JP3064166B2 - 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 processing jig for rounding a cylindrical metal edge in a process of manufacturing a container such as a can.

[0002]

2. Description of the Related Art Conventionally, metal working methods using plastic deformation include rolling, drawing, shearing, bending, and the like.
Drawing, compression, and rolling are known. In order to perform these processes, a processing jig such as a punch or a die is used to plastically deform the metal to be processed.

[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] In addition, especially in containers for food storage such as cans, soft drink cans, and beer cans, aluminum is used to prevent corrosion of the can material by the components in the container and leakage of the can material components into the food. The surface of a metal such as iron or soft iron is covered with a thin organic film.

The organic film is mainly made of an epoxy resin or the like, and has a very small thickness of several μm. When processing these containers, it is necessary to plastically deform the metal from above the organic film.However, if the organic film is damaged during processing and the can material is exposed, food can be contaminated or corrosion of the can material occurs. In general, the jig is mirror-polished and processed using the mirror surface.

As the types of cans currently manufactured, there are a three-piece can (a) and a two-piece can (b) as shown in FIG. The three-piece can (a) has a hollow cylindrical body 1 and upper and lower lids 2 and 3, and the two-piece can (b) has a bottom formed by processing one metal plate. It consists of a two-piece body 4 and a lid 5. In either case, before the lid is fitted to the cylindrical body, a step of rounding the edge of the cylindrical body is necessary before manufacturing the can. The body portions 1, 4 and the lids 2, 3, 5
Can be firmly fixed.

[0007] The step of rounding the edge of the cylindrical portion is usually performed by using a method shown in FIG.
The jig shown in FIG. That is, an R surface 9 is formed at a portion of the processing jig 6 where the edge 8 of the body 7 of the can comes into contact, and the edge 8 of the body 7 is brought into contact with the R surface 9 to extend the length of the can. The edge 8 is rounded by applying mechanical pressure in the direction.

[0008]

However, when a sintered body such as a cemented carbide is used as a processing jig, minute voids are inevitably present in the sintered body, and the surface of the cemented carbide is small. Even if the surface is mirror-finished, the void is exposed on the mirror surface. When soft metal is machined using a jig that has voids on its surface in this way, a so-called build-up phenomenon occurs in which the voids are clogged with metal and welded, resulting in a roughened surface of the processed metal product. There is a problem that occurs. Therefore, a step of polishing the surface of the jig with diamond powder or the like is necessary in order to reuse the jig, which causes a problem that the dimensions of the jig itself change.

When a metal having an organic film formed on its surface is processed by a jig made of cemented carbide, the organic film adheres to the surface of the processing jig while sliding on the organic film for a long period of time. There is a problem of getting up. When such adhesion occurs on the surface of the jig, the organic materials slide with a high friction coefficient on the sliding surface, so that the organic film on the surface of the metal to be processed is easily damaged, and the jig is re-mounted. There is a problem that polishing is required.

Further, when processing a metal on which an organic film is partially covered, the jig slides at the same time as the jig slides on the organic film and also on the metal portion where the organic film does not exist. Therefore, it is required that the jig has good sliding characteristics with the organic film and that the build-up phenomenon does not easily occur at the same time as the jig. At present, the organic film is frequently damaged by the raised portion.

Particularly, in the above-mentioned processing for rounding the edge of the metal cylinder, the metal member to which an organic film has already been applied is mostly processed, and the force applied to the working surface of the jig is large. It is very easy to damage the organic film. Furthermore, since the jig is very easily built up, the rounded edge of the processed product is easily damaged.

In recent years, in order to reduce the weight and cost of products, there is a tendency to reduce the thickness of the products when, for example, drawing is performed. In such a case, it is necessary to reduce the molding pressure. However, the conventional jig has a high friction coefficient, so that the organic film is easily damaged, and it is difficult to reduce the molding pressure.

Conventionally, 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. However, adverse effects on the product have been inevitable. In addition, in applications such as the aforementioned food storage containers, it is desirable to suppress the use of lubricants as much as possible from the viewpoint of preventing contamination of foods.

[0014] Recently, it has been proposed to form a diamond film on the surface of a metal working jig to improve the wear resistance. In particular, a base material for processing a metal having an organic resin on its surface has been proposed. Has not been sufficiently studied from the viewpoint of optimization of friction coefficient and reduction of friction coefficient.
Problems such as breakage of the organic film are not considered at all.

