JP2000071103A - Guide bush, and forming method for diamond-like carbon film to guide bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To tightly and uniformly form a carbon film on a super hard member by providing the super hard member containing cobalt on the inner peripheral surface of a guide bush, and by removing cobalt from a surface abutting to the carbon film of the super hard member when the diamond-like carbon film is formed on the super hard member. SOLUTION: This guide bush 11 which is mounted to a column of an automatic lathe and rotates and slidingly holds a machined object is a substantially cylindrical matter having a center bore 11j and has an outer peripheral tapered surface 11a on its one end. A bush sleeve having an inner peripheral tapered surface for pressing the outer peripheral tapered surface 11a is engaged outside it. A super hard member 12 containing cobalt as a binder is brazed and fixed to an inner peripheral surface 11b of the guide bush 11, and a DLC(the diamond- like carbon) film 15 is formed on a surface of the super hard member 12. A part abutting to the DLC film 15 of the surface of the super hard member 12 is improved in adhesion to the DLC film 15 by selectively removing cobalt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a guide bush attached to a column of an automatic lathe and rotatably and slidably holding a workpiece, and a diamond-like carbon on the inner peripheral surface of the guide bush. The present invention relates to a method for forming a film.

[0002]

2. Description of the Related Art A guide bush is a member that is attached to a column of an automatic lathe and holds a workpiece so that it can rotate and slide. To describe this guide bush in more detail, it has a substantially cylindrical shape having a central opening penetrating in the axial direction, and has an outer peripheral tapered surface and a slit for giving it elasticity at one end in the longitudinal direction, The other end has a screw portion for attaching to a column of an automatic lathe, and has an inner peripheral surface for holding a workpiece (work) on an inner periphery of a portion having an outer tapered surface,
By being attached to the automatic lathe, the workpiece inserted into the center opening is held by the inner peripheral surface so as to be rotatable and slidable in the axial direction near the cutting tool.

Accordingly, the inner peripheral surface of the guide bush is always in contact with the workpiece and rotates together, or the workpiece rotates on the inner peripheral surface, and the workpiece moves in the axial direction. To slide. For this reason, the inner peripheral surface of the guide bush holding the workpiece is easily worn.

Therefore, a guide bush with which a workpiece comes into contact with the rotation or sliding of the guide bush is provided with an ultra-hard member or ceramics on the inner peripheral surface thereof.
No. 3 proposes this. By providing a superhard member or ceramics having excellent wear resistance and heat resistance on the inner peripheral surface of the guide bush, the effect of suppressing the inner peripheral surface wear to some extent is recognized.

[0005] However, even when such a guide bush is used in an automatic lathe, for heavy cutting in which the cutting amount is large and the machining speed is large, the carbide member and ceramics have a large friction coefficient and a low thermal conductivity. In addition, there is a problem in that the workpiece is scratched, or the radial gap between the guide bush and the workpiece is reduced to cause seizure.

Therefore, it has been proposed that a carbide member provided on the inner peripheral surface of such a guide bush is coated with a diamond-like carbon film to suppress wear of the inner peripheral surface. This diamond-like carbon film is a black film and is a hard carbon film having properties very similar to diamond. That is, the diamond-like carbon film has excellent characteristics such as high mechanical hardness, low friction coefficient, good electrical insulation, high thermal conductivity, and high corrosion resistance.

For this reason, by coating the surface of the super hard member on the inner peripheral surface of the guide bush with the diamond-like carbon film, its wear resistance can be remarkably improved and the occurrence of seizure can be prevented. The diamond-like carbon film (hard carbon film) is a hydrogenated amorphous carbon film, and has properties similar to diamond as described above. Therefore, in general, the diamond-like carbon film ("DLC film") (Abbreviated), but also called an i-carbon film.

[Conventional Method for Forming DLC Film on Guide Bush: FIG. 16] Here, a conventional method for forming a DLC film on the inner peripheral surface of the guide bush using plasma chemical vapor deposition is shown in FIG. 16 will be described. As shown in FIG. 16, a vacuum chamber 61 having a gas inlet 63 and an exhaust port 65
Inside, a guide bush 11 for forming a DLC film is arranged. The guide bush 11 is formed by quenching and tempering after forming its outer shape and inner shape using alloy tool steel (SKS). Further, a super hard member is provided on the inner peripheral surface 11b of the guide bush 11.

A DC voltage is applied to the guide bush 11 from a DC power supply 73. Further, a DC positive voltage is applied from an anode power supply 75 to an anode 79 disposed in the vacuum chamber 61 so as to face the guide bush 11, and a filament power supply 77 is applied to the filament 81.
To apply an AC voltage.

Further, after the inside of the vacuum chamber 61 is evacuated from the exhaust port 65 by an exhaust means (not shown), a gas containing carbon is introduced into the vacuum chamber 61 from the gas inlet 63, and plasma is generated in the vacuum chamber 61. Generate the guide bush 1
A hard carbon film is formed on the surface including the inner peripheral surface 11b.

In the method of forming a DLC film using the apparatus shown in FIG. 16, a plasma generated by a DC voltage applied to the guide bush 11, a filament 81 for applying an AC voltage, and an anode 79 for applying a DC voltage are used. The generated plasma is generated. And DL
Due to the pressure in the vacuum chamber 61 when the C film is formed, the plasma around the guide bush 11 or the filament 81
And any of the plasma near the anode 79 mainly forms the DLC film.

[0012]

SUMMARY OF THE INVENTION The above-mentioned conventional DLC
In the film forming method, the pressure in the vacuum chamber 61 is 3 × 1
0- ³ torr or more time, become the main plasma generated in the peripheral region of the guide bush 11, to form a DLC film by decomposing a gas containing carbon. At this time, a DLC film can be formed on the outer peripheral portion of the guide bush 11 with good uniformity.
The hard carbon film formed on the inner surface of 1j has poor adhesion,
Further, the film quality such as hardness is inferior.

This is because the same potential is applied to the guide bush 11, and the inner surface of the center opening 11j is a space in which electrodes of the same potential face each other.
The plasma inside generates abnormal discharge called hollow discharge. The DLC film formed by this hollow discharge is a polymer-like film having poor adhesion, and is easily peeled from the inner peripheral surface 11b of the guide bush 11 and has a low hardness.

On the other hand, when the pressure inside the vacuum chamber 61 is lower than 3 × 10 ⁻³ torr, the plasma around the guide bush 11 is used to form the DLC film near the filament 81 and the anode 79. The generated plasma mainly contributes. In this case, a DLC film can be formed on the outer peripheral portion of the guide bush 11 with good uniformity, but the DLC film formed on the inner surface of the center opening 11j of the guide bush 11 has a thickness in the longitudinal direction of the guide bush 11. Cannot be formed uniformly.

Here, the filament 81 and the anode 79
The carbon ions ionized by the plasma generated in the vicinity of are drawn by the DC negative potential applied to the guide bush 11 and deposited, thereby forming a DLC film on the guide bush 11. The pressure in the vacuum chamber 61 is 3 × 1
0 ³ is higher than torr is that the DLC film is chemically vapor deposition formed, the pressure is 3 × ^10- 3 t
When it is lower than orr, the DLC film is formed by physical vapor deposition.

For this reason, at the time of forming a DLC film to which plasma generated in the vicinity of the filament 81 and the anode 79 mainly contributes, the center opening 11j of the guide bush 11 is formed similarly to the physical vapor deposition method such as the vacuum evaporation method. The thickness of the DLC film becomes thinner toward the inner side of the opening from the end face of the opening. As a result, the DLC film formed on the inner peripheral surface 11b of the guide bush 11 cannot have a uniform thickness in the longitudinal direction of the guide bush 11.

Further, in the case of the guide bush having the above-mentioned conventional DLC film formed thereon, a super hard member is provided on the inner peripheral surface of the guide bush base material made of alloy tool steel (SKS). A DLC film is formed on the surface of the substrate.
As the cemented carbide member, Class G No. 2 of Japanese Industrial Standard (JIS) is often used. As a chemical component of the cemented carbide member of type G, tungsten (W) is 87% to 90%.
In general, those having a composition of 5% to 7% of carbon (C) and 5% to 7% of cobalt (Co) as a binder are used.

If a DLC film is formed directly on the surface of a cemented carbide member having this composition, the DLC film cannot be formed with good adhesion, and there is a problem that the DLC film is easily peeled off.

