JP3043670B2 - Method of forming hard carbon film on inner peripheral surface of guide bush - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guide bush, which is mounted on an automatic lathe and holds a round bar-shaped workpiece slidably and axially near a cutting tool (blade). The present invention relates to a method for forming a hard carbon film on an inner peripheral surface in sliding contact.

[0002]

2. Description of the Related Art There are a rotary bush and a fixed bush mounted on a column of an automatic lathe and rotatably holding a round bar-shaped workpiece near a cutting tool. The rotary type keeps the workpiece slidable in the axial direction while always rotating with the workpiece, and the fixed type allows the workpiece to rotate and slide in the axial direction without rotating. Hold.

[0003] Each type of guide bush has an outer tapered surface, a slit for making it elastic, a screw portion for attaching to a column, and an inner peripheral surface for holding a workpiece. The inner peripheral surface is always in sliding contact with the workpiece, so that the inner peripheral surface is liable to be worn. Particularly, in the case of the fixed type, the abrasion is severe.

For this purpose, a hard metal or ceramic is fixed to the inner peripheral surface of a guide bush which is brought into sliding contact with the workpiece by rotation or sliding of the workpiece by brazing or the like. It has been proposed as seen in US Pat. As described above, by providing a cemented carbide or ceramic having excellent wear resistance and heat resistance on the inner peripheral surface of the guide bush, an effect of suppressing the wear to some extent is recognized.

[0005] However, even if the cemented carbide or ceramic is provided on the inner peripheral surface as described above, the friction coefficient of the cemented carbide or ceramic is large for heavy cutting in which the cutting amount is large and the machining speed is large with an automatic lathe. Since the thermal conductivity is low, there is a problem in that the workpiece is scratched, the gap between the guide bush and the workpiece in the diameter direction is reduced, and seizure occurs. Could not be raised.

[0006] The fixed type guide bush can hold the workpiece without deviation of the axis of the workpiece, so that the processing can be performed with high roundness and high accuracy, the noise is small, and the structure of the automatic lathe is complicated. There are advantages such as being able to be compact without becoming unnecessary. However, since the inner peripheral surface of the guide bush wears much more than the rotary type, there is a problem that it is difficult to further increase the cutting amount and the processing speed.

In order to solve this problem, we formed a hard carbon film on the inner peripheral surface of such a guide bush that is in sliding contact with the workpiece, thereby dramatically improving the wear resistance of the inner peripheral surface. It has been proposed that the amount of machining and the machining speed by an automatic lathe can be increased without causing scratches or seizure on a workpiece.

[0008] The hard carbon film is a hydrogenated amorphous carbon film, which has properties very similar to diamond, and is also called diamond-like carbon (DLC). This hard carbon film (DL
C) has a high hardness (Vickers hardness of 3000 Hv or more), is excellent in wear resistance, has a small friction coefficient (about 1/8 of cemented carbide), and is excellent in corrosion resistance.

As a method of forming a hard carbon film on the inner peripheral surface of the guide bush, for example, the pressure is reduced to 5 × 10 ⁻³ torr which is a film forming pressure in an atmosphere of a gas containing carbon, and a DC power supply is applied to the guide bush. There is a plasma CVD method in which a DC voltage of -3 kV is applied to generate plasma to form a hard carbon film.

[0010]

However, in this plasma CVD method, the plasma generated mainly in the peripheral region of the guide bush decomposes a gas containing carbon to form a hard carbon film. A hard carbon film can be formed on the outer periphery of the guide bush with good uniformity. However, the hard carbon film formed on the inner periphery of the guide bush has poor adhesion and further has a problem of poor film quality such as hardness. is there.

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

Further, in the method for forming a hard carbon film described above, at a film forming pressure of 5 × 10 ^-3 torr,
-3 kV from DC power supply 73 to guide bush 11
DC voltage is applied. When the pressure in the vacuum chamber is about 5 × 10 ⁻³ torr, the space in the vacuum chamber contains a large amount of charges such as electrons, and the spatial impedance is low. Therefore, an arc discharge, which is an abnormal discharge, is likely to occur in the guide bush at the moment when the plasma discharge starts.

Furthermore, since the start of the plasma discharge is also at the initial stage of the formation of the hard carbon film, the adhesion to the guide bush depends on the quality of the film formed at the initial stage of the film formation. Therefore, when an arc discharge, which is an abnormal discharge, occurs in the initial stage of the plasma discharge, the film quality and adhesion of the hard carbon film deteriorate, and a problem occurs that the hard carbon film is separated from the inner peripheral surface of the guide bush.

An object of the present invention is to solve these problems and to form a hard carbon film having good film quality and good adhesion on the inner peripheral surface of a guide bush that is in sliding contact with a workpiece.

[0015]

In order to achieve the above object, the present invention is formed in a substantially cylindrical shape having a central opening in the axial direction, and has an outer peripheral tapered surface at one end and an inner peripheral surface which is in sliding contact with a workpiece. And when it is mounted on an automatic lathe,
A hard carbon film is formed on the inner peripheral surface of a guide bush that holds the workpiece inserted into the center opening so as to be able to rotate and slide in the axial direction near the cutting tool by the following procedure.

The guide bush is disposed in a vacuum chamber provided with a gas inlet, an exhaust port, an anode and a filament, and an auxiliary electrode is inserted into a central opening forming an inner peripheral surface of the guide bush. Bring it to ground potential.

After evacuating the vacuum chamber, a gas containing carbon is introduced into the vacuum chamber through the gas inlet, a DC voltage is applied to the guide bush via a reactor, and a DC voltage is applied to the anode. An AC voltage is applied to the filament to generate plasma in the vacuum chamber, and a hard carbon film is formed on the inner peripheral surface of the guide bush by a plasma CVD method.

As a method of generating plasma in a vacuum chamber, a plasma may be generated by applying a DC voltage to a guide bush via a reactor without providing an anode and a filament in the vacuum chamber. Good.

Also, a plurality of guide bushes are arranged in a vacuum chamber, auxiliary electrodes are inserted into the respective guide bushes, and a DC voltage is applied to each guide bush via a reactor to generate a plasma in the vacuum chamber. The hard carbon film can be simultaneously formed on the inner peripheral surfaces of the plurality of guide bushes in one vacuum chamber. In this case, a DC voltage may be applied to each of the plurality of guide bushes via a single reactor, or a DC voltage may be applied from an individual DC power supply or a common DC power supply via each individual reactor. Is also good.

As described above, by applying a DC voltage to the guide bush via the reactor to generate plasma in the vacuum chamber, a coating that affects the quality of the hard carbon film formed on the inner peripheral surface of the guide bush is determined. In the initial stage of formation, arc discharge, which is abnormal discharge, is not generated, and a hard carbon film having good film quality and adhesion can be formed.

