JPH05169162A - Metal working jig - Google Patents

Abstract

PURPOSE:To improve wear resistance and slidability of a jig and to elongate the life of the jig without depositing mild metal on the surface of the jig. CONSTITUTION:This is a metal working jig to plastically deform a mild metal such as aluminum, copper, or mild alloy containing them. At least the sliding surface of this jig to this metal is covered with a hard carbon film which consists of diamond and amorphous carbon under a condition where pressure in a furnace is <=1 Torr in a reaction furnace and by the electronic cyclotron resonance plasma CVD method and where surface roughness is <=2mum, preferably, the ratio H2/H1 is 0.2-20 in the max. peak strength H1 of 1333+ or -10cm<-1> and the max. peak strength H2 of 1500+ or -100cm<-1> in the Raman spectroscopic analysis.

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 containing aluminum, copper or the like.

[0002]

2. Description of the Related Art Conventionally, metal working methods using plastic deformation include rolling, drawing, shearing, bending, drawing, compressing,
Rolling is known. In order to perform these processes, there is a processing jig which comes into contact with the metal to be processed at points, lines or surfaces to plastically deform the metal to be processed. For example, punches and dies for punching, punches and dies for drawing, and dies for wire drawing correspond to this.

These jigs have a high wear resistance and a low friction coefficient, that is, sliding characteristics, because they are brought into contact with the metal to be processed and in some cases undergo plastic deformation while sliding. It is required to be excellent. From such a point of view, conventionally, a jig made of cemented carbide is most commonly used as a working jig.

[0004]

However, when processing a soft metal such as aluminum or copper, for example, when the jig is made of a sintered body, the void portion existing on the surface of the sintered body is There is a problem that a build-up phenomenon occurs such that the metal is clogged and welded, which causes the surface of the processed metal product to become rough. Therefore, in order to reuse the jig, a step of polishing the surface of the jig with diamond powder or the like is necessary, and there is a problem that the dimensions of the jig itself change.

In recent years, there has been a tendency to reduce the thickness of the product when the product is lightened and the cost is reduced, for example, when drawing is performed. In such a case, it is necessary to reduce the molding pressure, but it has been difficult to lower the molding pressure because the conventional jig has a high friction coefficient.

Solid or liquid lubricants are used to solve these problems, but these 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 be adversely affected.

Recently, it has been proposed to form a diamond film on the surface of a metal working jig to improve wear resistance, but it has not been sufficiently studied from the viewpoint of reducing the friction coefficient. Much less, problems such as welding in the processing of soft metals have not been studied at all.

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

[0009]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies on the above objects, and various film forming methods and methods for forming a hard carbon film on a jig for metal processing are produced. When the characteristics of the carbon film were examined in detail, a hard carbon film composed of diamond and amorphous carbon and having a surface roughness of 2 μm or less and having excellent surface smoothness was formed by coating on the surface of a predetermined base material. Therefore, it was found that the above-mentioned object can be achieved.

Further, in the above-mentioned constitution of the present invention, the hard carbon film is 1333 ± in Raman spectrum analysis.
The intensity of the maximum peak existing at 10 cm ⁻¹ is H ₁ , 15
The intensity of the maximum peak existing at 00 ± 100 cm ^-1 is H
_{When 2} , the strength ratio represented by H ₂ / H ₁ is particularly preferably 0.2 to 20.

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

Further, according to the present invention, the crystallinity of the film itself is high, and when the film is composed only of diamond, the grain size of the crystals constituting the film tends to be large, so that the surface roughness of the film is Tends to increase. On the other hand, by lowering the crystallinity of the hard carbon film and allowing the amorphous carbon to exist in the diamond, the surface roughness of the film tends to be small. 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.

Further, the diamond in the present invention itself has a cubic crystal structure and can impart abrasion resistance to the film, but the amorphous carbon has a graphitic structure and the film slides. The characteristics can be improved. In such a hard carbon film, the abundance ratio of diamond and amorphous carbon is 1333 ± 10 in Raman spectroscopic analysis.
The intensity of the maximum peak existing at cm ⁻¹ is H ₁ , 1500
When the intensity of the maximum peak existing at ± 100 cm ⁻¹ is H ₂ , the intensity ratio represented by H ₂ / H ₁ is 0.2 to 20,
It is particularly desirable that the range is 1 to 10. This ratio means that the crystallinity of the film increases as the value decreases, and if the ratio is less than 0.2, the crystallinity is high, the amount of diamond increases, and the hardness of the film increases. Since the surface roughness increases and the coefficient of friction with the metal increases, it is necessary to polish the surface of the film. On the other hand, if the above ratio exceeds 20, the amount of amorphous carbon will increase and the sliding characteristics will be maintained, but the abrasion resistance of the film will tend to decrease.