Therefore, an object of the present invention is to provide an excellent sliding property when a soft metal containing aluminum or soft iron having a cylindrical shape, particularly a surface whose surface is covered with an organic film, is rounded. An object of the present invention is to provide a long-life processing jig capable of suppressing welding and breakage of an organic film.

[0016]

The inventor of the present invention has studied the above object, and has formed an R surface at a portion where an edge of a cylindrical metal abuts, and this R surface has an edge of a body portion. And a jig for rounding the edge by applying mechanical pressure in the longitudinal direction of the cylindrical metal to form a hard carbon film. The characteristics of the carbon film to be formed, the surface shape, and the type of the jig base were examined in detail. As a result, Y ₂ O ₃ and Al ₂ O ₃ were added as sintering aids and fired to obtain a relative density of 99% or more. A silicon nitride sintered body is used as a substrate, and a surface roughness (R
It has been found that the above object can be achieved by forming a hard carbon film having a max of 1 μm or less.

Hereinafter, the present invention will be described in detail. The processing jig of the present invention is based on a high-density silicon nitride sintered body as a base material and has a surface coated with a hard carbon film.
It is important to use a high-density silicon nitride sintered body.
The reason is that the silicon nitride and the diamond in the hard carbon film have similar linear thermal expansion coefficients, so that a film having small thermal stress at the time of film formation and high adhesion can be obtained. In the rounding of the edge portion of the cylindrical metal in the present invention, a large shear stress is applied to the film at the time of processing, and the film is separated without sufficient adhesion between the film and the substrate. Unless a high-density silicon nitride-based sintered body is used, it is impossible to obtain an adhesive property enough to withstand the above-mentioned metal working.

Further, since the hard carbon film reflects the surface state of the substrate, if a void exists in the substrate, this portion remains in a void shape on the surface of the hard carbon film. When processing the metal, the metal may enter the void portion and cause build-up or welding. Therefore, since it is necessary to minimize voids on the surface of the base, the density of the sintered body used must be high. Specifically, it is desirable that the relative density of the sintered body is 99% or more.

It should be noted that such a high-density silicon nitride-based sintered body having a relative density of 99% or more has a higher Y density than silicon nitride.
_The mixture obtained by adding and mixing sintering aids of ₂ O ₃ and Al ₂ O ₃ is processed by a desired molding means, for example, a die press, a cold isostatic press, an extrusion molding or the like, as shown in FIG. After shaping into a jig shape, baking in nitrogen at 1600 to 2000 ° C. or in a nitrogen pressurization, and further in a nitrogen or argon atmosphere under a high pressure of 1000 atm or more, 1600 to 1
It can be obtained by refiring at 900 ° C.

Further, according to the present invention, the surface roughness of the hard carbon film in at least the sliding portion with the metal of the processing jig is 1 μm.
It is important to control to less than m. This is because the surface roughness of the jig at the contact portion with the metal greatly affects the surface condition of the product after processing, and the surface roughness of the film is 1 μm.
Exceeding the limit, the metal adheres to the carbon film when sliding with the soft metal or the organic film, causing the surface of the processed product to be rough or the organic film to be damaged. Desirably.

If the surface roughness of the carbon film after film formation is within this range, the carbon film can be used as it is, but if the surface roughness Rmax after film formation exceeds 1 μm, The film needs to be polished to have a surface roughness of 1 μm or less. In order to reduce the amount of polishing of the film after film formation, it is desirable that the substrate on which the film is formed is polished in advance to a surface roughness of 1 μm or less.

As a method of forming a hard carbon film, a 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, and these methods can generally form a film. Since the area is small, it is difficult to uniformly form a film on the entire required portion of the processing jig of the present invention. In the case of the hot filament method, by stretching the filament in accordance with the jig shape, it is possible to form a film on a relatively large area, but there is a difference in the uniformity of the film depending on the distance from the filament. There is a problem such as carbonization and disconnection of the filament due to carbonization, and thus lacks versatility and productivity.

Therefore, in the present invention, an electron cyclotron plasma CVD method (hereinafter, referred to as an ECR plasma method) is employed as a method for forming a hard carbon film. According to this method, a uniform and high-density plasma can be generated in a large space, and therefore, a uniform plasma can be generated for many jigs while maintaining a growth rate similar to that of a normal microwave plasma CVD method. A hard carbon film can be grown with a thickness.