The present invention solves such conventional problems and provides an extremely durable guide bush. Further, the present invention provides a guide bush with a super hard member on an inner peripheral surface for holding a workpiece. An object of the present invention is to provide a method of forming a DLC film capable of forming a DLC film with good adhesion and a uniform film thickness.

[0020]

According to the present invention, an inner peripheral surface which holds a workpiece as described above so as to be able to rotate and slide is provided.
A guide bush provided with a super hard member containing at least cobalt and having a DLC film formed on the super hard member. In order to achieve the above object, the surface of the super hard member in contact with the DLC film is free of cobalt. Provide the guide bush that has been. The surface in contact with the DLC film of the superhard member is
It is preferable that traces of the polishing process are removed. The surface of the superhard member which is in contact with the DLC film is preferably not mirror-finished but satin-finished.

The present invention also provides a guide bush in which a DLC film is formed on the surface of the above-mentioned superhard member from which cobalt has been removed, via an intermediate layer. The intermediate layer can be formed of an alloy material containing carbon. The intermediate layer may be composed of a plurality of layers made of different materials. The intermediate layer is formed by a first intermediate layer made of titanium or chromium formed directly on the super hard member and a second intermediate layer made of silicon or germanium formed on the first intermediate layer. It is good to configure.

DLC to guide bush according to the present invention
The method for forming a film includes the following steps. (1) a step of removing cobalt from the surface of the superhard member by etching; (2) a step of inserting the guide bush into a vacuum chamber by inserting an electrode into a center opening; and (3).
After exhausting the inside of the vacuum chamber, a gas containing carbon is introduced into the vacuum chamber, and a DC voltage or a high-frequency power is applied to the guide bush while the electrodes are grounded, thereby generating plasma in the center opening. Generating and forming a DLC film on the surface of the superhard member on the inner peripheral surface of the guide bush;

DLC to guide bush according to the present invention
The film forming method may include the following steps. (1) a step of removing cobalt from the surface of the superhard member by etching; (2) disposing the guide bush and the target in a vacuum chamber such that the center opening of the guide bush faces the target; After evacuating the vacuum chamber, introducing an argon gas into the vacuum chamber, and forming an intermediate layer of a target material on the surface of the superhard member by a sputtering method,

(3) arranging the guide bush on which the intermediate layer is formed in a vacuum chamber so that an electrode is inserted into the center opening; (4) evacuating the vacuum chamber and then evacuating the vacuum chamber. A gas containing carbon is introduced into the electrode, and while the electrode is grounded, a DC voltage or a high-frequency power is applied to the guide bush to generate plasma in a center opening, and the intermediate layer on the inner peripheral surface of the guide bush is generated. DL on the surface of
Forming a C film,

In the step of forming the DLC film, a DC positive voltage may be applied instead of grounding the electrode. In the step of removing cobalt on the surface of the superhard member by etching, it is preferable to remove cobalt by wet etching. The wet etching is
It can be performed by a mixed solution of sodium hydroxide and hydrogen peroxide solution. In the step of forming the DLC film on the surface of the superhard member on the inner peripheral surface of the guide bush, benzene or methane may be used as the gas containing carbon introduced into the vacuum chamber.

In the step of forming the intermediate layer, an intermediate layer of a tungsten carbide film can be formed on the surface of the superhard member by using a material obtained by alloying tungsten and carbon in a one-to-one relationship as a target. In the step of forming the intermediate layer, after forming a first intermediate layer of a titanium film or a chromium film on the surface of the superhard member using titanium or chromium as a target, the upper target is formed of silicon or germanium. Alternatively, a second intermediate layer made of a silicon film or a germanium film may be formed on the first intermediate layer.

In the step of forming a DLC film on the surface of the superhard member or the intermediate layer on the inner peripheral surface of the guide bush, benzene or methane may be used as the gas containing carbon to be introduced into the vacuum chamber.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the structure of a guide bush and a method of forming a diamond-like carbon film on the guide bush according to the present invention will be specifically described below with reference to the drawings.

[Description of Structure of Automatic Lathe: FIG. 14] First, the structure of a guide bush device to which the guide bush according to the present invention is applied and the structure of a numerically controlled automatic lathe equipped with the guide bush will be described with reference to FIG. explain. FIG.
FIG. 4 is a cross-sectional view showing a fixed type guide bush device that fixes the guide bush according to the present invention as a guide bush device and uses the guide bush in a state where a workpiece rotates on the inner peripheral surface of the guide bush.

The headstock 17 is slidable on the bed of a numerically controlled automatic lathe (not shown) in the left-right direction in FIG. The headstock 17 is provided with a spindle 19 rotatably supported by a bearing 21. The collet chuck 13 is attached to the tip of the spindle 19. The collet chuck 13 is disposed in the center hole of the chuck sleeve 41. The outer tapered surface 13a at the tip of the collet chuck 13 and the inner tapered surface 41a of the chuck sleeve 41 are in surface contact with each other.

Further, a spring 25 is provided at the rear end of the collet chuck 13 in the intermediate sleeve 29. The collet chuck 13 can be pushed out of the intermediate sleeve 29 by the action of the elastic force of the spring 25. The position of the distal end of the collet chuck 13 is in contact with a cap nut 27 which is screwed to the distal end of the main shaft 19, and the position is regulated. This cap nut 2
7 prevents the collet chuck 13 from jumping out of the intermediate sleeve 29 due to the spring force of the spring 25.

At the rear end of the intermediate sleeve 29, a chuck opening / closing mechanism 31 is provided via the intermediate sleeve 29.
Then, the collet chuck 13 is opened and closed by opening and closing the chuck opening and closing claws 33, so that the workpiece 51 indicated by a virtual line can be gripped or released.

That is, when the distal ends of the chuck opening / closing claws 33 of the chuck opening / closing mechanism 31 move so as to open each other,
The portion of the chuck opening / closing claw 33 in contact with the intermediate sleeve 29 moves leftward in FIG. 14 and pushes the intermediate sleeve 29 leftward. As the intermediate sleeve 29 moves leftward, the chuck sleeve 41 that is in contact with the left end of the intermediate sleeve 29 moves leftward.

The collet chuck 13 is prevented from jumping forward from the spindle 19 by the cap nut 27 screwed to the tip of the spindle 19 as described above. Therefore, the outer circumferential taper 13a of the collet chuck 13 and the inner circumferential taper 41a of the chuck sleeve 41 are moved by the leftward movement of the chuck sleeve 41.
Is strongly pushed and moves along the tapered surface. As a result, the diameter of the inner peripheral surface of the collet chuck 13 is reduced, and the workpiece 51 can be gripped.

When the workpiece 51 is released by increasing the diameter of the inner peripheral surface of the collet chuck 13, the chuck sleeves 41 are moved by closing the tips of the chuck opening / closing claws 33 so as to close each other. Excludes the pushing force to the left. Then, the intermediate sleeve 29 and the chuck sleeve 41 are moved rightward in FIG. 14 by the restoring force of the spring 25.

Therefore, the pressing force between the outer tapered surface 13a of the collet chuck 13 and the inner tapered surface 41a of the chuck sleeve 41 is eliminated. As a result, the diameter of the inner peripheral surface of the collet chuck 13 is increased by its own elastic force, and the workpiece 51 can be released.
Further, in front of the headstock 17, a fixed type guide bush device 37 is provided which is arranged on the centerline of the main shaft of the column 35.

The guide bush device 37 shown in FIG.
A fixed type guide bush device 37 that fixes the guide bush 11 as described above and holds the workpiece 51 in a state of being rotated on the inner peripheral surface 11b of the guide bush 11, and is a holder fixed to the column 35. In the center hole of 39,
The bush sleeve 23 is arranged. An inner peripheral tapered surface 23a is provided at the tip of the bush sleeve 23.

In the center hole of the bush sleeve 23, a guide bush 11 having a tapered outer peripheral surface 11a at the end is disposed. This guide bush device 3
By rotating the adjustment nut 43 provided at the rear end of the workpiece 7, the gap between the inner diameter of the guide bush 11 and the outer shape of the workpiece 51 can be adjusted.

When the adjustment nut 43 is rotated,
The inner tapered surface 23a of the bush sleeve 23 and the outer tapered surface 11a of the guide bush 11 are, like the collet chuck 13, formed of the inner tapered surface 23a and the outer tapered surface 11a.
Are pressed against each other to reduce the inner diameter of the guide bush 11.

