JP2012066285A - Aluminum plate processing metal mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DLC coating metal mold capable of maintaining and improving product accuracy, especially smoothness of surface while enabling burring and ironing, etc. of an aluminum plate or an aluminum alloy plate by using aqueous lubricant instead of lubricating oil.SOLUTION: In a punch and a metal mold such as a die, a substantially hydrogen-free DLC film is formed on a surface of the metal mold, wherein the DLC film has a density of 3.0 g/cmor more and 3.4 g/cmor less, a nanoindentation hardness of 40 GPa or more and 100 GPa or less, an arithmetic mean roughness of 0.03 μm or less, a maximum height of 0.20 μm or less, and a defect density of surface of 10 pieces/mmor less.

Description

  The present invention relates to a mold for processing an aluminum plate or an aluminum alloy plate, and in particular, a punch or die for processing an aluminum plate or the like using a water-based lubricant instead of a lubricating oil, and a DLC film is formed on the surface. It relates to a processing mold.

  Conventionally, for example, an aluminum plate or an aluminum alloy plate to which Si or the like is added in order to impart hardness is frequently used for fins of an air conditioner or other heat exchanger because of its high thermal conductivity.

  In order to insert a large number of pipes into the fin, a large number of cylindrical holes having a predetermined collar are formed with high accuracy. Specifically, piercing (perforation), burring (expansion and flange formation), ironing (collar formation), and reflaring (flare formation) are performed using a die such as a punch or die. Is done.

  In such processing, if you simply use the mold, the aluminum will adhere to the mold, creating so-called mold galling, creating a streak on the product, and causing cracks from the product. Accuracy is significantly reduced. For this reason, conventionally, processing using a lubricating oil has been carried out to prevent seizure.

  In addition, when lubricating oil is used, there is an advantage that the surface property of the workpiece that comes into contact with the mold becomes smooth. In particular, in the case of fins, the collar inner side (cylindrical inner side) and the tube are preferably in close contact with each other from the viewpoint of heat exchange efficiency, and the processed surface is required to be as smooth as possible. Similarly, when laminating fins, smoothness is also required for a flare portion to be brought into contact with an adjacent fin, and lubricating oil plays an important role.

  That is, by using a lubricating oil, it was possible to ensure sufficient product accuracy with a conventional mold created for aluminum processing and to suitably manufacture fins and the like.

On the other hand, as a technique for improving mold quality and product quality, there is a technique for coating DLC (diamond-like carbon) on the mold surface. For example, Patent Document 1 discloses a DLC coated tool. “A DLC-coated tool formed by forming a DLC film substantially free of hydrogen on a substrate, wherein the DLC film has a density of 3.0 to 3.4 g / cm ³ and a nanoindentation hardness of 40. In the surface scanning detection with a measurement feed of 0.01 mm by a stylus type surface shape measuring instrument having a needle tip curvature radius of 2 μm and an arithmetic average roughness Ra of the film formation surface before the film formation of the substrate. The ratio ΔRa / t (= | Ra (D) −) of the absolute value change ΔRa (nm) of the arithmetic average roughness Ra (D) of the DLC film surface to (S) and the film thickness t (nm) of the DLC film Ra (S) | / t) is 0.1 or less, and the ratio s / t of the occupying area ratio s of unevenness due to adhesion and / or desorption of foreign particles on the surface of the DLC film is 0. DLC coating characterized by being 01 (% / nm) or less Tool "(claim 1). According to the present invention, it is said that a tool with ensured wear resistance and adhesion resistance is obtained.

However, the conventional technique has the following problems.
Due to the recent increase in environmental regulations, processing using lubricants has been avoided, and lubricants other than lubricants are being demanded from the trend of tightening regulations. Water or water based lubricants are good candidates.

  Here, some metal processing can be easily replaced with water-based lubricants, but piercing, burring, ironing, and flaring for aluminum plates or aluminum alloy plates are extremely difficult. There is a problem that galling occurs in the mold, resulting in poor product quality and thus heat exchange efficiency of the fins.