Further, by introducing a gas containing carbon into the vacuum chamber and generating plasma with the auxiliary electrode at the ground potential inserted into the center opening of the guide bush, the inner peripheral surface of the guide bush is formed. A hard carbon film can be formed quickly and with a uniform thickness from the opening end side to the back side. Further, it is preferable to form a hard carbon film by the above-described method after providing an intermediate layer for improving the adhesion on the inner peripheral surface of the guide bush.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. [Description of Automatic Lathe Using Guide Bush] First, the structure of an automatic lathe using a guide bush in which a hard carbon film is formed on an inner peripheral surface in sliding contact with a workpiece by applying the method of the present invention will be briefly described. .

FIG. 23 is a sectional view showing only the vicinity of the spindle of the numerically controlled automatic lathe. In this automatic lathe, a guide bush 11 is fixed, and a workpiece 51 is fixed on an inner peripheral surface 11b thereof.
(Shown by phantom lines) is provided with a fixed type guide bush device 37 which is used in a state of being rotatably held. The headstock 17 is slidable on the bed (not shown) of the numerically controlled automatic lathe in the left-right direction in the figure.

The headstock 17 is provided with a main shaft 19 rotatably supported by bearings 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, at the rear end of the collet chuck 13 in the intermediate sleeve 29, there is provided a spring 25 made of a band-shaped spring material in a coil shape. Then, the collet chuck 13 can be pushed out of the intermediate sleeve 29 by the action of the spring 25. The tip position of the collet chuck 13 is in contact with a cap nut 27 screwed to the tip of the main shaft 19 to regulate the position. Therefore, the collet chuck 13 is prevented 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.
By opening and closing the chuck opening / closing claws 33, the collet chuck 13 opens and closes, and grips and releases the workpiece 51. 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 that is in contact with the intermediate sleeve 29 moves leftward in FIG. Press 29 to the left. 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 connected to the spindle 1
The cap nut 27 screwed to the tip of the nut 9 prevents the spindle 9 from jumping out of the main shaft 19. Therefore, by the movement of the chuck sleeve 41 to the left, the outer peripheral tapered surface 13a of the portion where the slit of the collet chuck 13 is formed and the inner peripheral tapered surface 41a of the chuck sleeve 41 are strongly pushed, They will move along the tapered surfaces.

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 opening / closing claw 33 is used.
Are moved to close each other, thereby removing the force for pushing the chuck sleeve 41 to the left. Then, the intermediate sleeve 29 and the chuck sleeve 41 move rightward in the drawing due to 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. Thereby, 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, a column 35 is provided in front of the headstock 17, and the guide bush device 37 is arranged there so that the center axis of the guide bush device 37 coincides with the center axis of the spindle.

The guide bush device 37 is a fixed type guide bush device 37 that fixes the guide bush 11 and holds the workpiece 51 in a rotatable state on the inner peripheral surface 11b of the guide bush 11. The bush sleeve 23 is fitted into the center hole of the holder 39 fixed to the column 35, and the inner peripheral taper surface 23 a is provided at the tip of the bush sleeve 23.

The outer peripheral tapered surface 11a and the slit 11c
The guide bush 11 formed with is fitted and arranged. The gap between the inner diameter of the guide bush 11 and the outer shape of the workpiece 51 is adjusted by rotating an adjustment nut 43 provided at the rear end of the guide bush device 37 by screwing the screw portion of the guide bush 11. can do.

That is, when the adjustment nut 43 is rotated clockwise, the guide bush 11
Moves rightward in the figure, and similarly to the case of the collet chuck 13, the inner peripheral tapered surface 23 a of the bush sleeve 23 and the outer peripheral tapered surface 11 a of the guide bush 11 are pressed against each other, and the leading end of the guide bush 11 is moved. This is because the inner diameter of the becomes smaller.

In front of the guide bush device 37, a cutting tool (blade) 45 is provided. The workpiece 51 is gripped by the collet chuck 13 of the spindle 19 and supported by the guide bush device 37, and the workpiece 51 protruding into the processing area through the guide bush device 37 is removed by the cutting tool 45. Forward and backward and headstock 17
A predetermined cutting process is performed by a combined motion with the movement of the object.

Next, a description will be given of a rotary guide bush device used in a state where the guide bush 11 for gripping a workpiece is rotated, with reference to FIG. This FIG.
In FIG. 23, portions corresponding to those in FIG. 23 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, and a guide bush device in which the collet chuck 13 and the guide bush rotate without synchronization. In the guide bush device 37 shown in this figure, the collet chuck 13 and the guide bush 11 rotate in synchronization.

This rotary type guide bush device 37 is
The guide bush device 37 is driven by a rotation drive rod 47 protruding from the cap nut 27 of the main shaft 19.
In some cases, the guide bush device 37 is driven by a gear or a belt pulley instead of the rotary drive rod 47.

This rotary type guide bush device 37 is
The bearing 21 is fixed to the center hole of the holder 39 fixed to the column 35.
The bush sleeve 23 is fitted and arranged so as to be rotatable via the. Furthermore, this bush sleeve 2
The guide bush 11 is fitted into the center hole 3 and arranged.

Bush sleeve 23 and guide bush 1
1 has the same configuration as that described with reference to FIG. An adjusting nut 43 is provided at the rear end of the guide bush device 37 by screwing the screw portion of the guide bush 11.
The inner diameter of the guide bush 11 is reduced by rotating the
The gap size with the outer shape of the device can be adjusted. Except for the configuration in which the guide bush device 37 is a rotary type, the configuration is the same as that of the automatic lathe described with reference to FIG.

[Description of Guide Bush to which the Present Invention is Applied] Next, the configuration of a guide bush in which a hard carbon film is formed on the inner peripheral surface by applying the present invention will be described. FIG. 1 is a longitudinal sectional view showing an example of the guide bush, and FIG.
Is a perspective view showing its appearance.

The guide bush 11 shown in these figures is
This shows a free state in which the tip is open. The guide bush 11 is formed in a substantially cylindrical shape having a central opening 11j in the axial direction, and has an outer peripheral tapered surface 11a at one end in the longitudinal direction.
And has a screw portion 11f at the other end.

The central opening 11j of the guide bush 11 forms an inner peripheral surface 11b for holding the workpiece 51 inside one end portion provided with the outer tapered surface 11a. In the region, a step portion 11g having an inner diameter larger than the inner diameter of the inner peripheral surface 11b is formed. The guide bush 11 is provided with three slits 11c at 120 ° intervals from the outer peripheral tapered surface 11a to the spring portion 11d so as to divide the outer peripheral tapered surface 11a into three equal parts in the circumferential direction.

The outer peripheral taper surface 11 of the guide bush 11 is formed on the inner peripheral taper surface of the bush sleeve.
By pressing a, the spring portion 11d bends, and the gap size between the inner peripheral surface 11b and the workpiece 51 indicated by a virtual line in FIG. 1 can be adjusted. Further, the guide bush 11 is provided with a fitting portion 11e between the spring portion 11d and the screw portion 11f. By fitting the fitting portion 11e into the center hole of the bush sleeve 23 shown in FIGS. 23 and 24, the guide bush 11 can be arranged on the center line of the main shaft and parallel to the main shaft center line. it can.

