JP2801451B2 - Jig for metal processing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for processing a soft metal including aluminum, copper and the like.

[0002]

2. Description of the Related Art Conventionally, metal working methods using plastic deformation include rolling, drawing, shearing, bending, drawing, compression,
Rolling and the like are known. In order to perform these processes, there is a processing jig that contacts the metal to be processed at a point, a line, or a plane and plastically deforms the metal to be processed. For example, punches and dies for punching, punches and dies for drawing, dies for drawing, and the like correspond to this.

[0003] Since these jigs come into contact with the metal to be processed and, in some cases, undergo plastic deformation while sliding, the jigs themselves have high wear resistance and a low friction coefficient, that is, have low sliding characteristics. It is required to be excellent. From such a viewpoint, a jig made of cemented carbide is most generally used as a processing jig.

[0004]

However, when a soft metal such as aluminum or copper is processed, for example, when the jig is made of a sintered body, the voids existing on the surface of the sintered body may be damaged. There is a problem that a build-up phenomenon such as clogging and welding of metal occurs, which causes roughness on the surface of the processed metal product. Therefore, in order to reuse the jig, a step of polishing the surface of the jig with diamond powder or the like is required, and there is a problem that the dimensions of the jig itself change.

In recent years, in order to reduce the weight and cost of a product, the thickness of the product tends to be reduced when, for example, drawing is performed. In such a case, it is necessary to reduce the molding pressure, but it is difficult to reduce the molding pressure with a conventional jig due to a high friction coefficient.

[0006] Solid or liquid lubricants have been used to solve these problems, but their effects are not sufficient, and the surface condition of the jig as described above deteriorates due to long-term use. At present, it is inevitable that the product will have an adverse effect.

In recent years, it has been proposed to form a diamond film on the surface of a jig for metal working to improve wear resistance, but it has not been sufficiently studied from the viewpoint of reducing the friction coefficient. In addition, the problem of welding and the like in the processing of soft metals has not been studied at all.

Accordingly, an object of the present invention is to have excellent sliding characteristics when processing a soft metal such as aluminum or copper,
An object of the present invention is to provide a jig for metal processing in which occurrence of welding or the like is suppressed.

[0009]

Means for Solving the Problems The inventors of the present invention have studied the above objects and have studied various methods for forming a hard carbon film on a metal working jig, and various methods for forming a hard carbon film. characteristics of the carbon film was examined in detail that is composed of diamond and amorphous carbon on the surface of a predetermined base material, the intensity of the largest peak present in 1333 ± 10 cm ^-1 in the Raman spectrum analysis H ₁ 1500 ± 100c
When the intensity of the largest peak existing at m ⁻¹ is H ₂ , H
_The above object is achieved by forming a hard carbon film having an intensity ratio represented by ₂ / H ₁ of 0.2 to 20 and a surface roughness (Rmax) of 2 μm or less and having excellent surface smoothness. I learned that

[0010]

Hereinafter, the present invention will be described in detail. The metal working jig of the present invention is formed by coating a hard carbon film formed on the surface of a predetermined base material.
It is important to control the thickness to less than μm. This is because the surface roughness of the jig at the point of contact with the metal greatly affects the surface condition of the product after processing. If the surface roughness of the film exceeds 2 μm, The metal is easily welded, the surface of the processed product becomes rough and scratched, and the contact resistance with the metal during processing is large, the wear of the hard carbon film increases, the carbon film peels off, etc. It is particularly desirable that the thickness be 1 μm or less.

Further, according to the present invention, when the film itself has a high crystallinity and is composed only of diamond, the crystal constituting the film tends to have a large grain size, so that the surface roughness of the film is high. Tend to increase. On the other hand, by lowering the crystallinity of the hard carbon film and allowing amorphous carbon to be present in the diamond, the surface roughness of the film tends to decrease. According to the present invention, the average crystal grain size of the film is preferably a fine crystal having an average crystal grain size of 3 μm or less, particularly 1 μm or less.