  In addition, when an aqueous lubricant is used, an organic lubricant may be coated on the material to be processed (target metal) and processed. However, in the above-described processing, an organic lubricant is coated on the aluminum plate. However, there was still a problem that type galling occurred.

  On the other hand, the DLC-coated tool of Patent Document 1 describes a molding punch or die (Claim 17). The inventors of the present application recognize that there is no DLC film on an aluminum fin processing punch or the like, and the embodiment corresponding to the claim has not been disclosed. A punch or die coated with the DLC film described in 1 was made on a trial basis, and the aluminum plate was processed using only an aqueous lubricant.

  As a result, it was found that the DLC film was peeled off even if the organic lubricant was not applied to the aluminum plate, causing galling, and the problem could not be solved.

  That is, conventionally, if lubricating oil is used, a good aluminum fin can be obtained without attaching a DLC film to the mold. However, if a water-based lubricant is used, the product quality is improved even if a DLC film is attached to the mold. It turns out that there is a problem of being inferior.

JP 2009-6470 A

  The present invention has been made in view of the above, and it is possible to burring or ironing an aluminum plate or an aluminum alloy plate using a water-based lubricant instead of a lubricating oil, while maintaining product accuracy, particularly the surface An object of the present invention is to provide a DLC film mold capable of maintaining and improving the smoothness of properties.

The mold according to claim 1 is a mold for piercing, burring, ironing, or flaring an aluminum plate or an aluminum alloy plate using an aqueous lubricant, and the surface of the mold In addition, a DLC film substantially free of hydrogen is formed, and the DLC film has a density of 3.0 g / cm ³ or more and 3.4 g / cm ³ or less, a nanoindentation hardness of 40 GPa or more and 100 GPa or less, an arithmetic average The roughness is 0.03 μm or less, the maximum height is 0.20 μm or less, and the surface defect density is 10 / mm ² or less.

  That is, the invention according to claim 1 makes it possible to burring or ironing an aluminum plate or an aluminum alloy plate using a water-based lubricant in place of the lubricating oil, while maintaining product accuracy, particularly smoothness of the surface properties. It is possible to provide a DLC coated mold that can maintain and improve the above.

  In the present invention, in order to further increase the hardness, the DLC film is a DLC film that does not substantially contain hydrogen. The term “substantially free of hydrogen” means that the film is formed in an environment in which hydrogen is not intentionally added. Examples of the manufacturing method include a sputtering method and a vacuum arc method, but a filter that realizes good film quality. Film formation by means of arc ion plating is particularly preferred.

Also, the density of the DLC film is 3.0 g / cm ³ or more and 3.4 g / cm ³ or less, and the nanoindentation hardness is 40 GPa or more and 100 GPa or less. It has been identified.

  In addition, the arithmetic average roughness (Ra) is set to 0.03 μm or less because the piercing process is performed in a severer environment than the conventional case where only the water-based lubricant is used instead of the lubricating oil for the aluminum plate or the aluminum alloy plate. It defines the conditions under which the DLC coating does not peel even when burring, ironing, or flaring.

  The maximum height (Rz) is set to 0.20 μm or less in order to define conditions for ensuring that the DLC coating does not peel and the smoothness of the processed surface is ensured. In addition, as a method of adjusting the arithmetic average roughness and the maximum height to the above-mentioned values, there is a film forming method by filtered arc ion plating after the surface of the mold base is smoothed by polishing or the like. Can do.

The defect density on the surface refers to defects that hinder the homogeneity of the film. For example, in film formation by arc ion plating, fine particles that are inevitably generated from the film forming raw material, that is, droplets are mixed in, so the defect density means the number of droplets per unit area. It becomes. The density of the droplets can be measured with a scanning microscope (SEM). The defect density of 10 pieces / mm ² or less is an upper limit value that does not cause DLC peeling and does not reduce the mold life. In the case of arc ion plating, the number of droplets can be reduced to 10 / mm ² or less by adjusting the conditions with filtered arc ion plating. The surface defect density means the density observed from the surface.

  The aluminum plate refers to pure aluminum, that is, a plate made of aluminum except for inevitable impurities, and the aluminum alloy plate refers to an alloy plate based on aluminum. Examples of the alloy plate include KS-176 and 612, and examples of the aluminum plate include 1M30-H26 (both made by Kobe Steel).