The material of the guide bush 11 is as follows.
After forming an outer shape and an inner shape using alloy tool steel (SKS), a quenching process and a tempering process are performed.
Furthermore, preferably, the inner peripheral surface 1 of the guide bush 11
As shown in FIG. 3, the super hard member 12 may be fixed to 1b by brazing means. As the super hard member 12, tungsten (W) is 85% to 90%, and carbon (C) is 5%.
~ 7%, Cobalt (Co) as binder 3% ~ 10
% Is used.

However, the guide bush 11 has a gap of 5 μm to 10 μm in the radial direction between the inner peripheral surface 11b and the workpiece 51 with the outer peripheral tapered surface 11a closed. As a result, the workpiece 51 comes in and out and comes into sliding contact with the inner peripheral surface 11b, so that its wear becomes a problem.

Further, when used in a fixed type guide bush device as shown in FIG. 23, the workpiece 51 held by the fixed guide bush 11 rotates at a high speed and is processed. There is a problem that sliding occurs between the surface 11b and the workpiece 51 at a high speed, and furthermore, seizure occurs due to excessive pressing force of the workpiece 51 against the inner peripheral surface 11b due to a cutting load.

Therefore, the above-mentioned hard carbon film (DLC) 15 is provided on the inner peripheral surface 11b of the guide bush 11. The thickness of the hard carbon film 15 is 1 μm to 5 μm. In the example of FIG. 1, a hard carbon film 15 is formed on the base material (alloy tool steel) of the guide bush 11 via an intermediate layer described later, and in the example of FIG. The hard carbon film 15 is formed via the intermediate layer.

This hard carbon film has properties very similar to diamond. That is, it is characterized by high mechanical strength, low coefficient of friction, lubricity, good electrical insulation, high thermal conductivity, and excellent corrosion.

Therefore, the guide bush 11 provided with the hard carbon film 15 on the inner peripheral surface 11b has remarkably improved abrasion resistance, and can be used for a long time or in heavy cutting.
Wear of the inner peripheral surface 11b that comes into contact with the workpiece 51 can be suppressed. In addition, it is possible to suppress the occurrence of scratches on the workpiece 51, and the guide bush 11 and the workpiece 5
The occurrence of image sticking with 1 can also be suppressed.

Therefore, the reliability of the guide bush 11 for long-term use can be remarkably improved, and the guide bush 11 can be sufficiently used for a fixed type guide bush device.
Here, various configuration examples of the portion of the inner peripheral surface 11b of the guide bush 11 where the hard carbon film 15 is formed are shown in FIG.
4 to 7 which are enlarged cross-sectional views corresponding to a portion surrounded by a circle A in FIG. 33, and FIG. 8 which shows a configuration example of an intermediate layer by enlarging a part of FIG. .

FIG. 4 corresponds to an enlarged view of a portion A in FIG. 1, and is disposed on a base material (alloy tool steel) of the inner peripheral surface 11b of the guide bush 11 via an intermediate layer 16 for improving adhesion. The hard carbon film is formed with a thickness of 1 μm to 5 μm. Depending on the material of the base material of the guide bush 11, it is also possible to form a hard carbon film directly on the surface without the intermediate layer 16.

FIGS. 5 and 6 correspond to enlarged views of the portion A in FIG. 3. In both cases, the super hard member 12 having a thickness of 2 mm to 5 mm is fixed on the base material of the inner peripheral surface 11b of the guide bush 11. The hard carbon film 15 is formed on the inner peripheral surface of the substrate. By doing so, the guide bush 11
Is further improved in durability. In the example shown in FIG. 5, the hard carbon film 15 is formed on the inner peripheral surface of the super hard member 12 via the intermediate layer 16 for further improving the adhesion.

In these examples, the hard carbon film 15
A cemented carbide such as tungsten carbide (WC) or a sintered body of ceramics such as silicon carbide (SiC) can be used as the cemented carbide member 12 provided in the lower layer. When sintering ceramics, Cr, N
Although i, Co and the like are added as a binder, when the addition is small, the hard carbon film 15 can be formed directly on the super hard member 12 without the intermediate layer 16.

FIG. 7 shows the inner peripheral surface 11 of the guide bush 11.
b, the guide bush 1
1 to form a carburized layer 11k on the base material near the inner peripheral surface 11b,
An example in which a hard carbon film 15 is formed on the inner peripheral surface 11b by the carburized layer 11k is shown.

Carburization is one of the methods of hardening steel materials.
This is a well-known process in which the surface layer is hardened and the deep portion remains tough. For example, methane (CH ₄ ) or ethylene (C ₂
Carburizing is performed under the following conditions in a mixed gas atmosphere of a carburizing gas containing carbon such as H ₄ ) and a carrier gas of nitrogen (N ₂ ).

(Carburizing conditions) Temperature 1100 ° C. Time 30 minutes Carburizing depth 0.5 mm

When the carburized layer 11k is formed on the inner peripheral surface 11b of the guide bush 11 as described above, the hard carbon film 15 can be formed directly on the surface, but the adhesion is further improved on the surface. It is more preferable to form an intermediate layer 16 for increasing the hardness, and to form the hard carbon film 15 via the intermediate layer 16.

The intermediate layer 16 is made of a material of the Periodic Table IV.
Group b silicon (Si) or germanium (Ge) or a compound of silicon or germanium may be used. Alternatively, a compound containing carbon such as silicon carbide (SiC) or titanium carbide (TiC) may be used. Also,
As the intermediate layer 16, titanium (Ti), tungsten (W), molybdenum (Mo), or tantalum (Ta) is used.
And a compound of silicon (Si).

Further, as shown in FIG. 8, the intermediate layer 16 is made of a lower layer 16a of titanium (Ti) or chromium (Cr) and silicon (Si) or germanium (Ge).
May be formed as a two-layer film with the upper layer 16b. In this case, the titanium and chromium of the lower layer 16a of the intermediate layer 16 play a role of maintaining the adhesion to the base material of the guide bush 11, and the silicon and germanium of the upper layer 16b are covalently bonded to the hard carbon film 15, and It plays a role of strongly bonding to the hard carbon film 15.

Further, the intermediate layer 16 may be formed of a two-layer film of a lower layer of a titanium compound or a chromium compound and an upper layer of a silicon compound or a germanium compound. Alternatively, a two-layer film of a lower layer of titanium or chromium and an upper layer of a silicon compound or a germanium compound may be used. Further, a two-layer film of a lower layer of a titanium compound or a chromium compound and an upper layer of silicon or germanium may be used.

[Example of Method for Forming Intermediate Layer] The intermediate layer 16
May be applied by a sputtering method, an ion plating method, a chemical vapor deposition (CVD) method, or a thermal spraying method. Hereinafter, a method for forming the intermediate layer 16 using a sputtering method will be described with reference to FIGS.

As shown in FIG. 9, one wall 9 of the vacuum chamber 91 is provided.
A target cover 96 is fixedly provided inside 1a, and a target 90, which is a material of an intermediate layer, is disposed there. Then, the guide bush 11 is disposed so as to face the target 90 with the end on the side having the inner peripheral surface 11b facing the target. At this time, the center opening 1 of the guide bush 11
The axis 1j is arranged so as to be perpendicular to the surface of the target 90.

