JP2002307124A - Cold forging method of aluminum metal parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold forging method of an aluminum metal parts in which a firm lubricating film is formed on the surface of the metal parts and the time required for forming the lubricating film is considerably shortened. SOLUTION: The cold forging method of the aluminum metal parts comprises a base metal treating step of treating a base metal so as to easily form a firm lubricating film on the surface of the metal parts, a step of forming the lubricating film by applying a lubricant mainly consisting of vegetable oils to the surface of the metal parts, and a forging step of cold-forging the metal parts with the lubricating film formed thereon. By forming the lubricating film of the lubricant mainly consisting of vegetable oil with excellent oiliness, the boundary friction of the surface of the metal parts is considerably reduced, and the film forming step can be considerably shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold forging method for an aluminum-based metal part, and more particularly to a method for forming a strong lubricating film on the surface of a metal part and capable of significantly reducing the steps required for forming the lubricating film.

[0002]

2. Description of the Related Art Conventionally, in cold forging, in which a workpiece is processed by a mold at normal temperature, a lubricant for reducing friction is interposed between the mold and a metal part. Typically,
Liquid lubricants may have insufficient oil film strength, so a layer (chemical conversion coating) that holds the lubricant is formed on the surface of the metal component so that the metal component does not come into contact with the mold. , A film (lubricating film) to prevent seizure between the mold and metal parts and to smoothly release the metal parts from the mold
Is formed. Prior to cold forging, a base treatment step for forming these coats and a coat formation step for forming the coat were sequentially performed on the metal parts, and a chemical conversion coat and a lubricating coat were formed on the metal parts surface. Thereafter, cold forging is performed on the metal component.

[0003] Among metal parts, a metal part made of aluminum or an aluminum alloy has a luster due to its luster.
It is often used for optical components and components where appearance is important. Therefore, particularly in the case of cold forging of aluminum-based metal parts, it is necessary to prevent slight seizure and to remove surface products generated in the process of forming a film, so that the surface of the metal parts has a good gloss. is there.

[0004] For this reason, the applicant of the present invention has formed a lubricating film on a metal part through a process as shown in FIG. 4 when cold forging an aluminum-based metal part. That is, in the base treatment step, in the degreasing step, the metal component is immersed in a weak alkaline solution for several minutes to degrease it, washed with water, and then, in the etching step, immersed in an acid such as nitric acid for 10 to 20 minutes to perform etching, A minute uneven portion is formed on the substrate.

[0005] Next, in a film forming step, after the acid is washed away by water washing, in the chemical conversion film forming step, the metal part is immersed in a treating agent such as a zinc phosphate solution for several minutes to form a chemical conversion film on the surface of the metal part. I do. After washing with water, neutralize with a weak alkaline solution in the neutralization step, immerse in a metal soap solution such as sodium stearate for several minutes to form a lubricating film on the metal component surface in the lubricating film forming process, and dry the metal component surface in the drying process. Allow to dry.

[0006] After cold forging a metal part in the forging process,
Usually, heat treatment is performed on this metal part, but if the lubricating film remains on the surface, the soap will ooze out during the heat treatment. Completely removes the lubricating film. Further, in the surface product removing step, a surface product generated by reacting with an acid or an alkali in the process of forming a film by pickling or the like is removed.

[0007] As shown in FIG. 5, “New Press Working Data Book” published by Nikkan Kogyo Shimbun, Vol.
The same processes as those described above are described as a base treatment process and a film formation process for aluminum and an aluminum alloy.

[0008]

In the above-described method for cold forging an aluminum-based metal part, a very large number of steps are required in a film forming step, and a lubricant film is removed by boiling after cold forging. Since a process is also required, the number of man-hours for cold forging increases, and the production cost of metal parts becomes extremely high. Further, many equipment for these processes are required, which is disadvantageous in terms of equipment economics.
Further, since an acid or an alkali is used, waste liquid treatment and equipment for treating the waste liquid are also required.