  The mold according to claim 2 is the mold according to claim 1, wherein the arithmetic average roughness of the surface of the base material itself before forming the DLC film is 0.03 μm or less, and the maximum height is 0.20 μm. It is characterized as follows.

  That is, the invention according to claim 2 ensures the uniformity of the film thickness and prevents stress concentration on the convex portion of the substrate surface, which becomes a peeling factor. Since the DLC film follows the surface of the base material, the smoothness of the base material is defined.

  According to a third aspect of the present invention, in the mold according to the first or second aspect, the thickness of the DLC film is 0.2 μm or more and 0.6 μm or less.

  That is, the invention according to claim 3 makes it difficult for film peeling of the mold to occur, and improves the mold life. That is, if the film is too thick, the surface roughness increases and galling is likely to occur. On the other hand, if the film is too thin, film peeling is likely to occur. .

  According to a fourth aspect of the present invention, in the metal mold according to the first, second, or third aspect, the base material is powder high-speed tool steel or cemented carbide.

  That is, the invention concerning Claim 4 can provide the metal mold | die using the base material suitable for a piercing process etc.

  According to the present invention, it is possible to maintain and improve product accuracy, particularly smoothness of surface properties, while enabling burring and ironing of an aluminum plate or an aluminum alloy plate using a water-based lubricant instead of a lubricating oil. A DLC coated mold can be provided.

It is the plane schematic ((a), (b)) and side schematic (c) of the metal mold apparatus incorporating the metal mold | die of this invention. It is the figure which showed the example of a metal mold | die (piercing punch, burring punch, ironing punch, ironing die) of this invention. It is the photograph which showed the mode of film | membrane peeling in case there exists an abrasion flaw on the base-material surface. FIG. 3B is an enlarged photograph of FIG. It is the photograph which showed the example of an ironing die galling. It is the photograph which showed the mode of film | membrane peeling in case a film thickness is thin. FIG. 5B is an enlarged photograph of FIG. It is a photograph before using the ironing punch and after 16000 shots. FIG. 6B is a photograph after use, and is a partially enlarged photograph of FIG. 6A before use. It is the photograph which showed the mode of the color inner surface of the aluminum plate after an ironing process. FIG. 7 (a) is a photograph after the ironing processing of the present invention, and FIG. 7 (b) is a photograph after the processing by the mold having the DLC film out of the condition. It is the photograph taken from the diagonal and the plane photograph of the aluminum plate after the burring process by the metal mold | die (metal mold | die from which film | membrane conditions remove | deviate from film conditions) which are not this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view and a schematic side view of a mold apparatus incorporating the mold of the present invention. FIG. 2 is a view showing an example of a mold according to the present invention (piercing punch, burring punch, ironing punch, ironing die). In FIG. 2, the ironing punch is shown as a cross-sectional view along the central axis.

  As shown in FIG. 1, the mold apparatus 100 is provided with a piercing unit 110, a burring unit 120, an ironing unit 130, and a flaring unit 140, the lower mold 101 is fixed, and the upper mold 102 moves up and down. The aluminum plate A is transported from the left and sequentially subjected to piercing processing in the piercing section 110, burring processing in the burring section 120, ironing processing in the ironing section 130, and flaring processing in the flaring section 140.

  In each processing part, the punches and dies shown in FIG. 2 are planted in a plurality of rows, and the arrangement is the same so that the eyes meet each other when the aluminum plate A is transferred to the next processing part. . The number of punches and dies in each processed portion is not limited, but can be, for example, 50 to 200 per processed portion. Further, the vertical movement speed (number of shots) of the upper mold 102 can be 200 to 400 times per minute.

  In the example shown in FIG. 2, a water passage is appropriately provided along the central axis inside the punch or die so that the water-based lubricant is supplied.

  Next, an ironing punch was used, and various conditions were changed, and an aluminum plate was ironed and evaluated. The used work material is a 0.1 mm thick aluminum plate (KS-176: manufactured by Kobe Steel Co., Ltd.) in which a bare resin material is provided with a hydrophilic resin film.