The target 90 here is made of titanium (Ti) or chromium (C
r), silicon (Si), silicon carbide (Si
C) or tungsten carbide (WC). Then, the guide bush 11 is connected to a DC power supply 92. The target 90 is connected to a target power supply 97. Then, the exhaust port 9 is evacuated by an exhaust means (not shown) so that the degree of vacuum in the vacuum chamber 91 becomes 3 × 10 ⁻⁵ torr or less.
Evacuate from 5

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.
After that, a negative DC voltage of −50 V is applied to the guide bush 11 from a DC power supply 92 to
A DC voltage of -600 V is applied to 0 from the target power supply 97. Then, plasma is generated in the vacuum chamber 91, and the surface of the target 90 is sputtered by ions in the plasma.

As a result, the material of the intermediate layer struck from the surface of the target 90 is transferred to the guide bush 11.
4 adheres to a portion not covered by the cover member 94 of FIG.
Is formed. Or Figure 5
As shown in (1), the intermediate layer 16 can be formed on the superhard member 12 fixed to the inner peripheral surface 11b of the guide bush 11. The thickness of the intermediate layer 16 is 0.5 μm.
m.

However, as shown in FIG.
Is formed in a two-layer film of the lower layer 16a and the upper layer 16b,
First, the lower layer 16a having a thickness of about 0.5 μm is formed using a lower layer material (eg, titanium or chromium) as the target 90, and then the lower layer 16a is formed using the upper layer material (eg, silicon or germanium) as the target 90. The upper layer 16b is formed.

When the intermediate layer is formed, as shown in FIG. 9, if the outer peripheral surface of the guide bush 11 is covered with a cover member 94 such as aluminum foil, the intermediate layer is formed only on the inner surface of the guide bush 11. can do.

In the case where silicon carbide (SiC) is used as the super hard member 12, the formation of the intermediate layer 16 can be omitted. This is because silicon carbide is a compound of silicon and carbon belonging to Group IVb of the periodic table and is covalently bonded to the hard carbon film 15 formed on the surface thereof, thereby obtaining high adhesion.

[Description of Method for Forming Hard Carbon Film on Inner Peripheral Surface of Guide Bush] Next, various embodiments of the method for forming a hard carbon film on the inner peripheral surface of the guide bush according to the present invention will be described. First, using the guide bush 11 shown in FIG. 3 as an example, a process of forming the guide bush before forming a hard carbon film on the inner peripheral surface 11b will be described.

The guide bush 11 is formed by cutting using alloy tool steel (SKS) to form an outer tapered surface 11a, a spring portion 11d, a fitting portion 11e, and a screw portion 11f.
Then, an inner peripheral surface 11b formed by the center opening 11j and a step portion 11g having a larger inner diameter than the inner peripheral surface 11b are formed. Thereafter, the cylindrical super hard member 12 is moved to the inner peripheral surface 11 of the guide bush 11.
b, and is fixedly joined by brazing.

Then, electric discharge machining is performed to form a slit 11c at an interval of 120 ° on the outer peripheral tapered surface 11a side of the guide bush 11. Polishing is further performed to form an inner peripheral surface 11b, an outer peripheral tapered surface 11a, and a fitting portion 11e.
Is performed to obtain the guide bush 11 before the hard carbon film is formed. Thereafter, it is desirable to form one or two intermediate layers by the method described with reference to FIG.

[First Embodiment: FIG. 10] Next, FIG.
0 describes a first embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention. In FIG. 10, reference numeral 61 denotes a vacuum chamber having a gas inlet 63 and an exhaust port 65, in which an anode 79 and a filament 78 are provided at the upper center.

The above-described guide bush 11 is vertically arranged at the lower center in the vacuum chamber 61 with the lower portion fixed by an insulating support 80. And this guide bush 1
In one central opening 11j, a thin rod-shaped auxiliary electrode 71 connected to the ground potential via a vacuum chamber 61 is arranged to be inserted. At this time, the auxiliary electrode 71 is positioned at the center (substantially on the axis) of the center opening 11j of the guide bush 11.

The auxiliary electrode 71 is made of a metal material such as stainless steel. It is desirable that the auxiliary electrode 71 be disposed about 1 mm inward so that its tip does not protrude from the opening end face 11h of the guide bush 11. Then, the degree of vacuum in the vacuum chamber 61 is 3 × 1.
0 such that the ⁵ torr, evacuated from the exhaust port 65.
Further, benzene is introduced into the vacuum chamber 61 as a gas containing carbon from the gas inlet port 63, and the pressure in the vacuum chamber 61 is controlled to be 5 × 10 ⁻³ torr.

Thereafter, a negative DC voltage is applied to the guide bush 11 from the DC power supply 73 via the reactor 74, a positive DC voltage is applied to the anode 79 from the anode power supply 75, and a filament power supply is applied to the filament 78. An AC voltage is applied from 77 to generate plasma in the vacuum chamber 61, and a hard carbon film made of hydrogenated amorphous carbon is formed on the inner peripheral surface 11b of the guide bush 11 by a plasma CVD method.

At this time, the DC voltage applied from the DC power supply 73 to the guide bush 11 is -3 kV, and the DC voltage applied from the anode power supply 75 to the anode 79 is about +50 V. The AC voltage applied from the filament power supply 77 to the filament 78 is an AC voltage of about 10 V so that a current of 30 A flows. The reactor 74 is configured by winding a copper wire around a core made of a magnetic material, and sets the reactance value to about 100 mH.

As described above, by applying a negative DC voltage to the guide bush 11 from the DC power supply 73 via the reactor 74, stable plasma is generated in a region around the guide bush 11 arranged in the vacuum chamber 61. Can be done. In addition, since an arc discharge, which is an abnormal discharge, does not occur in the guide bush 11 in the initial stage of film formation that affects the film quality of the hard carbon film, the film quality and adhesion of the hard carbon film are improved.

Further, the center opening 1 of the guide bush 11
1j, the auxiliary electrode 71 is provided to be grounded, so that not only the outer peripheral portion of the guide bush 11 but also
Plasma can be sufficiently generated also in the center opening 11j. In addition, the hollow discharge, which is an abnormal discharge, does not occur, thereby improving the adhesion of the hard carbon film to the inner peripheral surface 11b of the guide bush 11.

Further, since the potential characteristics become uniform in the longitudinal direction of the inner peripheral surface of the guide bush 11, the thickness distribution of the hard carbon film formed on the inner peripheral surface 11b becomes uniform. Moreover, since the film formation speed is increased, a hard carbon film having a uniform thickness from the opening end surface 11h side to the back side can be formed in a short time.

The diameter of the auxiliary electrode 71 may be smaller than the diameter of the center opening 11j of the guide bush 11, but is preferably about 5 mm from the inner peripheral surface 11b on which the hard carbon film is formed, that is, the plasma forming region. Is desirably provided. It is desirable that the ratio between the diameter of the auxiliary electrode 71 and the opening diameter of the guide bush 11 be 1/10 or less. When the auxiliary electrode 71 is made thinner, it can be made linear. Although the auxiliary electrode 71 is described as being formed of stainless steel, it may be formed of a high melting point metal material such as tungsten (W) or tantalum (Ta). The cross-sectional shape of the auxiliary electrode 71 is circular.