The diamond of the present invention itself has a cubic structure and can provide abrasion resistance to the film. However, amorphous carbon has a graphite-like structure and the film has a sliding property. Characteristics can be improved. In such a hard carbon film, the existence ratio of diamond to amorphous carbon was 1333 ± 10
The intensity of the largest peak present at cm ^-1 is H ₁ , 1500
When the intensity of the maximum peak existing at ± 100 cm ⁻¹ is defined as H ₂ , the intensity ratio represented by H ₂ / H ₁ is 0.2 to 20,
In particular, it is desirable to be in the range of 1 to 10. This ratio means that the crystallinity of the film increases as the value decreases.If the ratio is lower than 0.2, the crystallinity increases, the amount of diamond increases, and the hardness of the film increases. Since the surface roughness increases and the coefficient of friction with metal increases, it is necessary to polish the surface of the film. On the other hand, when the above ratio exceeds 20, the amount of amorphous carbon increases, and the sliding characteristics are maintained, but the abrasion resistance of the film tends to decrease.

In the present invention, the base material of the jig for metal working is not particularly limited. For example, in addition to ceramic materials such as silicon nitride and silicon carbide, WC-C
An o-based cemented carbide, a cermet containing TiC or TiCN as a main component, or the like can be used. Among them, a ceramic mainly containing silicon nitride is particularly preferable because of its high adhesive force.

As a method of forming a hard carbon film, a general microwave plasma CVD method, a hot filament CVD method,
A high-frequency plasma CVD method, a thermal plasma CVD method, and the like are known. However, these methods generally have a small area where a film can be formed. Must be formed several times. Further, in the case of the hot filament method, there is a problem that versatility is lacking because an operation such as stretching a filament in accordance with the shape of the jig is required. Therefore, in order to manufacture the jig for metal working in the present invention, an electron cyclotron plasma CVD method (hereinafter referred to as EC) is used as a film forming method.
R plasma method). A manufacturing method according to this method will be described with reference to FIG. A base material 2 on which a carbon film is formed is installed in a reaction furnace 1. A microwave generator 3 for generating plasma in the reactor and an electromagnetic coil 4 for generating a magnetic field are arranged around the reactor.

When a film is formed by using such an apparatus, a raw material gas containing at least carbon as a gas for forming a carbon film is supplied through a gas introduction path 5 together with a carrier gas such as hydrogen, if necessary, into a reaction furnace. Introduce in the road. And
While maintaining the inside of the reaction furnace at a low pressure of 1 torr or less, a microwave of 2.45 GHz is introduced into the furnace through the waveguide 6. At the same time, about 87
A magnetic field of a level of 5 gauss or more is applied. This allows
Electrons cause cyclotron motion based on the cyclotron frequency f = eB / 2πm (m: mass of electrons, e: charge of electrons, B: magnetic flux density). When this frequency coincides with the microwave frequency (2.45 GHz), that is, when the magnetic flux density B becomes 875 Gauss, electron cyclotron resonance occurs. As a result, the electrons are remarkably absorbed by the microwave energy, accelerated, collide with neutral molecules and cause ionization, and generate high-density plasma even at a low pressure.

The temperature of the substrate at this time is set to 150 to 12
By maintaining the temperature at 00 ° C., a carbon film can be formed on the substrate surface.

In the present invention, when a hard carbon film having the above-mentioned predetermined characteristics is to be formed, the substrate temperature is about 150 ° C. to 800 ° C., the raw material gas concentration is about 10% to 60%,
The furnace pressure may be set in the range of 1 × 10 ⁻³ torr to 1 torr.

As the carbon-containing source gas used in the above-mentioned production method, in addition to hydrocarbon gases such as methane, ethane and propane, C _x H _Y O _Z (x, y and z are each 1)
Organic compounds and gases such as CO and CO ₂ as described above can also be used.

The mixing ratio and type of these gases have no effect on the effects of the present invention regardless of any of the known methods disclosed in JP-A-60-19197 and JP-A-61-183198. Has no effect.

