US 6,056,443 A · Guide bush and method of forming film over guide bush

Abstract

A hard carbon film (15) is formed directly or through an intermediate layer for enhancing adhesion over an inner surface (11b) and over a portion (11h.sub.1) of an end face (11h) of a guide bush 11 adjacent to the end of the inner surface for holding a workpiece (51) rotatably and axially slidable on an automatic lathe at a position near a cutting tool, to be in sliding contact with the workpiece (51) or directly or through an intermediate layer for enhancing adhesion on the surface of a superhard lining fixed to the inner surface (11b) in a plasma CVD process employing an auxiliary electrode and a dummy member. Thereby, the guide bush (11) has remarkably enhanced durability and prevents seizing that makes a machining operation impossible, even when the guide bush (11) is used for an extended period of time and when the automatic lathe operates for heavy machining. Flaws caused by flashes on the workpiece are prevented from occurring on the inner surface of the guide bush (11).

Claims19

Dependent claims

A method of forming a hard carbon film over a guide bush formed substantially in a cylindrical shape and having a center bore in its axial direction, further including a taper outer surface, an inner surface to be in sliding contact with a workpiece and slits provided at one end, the guide bush holding the workpiece inserted into the center bore rotatably and slidably in the axial direction near a cutting tool when the guide bush is mounted on an automatic lathe, wherein the guide bush is disposed in a vacuum vessel provided with a gas inlet port and an evacuation port;

an auxiliary electrode is inserted into the center bore forming the inner surface of the guide bush and is connected to a ground potential;
a ringlike dummy member having an opening of a diameter larger than that of the center bore of the guide bush is placed on an end face of the guide bush boring at the end of the inner surface with its axis in alignment with that of the center bore so as to expose a portion of the end face adjacent to the inner surface annularly;
a gas containing carbon is introduced through the gas inlet port into the vacuum vessel after evacuating the vacuum vessel;
and
a plasma is produced in the vacuum vessel to form a hard carbon film of hydrogenated amorphous carbon over the inner surface of the guide bush and over a portion of the end face of the guide bush adjacent to the end of the inner surface with a plasma CVD method.

2 more elements

the guide bush is disposed in a vacuum vessel provided with a gas inlet port and an evacuation port;
an auxiliary electrode is inserted into the center bore forming the inner surface of the guide bush to which is applied a positive DC voltage;
a ringlike dummy member having an opening of a diameter larger than that of the center bore of the guide bush is placed on an end face of the guide bush boring at the inner surface with its axis in alignment with that of the center bore so as to expose a portion of the end face adjacent to the inner surface annularly;
a gas containing carbon is introduced through the gas inlet port into the vacuum vessel after evacuating the vacuum vessel;
and
a plasma is produced in the vacuum vessel to form a hard carbon film of hydrogenated amorphous carbon over the inner surface of the guide bush and over a portion of the end face of the guide bush adjacent to the end of the inner surface with a plasma CVD method.

3 more elements

Dependencies are inferred from the claim text.

Guide bush and method of forming film over guide bush

Life of this patent

Guide bush and method of forming film over guide bush

Life of this patent

Abstract

Claims19