In the present invention, the base material of the metal working jig is not particularly limited, but for example, in addition to ceramic materials such as silicon nitride and silicon carbide, WC-C.
O-based cemented carbide, cermet having TiC or TiCN as a main component, and the like can be used. Among these, ceramics mainly containing silicon nitride is 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, etc. are known. However, since these methods generally have a small film forming area, the metal forming jig of the present invention is required to be formed on the entire surface of a necessary portion. Must be divided into several layers for film formation. Further, in the case of the hot filament method, there is a problem that it lacks versatility because it requires an operation such as stretching the filament according to the shape of the jig. Therefore, in order to manufacture the metal working jig in the present invention, an electron cyclotron plasma CVD method (hereinafter referred to as EC
R plasma method) is adopted. A manufacturing method by 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. Further, a microwave generator 3 for generating plasma and an electromagnetic coil 4 for generating a magnetic field are arranged around the reaction furnace.

When a film is formed using such an apparatus, a raw material gas containing at least carbon as a carbon film-forming gas is introduced into a reaction furnace through a gas introduction path 5 together with a carrier gas such as hydrogen, if necessary. Install on the road. And
The inside of the reaction furnace is maintained at a low pressure of 1 torr or less, and at the same time, the microwave of 2.45 GHz is introduced into the furnace by the waveguide 6. At the same time, about 87 by the electromagnetic coil 4.
A magnetic field of a level of 5 gauss or more is applied. This allows
The electron causes a cyclotron motion based on the cyclotron frequency f = eB / 2πm (m: electron mass, e: electron charge, B: magnetic flux density). When this frequency matches 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 and accelerated, collide with neutral molecules and cause ionization, and generate high-density plasma even at 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 surface of the substrate.

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

As the carbon-containing raw material gas used in the above-mentioned production method, C _X H _Y O _Z (x, y, z are all 1 in addition to hydrocarbon gas such as methane, ethane, propane, etc.)
It is also possible to use gases such as organic compounds and CO, CO ₂ and the like shown in the above).

The mixing ratios and types of these gases have no influence on the effect of the present invention by using any of the known methods disclosed in JP-A-60-19197 and JP-A-61-183198. Does not reach.

Further, the jig for metal processing of the present invention is particularly effective when processing a soft metal such as aluminum, copper or an alloy mainly of these, and the jig is, for example, for drawing. Examples thereof include dies used, punches and drawing dies 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, it is possible to reduce wear coefficient while reducing friction coefficient and improve slidability.

As a result, when the soft work metal such as aluminum or copper is processed by plastic deformation, it has excellent wear resistance in contact with the work metal and can reduce the friction coefficient and It is possible to suppress the welding of the soft metal to the jig.

Further, since the hard carbon film of the present invention has a low friction coefficient and can be processed even at a low molding pressure, it is possible to process a thin metal.

[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 surface roughness Rmax of 0 mm and a surface roughness Rmax of 0.1 μm as an auxiliary was set, and ECR plasma CVD was performed.
By applying a magnetic field with a maximum strength of 2 kGauss and a substrate temperature of 6 kW under the condition of microwave output of 3.0 kW.
A film was formed on the surface of the substrate under the conditions of 50 ° C. and a furnace pressure of 0.3 torr. As the reaction gas, methane gas, CO
54 sccm and 36 sccc for ₂ and hydrogen gas, respectively
A mixture of m and 210 sccm was used.
Under this condition, the carbon film was formed to have a film thickness of about 6 μm.

When Raman spectroscopic spectrum analysis of the film surface was performed on the obtained carbon film, a peak of diamond and a peak of amorphous carbon were observed, and a two-phase structure of diamond and amorphous carbon was observed. I knew it was. In addition,
Raman spectroscopy was performed by narrowing the 488 nm Ar laser beam to a beam diameter of about 1 μm. Peak intensity ratio is 1100 cm
^-1 and 1700 cm ^-1 A diagonal line is drawn, and using this as a baseline, each peak is subjected to curve fitting with Lorentz type, and after peak separation, the heights H ₁ and H ₂ of each peak are calculated and the ratio is calculated. Was calculated, it was H ₂ / H ₁ = 17. Where H ₁ is 13
The maximum peak intensity existing at 33 ± 10 cm ⁻¹ and H ₂ are the maximum peak intensity existing at 1500 ± 100 cm ⁻¹ .