A cutting tool 45 is provided further forward of the guide bush device 37. Then, the workpiece 51 is gripped by the collet chuck 13 of the spindle 19 and further supported by the guide bush device 37. Further, the workpiece 51 that has passed through the guide bush device 37 and protruded into the processing area is cut into a predetermined shape by a combined movement of the forward and backward movement of the cutting tool 45 and the movement of the headstock 17.

[Description of Rotary Guide Bush Device: FIG. 15] Next, the configuration of a rotary guide bush device used in a state where the guide bush for gripping a workpiece is rotated will be described with reference to FIG. explain. FIG. 15 is a cross-sectional view showing a configuration of a rotary type guide bush device. FIG.
In FIG. 14, portions corresponding to those in FIG. 14 are denoted by the same reference numerals.

The rotary guide bush device includes a guide bush device in which the collet chuck 13 and the guide bush 11 rotate in synchronization with each other, and a guide bush device in which the collet chuck 13 and the guide bush rotate without synchronization. The guide bush device 37 shown in FIG. 15 is a rotary guide bush device in which the collet chuck 13 and the guide bush 11 rotate in synchronization.

The rotary type guide bush device 37 includes a rotary drive rod 4 protruding from the cap nut 27 of the main shaft 19.
7, the guide bush device 37 is driven. In addition to the drive by the rotary drive rod 47, there is also a drive in which the guide bush device 37 is driven by a gear, a belt, and a pulley.

This rotary type guide bush device 37 is
The center hole of the holder 39 fixed to the column 35 has the bearing 2
The bush sleeve 23 is disposed so as to be rotatable through the first bushing 1. Further, the guide bush 11 is disposed in a center hole of the bush sleeve 23.

The bush sleeve 23 and the guide bush 11 have the same structure as that described with reference to FIG. By rotating an adjusting nut 43 provided at the rear end of the guide bush device 37, the inner diameter of the guide bush 11 is reduced, and the clearance between the inner diameter of the guide bush 11 and the outer shape of a workpiece (not shown) is reduced. The dimensions can be adjusted.

The configuration of the automatic lathe shown in FIG. 15 is the same as that of the automatic lathe described with reference to FIG. 14 except that the guide bush device 37 is a rotary type. Omitted. As is clear from the above description, the fixed type guide bush device and the rotary type guide bush device have substantially the same structure and operate in the same manner.

[Embodiment of Guide Bush: FIGS. 1 to 5] Next, an embodiment of a guide bush according to the present invention will be described with reference to FIGS. 1 to 5.

FIG. 2 is a perspective view showing an embodiment of the guide bush according to the present invention, and FIG. 3 is a sectional view along a longitudinal direction of the guide bush, in which a bar-shaped workpiece (work) is indicated by a virtual line. The guide bush 11 shown in these figures shows an open and free state. And this guide bush 11
Has a substantially cylindrical shape having a central opening (center bore) 11j penetrating in the axial direction, has an outer peripheral tapered surface 11a on the outer periphery of one end in the longitudinal direction, and has a column of an automatic lathe on the outer periphery of the other end. It has a screw portion 11f for attachment.

An inner peripheral surface 11b for holding the workpiece 51 is formed on the inner periphery on the side where the outer peripheral tapered surface 11a is provided, and a region other than the inner peripheral surface 11b in the center opening 11j is an inner peripheral surface. The step 11g has an inner diameter larger than the inner diameter of the surface 11b. Further, the guide bush 11 is provided with a slit 11c for giving elasticity from the outer peripheral tapered surface 11a to the spring portion 11d. The slits 11c are provided at three positions at intervals of 120 °.

By pressing the outer peripheral taper surface 11a of the guide bush 11 against the inner peripheral taper surface of the bush sleeve, the spring portion 11d bends and the gap between the inner peripheral surface 11b and the workpiece 51 is adjusted. Can be. Further, the guide bush 11 is provided with a fitting portion 11e between the spring portion 11d and the screw portion 11f. And
By this fitting portion 11e, the guide bush 11 can be arranged on the center line of the main shaft of the automatic lathe and in parallel with the main shaft center line.

As a base material of the guide bush 11,
An alloy tool steel (SKS) is used. After forming the outer shape and the inner shape with the alloy tool steel, quenching and tempering are performed. Thereafter, a cemented carbide member having a thickness of 2 mm to 5 mm is further fixed to the inner peripheral surface 11b of the guide bush 11 by a brazing means to obtain a cemented carbide member 12 shown in FIG. In this super hard member 12,
Use Japanese Industrial Standards (JIS) G type 2

The chemical components of the cemented carbide member of Class G No. 2 are 87% to 90% of tungsten (W), 5% to 7% of carbon (C), and 5% of cobalt (Co) as a binder. From 7% to 7%.

When the guide bush 11 is open, the guide bush 11 is 5 μm in the radial direction between the inner peripheral surface 11 b and the workpiece 51.
A gap of m to 10 μm is provided. For this reason, abrasion of the inner peripheral surface 11b of the guide bush 11 due to the entry and exit of the workpiece 51 poses a problem. Furthermore, the guide bush 11 slides at a high speed between the inner peripheral surface 11b and the workpiece 51 as described above, and furthermore, due to the excessive pressing force of the workpiece 51 against the inner peripheral surface 11b due to the cutting load. There is a problem that image sticking occurs.

Therefore, the guide bush 1 according to the present invention
3, a diamond-like carbon (DLC) film 15 is formed on the surface (inner peripheral surface) of the superhard member 12 provided on the inner peripheral surface holding the workpiece 51, as shown in FIG.
FIG. 1 is an enlarged view of a portion surrounded by a circle A in FIG. 3, that is, the structure of the first embodiment around the inner peripheral surface 11 b of the guide bush 11. The DLC film 15 and the super hard member 12
The thickness ratios are actually more than 1000 times different,
Although the super hard member 12 is much thicker, the thickness of the super hard member 12 is extremely thin in FIG. 1 for convenience of illustration.

In the first embodiment of the guide bush according to the present invention, as shown in FIG. 1, the inner surface 11b of the guide bush 11 (substrate) is in contact with the surface of the guide bush 11 (see FIG. 3) which is in contact with the workpiece 51. The super hard member 12 is fixed, and the DLC film 15 is formed directly on the surface thereof. The surface of the superhard member 12 that is in contact with the DLC film 15 is made of cobalt (C) that functions as a binder among the constituent materials of the superhard member 12.
o) has been selectively removed. That is, the DLC film 1 is formed on the surface of the cemented carbide member 12 from which cobalt (Co) has been removed.
5 are formed.

According to the present invention, it has been found that the poor adhesion of the DLC film to the cemented carbide member in the conventional guide bush is caused by cobalt which functions as a binder when the cemented carbide member is formed by sintering. We obtained by experiment. That is, since the cobalt contained in the super hard member is dissolved in the carbon of the DLC film,
An experimental result was obtained that the adhesion of the DLC film was deteriorated and peeled off.

For this reason, the guide bush 11 according to the present invention removes cobalt which adversely affects the adhesion of the surface of the superhard member 12 in contact with the hard carbon film 15.
Therefore, the DLC film 1 in this guide bush 11
No. 5 can be formed with good adhesion to the superhard member 12, and the problem of peeling does not occur. Therefore, the service life of the guide bush can be greatly extended as compared with the related art, and the reliability for long-term use can be improved.

Further, the surface condition before and after removing cobalt on the surface of the superhard member 12 in contact with the DLC film 15 was observed by a scanning electron microscope (SEM). As a result, on the surface of the super hard member 12 before the cobalt was removed, a trace of polishing the inner peripheral surface of the super hard member 12 was observed. On the other hand, the super hard member 1
No processing marks were observed on the surface of the surface of No. 2 from which cobalt was removed.

When the surface of the super hard member 12 was observed with the naked eye, the difference was obvious. That is, the super hard member 12
The surface before removing cobalt on the surface of the cemented carbide member 12 was mirror-polished, whereas the surface after removing cobalt on the surface of the cemented carbide member 12 was not mirror-finished but satin-finished (due to fine irregularities). (A rough surface).

