Claims
- 1. A rolling die comprising:a rolling die with a rolling cutting-edge surface; an electrode exhaustion-melted substance or its reactive substance, which is generated during a discharging in a liquid, adhered to and deposited onto said rolling cutting-edge surface of said rolling die to form a hard film of the electrode exhaustion-melted substance or its reactive substance on said rolling cutting-edge surface, wherein the surface of said hard film at a bite-starting end of a thread-rolled material is rougher than the surface of said hard film toward a rolling finishing end along a rolling direction.
- 2. The rolling die according to claim 1, wherein said hard film is thicker at the bite-starting end of the thread-rolled material and thinner toward the rolling finishing end along the rolling direction.
- 3. The rolling die according to claim 1, wherein said hard film has a multi-layer and a multi-type material construction comprising:a primary hard film made of a primary material formed on the rolling cutting-edge surface; and a secondary hard film made of a secondary material different from the primary material formed on the primary hard film.
- 4. The rolling die according to claim 3, wherein the primary hard film is formed of a hard metal carbide including WC, TiC, TaC, ZrC, SiC, or VC, and the secondary hard film is formed of (1) a self-lubricating metal (2) or a metal compound or (3) Mo, B, N, MoS2, C, or WS2.
- 5. A surface processing method for a rolling die comprising the steps of:arranging a rolling die material and a discharge electrode opposite to each other in a processing liquid with a predetermined discharge gap between the rolling die material and the discharge electrode; generating an electric discharge between the rolling die material and the discharge electrode to produce an electrode exhaustion-melted substance or its reactive substance; depositing the electrode exhaustion-melted substance or its reactive substance onto a rolling cutting-edge surface of the rolling die material to form a hard film on the rolling cutting-edge surface, wherein said generating step is performed while relatively moving the discharge electrode along a long-axis direction of projections on the rolling cutting edge surface.
- 6. The surface processing method for a rolling die according to claim 5, further comprising the step of:maintaining a processing condition such that a shape of the rolling cutting-edge surface of the rolling die material is copied onto an opposite surface of the discharge electrode as the formation of the hard film progresses, wherein (1) the discharge electrode has a plane surface as an initial shape facing the rolling die material, and (2) has a predetermined width in a relative movement direction with respect to the rolling die material.
- 7. The surface processing method for a rolling die according to claim 5, wherein the surface of the hard film at the bite-starting end of the thread-rolled material is rougher than the surface of the hard film toward the rolling finishing end along the rolling direction.
- 8. The surface processing method for a rolling die according to claim 7, wherein (1) the hard film at the bite-starting end of the thread-rolled material is achieved by setting a predetermined discharge processing current, and (2) the hard film toward the rolling finishing end is achieved by setting another discharge processing current that is lower than the predetermined discharge processing current.
- 9. The surface processing method for a rolling die according to claim 5, wherein a thickness of the hard film at a bite-starting end of the thread-rolled material is greater than a thickness of the hard film toward the rolling finishing end along the rolling direction.
- 10. The surface processing method for a rolling die according to claim 9, wherein the hard film is formed by (1) setting a predetermined feeding speed at the bite starting end of the thread rolled material, and (2) setting another feeding speed, which is faster than the predetermined feeding speed, toward the rolling finishing end.
- 11. The surface processing method for a rolling die according to claim 5, wherein the rolling cutting-edge surface is covered with a hard film of a multi-layer and multi-type material construction byfirst forming a primary hard film made of a primary material on the rolling cutting-edge surface using a discharge electrode, and thereafter forming a secondary hard film made of a secondary material, which is different than the primary material, on the primary hard film using a discharge electrode.
- 12. The surface processing method for a rolling die according to claim 11, wherein the secondary hard film is formed by using(1) a discharge electrode including (a) a self-lubricant metal, or (b) a metal compound, or (c) Mo, B, N, MoS2, C, or WS2, and (2) a processing liquid having oil as a main component.
- 13. The surface processing method for a rolling die according to claim 11, wherein the secondary hard film is formed by using(1) a discharge electrode including (a) a self-lubricant metal, or (2) a metal compound, or (3) Mo, B, N, MoS2, C, or WS2, and (2) a processing liquid having water as a main component.
Parent Case Info
This is a continuation of International Applications PCT/JP98/01137 and PCT/JP98/05105, with respective international filing dates of Mar. 18 and Nov. 13, 1998, both of which are now abandoned.
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Continuations (2)
|
Number |
Date |
Country |
Parent |
PCT/JP98/05105 |
Nov 1998 |
US |
Child |
09/657010 |
|
US |
Parent |
PCT/JP98/01137 |
Mar 1998 |
US |
Child |
PCT/JP98/05105 |
|
US |