Patent Application

App. No. 12/336,806

Abstract

Claims (30)

1 . A method of broaching a hardened steel workpiece with diamond-tipped tools, comprising:

forming a polycrystalline diamond insert;

finish-grinding the polycrystalline diamond insert;

attaching the polycrystalline diamond insert to an insert holder of a broach bar;

heat treating a gear blank formed from steel; and

broaching an interior portion of the heat treated gear blank with the broach bar, wherein said broaching occurs in a single pass.

2 . The method of claim 1 , wherein forming the polycrystalline diamond insert includes electrical discharge machining.

3 . The method of claim 2 , wherein finish-grinding the polycrystalline diamond insert includes grinding with a diamond grinding wheel.

4 . The method of claim 3 , wherein attaching the polycrystalline diamond insert to the insert holder of the broach bar includes brazing.

5 . The method of claim 4 , wherein attaching the polycrystalline diamond insert to the insert holder of the broach bar occurs prior to the finish-grinding the polycrystalline diamond insert.

6 . The method of claim 5 , further comprising:

forming a second polycrystalline diamond insert;

finish-grinding the second polycrystalline diamond insert; and

attaching the second polycrystalline diamond insert to a second insert holder of the broach bar.

7 . The method of claim 6 , wherein broaching the interior portion is characterized by an absence of interaction between the polycrystalline diamond insert and a cooling fluid.

8 . The method of claim 7 , further comprising, maintaining the polycrystalline diamond insert and the gear blank at or below a temperature of 500 degrees Celsius.

9 . The method of claim 8 , wherein heat treating the gear blank includes one of carburizing and surface-hardening.

10 . The method of claim 9 , wherein heat treating the gear blank includes hardening the gear blank to HRC 58-60.

11 . The method of claim 10 , wherein broaching of the heat treated gear occurs at a speed between approximately 6 to 60 meters per minute and a feed rate between approximately 10 to 100 micrometers between the polycrystalline diamond inserts.

12 . A method of broaching a hardened steel workpiece with diamond-tipped tools, comprising:

forming a plurality of polycrystalline diamond inserts;

brazing the plurality of polycrystalline diamond inserts to a plurality of insert holders of a broach bar;

finish-grinding the plurality of polycrystalline diamond insert;

heat treating a gear blank formed from steel; and

broaching an interior portion of the heat treated gear blank with the broach bar.

13 . The method of claim 12 , wherein broaching the interior portion of the heat treated gear blank occurs in a single pass.

14 . The method of claim 13 , wherein finish-grinding the plurality of polycrystalline diamond inserts includes grinding with a diamond grinding wheel.

15 . The method of claim 14 , wherein forming the plurality of polycrystalline diamond inserts includes electrical discharge machining.

16 . The method of claim 15 , wherein heat treating the gear blank includes one of carburizing and surface-hardening.

17 . The method of claim 16 , wherein broaching the interior portion is characterized by an absence of interaction between the polycrystalline diamond insert and a cooling fluid.

Assignments (11)