This is because when the cobalt on the surface of the superhard member 12 that comes into contact with the hard carbon film 15 is removed, the cobalt functions as a binder, so that tungsten and carbon bonded to the binder by the sintering process are also removed. Peeling off, as described above, no processing marks were observed, and the surface was matte. As described above, since the processing marks on the surface of the super hard member 12 in contact with the DLC film 15 disappear and are not observed, and the matte state is provided, the adhesion of the DLC film 15 is further improved. I do.

In particular, regarding the processing marks, when the DLC film 15 is formed at a position where the processing marks exist, a film stress such as elongation or compression occurs at the position, and poor adhesion of the DLC film 15 is caused by the film stress. Is considered to have occurred, and the phenomenon that the adhesion due to the film stress is deteriorated due to the disappearance of the processing mark does not occur.

As a result, in the guide bush 11 according to the present invention, the phenomenon that the DLC film 15 is not peeled off does not occur, and the service life of the guide bush can be greatly extended as compared with the conventional art, and the reliability for long-term use is improved. I do. The DLC film 15 is a black hard carbon film, and has properties similar to diamond as described above. That is, the DLC film 15 has a high mechanical hardness, a low coefficient of friction, a high electrical insulation, a high thermal conductivity,
It also has excellent corrosion resistance.

Therefore, the guide bush 11 of the present invention
Can reduce the wear of the inner peripheral surface that comes in contact with the workpiece even in heavy cutting with a large amount of cutting and a high processing speed, eliminating the possibility of scratching the workpiece, The occurrence of seizure between the bush 11 and the workpiece can also be suppressed.

Further, the guide bush 11 is provided on its inner peripheral surface 11b with a DLC
A film 15 is provided. When the superhard member 12 having a high hardness is provided below the hard carbon film 15, the local D
The peeling and abrasion of the LC film 15 can be suppressed, and the reliability of the guide bush 11 for long-term use can be improved. The thickness of the DLC film 15 provided on the inner peripheral surface 11b of the guide bush 11 is 1 μm to 5 μm.
Is appropriate.

Next, second and third embodiments of the guide bush according to the present invention will be described with reference to FIGS. FIGS. 4 and 5 are views similar to FIG. 1 showing second and third embodiments of the guide bush according to the present invention. That is, the structure of the second and third embodiments near the inner peripheral surface 11b of the guide bush 11, which is the portion surrounded by the circle A in FIG. Also in these figures,
Actually, the super hard member 12 is much thicker than the DLC film 15, but for the sake of illustration, the thickness of the super hard member 12 is shown to be extremely thin.

The base of the guide bush 11 is also made of alloy tool steel (SKS), and after forming an outer shape and an inner shape, quenching and tempering are performed. Further, the inner peripheral surface 11 of the guide bush 11
Also in FIG. 2B, a superhard member having a thickness of 2 mm to 5 mm is fixed by brazing means to form a superhard member 12. This cemented carbide member contains 83% to 89% of tungsten (W) and 5% to 8% of cobalt (Co) as a binder.
The remainder has a composition of carbon (C).

In the second embodiment shown in FIG. 5, a super hard member 12 is fixed to the inner peripheral surface 11b of the guide bush 11, and an intermediate layer 14 is provided on the super hard member 12. A DLC film 15 is formed on the intermediate layer 14.
Then, cobalt (Co) functioning as a binder for the super hard member 12 is selectively removed from the surface of the super hard member 12 which is in contact with the intermediate layer 14. That is, the DLC film 15 is formed on the surface of the cemented carbide member 12 from which cobalt (Co) has been removed via the intermediate layer 14.

As a result, the DL of this guide bush 11
The C film 15 is formed on the inner peripheral surface 11 b of the base material of the guide bush 11.
It can be formed with good adhesion, and the problem of peeling does not occur. Therefore, the guide bush 1
The service life of the device 1 can be greatly extended as compared with the related art, and the reliability for long-term use can be improved.

It is considered that such excellent points of the guide bush 11 of this embodiment can be obtained for the following reasons. The surface states before and after the removal of cobalt on the surface of the superhard member 12 in contact with the intermediate layer 14 were observed with a scanning electron microscope (SEM).

On the surface of the super hard member 12 before removing cobalt, a trace of the inner peripheral surface of the super hard member 12 polished was observed. On the other hand, no machining marks were observed on the surface of the superhard member 12 from which cobalt was removed. Further, even when the surface of the super hard member 12 was observed with the naked eye, the difference was obvious. That is, the super hard member 12
The surface of the surface of the superhard member 12 after the cobalt was removed was not a mirror surface but a matte surface, whereas the surface of the surface before removing cobalt was a polished surface.

This is because the super hard member 1 in contact with the intermediate layer 14
2 When the cobalt on the surface was removed, this cobalt functioned as a binder, so the tungsten and carbon that had been bonded to this binder by sintering also peeled off,
As described above, no processing marks are observed, and the surface is in a satin state. Thus, the super hard member 1 that comes into contact with the intermediate layer 14
Since the processed traces on the two surfaces disappear and are not observed, and are in a matte state, the adhesion to the intermediate layer is improved.

In particular, regarding the processing marks, the intermediate layer 14 formed at the position where the processing marks exist has a film stress such as elongation or compression at the position. It is considered that poor adhesion has occurred, and the phenomenon that the adhesion is deteriorated due to the film stress does not occur due to the disappearance of the processing mark.
As a result, in the guide bush 11, the phenomenon that the intermediate layer 14 is not peeled off does not occur, and therefore, the adhesion of the DLC film 15 formed on the upper surface of the intermediate layer 14 is improved, and the service life of the guide bush 11 is improved. Can be greatly extended as compared with the conventional case, and the reliability for long-term use is improved.

When the intermediate layer 14 is formed of a single-layer film as in the second embodiment, a film of a carbon-containing alloy material such as a silicon carbide film (SiC) or a tungsten carbide film (WC) is used. It is good to consist of. in this way,
When the intermediate layer 14 is interposed between the cemented carbide member 12 and the DLC film 15, the adhesion of the DLC film 15 increases.

When the intermediate layer and the DLC film in the conventional guide bush were observed in detail, the intermediate layer and the DLC film could not obtain the adhesion with cobalt contained as a binder in the super hard member. Peeled from that location. Although the cause is not well understood, one of the causes is thought to be that the cobalt film is oxidized to form an oxide film having poor adhesion, and the DLC film and the intermediate layer are peeled off from the inner peripheral surface of the guide bush. Be guessed.

Therefore, in the guide bush 11 of the present invention, cobalt contained as a binder in the superhard member 12 is removed from the surface of the inner peripheral surface of the superhard member 12 on which the intermediate layer 14 is formed. As described above, since the cobalt which causes the poor adhesion of the intermediate layer 14 is removed from the inner peripheral surface of the cemented carbide member 12, the inner peripheral surface 1 of the guide bush 11 is removed.
1b, the intermediate layer 14 and the DLC film 15 can be formed with good adhesion, and as a result, the inner peripheral surface 1 of the guide bush 11 can be formed.
The peeling phenomenon of the DLC film for 1b does not occur. Hard carbon film 1 provided on inner peripheral surface 11b of guide bush 11
The film thickness of No. 5 is about 1 μm to 10 μm. The intermediate layer 14 has a thickness of about 0.5 μm.

Next, in the third embodiment shown in FIG. 5, the inner surface 11b of the guide bush 11 is
Are fixed, the first intermediate layer 14a and the second intermediate layer 14b are formed on the super hard member 12 in an overlapping manner, and the DLC film 15 is formed on the second intermediate layer 14b. The thickness of the hard carbon film 15 is 1 μm to 10 μm. The second embodiment shows that the surface of the superhard member 12 in contact with the first intermediate layer 14a is selectively removed from cobalt (Co) functioning as a binder of the superhard member 12. Is the same as

The first intermediate layer 14a is made of titanium (T
i) a film or a chromium (Cr) film, and the second intermediate layer 14b is formed of a silicon film (Si) or a germanium (G
e) consist of a membrane. The first and second intermediate layers 14a, 14
The film thickness of b is about 0.5 μm. Since the first intermediate layer 14a and the second intermediate layer 14b are formed by a sputtering method, the first intermediate layer 14a and the second intermediate layer 14b are formed to have a thickness such that the film is thick at the edge of the opening and thin at the depth from the opening. I have.