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

Further, in order to evaluate the sliding characteristics of this film, the disk on which the carbon film was formed and the tip portion were slid by a pin-on-disk method using an aluminum pin having a radius of curvature R = 4.763 mm. A dynamic test was conducted. The sliding conditions were a load of 19.6 N, a sliding speed of 2 m / sec, room temperature, in air, and no lubrication for about 45 hours.

The friction coefficient and the specific wear amount were evaluated by this test. For comparison, a similar sliding test was performed on a disk having no carbon film. The result is sliding characteristics (distance)
Is shown in FIG.

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

On the other hand, the disk coated with the carbon film was hardly scraped off by the aluminum pin, and the depth was 1
It was less than μm, and almost no aluminum welding was observed.

FIG. 3 shows the result of measurement of sliding marks with a surface roughness meter.
It was shown to. The cross-sectional area of the sliding mark was obtained from FIG. 3, the weight change of the aluminum pin before and after the test was measured, and the specific wear amount of the disk was calculated from it. As a result, the weight loss of the aluminum pin is 0.
While the specific wear amount was 012 g and the specific wear amount was 1.9 × 10 ⁻¹⁷ m ² / N, the weight loss of the aluminum pin was 0.096 g and the specific wear amount was 1.9 in the disk on which the carbon film was not formed. × a 10 ^-15 m ² / N, the disc forming a carbon film by the above method has the abrasion resistance of 100 times compared to the silicon nitride sintered body which does not cover the carbon film, a decrease in aluminum Could be suppressed to 1/10 or less.

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

Further, in a die portion 7 and a punch portion 8 made of silicon nitride for deep drawing as shown in FIG. 4, a carbon film 9 formed under the conditions of Table 1 is coated on a portion sliding on the metal to be processed. Formed. After that, a container made of aluminum or Cu was prepared by deep drawing using this jig, and the state of the jig sliding surface and the surface of the container due to the processing were observed. The results are shown in Table 1.

[0035]

[Table 1]

According to Table 1, in the jigs (Sample Nos. 4 and 5) in which the carbon film substantially consisting of diamond is formed, the surface roughness exceeds 2 μm, the friction coefficient is large, and Scratches were found on the surface of the resulting container.

On the other hand, the carbon film containing diamond and amorphous carbon has a small surface roughness and a small friction coefficient, and does not cause a build-up phenomenon even during deep drawing, and the surface of the container Was good without any scratches. In addition, the sample No. The film surface of the jigs Nos. 4 and 5 finished to a mirror surface with Rmax of 1 μm or less by skiving (Sample Nos. 6 and 7) has a small friction coefficient, and the surface of the container obtained by deep drawing is beautiful and no scratches are visible. I couldn't do it.

[0038]

As described above in detail, according to the present invention, it is possible to impart excellent wear resistance and slidability to a jig used for processing by plastic deformation of a soft metal such as aluminum or copper. As a result, it is possible to prevent the soft metal from welding to the jig at the time of processing and to extend the life of the jig.

[Brief description of drawings]

FIG. 1 is a schematic layout diagram for explaining a method for forming a hard carbon film in a metal working jig 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.

FIG. 3 is a diagram showing the surface roughness of sliding marks on the disc surface after the pin-on-disc test of Example 1, where (a) shows the product of the present invention and (b) shows the comparative product.

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

[Explanation of symbols]

 1 Reactor 2 Base material 3 Microwave generator 4 Electromagnetic coil 5 Gas introduction furnace

Claims (2)

[Claims] 1. A jig for processing aluminum, copper or an alloy containing them, which comprises diamond and amorphous carbon on at least the sliding surface of the jig with the metal and has a rough surface. A jig for metal working, characterized by being coated with a hard carbon film having a size of 2 μm or less. 2. The intensity of the maximum peak existing at 1333 ± 10 cm ⁻¹ in the hard carbon film in Raman spectroscopic analysis is H ₁ , and the intensity of the maximum peak existing at 1500 ± 100 cm ⁻¹ is H ₂ . The jig for metal working according to claim ₁ , wherein the strength ratio represented by H ₂ / H ₁ is 0.2 to 20.