[Specific structural example of insulating support: FIG. 11] Here, a specific structure of the insulating support 80 for supporting the guide bush 11 and the auxiliary electrode 71 shown in a simplified form in FIG. 11 is shown in FIG. This insulating support 8
0, as shown in FIG. 11, has a first electrode plate 85 for electrically connecting to the guide bush 11, and has an exposed surface formed with a first insulating member 87 made of ceramics or a resin material. And the second insulating member 88. This first electrode plate 85 is connected to a DC power supply 73 via a reactor 74.

The inner peripheral surface 11b of the guide bush 11
When a hard carbon film is formed on the inner peripheral surface 11b
Is disposed on the inner surface of the center opening 11j of the guide bush 11 having a role of eliminating a step caused by the step 11g near the center. The inner diameter of the insertion member 83 is substantially the same as the opening of the inner peripheral surface 11b of the guide bush 11. The outer shape of the insertion member 83 is adapted to the inner surface shape near the inner peripheral surface 11b of the center opening 11j of the guide bush 11.

Further, the first insulator 81 for receiving the insertion member 83 and the second insulator 82 for receiving the first insulator 81 are arranged on the step 11g in the center opening 11j of the guide bush 11. The first insulator 81 and the second insulator
The insulator 82 is made of an insulating material made of ceramic.

The first insulator 81 and the second insulator 82 are provided with a through hole for inserting an auxiliary electrode 71 and an auxiliary electrode support member 72 for supporting the auxiliary electrode 71 by being fitted therein. The second insulator 82 is provided with a protruding portion 82a protruding from the guide bush 11. The auxiliary electrode 71 is supported by the auxiliary electrode support member 72 so as to be disposed at the center of the center opening 11j of the guide bush 11.

The first insulator 81 has a small-diameter hole portion 81a through which the auxiliary electrode 71 passes with a gap of about 0.01 mm to 0.05 mm, and a large-diameter portion for positioning the large-diameter portion 72a of the auxiliary electrode support member 72. Hole 81b.
That is, the first insulator 81 is provided with a stepped hole. On the other hand, the second insulator 82 is provided with a stepped hole portion 82b for positioning the large-diameter portion 72a and the small-diameter portion 72b of the auxiliary electrode support member 72. This second insulator 82
The aforementioned protruding portion 82 a is formed in the hole 8 of the first electrode plate 85.
5a.

Further, the screw portion 11 of the guide bush 11
guide bush receiver 84 provided with a female screw on a male screw of f
Screw. The guide bush receiver 84 has a role of preventing the first insulator 81 and the second insulator 82 from dropping out of the center opening 11j of the guide bush 11. The guide bush receiver 84 is made of a metal material such as stainless steel. The first insulating member 87 has an opening 8 corresponding to the outer dimensions of the guide bush receiver 84.
7a is provided.

Since the bottom surface of the guide bush receiver 84 is in contact with the upper surface of the first electrode plate 85, the contact area between the guide bush 11 and the first electrode plate 85 increases. Therefore, a DC negative voltage can be stably applied from the DC power supply 73 via the reactor 74, and variations in the thickness and quality of the hard carbon film can be suppressed.

On the other hand, when the third insulating member 88 is placed on the third
The insulating member 89 is provided with a concave portion 89a, and the second electrode plate 86 is fitted therein and held flush. The small-diameter portion 72b of the auxiliary electrode support member 72 is
, Penetrates through the second insulating member 88, and fits into the center hole 86 a of the second electrode plate 86.

A plurality of metal legs 100 which are fitted into the third insulating member 89 are provided vertically so as to be in contact with the back surface of the second electrode plate 86, as shown in FIG. It is placed on the bottom of a vacuum chamber 61 made of a conductive material. Therefore, the auxiliary electrode 71 is grounded via the auxiliary electrode support member 72, the second electrode plate 86, the leg 100, and the vacuum chamber 61.

As described above, by disposing the auxiliary electrode 71 and the auxiliary electrode support member 72 on the step portion 11g of the guide bush 11 via the first insulator 81 and the second insulator 82, the center of the guide bush 11 is formed. The auxiliary electrode 71 can be accurately arranged at the center of the opening 11j. When the auxiliary electrode 71 is displaced from the center of the center opening 11j of the guide bush 11, the auxiliary electrode 71 and the guide bush 1
The balance of the plasma discharge with the inner peripheral surface 11b of the hard carbon film is lost, and the thickness and quality of the hard carbon film vary.

Therefore, the step 11 of the guide bush 11
The first bushing 81 and the second bushing 82 are inserted so as to match the inner diameter of the guide bush g, and the position of the auxiliary electrode 71 is regulated by the holes 81a, 81b, 82b of the bushings 81, 82, so that the guide bushing is formed. The auxiliary electrode 71 can be accurately arranged at the center of the 11 central opening 11j. Therefore, the thickness and quality of the hard carbon film formed on the inner peripheral surface 11b do not vary.

Further, the projecting portion 82a of the second insulator 82 projecting from the guide bush 11 has the first
The protrusion 82a allows the guide bush 11 and the auxiliary electrode 71 to be completely insulated and separated from each other.

[Second Embodiment: FIG. 12] Next, FIG.
2, a second embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described. In the second embodiment and the third and fourth embodiments to be described subsequently, a plurality of guide bushes are arranged in a vacuum chamber similar to that shown in FIG. This is an embodiment in which a hard carbon film is simultaneously formed on a surface.

The second embodiment shown in FIG.
Arrange two guide bushes 11A and 11B in one,
An auxiliary electrode 71 is provided at the center of each central opening 11j.
A, 71B are inserted. Two guide bushes 11A,
11B is an opening 55a through which the auxiliary electrodes 71A and 71B pass,
Each of the auxiliary electrodes 71 on the conductive plate 55 having the
A and 71B are placed so as to be located at the center of each central opening 11j.

The auxiliary electrodes 71A and 71B are vertically fixed to the bottom of a vacuum chamber 61 made of a conductive material.
1 is grounded. The conductive plate 55 is insulated and placed on the bottom surface of the vacuum chamber 61 by legs 56 made of an insulating material.

Then, a negative DC voltage is applied to the conductive plate 55 from the DC power supply 73 via the reactor 74, and the negative DC voltage is applied to each of the guide bushes 11A and 11B. That is, in this embodiment, a DC voltage is applied to the two guide bushes 11A and 11B via a single reactor. Other conditions are shown in FIG.
0 and the same as in the first embodiment,
Plasma is generated in the vacuum chamber 61 by plasma CVD.
By the method, a hard carbon film is simultaneously formed on the inner peripheral surface 11b of each of the guide bushes 11A and 11B.

[Third Embodiment: FIG. 13] Next, FIG.
3, a third embodiment of the method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described.