As described above, the first intermediate layer 14 a and the second intermediate layer 14 are provided between the super hard member 12 and the hard carbon film 15.
When b is interposed, it has the features described below. That is, since the first intermediate layer 14a made of titanium or chromium has excellent adhesion to the super hard member 12, the adhesion between the two is strengthened.
It is possible to suppress the reaction of cobalt contained in the superhard member 12 as a binder with carbon of the hard carbon film 15.

Each of the second intermediate layers 14b made of silicon or germanium is an element belonging to Group IV of the periodic table, and similarly, the second intermediate layer 14b is an element belonging to Group IV of the periodic table.
Since they have excellent adhesion to the C film, they are covalently bonded to each other to obtain strong adhesion. Therefore, guide bush 1
The hard carbon film 15 can be formed on the inner peripheral surface 11b with good adhesion.

As the second intermediate layer 14b, a film made of an alloy material containing carbon, such as a silicon carbide film (SiC) or a tungsten carbide (WC) film, instead of silicon or germanium, can be applied. The silicon carbide film and the tungsten carbide film also have substantially the same functions as the silicon film and the germanium film, and have substantially the same effects as when a silicon film or a germanium film is used as the second intermediate layer 14b.

[Embodiment of DLC Film Forming Method: FIGS. 1 to 5 and FIGS. 6 to 13] Next, diamond-like carbon (DLC) is applied to the guide bush according to the present invention.
An embodiment of a method for forming a film will be described. First, FIG.
A method of forming a DLC film on a guide bush for obtaining the coating structure of the first embodiment of the guide bush according to the present invention described with reference to FIGS.

The method for forming the DLC film is as follows. The DLC film 15 is formed on a guide bush 11 having at least an ultra-hard member 12 containing cobalt on an inner peripheral surface 11b for holding a workpiece 51 shown in FIG. Comprising the following steps.

(1) A step of removing cobalt from the surface of the superhard member 12 by etching, (2) A step of inserting the guide bush 11 into the vacuum chamber by inserting an electrode into the center opening 11j, 3) After evacuating the vacuum chamber, introducing a gas containing carbon into the vacuum chamber, applying a DC voltage or a high-frequency power to the guide bush 11 while applying a DC positive voltage to the electrodes, and opening the central opening. 11j, a plasma is generated in the inner peripheral surface 11b of the guide bush 11.
Forming a DLC film 15 on the surface of the super hard member 12 of

First, the step (1) of removing cobalt from the surface of the superhard member 12 by etching will be described. This removal of cobalt is preferably performed by wet etching. As a wet etching solution for selectively removing cobalt, a mixed solution of sodium hydroxide (NaOH) and a hydrogen peroxide solution (H ₂ O ₂ ) is used.

In this mixed solution, tungsten and carbon, which are the other constituent materials of the super hard member 12, and the alloy tool item (SKS), which is the constituent material of the guide bush 11, are not etched at all, and only the cobalt is selectively etched. Can be etched. This sodium hydroxide (N
aOH) and an aqueous solution of hydrogen peroxide (H ₂ O ₂ ) for etching cobalt with a mixed solution at room temperature;
The etching time is 3 hours to 5 hours, and the guide bush 11 is immersed in the etching solution.

Next, the step (2) of disposing the guide bush 11 in the vacuum chamber and the step (3) of forming the DLC film 15 on the surface of the superhard member 12 will be described. There are three types of apparatuses for performing these steps. Further, there are two types depending on whether the electrode inserted into the center opening of the guide bush is grounded or a DC positive voltage is applied. FIG. 6 is a schematic sectional view showing one example. In this example, a vacuum chamber 61 having a gas inlet 63 and an exhaust port 65, an anode 79 and a filament 81 is used.

The guide bush 11 from which the cobalt on the surface of the superhard member 12 has been removed is inserted into the center opening 11 j of the guide bush 11 by inserting the rod-shaped electrode 71 into the insulating support base 8 in the vacuum chamber 61.
0. At this time, the opening end face on the inner peripheral surface 11b side of the guide bush 11 faces the anode 79, and the dummy member 53 is arranged on the opening end face. The dummy member 53 has a ring shape and has a guide bush 1 at its center.
The first inner peripheral surface 11b has an opening having an inner diameter substantially the same as that of the inner peripheral surface 11b. The outer diameter of the dummy member 53 is the same as the size of the opening end face of the guide bush 11.

The electrode 71 inserted into the center opening 11j of the guide bush 11 is connected to the grounded vacuum chamber 61.
Connect to and ground. This electrode 71 is a guide bush 1
So as to be located on the central axis of the central opening 11j
The tip is set to a position slightly retracted from the upper end of the dummy member 53.

Then, the degree of vacuum in the vacuum chamber 61 is 3 × 10
- so that the ⁵ torr or less, evacuated from the exhaust port 65 by the exhaust means (not shown). Thereafter, benzene (C ₆ H ₆ ) is supplied from the gas inlet 63 as a gas containing carbon.
Is introduced into the vacuum chamber 61, and the pressure in the vacuum chamber 61 is increased by 5 ×
Controlled to be 10- ³ torr.

Thereafter, a DC voltage of −3 kV is applied to the guide bush 11 from the DC power supply 73, a DC voltage of +50 V is applied to the anode 79 from the anode power supply 75, and the filament power supply 7 is applied to the filament 81.
7, an AC voltage of 10 V is applied so that a current of 30 A flows.

Then, the guide bush 1 in the vacuum chamber 61
Plasma is generated in the peripheral region 1 and in the center opening 11j, and the DLC film 15 (see FIG. 3) is formed on the surface of the superhard member 12 fixed to the inner peripheral surface 11b. This DLC
In the method of forming the film, the grounded rod-shaped electrode 71 is inserted and provided in the center opening 11j of the guide bush 11, so that not only the outer peripheral portion of the guide bush 11 but also
Plasma can be generated also in the center opening 11j.

The center opening 11j of the guide bush 11
By providing the electrode 71 at the ground potential inside, the same potential does not face each other in the region inside the central opening 11j. Therefore, there is no occurrence of hollow discharge, which is abnormal discharge, and the adhesion of the DLC film formed on the inner peripheral surface 11b of the guide bush 11 is improved. Furthermore, since the potential characteristics in the longitudinal direction become uniform in the center opening 11j of the guide bush 11, the thickness of the DLC film formed on the inner peripheral surface 11b becomes uniform.

The electrode 71 may have a diameter smaller than the inner diameter of the center opening 11j of the guide bush 11.
Preferably, a plasma forming region with a gap of about 4 mm is provided between the inner peripheral surface 11b and the electrode 71.
The electrode 71 is formed of a metal material such as stainless steel. Furthermore, the cross-sectional shape of the electrode 71 is circular, and when the electrode 71 is inserted into the guide bush 11, the electrode 71 has a length that aligns with the opening end face of the dummy member 53,
Alternatively, the length may be such that the electrode 71 protrudes from the end face of the dummy member 53, but in the illustrated example, the length is such that the tip of the electrode 71 is at a position of 1 mm to 2 mm withdrawn from the end face of the dummy member 53. I have.

The dummy member 53 arranged on the open end face of the guide bush 11 plays the following role.
That is, in the method of forming the DLC film shown in FIG.
Plasma is generated in the center opening 11j and the outer peripheral portion of the guide bush 11.

Then, the electric charges are easily concentrated on the end face of the guide bush 11, and the electric charges are higher than in the center opening 11j, so that the so-called edge effect occurs. Therefore, the plasma intensity in the vicinity of the end face of the guide bush 11 is higher than in other regions, and is also unstable. Furthermore, the end region of the guide bush 11 is affected by both the plasma in the center opening 11j of the guide bush 11 and the plasma on the outer peripheral portion.

When the DLC film is formed in such a state, the adhesion of the DLC film is different between a region several mm deep from the opening end surface of the guide bush 11 and another region.
Further, the film quality is slightly different. Therefore, the guide bush 11
If the DLC film is formed by arranging the dummy member 53 on the opening end surface of the guide bush 11, the regions having different film quality and adhesion are not formed on the inner peripheral surface of the guide bush 11, but are formed on the inner surface of the opening.

When the DLC film was formed using the apparatus as shown in FIG. 6 without using the dummy member 53, according to the experiment, the width dimension was set to about 4 mm deeper from the open end face of the guide bush 11. A region having a film quality and adhesion different from 1 mm to 2 mm was formed.