Next, a manufacturing method based on the ECR plasma method will be described with reference to FIG. A base material 11 on which a carbon film is formed is provided in the reaction furnace 10. Also,
A microwave generator 12 for generating plasma in the reactor and an electromagnetic coil 13 for generating a magnetic field are arranged around the reactor 10. When a film is formed using such an apparatus, a raw material gas containing at least carbon such as methane as a carbon film-forming gas is optionally passed through a gas introduction furnace 14 together with a carrier gas such as hydrogen in a reaction furnace 10. And introduced into the reaction furnace 10. Then, while keeping the inside of the reaction furnace 10 at a low pressure of 1 torr or less, a microwave of 2.45 GHz is introduced into the furnace through the waveguide 15. At the same time, the electromagnetic coil 13
To apply a magnetic field of a level of about 875 gauss or more.
As a result, the electrons move to the cyclotron frequency f = eB / 2.
Cyclotron motion is generated based on πm (e: electron charge, B: magnetic flux density, m: electron mass). 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. By maintaining the temperature of the substrate at 100 to 1200 ° C. at this time, a hard carbon film can be formed on the surface of the substrate.

Examples of the carbon-containing source gas used in the above-mentioned production method include hydrocarbon compounds such as methane, ethane, and propane, and organic compounds such as CxHyOz (where x, y, and z are at least one). Gases such as CO and CO ₂ 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.

The hard carbon film obtained by the above-mentioned method is mainly composed of diamond, and has a characteristic almost similar to diamond. However, it is mixed with a slight amount of amorphous carbon component, gas, film forming apparatus, base material and the like. Unavoidable impurities.

The processing jig of the present invention is particularly effective when processing a material such as aluminum, soft iron or an alloy mainly composed of these, and a material coated with an organic film. For example, it is particularly useful as a punch used in the rounding process of the edge portion of a container in a can manufacturing process of a container for food or drinking water.

[0029]

According to the present invention, in particular, as a processing jig for rounding a metal edge, a substrate made of a high-density silicon nitride sintered body has a surface roughness Rmax of 1 μm or less.
By forming a hard carbon film made of diamond or the like, it is possible to process the workpiece without damaging the workpiece while having excellent wear resistance.

As a result, even when processing a soft metal such as aluminum or soft iron, or a material coated with an organic film thereon, it has excellent wear resistance in contact with a workpiece and a low friction coefficient. It is possible to reduce the size and suppress build-up and welding of the soft metal to the jig. In addition, since the deposition of metal is prevented, it is possible to process the organic film without damaging it.

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.

[0032]

【Example】

Example 1 First, as a base material, a material obtained by adding and mixing 5 wt% of Y ₂ O _{3 and} 5 wt% of Al ₂ O _{3 to} silicon nitride was formed into a processing jig shape, and then fired in nitrogen at 1800 ° C. After that, the resultant was further fired at 1900 ° C. in nitrogen at 2000 atm to obtain a processing jig base having a diameter of 30 mm and made of a high-density silicon nitride sintered body having a relative density of 99.8%. Further, the surface of the jig was polished to adjust the surface roughness Rmax to 0.4 μm.

Next, the processing jig base was set in a reaction furnace in an ECR plasma apparatus as shown in FIG. Thereafter, a magnetic field having a maximum intensity of 2 kGauss is applied by ECR plasma CVD, and a microwave output is applied.
Under the condition of 5 kW, the substrate temperature is 800 ° C. and the furnace pressure is 0.3 t.
Film formation was performed on the substrate surface under the conditions of orr. In addition, as a reaction gas, methane gas, carbon dioxide, and hydrogen gas were 4.5 sccm, 9 sccm, and 286.5 sccc, respectively.
m mixed at a flow ratio of m. Under these conditions, the carbon film was formed so as to have a thickness of about 10 μm.

When the surface roughness of the obtained carbon film was evaluated using a stylus type surface roughness meter, Rmax was 0.8 μm. When the coefficient of friction between this hard carbon film and metallic aluminum was measured by the pin-on-disk method, a low value of 0.11 was obtained. For comparison, when the same friction coefficient value was measured for a cemented carbide, the value was as large as 0.75.

With the jig on which the hard carbon film is formed,
Using a soft iron plate having a thickness of 0.4 mm and containing 0.1% of carbon coated with an organic film of epoxy resin with a thickness of 5 μm, 10,000 round edges of the cylindrical portion were rounded. For comparison, a similar processing test was performed on a jig made of cemented carbide. The results are shown in Table 1 as Sample Nos. 1 and 2.