Further, the jig for metal working of the present invention is particularly effective when working with soft metals such as aluminum, copper or alloys mainly composed of aluminum and copper. Examples of the die include a die used, a punch and a drawing die used for wire drawing.

[0022]

According to the present invention, since the hard carbon film formed on the surface of the metal working jig has low crystallinity and is composed of diamond and amorphous carbon, the crystal grain size of the film is small. The surface roughness of the film can be reduced. Further, since the film itself contains not only diamond but also amorphous carbon, the friction coefficient can be reduced while imparting wear resistance, and the slidability can be improved.

As a result, when a soft work metal such as aluminum or copper is worked by plastic deformation, it has excellent abrasion resistance in contact with the work metal and can have a small friction coefficient. Welding of the soft metal to the jig can be suppressed.

Further, the hard carbon film of the present invention has a low coefficient of friction and can be processed even at a low molding pressure, so that a thin metal can be processed.

[0025]

【Example】

Example 1 Using a device as shown in FIG.
A disk substrate made of a high-density silicon nitride sintered body containing Al ₂ O ₃ and Y ₂ O ₃ having a thickness of 0 μm and a surface roughness Rmax of 0.1 μm as an auxiliary agent is installed, and ECR plasma CVD is performed.
By applying a magnetic field having a maximum intensity of 2 kGauss by the method and applying a microwave power of 3.0 kW, the substrate temperature 6
A film was formed on the substrate surface under the conditions of 50 ° C. and a furnace pressure of 0.3 torr. In addition, methane gas, CO
₂ and hydrogen gas at 54 sccm and 36 sccc respectively
m, and mixed at a flow rate of 210 sccm.
Under these conditions, the carbon film was formed so as to have a thickness of about 6 μm.

When the obtained carbon film was subjected to Raman spectroscopic analysis of the film surface, a diamond peak and an amorphous carbon peak were observed, and a two-phase structure of diamond and amorphous carbon was observed. I found it. In addition,
The Raman spectroscopy was performed by narrowing an 488 nm Ar laser beam to a beam diameter of about 1 μm. Peak intensity ratio is 1100cm
Pull the hatched between positions ^-1 and 1700 cm ^-1, which performs curve fitting process each peak as the baseline as the Lorentz type, after peak separation, the ratio determined height H _1, H ₂ of each peak was calculated, it was H ₂ / H ₁ = 17. Here, H ₁ is 13
H ₂ is the maximum peak intensity existing at 33 ± 10 cm ⁻¹ , and H ₂ is the maximum peak intensity existing at 1500 ± 100 cm ⁻¹ .

When the surface roughness of the carbon film was evaluated by a stylus type surface roughness meter, it was Rmax 0.3 μm or less.

Further, in order to evaluate the sliding characteristics of the film, the disk on which the carbon film was formed and an aluminum pin having a tip having a radius of curvature R = 4.763 mm were slid by a pin-on-disk method. A dynamic test was performed. The sliding conditions were a load of 19.6 N, a sliding speed of 2 m / sec, room temperature, in the air, and without lubrication for about 45 hours.

By this test, the friction coefficient and the specific wear amount were evaluated. For comparison, a similar sliding test was performed on a disk having no carbon film. The result is expressed in sliding characteristics (distance)
FIG. 2 shows the change in the coefficient of friction with respect to.

According to FIG. 2, the friction coefficient of the ceramic disk not coated with the carbon film varies between 0.4 and 0.5, and the dispersion is large. On the other hand, the disk on which the carbon film is formed according to the present invention is 0.1% from the beginning of sliding.
It shows the following low coefficient of friction, and shows that there is almost no variation. Observation of the sliding trace of the disk revealed that the disk not covered with the carbon film had a trace of being scraped off with a pin and had a depth of about 5 μm. It was also observed that aluminum was welded to the entire sliding mark.