In the third embodiment, the second
The difference from the third embodiment is that, as shown in FIG. 13, two guide bushes 11A and 11B are respectively
Are placed on individual conductive plates 55A and 55B installed on the bottom surface of the inside via legs 56A and 56B,
Each guide bush 11 is connected to each of the guide bushes 11 from the respective reactors 3A, 73B via the individual reactors 74A, 74B and the conductive plates 55A, 55B.
The only difference is that negative DC voltages are individually applied to A and 11B. The reactance values of the reactors 74A and 74B are both set to about 100 mH.

According to this embodiment, the independence of the plasma discharge between the plurality of guide bushes 11A and 11B can be improved. Therefore, no interference occurs between the respective plasma discharges, and the plasma discharge is stabilized,
A hard carbon film having good film quality and good adhesion can be formed on the inner peripheral surface 11b of each guide bush 11A, 11B.

[Fourth Embodiment: FIG. 14] Next, FIG.
4, a fourth embodiment of the method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described. The fourth embodiment differs from the third embodiment in that, as shown in FIG. 14, a common DC power supply 7 is connected to two guide bushes 11A and 11B.
3 and the individual reactors 74A and 74B and the conductive plate 55
The only difference is that a negative DC voltage is applied via A and 55B.

According to this embodiment, the DC power supply 73 is shared while increasing the independence of the plasma discharge between the plurality of guide bushes 11A and 11B.
The cost of the device can be reduced.

[Fifth Embodiment: FIG. 15] Next, FIG.
5, a fifth embodiment of the method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described. 15, parts corresponding to those in FIG. 10 are given the same reference numerals, and descriptions thereof will be omitted. The anode 79 and the filament 78 shown in FIG. 10 are not provided in the vacuum chamber 61 used in this embodiment.

The fifth embodiment is different from the method for forming a hard carbon film according to the first embodiment shown in FIG. 10 in that an auxiliary electrode grounded is inserted and arranged in a vacuum chamber 61. A DC power supply 73 ′ is connected to the guide bush 11.
And a methane (CH ₄ ) gas is introduced into the vacuum chamber 61 as a carbon-containing gas, and the degree of vacuum is reduced to 0.1 Torr. The only difference is that it is adjusted so that

Even in this case, stable plasma is generated not only on the outer peripheral surface side but also on the inner peripheral surface side of the guide bush 11, and a hard carbon film having good film quality and adhesion is formed on the entire surface of the guide bush 11. You. In particular, the hard carbon film 15 having a substantially uniform thickness over the entire length can be formed on the inner peripheral surface 11b facing the auxiliary electrode 71 in a short time.

[Sixth Embodiment: FIG. 16] Next, FIG.
6, a sixth embodiment of the method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described.

The sixth embodiment and the seventh and eighth embodiments to be described subsequently are similar to the second to fourth embodiments described with reference to FIG. 12 to FIG. In this embodiment, a plurality of guide bushes are arranged, and a hard carbon film is simultaneously formed on each inner peripheral surface thereof. 16, the same parts as those in FIG. 12 are denoted by the same reference numerals, and the description thereof will be omitted.

The sixth embodiment shown in FIG. 16 differs from the second embodiment shown in FIG.
5, a vacuum chamber 61 without an anode 79 and a filament 81 is used,
The two guide bushes 11A, 11
The only difference is that plasma is generated in the vacuum chamber 61 by simply applying a DC voltage of −600 V to DC from the DC power supply 73 ′ via the single reactor 74. According to this method, the same effect as in the above-described second embodiment can be obtained.

[Seventh Embodiment: FIG. 17] Next, FIG.
7, a seventh embodiment of the method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described. 17, the same parts as those in FIG. 13 are denoted by the same reference numerals, and the description thereof will be omitted.

The seventh embodiment shown in FIG. 17 is different from the third embodiment shown in FIG. 13 in that an anode 79 and a filament 78 are provided similarly to the fifth embodiment shown in FIG. The vacuum chamber 61 is used, and two guide bushes 11A and 11B arranged inside the vacuum chamber 61,
The only difference is that plasma is generated in the vacuum chamber 61 only by applying a DC voltage of minus 600 V from the individual DC power supplies 73A 'and 73B' via the individual reactors 74A and 74B. According to this method, the same effect as in the third embodiment can be obtained.

[Eighth Embodiment: FIG. 18] Next, FIG.
8, an eighth embodiment of the method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described. In FIG. 18, the same portions as those in FIG. 14 are denoted by the same reference numerals, and description thereof will be omitted.

The eighth embodiment shown in FIG. 18 differs from the fourth embodiment shown in FIG.
As in the fifth embodiment shown in FIG. 5, the vacuum chamber 61 without the anode 79 and the filament 78 is used,
The two guide bushes 11A, 11
The only difference is that plasma is generated in the vacuum chamber 61 by simply applying a DC voltage of −600 V to B through the individual reactors 74A and 74B from the common DC power supply 73 ′. According to this method, effects similar to those of the fourth embodiment can be obtained.

[Ninth Embodiment: FIG. 19] In the above description, the hard carbon film is formed on both the outer circumferential surface and the inner circumferential surface of the guide bush 11, but the hard carbon film is formed only on the inner circumferential surface. A film may be formed.
An embodiment in that case will be described with reference to FIG. The difference between FIG. 19 and FIG. 10 is that the guide bush 1
The only difference is that the outer peripheral portion 1 is covered with a cover member 67 such as an aluminum foil.

In this way, the hard carbon film can be firmly formed only on the surface inside the central opening 11j including the inner peripheral surface 11b of the guide bush 11. By doing so, the dimensional accuracy of the outer shape of the guide bush can be kept high, and the toughness of the slit formed by the formation of the hard carbon film on the entire peripheral surface of the guide bush is reduced. It can also be prevented.

[Tenth Embodiment: FIGS. 20 and 21] Next, referring to FIGS. 20 and 21, a tenth embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described. explain. In FIG. 20, FIG.
The same portions as 0 are denoted by the same reference numerals, and their description will be omitted.

20 is different from FIG. 10 in that a ring-shaped dummy member 5 having an inner diameter substantially equal to the diameter of the inner peripheral surface 11b of the guide bush 11 as shown in FIG.
The only difference is the use of 3. This dummy member 53 is also made of stainless steel, like the auxiliary electrode 71. The outer diameter of the dummy member 53 is substantially the same as the size of the opening end face 11h of the guide bush 11.

Then, as shown in FIG. 20, a guide bush 11 for forming a hard carbon film is arranged in a vacuum chamber 61 having a gas inlet 63 and an exhaust port 65. Then, the dummy member 53 is placed on the opening end face 11h of the guide bush 11. At this time, the inner peripheral surface 11b of the guide bush 11 and the inner peripheral surface of the dummy member 53 match.

As described above, a hard material may be fixed to the inner peripheral surface 11b of the guide bush 11 or an intermediate layer may be formed on the inner peripheral surface 11b. And, as in the case of FIG.
At the center of the center opening 11j of the guide bush 11,
The auxiliary electrode 71 having the ground potential is provided so as to be inserted. At this time, it is preferable that the tip of the auxiliary electrode 71 does not protrude from the upper end surface of the dummy member 53 and is located slightly inside.