The mold size was the same as that shown in FIG.
The material of the mold was powder high-speed tool steel (HAP40: manufactured by Hitachi Metals).
In addition, as a result of preliminary investigation, it was found that when an aqueous lubricant was used, aluminum adhered to the mold in a few shots. Therefore, the conditions of the DLC film were examined hereinafter. In addition, the lubricant used was a tap water that was passed through a treatment device that removes chlorine, oxygen, impurities, etc. (taken by Takemoto Yushi: product name Fintonic) at a ratio of 50: fintonic 1. Was used.

The DLC film is formed on the substrate by filtered arc ion plating, the film forming conditions are adjusted, the density is 3.0 g / cm ³ or more and 3.4 g / cm ³ or less, and the nanoindentation hardness is set. It was made to become 40 GPa or more and 100 GPa or less. This is a condition disclosed also in Patent Document 1, and indicates the degree of covalent bonding that results in DLC, that is, a diamond structure. The density of diamond is 3.52, and it is the reach limit that it is 3.4 g / cm 3. The same applies to the upper limit of hardness of 100 GPa.
It was.

<Experiment 1>
First, dies were prepared by varying the arithmetic average roughness Ra and the maximum height Rz of the surface of the base material itself before forming the DLC film. A DLC film was attached to this, and several shots of ironing were performed, and the presence or absence of film peeling was examined. The results (relationship between Ra and Rz of the substrate and film peeling) are shown in Table 1. From the table, it was found that if the surface of the substrate itself was not smooth (the arithmetic average roughness was 0.03 μm or less and the maximum height was 0.20 μm or less), the DLC film was peeled off and galling occurred. In addition, in FIG. 3, the mode of peeling derived from surface irregularities (polishing streaks) is shown. FIG. 4 shows an example of an ironing die.

Several shots of ironing were performed to examine the presence or absence of film peeling.

In addition, although the thickness of the DLC film of the convex part of the substrate is relatively slightly thin and the thickness of the concave part tends to be relatively slightly thick, a film that substantially follows the surface of the substrate is formed. Hereinafter, the arithmetic mean roughness of the surface was set to 0.03 μm or less and the maximum height was set to 0.20 μm or less.

<Experiment 2>
Next, the relationship between the number of droplets (defect density) mixed in the DLC film and film peeling was examined. The used ironing punch (test die) was prepared as the same lot, and based on the result of Experiment 1, the arithmetic average roughness of the base material was 0.03 μm or less, the maximum height was 0.20 μm or less, and DLC The arithmetic mean roughness of the film surface was also 0.03 μm or less, and the maximum height was also 0.20 μm or less. Several shots of ironing were performed to examine the presence or absence of film peeling. The results are shown in Table 2. From the table, it was found that the defect density on the surface of the DLC film is preferably 10 pieces / mm ² or less.

  The test mold 2-4 is formed using a magnetic field deflection filter, the test mold 2-3 is formed using a magnetic field 90 degree deflection filter, and the test mold 2-2 is formed using a magnetic field. The test mold 2-1 is formed by using a 90-degree deflection filter and an orifice with a magnetic field and keeping the ion flight distance 10 mm away from the test mold 2-2. .

  The droplets were measured by SEM. The diameter of the droplet was approximately 1 [μm].

<Experiment 3>
Next, the relationship between the film thickness of DLC and film peeling was examined. The ironing punch used was prepared as the same lot, and based on the results of Experiment 1 and Experiment 2, the arithmetic average roughness of the substrate was 0.03 μm or less, the maximum height was 0.20 μm or less, and the DLC film was The arithmetic average roughness of the substrate was 0.03 μm or less, the maximum height was 0.20 μm or less, and the defect density was 10 / mm ² or less. Several shots of ironing were performed to examine the presence or absence of film peeling. The results are shown in Table 3. From the table, it was found that the thickness of the DLC film is preferably 0.2 μm or more and 0.6 μm or less.