On the other hand, the disk coated with the carbon film is hardly scraped off by the aluminum pin and has a depth of 1
μm or less, and almost no aluminum welding was observed.

FIG. 3 shows the results of measuring the sliding marks with a surface roughness meter.
It was shown to. The cross-sectional area of the sliding mark was determined from FIG. 3, the weight change of the aluminum pin before and after the test was measured, and the specific wear of the disk was calculated from the measured change. As a result, the weight reduction of the aluminum pin was 0.3% in the disk on which the carbon film was formed.
012 g, the specific wear amount was 1.9 × 10 ⁻¹⁷ m ² / N, whereas the disk without the carbon film had a weight loss of the aluminum pin of 0.096 g, and the specific wear amount was 1.9. × 10 ⁻¹⁵ m ² / N, and the disk on which the carbon film was formed by the above method has abrasion resistance 100 times that of a silicon nitride sintered body not coated with a carbon film, and a reduction in aluminum. Was also reduced to 1/10 or less.

Example 2 A carbon film was formed on the surface of the disk made of the silicon nitride sintered body in the same manner as in Example 1 except that the conditions for forming the carbon film were as shown in Table 1. The surface roughness of the obtained film and the friction coefficient of the pin-on-disk were measured.

Further, in the die portion 7 and the punch portion 8 made of silicon nitride for deep drawing as shown in FIG. Formed. Thereafter, a container made of aluminum or Cu was prepared by deep drawing using the jig, and the state of the sliding surface of the jig and the surface of the container were observed. Table 1 shows the results.

[0035]

[Table 1]

According to Table 1, a jig (sample No. ₁₎ having an intensity ratio H ₂ / H ₁ by Raman spectroscopy less than 0.2 was used.
In Nos. 4 and 5), the surface roughness exceeded 2 μm, the friction coefficient was large, and scratches were observed on the surface of the container obtained by deep drawing. When they were skiff-polished and finished to a mirror surface of Rmax 1 μm or less (Samples Nos. 6 and 7), the coefficient of friction also became small. From this, the strength ratio H ₂ / H ₁ was 0.2.
If it is smaller, it cannot be used unless the surface is polished.

On the other hand, samples containing diamond and amorphous carbon and having an intensity ratio H ₂ / H ₁ of 0.2 to 20 by the Raman spectroscopic analysis all have small surface roughness,
The coefficient of friction was small, the build-up was not reduced even during deep drawing, and the surface of the container was good without scratches.

[0038]

As described above in detail, according to the present invention, a jig used for processing a soft metal such as aluminum or copper by plastic deformation is provided with excellent wear resistance and slidability. Thus, welding of the soft metal to the jig during processing can be prevented, and the life of the jig can be extended.

[Brief description of the drawings]

FIG. 1 is a schematic layout view for explaining a method for forming a hard carbon film in a jig for metal working of the present invention.

FIG. 2 is a diagram showing a relationship between a sliding time and a friction coefficient in a pin-on-disk test of Example 1.

3A and 3B are diagrams showing the surface roughness of sliding marks on the disk surface after the pin-on-disk test of Example 1, wherein FIG. 3A shows a product of the present invention and FIG. 3B shows a comparative product.

FIG. 4 is a view showing a jig for drawing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction furnace 2 Substrate 3 Microwave generator 4 Electromagnetic coil 5 Gas introduction furnace

Claims (1)

(57) [Claims] 1. A jig for processing aluminum, copper or an alloy containing the same, wherein at least a contact surface of the jig with the metal is made of diamond and amorphous carbon, and is subjected to Raman spectroscopy analysis. 1333 ± 1
The intensity of the largest peak existing at 0 cm ^-1 is H ₁ , 150
The intensity of the largest peak existing at 0 ± 100 cm ⁻¹ is represented by H ₂
, The intensity ratio represented by H ₂ / H ₁ is 0.2 to 2
A jig for metal working, which is coated with a hard carbon film having a surface roughness (Rmax) of 2 μm or less.