Therefore, a dummy member 53 having an end surface dimension substantially equal to that of the open end surface of the guide bush 11 and having a length of 10 mm is arranged on the open end surface of the guide bush 11 under the above-described conditions for forming the DLC film. A film was formed.
As a result, the areas where the film quality and adhesion are different are the dummy members 53
On the inner peripheral surface 11b of the guide bush 11, no region having a different film quality or adhesion was formed at all.

Next, another example of the method of forming the DLC film on the guide bush and a method of forming the same will be described with reference to FIGS. In these figures, parts corresponding to those in FIG. 6 are denoted by the same reference numerals. First, the inner peripheral surface 11b of the guide bush 11
The removal of cobalt, which functions as a binder, from the surface region of the super hard member 12 provided by the wet etching process is the same as in the above-described case.

In the example shown in FIG. 7, in a vacuum chamber 61 having a gas introduction port 63 and an exhaust port 65, a guide bush 11 in which cobalt on the surface of a superhard member provided on an inner peripheral surface 11b is removed is insulated. It is arranged to be supported by the support base 80.
At this time, the grounded rod-shaped electrode 71 is inserted into the center opening 11j of the guide bush 11, and the ring-shaped dummy member 53 is arranged on the opening end surface, as in the above-described example.

[0102] Then, by the exhaust means (not shown) within the vacuum chamber 61, so that the degree of vacuum is below 3 × ^10- 5 torr, was evacuated through the exhaust port 65, the gas inlet port 6
From step 3, methane gas (CH ₄ ) is introduced into the vacuum chamber 61 as a gas containing carbon, and the degree of vacuum is adjusted to 0.1 torr.

Then, high frequency power having a frequency of 13.56 MHz is applied to the guide bush 11 from the high frequency power supply 69 via the matching circuit 67. As a result, plasma is generated not only in the outer peripheral portion of the guide bush 11 but also in the center opening 11j.
A DLC film can be formed on the surface of the hard member on the inner peripheral surface 11b. The operation and effect in this case are the same as those in the case of the example shown in FIG.

In the example shown in FIG. 8, similarly to the above-described example, cobalt on the surface of the superhard member provided on the inner peripheral surface 11b is removed in a vacuum chamber 61 having a gas inlet 63 and an exhaust port 65. The guide bush 11 thus arranged is supported by the insulating support base 80 and arranged. At this time, a grounded rod-shaped electrode 71 is inserted into the center opening 11j of the guide bush 11, and a ring-shaped dummy member 53 is arranged on the end face of the opening.

[0104] Then, by the exhaust means (not shown) within the vacuum chamber 61, after evacuating to a vacuum degree is equal to or less than 3 × ^10- 5 torr, as a gas containing carbon through the gas inlet 63, methane gas (CH ₄ ) Is introduced into the vacuum chamber 61, and the degree of vacuum is adjusted to 0.1 torr.

Then, a negative DC voltage of -600 V is applied to the guide bush 11 from the DC power supply 73 '. As a result, plasma is also generated in the outer peripheral portion of the guide bush 11 and in the center opening 11j, and a DLC film can be formed on the surface of the super hard member on the inner peripheral surface 11b of the guide bush 11. The operation and effect are the same as those of the example shown in FIG.

Next, another example of a method of forming a DLC film on a guide bush will be described with reference to FIGS. 9, 10 and 11. FIGS. 9, 10, and 11 correspond to the examples shown in FIGS. 6, 7, and 8, respectively, which are different from the examples shown in the center opening 11j of the guide bush 11. The inserted rod-shaped electrode 71 is insulated and supported by an insulating support member 85 such as an insulator mounted in the center opening 11j, and a DC positive voltage of +20 V is applied thereto by a DC power supply 83. is there.

According to these examples, the plasma is generated in the peripheral region including the inside of the center opening 11j of the guide bush 11 in the vacuum chamber 61, and the inner peripheral surface 1 of the guide bush 11 is generated.
A DLC film having strong adhesion can be formed on the hard member 1b. FIG. 12 is a graph showing the relationship between the DC positive voltage applied to the electrode 71 and the thickness of the hard carbon film formed on the inner peripheral surface 11b of the guide bush 11 at this time.

In the graph of FIG. 12, when the DC positive voltage applied to the electrode 71 is changed from zero V to 30 V, and the gap between the inner peripheral surface 11b of the guide bush 11 and the electrode 71 is 3 mm and 5 mm, Shows the thickness of the hard carbon film. The curve a represents the inner peripheral surface 11 of the guide bush 11.
The characteristic when the gap between b and the electrode 71 is 3 mm is shown, and the curve b shows the characteristic when the gap is 5 mm.

As shown by the curves a and b in FIG. 12, when the DC positive voltage applied from the DC power supply 83 to the electrode 71 is increased, the film formation speed of the DLC film is improved. Further, the larger the gap size between the inner peripheral surface 11b of the guide bush 11 and the electrode 71, the higher the film forming speed of the DLC film. Then, the gap size shown in the curve a is 3 mm
In this case, if the voltage applied to the electrode 71 is zero V, the plasma is not generated in the center opening 11j of the guide bush 11, and the DLC film cannot be formed.

However, even when the gap is 3 mm, if the DC positive voltage applied to the electrode 71 is increased, plasma is generated around the electrode 71 in the center opening 11j, and a hard carbon film is formed. Can be. As described above, in the examples shown in FIGS. 9 to 11, by applying a DC positive voltage to the electrode 71 disposed in the center of the center opening 11 j of the guide bush 11 to form a hard carbon film, An effect of collecting electrons is generated in a region around the electrode 71, and the region around the electrode 71 has a high electron density.

When the electron density increases as described above, the probability of collision between the gas molecules containing carbon and electrons necessarily increases, and ionization of the gas molecules is promoted, and the plasma intensity in the center opening 11j of the guide bush 11 decreases. Get higher. for that reason,
The formation speed of the DLC film is higher than when no DC positive voltage is applied to the electrode 71.

Furthermore, the center opening 1 of the guide bush 11
When the inner diameter of the electrode 1j becomes smaller and the gap between the inner peripheral surface 11b and the electrode 71 becomes smaller, when the DLC film is formed without applying a DC positive voltage to the electrode 71, the center opening 11
No plasma is generated in j, and a film cannot be formed.

However, the center opening 1 of the guide bush 11
When a DC positive voltage is applied to the electrode 71 arranged in 1j,
Electrons are forcibly collected in a region around the electrode 71, and plasma can be generated around the electrode 71 in the center opening 11j, so that a DLC film can be formed on the inner peripheral surface 11b. Other functions and effects are the same as those of the respective examples described with reference to FIGS. 6 to 8, and thus description thereof will be omitted.

In the above description of the method of forming each DLC film, an example in which methane gas or benzene gas is introduced as a gas containing carbon into the vacuum chamber has been described. Also, a vapor containing a gas or a liquid containing carbon such as hexane can be used.

Further, in the above-described method for forming each DLC film, the embodiment in which the DLC film is formed on both the outer peripheral portion and the inner peripheral surface 11b of the guide bush 11 has been described.
A DLC film may be formed only on 1b. In this case, a method of arranging a covering member that covers the outer peripheral portion of the guide bush 11 or simply wrapping an aluminum foil around the outer peripheral portion of the guide bush 11 to obtain a DL
A C film may be formed.

Further, in the above-described method of forming each DLC film, it has been described that the dummy member 53 is arranged on the open end surface of the guide bush 11 to form a film. However, if the film quality of the DLC film near the opening end face is not so different from the other areas, the DLC film can be formed without disposing the dummy member 53 on the opening end face of the guide bush 11.

[Method of Forming Intermediate Layer: FIG. 13] Next, FIG.
The intermediate layer 15 is provided on the surface of the hard member 12 fixed to the inner peripheral surface 11b of the guide bush 11 described with reference to FIG.
The step of forming the intermediate layer when the DLC film 15 is formed through the intermediary will be described with reference to FIG. The step of forming the intermediate layer is performed, as shown in FIG.
A target 96 is provided in the vicinity of 1a, and a target 90 made of an alloy of, for example, tungsten and carbon, which is a material for forming an intermediate layer, is disposed on the target 96.

The gas inlet 93 and the exhaust 95
The guide bush 11 is arranged so that the target 90 and the opening end face are opposed to each other in a vacuum chamber 91 having the following. At this time, the guide bush 11 is arranged so that the longitudinal direction of the central opening 11j is perpendicular to the surface of the target 90. In this example, the outer peripheral surface of the guide bush 11 is covered with a covering material 94 such as an aluminum foil so as not to form an intermediate layer.