  As shown in the table, the surface color of the mold varies depending on the film thickness, yellowing occurs when the thickness is less than 0.2 μm, green to dark blue when 0.2 μm to 0.6 μm, and 0.6 μm. If it exceeds, it is dark green to black. FIG. 5 shows a state after a shot of an ironing punch having a film thickness of 0.1 μm. As is apparent from the figure, peeling occurs at various places when the film thickness is thin. On the other hand, when the film thickness exceeded 0.6 μm, the film tended to peel off.

From the above, the DLC film on the surface of the mold that pierces the aluminum plate or the aluminum alloy plate using a water-based lubricant (a DLC film that substantially does not contain hydrogen)
The density is 3.0 g / cm ³ or more and 3.4 g / cm ³ or less,
-Nanoindentation hardness is 40 GPa or more and 100 GPa or less,
-Arithmetic average roughness Ra is 0.03 μm or less,
-Maximum height Rz is 0.20 μm or less,
-The surface defect density is 10 pieces / mm ² or less,
-The film thickness is 0.2 μm or more and 0.6 μm or less,
It was found that the conditions described above were suitable. At this time, it was confirmed that the arithmetic average roughness Ra of the surface of the base material itself before forming the DLC film is preferably 0.03 μm or less and the maximum height Rz is preferably 0.20 μm or less.

  Since each of the above experiments is an evaluation by processing several shots, lastly, durability was examined. A DLC film satisfying all the above conditions was applied to an ironing punch, an ironing die, a piercing punch, a piercing die, a burring punch, a burring die, a burring punch, and a burring die, and an aluminum plate was processed by the apparatus shown in FIG. . As a result, it was confirmed that film peeling did not occur even after 16000 shots were performed. FIG. 6 shows photographs of the ironing punch before and after use. As shown in the figure, no peeling occurred, the mold before and after the shot was smooth, and no change in appearance was observed.

  FIG. 7 is a photograph showing the appearance of the color inner surface of the aluminum plate after the ironing process. FIG. 7 (a) is a photograph after the ironing processing of the present invention, and FIG. 7 (b) is a photograph after the processing by the mold having the DLC film out of the condition. In the mold of the present invention, the inner surface of the collar is as smooth as a mirror surface, whereas in the mold not according to the present invention (the mold out of film conditions), the inner surface of the collar has a cloudy edge and the product quality is inferior. Can be confirmed.

  FIG. 8 is a plan photograph and an oblique photograph of an aluminum plate after burring processing using a mold that is not the present invention (a mold that deviates from film conditions). It can be confirmed that streaks derived from galling or the like are widened and cracked. On the other hand, although illustration is omitted, it was confirmed that such a crack does not occur in the mold of the present invention.

  In the above example, the mold material is powder high-speed tool steel, but the same is true for a mold in which a DLC film having the above conditions is formed on a cemented carbide. In addition, as an example of a cemented carbide, the cemented carbide classified into a fine grain cemented carbide alloy or an ultrafine grained cemented carbide alloy can be mentioned.

The present invention is applicable not only to fin processing but also to a can manufacturing line. Since the surface of the aluminum plate can be smoothly deformed, it is possible to produce a can without any peeling of the coating by processing and deforming an aluminum plate coated with a coating that is applied in accordance with the inclusion (content).

Claims (4)

A mold for piercing, burring, ironing, or flaring an aluminum plate or an aluminum alloy plate using an aqueous lubricant,
Forming a DLC film substantially free of hydrogen on the surface of the mold;
The DLC film is
The density is 3.0 g / cm ³ or more and 3.4 g / cm ³ or less,
Nanoindentation hardness is 40 GPa or more and 100 GPa or less,
Arithmetic mean roughness is 0.03 μm or less,
The maximum height is 0.20 μm or less,
The defect density of the surface is 10 pieces / mm ² or less,
Mold characterized by that.   2. The mold according to claim 1, wherein the arithmetic average roughness of the surface of the base material itself before forming the DLC film is 0.03 [mu] m or less, and the maximum height is 0.20 [mu] m or less.   3. The mold according to claim 1, wherein the DLC film has a thickness of 0.2 μm to 0.6 μm. 4. The mold according to claim 1, 2, or 3, wherein the base material is powder high-speed tool steel or cemented carbide.

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