. The gear cutting tool of claim 1 , wherein the controller moves the cutting tool perpendicular to a tooth line of the workpiece.

3. The gear cutting tool of claim 2 , wherein when a contact point between the cutting tool and the workpiece is at one end of the cutting tool, the controller i) disengages the cutting tool from contact with the workpiece, ii) resets the cutting tool to establish the contact point using an opposite end of the cutting tool, and iii) restarts the motion of the cutting tool and the workpiece holder.

4. The gear cutting tool of claim 1 , wherein a space of gear teeth in the workpiece is independent of a width of the cutters on the cutting tool.

5. The gear cutting tool of claim 1 , wherein a rotation speed of the workpiece holder is independent of a rotation speed of the cutting tool.

6. The gear cutting tool of claim 1 , wherein a cutting tool base has a recess for inserting a replaceable cutter, the recess perpendicular to the cutting tool central axis.

7. A method of cutting gears, comprising:
providing a cutting tool with cutters having a zero lead angle;
orienting the cutting tool with respect to a workpiece;
rotating the cutting tool about a central axis of the cutting tool;
engaging the cutting tool with the workpiece to cut gear teeth into the workpiece;
shifting the cutting tool along the central axis of the cutting tool;
rotating the workpiece while shifting the cutting tool along the central axis of the cutting tool;
feeding the cutting tool axially along an axis parallel to a central rotation axis of the workpiece and perpendicular to the central axis of the cutting tool while engaging the workpiece; and
when a contact point between the cutting tool and the workpiece reaches one end of the cutting tool, indexing the cutting tool to reestablish the contact point of the workpiece with an opposite end of the cutting tool.

8. The method of claim 7 , further comprising:
rotating the central axis of the cutting tool with respect to the central rotation axis of the workpiece when cutting a helical gear.

9. The method of claim 7 , further comprising:
repeating a motion of the cutting tool at a deeper cut to produce a higher tolerance gear tooth in the workpiece.

10. The method of claim 7 , wherein providing the cutting tool with cutters having the zero lead angle comprises providing the cutting tool with replaceable cutters having the zero lead angle.

11. The method of claim 7 , wherein a rotation speed of the cutting tool is independent of a speed of rotating the workpiece.

12. The method of claim 11 , wherein the rotation speed of the cutting tool is increased to produce a higher tolerance finish in the workpiece and a speed of feeding the cutting tool axially along the axis parallel to a central rotation axis of the workpiece and perpendicular to the central axis of the cutting tool is decreased to produce a higher tolerance finish in the workpiece and a rate of shifting the cutting tool along the central axis of the cutting tool is decreased to produce a higher tolerance finish in the workpiece.

13. A gear cutting tool, comprising:
a head that is programmably moveable in three axes;
a rotary tool mounted to the head;
a cutting tool with cutters having a zero lead angle, the cutting tool attached to the rotary tool so that as the rotary tool spins the cutting tool about a cutting tool central axis, the cutting tool and the rotary tool are moveable in three dimensions;
a workpiece holder that holds a workpiece proximate to the cutting tool, the workpiece holder configured to rotate the workpiece about a workpiece axis in conjunction with at least one dimension of movement of the cutting tool;
a head rotator that reorients the cutting tool central axis radially about an axis of rotation of the head rotator;
a controller that coordinates independent motion of the head, the head rotator, and the workpiece holder according to a desired gear profile;
wherein the controller moves the cutting tool perpendicular to a tooth line of the workpiece; and
wherein when a contact point between the cutting tool and the workpiece is at one end of the cutting tool, the controller i) disengages the cutting tool from contact with the workpiece, ii) resets the cutting tool to establish the contact point using an opposite end of the cutting tool, and iii) restarts the motion of the cutting tool and the workpiece holder.

14. The gear cutting tool of claim 13 , wherein a cutting motion sequence of the cutting tool with respect to the workpiece is repeated at one of a deeper cut or an offset to make a higher tolerance gear tooth.

15. The gear cutting tool of claim 13 , wherein a space of gear teeth in the workpiece is independent of a width of the cutters on the cutting tool.

16. The gear cutting tool of claim 13 , wherein a rotation speed of the workpiece holder is independent of a rotation speed of the cutting tool.

17. The gear cutting tool of claim 13 , wherein a cutting tool base has a recess for inserting a replaceable cutter, the recess perpendicular to the cutting tool central axis.

Assignees

• Caterpillar Inc

Inventors

• Ellicott Gabriel J

Classifications

• B23F5/202 Primary

  the tool having a shape similar to that of a gear or part thereof, with cutting edges situated on the tooth contour lines (tools therefor B23F21/122) · CPC title

• Y10T409/106201

  Plural rotary cutters · CPC title

• Y10T409/103975

  Process · CPC title

• Y10T409/105883

  Using rotary cutter · CPC title

• B23F1/06

  by milling · CPC title