The rest is the same as the method described with reference to FIG.
The inner as vacuum is 3 × 10- ⁵ torr, exhaust port 65
Evacuate from. Thereafter, benzene (C ₆ H ₆ ) as a gas containing carbon is introduced into the vacuum chamber 61 from the gas inlet port 63, and the pressure in the vacuum chamber 61 is controlled to 5 × 10 ⁻³ torr.

The guide bush 11 is connected to the DC power source 7.
-3 is applied from the anode power supply 75 to the anode 79, a +50 V DC voltage is applied from the anode power supply 75, and the filament 78 is supplied with a 10 V voltage so that a current of 30 A flows from the filament power supply 77.
Are applied. As a result, plasma is generated in a region around the guide bush 11 in the vacuum chamber 61, and the guide bush 1 is formed by plasma CVD.
A hard carbon film is formed on the surface including the inner peripheral surface 11b.

The function of the auxiliary electrode at this time is the same as that of the first embodiment, but the dummy member 53 has the following function. That is, such a guide bush 11
In the method of forming a hard carbon film on the inside, plasma is generated on the inner surface and the outer peripheral portion of the guide bush 11. Then, the charges are easily concentrated on the end face of the guide bush 11, and the open end face area has a higher potential than the inner face, that is, a so-called edge effect occurs. Here the guide bush 11
The plasma intensity in the vicinity of the opening end face 11h is larger than that in other areas, and is also unstable.

Further, the end region of the guide bush 11 is affected by both the plasma on the inner surface and the plasma on the outer periphery. When the hard carbon film is formed in such a state, the guide bush 11
The adhesiveness of the hard carbon film is slightly different between the region several millimeters behind the opening end face and the other region, and the film quality is also slightly different.

Therefore, as shown in FIG. 20, if a hard carbon film is formed by arranging a dummy member 53 on the open end surface 11h of the guide bush 11, the region having a different film quality and adhesion is formed on the inner surface of the guide bush 11. And is formed on the inner surface of the opening of the dummy member 53. According to an experiment, when a hard carbon film is formed on the guide bush 11 by the method shown in FIG.
A region having a width of 1 mm to 2 mm and slightly different film quality and adhesion was formed about 4 mm behind the opening end face of No. 1.

However, as shown in FIG. 20, a dummy member 53 having an opening dimension substantially equal to that of the guide bush 11 and having a length of 10 mm is placed on the opening end face 11h of the guide bush 11. As a result of forming the film under the above-described conditions for forming the hard carbon film, regions having different film quality and adhesion are formed on the inner peripheral surface of the dummy member 53, and the inner surface 11b of the guide bush 11 has the film quality and adhesion. No different regions were formed.

[Eleventh Embodiment: FIG. 22] Next, an eleventh embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention will be described with reference to FIG. In FIG. 22, the same portions as those in FIG. 15 are denoted by the same reference numerals, and description thereof will be omitted.

In the eleventh embodiment, a dummy member is placed on the open end face 11h of the guide bush 11 using the same vacuum chamber 61 as shown in FIG. The only difference is that the formation of is performed. According to this embodiment, the same operation and effect as those of the tenth embodiment can be obtained.

[Other Embodiments] As described above, a plurality of guide bushes 11 are arranged in a vacuum chamber,
Also in the method of forming a hard carbon film on 1b at the same time, a dummy member 53 may be placed on the open end face 11h of each guide bush 11 to form the hard carbon film.

In each of the embodiments described above, a case has been described in which one or two guide bushes are arranged in one vacuum chamber and a hard carbon film is formed on each inner peripheral surface thereof. It is also possible to arrange more than one guide bush and simultaneously form a hard carbon film on each inner peripheral surface thereof.

Further, in any of the embodiments, before the guide bush is disposed in the vacuum chamber for forming the hard carbon film, the guide bush is formed on the inner peripheral surface 11b by the method described with reference to FIG. It is preferable to include a step of forming an intermediate layer that enhances adhesion to the hard carbon film. In that case, in the step of forming the hard carbon film by the plasma CVD method in each of the above-described embodiments, the hard carbon film is formed on the intermediate layer on the inner peripheral surface 11b of the guide bush 11.

In each embodiment of the method of forming a hard carbon film on the inner peripheral surface of the guide bush according to the present invention, methane (CH ₄ ) or benzene (C ₆ H ₆ ) is used as a gas containing carbon. As described in the example, ethylene (C ₂ H ₄ ) and hexane (C ₆ H ₁₄ ) can be used. Further, these carbon-containing gases may be used after being diluted with an inert gas having a low ionization voltage such as argon (Ar). In that case, there is an effect that the plasma in the cylinder of the guide bush is further stabilized.

Alternatively, lubricity and hardness can be increased by adding a small amount (1% or less) of an additive during the formation of the hard carbon film. For example, when fluorine (F) or boron (B) is added, lubricity increases, and chromium (C
When r), molybdenum (Mo) or tungsten (W) is added, the hardness increases.

Further, after the guide bush is arranged in the vacuum chamber and before the hard carbon film is formed, argon (A)
r) or nitrogen (N ₂ ) is generated to bombard the inner surface of the cylinder of the guide bush, and then a plasma is generated by a gas containing carbon such as methane and benzene to form a hard carbon film.

As described above, by performing the pretreatment of the bombard with the inert gas, the temperature of the inner wall of the cylinder of the guide bush is increased to be activated. At the same time, impurities on the surface of the inner wall of the cylinder are knocked out, and the surface is cleaned. Due to these effects, the adhesion of the hard carbon film formed on the inner peripheral surface of the guide bush is further improved.

[0131]

As described above, according to the present invention, a DC voltage is applied to the guide bush via the reactor to generate plasma in the vacuum chamber, so that the inner peripheral surface of the guide bush is An arc discharge, which is an abnormal discharge, does not occur in the initial stage of film formation that affects the film quality of the formed hard carbon film, and a hard carbon film having good film quality and good adhesion can be formed.

Further, by introducing a gas containing carbon into the vacuum chamber and generating plasma with the auxiliary electrode at the ground potential inserted in the center opening of the guide bush, the inner peripheral surface of the guide bush is formed. A hard carbon film can be formed quickly and with a uniform thickness from the opening end side to the back side.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a guide bush to which the present invention is applied.

FIG. 2 is a perspective view showing the appearance of the same.

FIG. 3 is a longitudinal sectional view showing another example of a guide bush to which the present invention is applied.

FIG. 4 is an enlarged cross-sectional view corresponding to a portion surrounded by a circle A in FIG.

FIG. 5 is an enlarged sectional view corresponding to a portion surrounded by a circle A in FIG.

FIG. 6 is an enlarged cross-sectional view of another example corresponding to a portion shown by a circle A in FIG.

FIG. 7 is an enlarged cross-sectional view of another example corresponding to a portion shown by a circle A in FIG.