As shown in FIG. 4, the guide bush 11 has a cemented carbide member 1 containing cobalt on the inner peripheral surface 11b of the base material.
2 are fixed, and the cobalt on the surface is removed by etching. The guide bush 11 is connected to a DC power supply 92, and the target 90 is connected to a target power supply 97. And by an unillustrated exhaust means, the degree of vacuum in the vacuum chamber 91 3 × ^10- 5 torr
Vacuum is exhausted from the exhaust port 95 so as to be as follows.

Thereafter, argon (Ar) gas is introduced as a sputtering gas from the gas inlet 93 to adjust the degree of vacuum in the vacuum chamber 91 to 3 × 10 ⁻³ torr. Thereafter, the guide bush 11 is connected to the DC power source 7.
A negative DC voltage of 3 to −50 V is applied, and a DC voltage of −500 V to 600 V from a target power supply 97 is applied to the target 90. Then, the vacuum chamber 61
Generates a plasma inside, and the surface of the target 90 is sputtered by ions in the plasma.

The tungsten and carbon struck out of the surface of the target 90 adhere to the inner peripheral surface 11b of the guide bush 11, and the intermediate layer 14 made of a tungsten carbide film (see FIG. 4) is removed. Can be formed on the inner peripheral surface of the super hard member 12. The film thickness of the intermediate layer 14 made of the tungsten carbide film is 0.5
It is about μm.

After forming the intermediate layer 14 on the superhard member 12 in this manner, the intermediate layer 1 is formed by any of the DLC film forming steps described with reference to FIGS.
4, the DLC film 15 can be formed with good adhesion.

The intermediate layer 14 can be formed of a multilayer film having a plurality of layers. As shown in FIG. 5, the first intermediate layer 14
a is formed of a titanium film or a chromium film, and the second intermediate layer 1
An intermediate layer forming step in the case where 4b is formed of a silicon film or a germanium film will be described.

In this case, titanium or chromium is placed as the target 90 in the vacuum chamber 91 shown in FIG.
The guide bush 11 is disposed to face the guide bush 11, and a negative DC voltage of −50 V is applied to the guide bush 11 from the DC power supply 73 in the same manner as described above.
A DC voltage of V is applied.

Then, argon (A) is used as a sputtering gas.
r), the titanium or chromium of the target 90 is beaten out, and the first intermediate layer 14a of the titanium or chromium film is formed on the surface of the superhard member 12 on the inner peripheral surface 11b of the guide bush 11 (see FIG. (See Fig. 5)
To form

Thereafter, the target 90 is replaced with silicon or germanium, and the other conditions are as follows.
If a film is formed under the same conditions as when forming 4a, the first
The second intermediate layer 14b of a silicon film or a germanium film can be formed on the surface of the intermediate layer 14a. The step of forming a DLC film on the second intermediate layer 14b includes:
The second intermediate layer 14 can be formed by any of the DLC film forming steps described with reference to FIGS.
The DLC film 15 can be formed on b with good adhesion.

The second intermediate layer 14b is formed by using an alloy material containing carbon, such as a silicon carbide film (SiC) or a tungsten carbide (WC) film, instead of silicon or germanium as a target, as shown in FIG. In the vacuum chamber 91 shown, the film can be formed by a sputtering method. The silicon carbide film and the tungsten carbide film also have substantially the same functions as the silicon film and the germanium film, and have substantially the same effects as when a silicon film or a germanium film is used as the second intermediate layer 14b.

[0128]

As described above, the guide bush according to the present invention can significantly improve the durability, and when used on an automatic lathe, causes damage to the processed part (work). And the risk of burn-in is eliminated. Further, if the method of forming a DLC film on a guide bush according to the present invention is carried out, the DLC film having good adhesion and a uniform film thickness can be formed on the super hard member on the inner peripheral surface holding the workpiece of the guide bush. Can be formed.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing a coating structure near an inner peripheral surface of a first embodiment of a guide bush according to the present invention.

FIG. 2 is a perspective view showing an example of the appearance of a guide bush according to the present invention.

FIG. 3 is a sectional view of the guide bush shown in FIG. 2 along a longitudinal direction.

FIG. 4 is an enlarged view showing a coating structure near an inner peripheral surface of a second embodiment of the guide bush according to the present invention.

FIG. 5 is an enlarged view showing a coating structure near an inner peripheral surface of a third embodiment of a guide bush according to the present invention.

FIG. 6 is a schematic sectional view for explaining an example of a DLC film forming step in the embodiment of the method for forming a DLC film on a guide bush according to the present invention.

FIG. 7 is a schematic cross-sectional view for explaining another example of the DLC film forming process.

FIG. 8 is a schematic cross-sectional view for explaining still another example of the DLC film forming step.

FIG. 9 is a schematic cross-sectional view for explaining an example in which a part of the example shown in FIG.

FIG. 10 is a schematic cross-sectional view for explaining an example in which a part of the example shown in FIG. 7 in the DLC film forming process is partially changed.

FIG. 11 is a schematic cross-sectional view for explaining an example in which a part of the example shown in FIG. 8 in the DLC film forming process is partially changed.

FIG. 12 is a diagram showing a relationship between a voltage applied to an electrode and a film thickness in a process of forming a DLC film on a guide bush shown in FIGS. 9 to 11;

FIG. 13 is a schematic sectional view for explaining an example of an intermediate layer forming step in the embodiment of the method for forming a DLC film on a guide bush according to the present invention.

FIG. 14 is a sectional view showing a main part of an automatic lathe equipped with a guide bush device to which the guide bush according to the present invention is applied.

FIG. 15 is a sectional view showing a main part of another example of an automatic lathe equipped with a guide bush device to which the guide bush according to the present invention is applied.

FIG. 16 is a schematic cross-sectional view for explaining a conventional method of forming a DLC film on a guide bush.

[Explanation of symbols]

 11: guide bush 11a: outer peripheral taper surface 11b: inner peripheral surface 11c: slit 11d: spring portion 11e: fitting portion 11f: screw portion 11g: step portion 11j: center opening 12: carbide member 13: collet chuck 14: Intermediate layer 14a: First intermediate layer 14b: Second intermediate layer 15: DLC film 17: Headstock 23: Bush sleeve 37: Guide bush device 51: Workpiece (work) 53: Dummy member 61: Vacuum tank 63 : Gas inlet port 65: Exhaust port 67: Matching circuit 69: High frequency power supply 71: Electrodes 73, 73 ′: DC power supply 75: Anode power supply 77: Filament power supply 79: Anode 80: Insulating support 81: Filament 83: DC power supply 85 : Insulating support member (insulator) 90: Target 91: Vacuum tank 92: DC power supply 94: Coating material 96: Target Get receiver 97: Target power supply

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koike ▲ Ryu ▼ Futana 6-1-12 Honcho, Tanashi-shi, Tokyo Citizen Watch Co., Ltd. Tanashi Factory (72) Inventor Takashi Toida Tokorozawa-shi, Saitama 840 Takeno, Fukuji Citizen Watch Co., Ltd.