As a result of the test, the jig of the sample No. 1 coated with the hard carbon film according to the present invention showed a good surface condition of the rounded portion even after the processing test of 10,000 pieces, and the organic film was formed on the metal part. No scratches were observed in the area. On the other hand, in the cemented carbide jig of sample No.2, when several hundred pieces were machined, scratches already appeared on the organic film and the metal part of the rounded part, and when the machining test of 10,000 pieces was completed, almost All the processed parts were scratched, and in some severe cases, the scratches on the metal part were split.

Further, Sample No. 1 coated with a hard carbon film
After processing 10000 jigs, no trace of abrasion was observed at all, and the sliding part did not change from the original state. However, the surface of the cemented carbide jig of Sample No. 2 The surface condition was very bad. When the sliding part on the surface of the cemented carbide jig was evaluated, the epoxy resin and iron were detected, and it was found that the organic film and iron were built up and adhered to the surface.

Example 2 The same procedure as in Example 1 was carried out except that the conditions for forming the hard carbon film, the type of the substrate, the surface roughness of the substrate, and the relative density of the substrate were as shown in Table 1. A hard carbon film is formed on the surface of a jig made of a sintered body, the surface roughness of the obtained film, the coefficient of friction with metal aluminum, the state of the processed portion after the metal cylinder edge rounding test, the jig The abrasion state, the organic film on the jig, and the adhesion state of the metal were evaluated. Table 1 shows the results. The samples Nos. 3, 4, and 7 were tested by polishing the film surface, and the surface roughness after polishing was also described.

[0039]

[Table 1]

As is clear from Table 1, the samples Nos. 3, 4, and 5 coated with the hard carbon film according to the present invention have a low coefficient of friction with metallic aluminum, which is about 0.1. Was. The surface condition of the rounded portion of the metal was good even after the rounding of 10,000 metal cylindrical edges, and no scratch was recognized on the metal portion or the organic film portion. Furthermore, no change was observed in the surface condition of the sliding portion of these samples compared to before the test, and no trace of wear or adhesion of a metal or organic film was observed. These results are exactly the same as those of the sample No. 1 shown in the first embodiment.

Samples Nos. 6 and 8 had a film surface roughness of 1 μm.
Therefore, it was found that the organic film on the metal surface was damaged during processing. Also, in sample No. 7, since the relative density of the silicon nitride sintered body was as low as 98%, the metal present in the voids present on the surface of the film during processing (this reflects the voids of the sintered body) And the organic film penetrated, resulting in a phenomenon such as adhesion, and the processed rounded portion was damaged.

Samples Nos. 9 and 10, which used SiC or alumina as the base material, did not have sufficient adhesion between the film and the base material as compared with the silicon nitride sintered body, and thus had a problem during the rounding test. The film peeled off and no good results were obtained.

[0043]

As described above in detail, the processing jig of the present invention rounds the edge of a soft metal containing aluminum or soft iron having a cylindrical shape, particularly a metal whose surface is covered with an organic film. During processing, it has excellent wear resistance and sliding characteristics, and can suppress welding and damage to the organic film. Further, since the adhesiveness to the substrate is strong, there is no possibility of peeling from the substrate during processing. In addition, since processing can be performed even at a low molding pressure, a metal having a small thickness can be processed.

[Brief description of the drawings]

FIG. 1 is a view for explaining the structure of a can, in which (a) shows a three-piece can and (b) shows a two-piece can.

FIG. 2 is a view for explaining a method of rounding an edge of a can.

FIG. 3 is a schematic layout diagram of an ECR plasma CVD apparatus.

[Explanation of symbols]

 1, 4, 7 Body 2, 3, 5 Lid 6 Processing jig 8 Edge 9 R surface

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification code FI C23C 16/26 C04B 35/58 102Y (58) Investigated field (Int.Cl. ⁷ , DB name) B21D 19/12 B21D 37 / 01 B21D 37/20 B21D 51/26 C04B 35/584 C23C 16/26

Claims (2)

(57) [Claims] An R surface is formed at a portion where an edge of a cylindrical metal having a thickness of 1 mm or less abuts, and an edge of a body portion abuts on the R surface so that a machine is formed in a longitudinal direction of the cylindrical metal. A jig for rounding the edge by applying an appropriate pressure,
Y ₂ O ₃ and Al ₂ O ₃ are added as sintering aids, and the surface of the substrate made of a silicon nitride sintered body having a relative density of 99% or more, which is baked, has a surface roughness ( A jig for metal working, which is formed by coating a hard carbon film having a Rmax of 1 μm or less. 2. The metal according to claim 1, wherein said cylindrical metal is a metal containing a soft metal such as aluminum or soft iron or an alloy thereof, and an organic film is formed on the surface thereof. Jig for processing.