FIG. 8 is a diagram showing a configuration example of an intermediate layer by further enlarging a part of FIG. 5;

FIG. 9 is a schematic sectional view of an apparatus for explaining an example of a method for forming an intermediate layer on an inner peripheral surface of a guide bush.

FIG. 10 is a schematic sectional view of an apparatus for explaining a first embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

11 is a cross-sectional view showing a specific example of the structure of the insulator supporter 80 shown in FIG.

FIG. 12 is a schematic sectional view of an apparatus for explaining a second embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

FIG. 13 is a schematic sectional view of an apparatus for explaining a third embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

FIG. 14 is a schematic sectional view of an apparatus for explaining a fourth embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

FIG. 15 is a schematic sectional view of an apparatus for explaining a fifth embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

FIG. 16 is a schematic sectional view of an apparatus for explaining a sixth embodiment of the method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

FIG. 17 is a schematic sectional view of an apparatus for explaining a seventh embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

FIG. 18 is a schematic sectional view of an apparatus for explaining an eighth embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush according to the present invention.

FIG. 19 is a cross-sectional view similar to FIG. 10 when a covering member is added to the embodiment of FIG. 10;

FIG. 20 is a schematic sectional view similar to FIG. 10 of an apparatus for describing an embodiment of a method for forming a hard carbon film on the inner peripheral surface of a guide bush using a dummy member.

FIG. 21 is a perspective view of a dummy member used in the embodiment of FIG.

FIG. 22 is a schematic sectional view similar to FIG. 15 of an apparatus for describing another embodiment of a method of forming a hard carbon film on the inner peripheral surface of a guide bush using a dummy member.

FIG. 23 is a cross-sectional view showing only the vicinity of the main shaft of an automatic lathe provided with a fixed type guide bush device using a guide bush to which the present invention is applied.

FIG. 24 is a cross-sectional view showing only the vicinity of a main spindle of an automatic lathe provided with a rotary type guide bush device using a guide bush to which the present invention is applied.

[Explanation of symbols]

 11: guide bush 11a: outer peripheral taper surface 11b: inner peripheral surface 11c: slot 11d: spring portion 11e: fitting portion 11f: screw portion 11g: step portion 11h: end surface 11j: center opening 15: hard carbon film 16: intermediate Layer 53: Dummy member 61: Vacuum tank 63: Gas introduction hole 65: Exhaust hole 67: Matching circuit 69: High frequency power supply 71: Auxiliary electrode 73, 73 ': DC power supply 74, 74A, 74B: Reactor 75: Anode power supply 78: Filament power supply 79: Anode 80: Insulation support 81: Filament

Continued on the front page (72) Inventor Takashi Toida 840 Takeno, Shimotomi, Tokorozawa-shi, Saitama Citizen Watch Co., Ltd. Tokorozawa Office (72) Inventor Shunichi Sekine 6-11-12 Honcho, Tanashi-shi, Tokyo SHICHI Dun Watch Co., Ltd. Tanashi Factory (56) References JP-A-62-182278 (JP, A) JP-A-7-88709 (JP, A) International Publication 96/28270 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 16/00-16/56 B23B 13/12 INSPEC (DIALOG)

Claims (6)

(57) [Claims] 1. When mounted on an automatic lathe, it is formed in a substantially cylindrical shape having a central opening in the axial direction, has an outer tapered surface at one end, an inner peripheral surface in sliding contact with a workpiece, and a slit. ,
A method of forming a hard carbon film on an inner peripheral surface of a guide bush that holds a workpiece inserted into the center opening slidably and axially close to a cutting tool, wherein the guide bush is It is arranged in a vacuum chamber provided with a gas inlet and an exhaust port and an anode and a filament, and an auxiliary electrode is inserted into a central opening forming the inner peripheral surface of the guide bush, and the auxiliary electrode is set to a ground potential, After evacuating the vacuum chamber, a gas containing carbon is introduced into the vacuum chamber from the gas inlet, and a DC voltage is applied to the guide bush via a reactor, and a DC voltage is applied to the anode. An AC voltage is applied to the filament to generate plasma in the vacuum chamber, and a hydrogenated amorphous carbon is applied to the inner peripheral surface of the guide bush by a plasma CVD method. Forming a hard carbon film on the inner peripheral surface of the guide bush, wherein the hard carbon film is formed by using a hard carbon film. 2. When mounted on an automatic lathe, it is formed in a substantially cylindrical shape having a central opening in the axial direction, has an outer peripheral tapered surface at one end, an inner peripheral surface in sliding contact with a workpiece, and a slit. ,
A method of forming a hard carbon film on an inner peripheral surface of a guide bush that holds a workpiece inserted in the center opening slidably and axially near a cutting tool, wherein the guide bush is It is arranged in a vacuum chamber provided with a gas inlet and an exhaust port, an auxiliary electrode is inserted into a central opening forming the inner peripheral surface of the guide bush, and the auxiliary electrode is set to a ground potential, and the vacuum chamber is evacuated. After that, a gas containing carbon is introduced into the vacuum chamber from the gas inlet, and a DC voltage is applied to the guide bush via a reactor to generate plasma in the vacuum chamber.
A method of forming a hard carbon film on the inner peripheral surface of the guide bush, wherein a hard carbon film made of hydrogenated amorphous carbon is formed on the inner peripheral surface of the guide bush by a VD method. 3. The method for forming a hard carbon film on an inner peripheral surface of a guide bush according to claim 1, wherein a plurality of the guide bushes are arranged in the vacuum chamber, and the central opening of each guide bush is provided. The auxiliary electrode is inserted into each of the guide bushes, the respective auxiliary electrodes are set to the ground potential, and a DC voltage is applied to each of the guide bushes through a single reactor. A method of forming a film. 4. The method for forming a hard carbon film on an inner peripheral surface of a guide bush according to claim 1, wherein a plurality of the guide bushes are arranged in the vacuum chamber, and the central opening of each guide bush is provided. An auxiliary electrode is inserted into the inside of the guide bush, and a DC voltage is applied to each of the guide bushes from an individual power supply via an individual reactor to each of the guide bushes. A method of forming a hard carbon film on a surface. 5. The method for forming a hard carbon film on an inner peripheral surface of a guide bush according to claim 1, wherein a plurality of the guide bushes are arranged in the vacuum chamber, and the central opening of each guide bush is provided. Auxiliary electrodes are inserted into the inside of each of the guide bushes, and each auxiliary electrode is set to the ground potential, and a DC voltage is applied to each of the guide bushes from a common power source via an individual reactor. A method of forming a hard carbon film on a surface. 6. The method of forming a hard carbon film on an inner peripheral surface of a guide bush according to claim 1, wherein the guide bush is arranged before the guide bush is arranged in the vacuum chamber. A step of forming an intermediate layer on the inner peripheral surface of the bush to enhance adhesion with the hard carbon film, wherein the step of forming the hard carbon film by the plasma CVD method comprises: A method for forming a hard carbon film on an inner peripheral surface of a guide bush, wherein the hard carbon film is formed on an intermediate layer.