Claims (21)

[Claims] 1. It has a substantially cylindrical shape having a central opening penetrating in the axial direction, and has a tapered outer peripheral surface at one end in the longitudinal direction and a slit for giving elasticity thereto.
The other end has a screw portion for attaching to a column of an automatic lathe, and has an inner peripheral surface for holding a workpiece on an inner periphery of a portion where the outer peripheral taper surface is formed. A work piece inserted into the center opening by being attached is slidably and axially slidably held near the cutting tool by the inner peripheral surface, and a carbide member including at least cobalt on the inner peripheral surface. And a guide bush having a diamond-like carbon film formed on the super-hard member, wherein cobalt is removed from a surface of the super-hard member in contact with the diamond-like carbon film. guide bush. 2. The guide bush according to claim 1, wherein a surface of the superhard member that is in contact with the diamond-like carbon film has no processing trace of polishing. 3. The guide bush according to claim 1, wherein the surface of the superhard member in contact with the diamond-like carbon film is not mirror-finished but matted. 4. It has a substantially cylindrical shape having a central opening penetrating in the axial direction, and has a tapered outer peripheral surface at one end in the longitudinal direction and a slit for giving elasticity thereto.
The other end has a screw portion for attaching to a column of an automatic lathe, and has an inner peripheral surface for holding a workpiece on an inner periphery of a portion where the outer peripheral taper surface is formed. The workpiece inserted into the center opening by being attached is held by the inner peripheral surface slidably and axially slidably near the cutting tool, and a carbide member including at least cobalt on the inner peripheral surface. A method of forming a diamond-like carbon film on a guide bush provided with: a step of removing cobalt on the surface of the superhard member by etching; and inserting an electrode into the center opening of the guide bush. Arranging in a vacuum chamber, and after evacuating the vacuum chamber, introducing a gas containing carbon into the vacuum chamber and, while the electrode is grounded, applying a DC voltage or high voltage to the guide bush. Applying a wave power to generate plasma in the center opening to form a diamond-like carbon film on the surface of the superhard member on the inner peripheral surface of the guide bush. Method of forming diamond-like carbon film on the surface. 5. A substantially cylindrical shape having a central opening penetrating in the axial direction, an outer peripheral tapered surface formed at one end in the longitudinal direction and a slit for giving elasticity thereto, and an automatic lathe at the other end. Has a threaded portion for attaching to the column, and has an inner peripheral surface for holding a workpiece on an inner periphery of a portion where the outer peripheral tapered surface is formed, and the center is attached to an automatic lathe. The workpiece inserted into the opening is held by the inner peripheral surface so as to be able to rotate and slide in the axial direction near the cutting tool, and to a guide bush provided with a carbide member containing at least cobalt on the inner peripheral surface. A method of forming a diamond-like carbon film by removing cobalt on the surface of the cemented carbide member by etching; inserting an electrode into the center opening of the guide bush to form a vacuum chamber. After evacuating the vacuum chamber, introducing a gas containing carbon into the vacuum chamber and applying a DC voltage or a high-frequency power to the guide bush while applying a DC positive voltage to the electrode. Generating plasma in the center opening to form a diamond-like carbon film on the surface of the superhard member on the inner peripheral surface of the guide bush. -A method of forming a carbon film. 6. The method for forming a diamond-like carbon film on a guide bush according to claim 4, wherein in the step of removing cobalt on the surface of the superhard member by etching, cobalt is removed by wet etching. 7. The method for forming a diamond-like carbon film on a guide bush according to claim 6, wherein said wet etching is performed with a mixed solution of sodium hydroxide and hydrogen peroxide solution. 8. The gas containing carbon introduced into the vacuum chamber in the step of forming a diamond-like carbon film on the surface of the superhard member on the inner peripheral surface of the guide bush is benzene or methane. The method for forming a diamond-like carbon film on a guide bush according to any one of claims 4 to 7. 9. It has a substantially cylindrical shape having a central opening penetrating in the axial direction, and has a tapered outer peripheral surface at one end in the longitudinal direction and a slit for giving elasticity thereto.
The other end has a screw portion for attaching to a column of an automatic lathe, and has an inner peripheral surface for holding a workpiece on an inner periphery of a portion where the outer peripheral taper surface is formed. A work piece inserted into the center opening by being attached is slidably and axially slidably held near the cutting tool by the inner peripheral surface, and a carbide member including at least cobalt on the inner peripheral surface. A guide bush in which an intermediate layer is provided on the superhard member, and a diamond-like carbon film is formed on the intermediate layer, wherein the surface of the superhard member in contact with the intermediate layer has cobalt removed. A guide bush characterized in that: 10. The guide bush according to claim 9, wherein a surface of the superhard member that is in contact with the intermediate layer is free of processing marks caused by polishing. 11. The guide bush according to claim 9, wherein a surface of the superhard member that is in contact with the intermediate layer is not a mirror surface but has a satin finish. 12. The guide bush according to claim 9, wherein the intermediate layer is made of an alloy material containing carbon. 13. The guide bush according to claim 9, wherein the intermediate layer is constituted by a plurality of layers made of different materials. 14. The intermediate layer, wherein a first intermediate layer made of titanium or grom formed directly on the super hard member, and a second intermediate layer made of silicon or germanium formed on the first intermediate layer. 14. The guide bush according to claim 13, wherein the guide bush is constituted by: 15. It has a substantially cylindrical shape having a central opening penetrating in the axial direction. An outer peripheral tapered surface and a slit for giving elasticity thereto are formed at one end in the longitudinal direction, and an automatic slit is formed at the other end. It has a screw portion for attaching to a column of a lathe, and has an inner peripheral surface for holding a workpiece on an inner periphery of a portion where the outer peripheral taper surface is formed, and is attached to an automatic lathe. A guide bush in which a workpiece inserted into a central opening is held by the inner peripheral surface so as to be rotatable and slidable in the vicinity of a cutting tool, and a carbide member containing at least cobalt is provided on the inner peripheral surface. Forming a diamond-like carbon film on the surface of the cemented carbide member by etching, and removing the guide bush and the target by using the guide bush. Arranged in a vacuum chamber so that the center opening faces the target, and after evacuation of the vacuum chamber, argon gas is introduced into the vacuum chamber, and the surface of the superhard member is sputtered by sputtering. A step of forming an intermediate layer of the target material; a step of disposing the guide bush on which the intermediate layer is formed in a vacuum chamber so as to insert an electrode into the center opening; and evacuation of the vacuum chamber Thereafter, a gas containing carbon is introduced into the vacuum chamber, and while the electrodes are grounded, a DC voltage or high-frequency power is applied to the guide bush to generate plasma in the center opening, and the guide bush is formed. Forming a diamond-like carbon film on the surface of the intermediate layer on the inner peripheral surface. Formation method. 16. It has a substantially cylindrical shape having a central opening penetrating in the axial direction. An outer peripheral tapered surface is formed at one end in the longitudinal direction and a slit is formed at the other end to make it elastic. It has a screw portion for attaching to a column of a lathe, and has an inner peripheral surface for holding a workpiece on an inner periphery of a portion where the outer peripheral taper surface is formed, and is attached to an automatic lathe. A guide bush in which a workpiece inserted into a central opening is held by the inner peripheral surface so as to be rotatable and slidable in the vicinity of a cutting tool, and a carbide member containing at least cobalt is provided on the inner peripheral surface. Forming a diamond-like carbon film on the surface of the cemented carbide member by etching, and removing the guide bush and the target by using the guide bush. Arranged in a vacuum chamber so that the center opening faces the target, and after evacuation of the vacuum chamber, argon gas was introduced into the vacuum chamber, and the surface of the superhard member was sputtered by sputtering. A step of forming an intermediate layer of the target material; a step of disposing the guide bush on which the intermediate layer is formed in a vacuum chamber so as to insert an electrode into the center opening; and evacuation of the vacuum chamber Thereafter, a gas containing carbon is introduced into the vacuum chamber, and a DC voltage or a high-frequency power is applied to the guide bush to generate plasma in the center opening while applying a DC positive voltage to the electrode. Forming a diamond-like carbon film on the surface of the intermediate layer on the inner peripheral surface of the guide bush. A method for forming a bon film. 17. The method for forming a diamond-like carbon film on a guide bush according to claim 15, wherein in the step of removing the cobalt on the surface of the superhard member by etching, the cobalt is removed by wet etching. 18. The method for forming a diamond-like carbon film on a guide bush according to claim 17, wherein the wet etching is performed with a mixed solution of sodium hydroxide and hydrogen peroxide solution. 19. In the step of forming the intermediate layer, a material obtained by alloying tungsten and carbon on a one-to-one basis is used as the target, and an intermediate layer of a tungsten carbide film is formed on the surface of the cemented carbide member. A method for forming a diamond-like carbon film on a guide bush according to any one of claims 15 to 18. 20. In the step of forming the intermediate layer, after forming a first intermediate layer of a titanium film or a chromium film on the surface of the superhard member using titanium or chromium as the target, 2. A second intermediate layer of a silicon film or a germanium film is formed on the first intermediate layer instead of silicon or germanium.
19. The method for forming a diamond-like carbon film on a guide bush according to any one of 5 to 18. 21. A gas containing carbon introduced into the vacuum chamber in the step of forming a diamond-like carbon film on the surface of the intermediate layer on the inner peripheral surface of the guide bush, is benzene or methane. Items 15 and 2
0. The method for forming a diamond-like carbon film on a guide bush according to any one of 0 to 1.