Therefore, the applicant of the present application has used a high-viscosity mineral lubricant containing mineral oil as a main component as a liquid lubricant that does not require many steps as described above, and has been able to cool aluminum-based metal parts. I tried forging, but with mineral lubricating oil,
The strength of the oil film between the mold and the metal part was insufficient, and a boundary lubrication state in which the oil film was interrupted occurred, causing seizure between the mold and the metal part. As a result of this seizure, flaws were formed on the surface of the metal component, and poor gloss was also generated on the surface of the metal component.

An object of the present invention is to form a strong lubricating film on the surface of a metal component in cold forging of an aluminum-based metal component to prevent seizure and greatly shorten the process for forming the film. Or no use of acids or alkalis or minimizing the use thereof to facilitate waste liquid treatment, and use of a biodegradable lubricant to suppress adverse effects on the environment.

[0011]

According to a first aspect of the present invention, there is provided a method of cold forging an aluminum or aluminum alloy, wherein a lubricating film is formed on a surface of the metal part. A base treatment step of performing a base treatment for facilitating the coating, a coating forming step of applying a lubricant containing a vegetable oil as a main component to the surface of the metal component to form a lubricating coating, and a metal component having the lubricating coating formed thereon. And a forging step of cold forging.

When cold forging a metal part made of aluminum or an aluminum alloy, first, a base treatment is performed in a base treatment step to facilitate formation of a lubricating film on the surface of the metal part. The underlayer treatment is preferably one that can form minute irregularities on the surface of the metal component, such as etching using an alkali, shot peening with steel grains, and liquid honing with alumina abrasive grains. Next, a lubricant is applied to the surface of the metal component by a coating forming process to form a lubricating coating, and the metal component having the lubricating coating formed by the forging process is cold forged. Between the surface of the metal part and the mold for cold forging, the strength of the oil film for fluid lubrication is insufficient, and the oil film is likely to be in a boundary lubrication state in which the oil film is partially interrupted.

Here, the vegetable oil contains a large amount of higher fatty acids,
Since these higher fatty acids have a polar group, they can easily form an adsorption film by physical adsorption (electrical adsorption) on the surface of a metal component and thus have excellent oiliness, and this adsorption film significantly reduces the friction coefficient of the surface of the metal component. Therefore, by using the lubricant containing the vegetable oil as a main component, it is possible to reduce boundary friction in a boundary lubrication state on the surface of the metal component, prevent seizure, and smoothly release the metal component from the mold. it can. Further, since the lubricating film can be formed only by applying this lubricant to the surface of the metal component, the film forming process can be remarkably shortened.

According to a second aspect of the present invention, there is provided a method for cold forging an aluminum-based metal part according to the first aspect of the invention, wherein a lubricant containing rapeseed oil as a main component is used as the lubricant. Rapeseed oil, which is a vegetable oil, is excellent in oiliness because it contains a lot of higher fatty acids, and by using a lubricant containing this rapeseed oil as a main component, boundary friction on the surface of metal parts is reduced,
Seizure can be prevented, and the metal component can be smoothly released from the mold.

In a third aspect of the present invention, there is provided a method for cold forging an aluminum-based metal part according to the first aspect of the present invention, wherein a lubricant obtained by adding a hindered ester to rapeseed oil is used as the lubricant. Rapeseed oil, which is a vegetable oil, is excellent in oiliness because it contains a large amount of higher fatty acids. By using a lubricant containing this rapeseed oil as a main component, boundary friction on the surface of a metal component can be reduced. Hindered esters are esters of hindered alcohols and higher fatty acids.Hindered alcohols are alcohols in which a hydrogen atom is not bonded to a carbon atom adjacent to a hydroxyl group bonded to a hydroxyl group such as trimethylolpropane. Therefore, even when heated, olefins are not generated by dehydration. Therefore, hindered esters are excellent in oiliness and have good heat resistance.By adding this hindered ester to rapeseed oil, the oiliness of the lubricant can be improved even in a high temperature state due to friction during cold forging, Boundary friction on the surface of the metal component is further reduced, seizure is prevented, and the metal component can be smoothly released from the mold.

According to a fourth aspect of the present invention, there is provided a method for cold forging an aluminum-based metal part according to the first aspect of the invention, wherein a lubricant obtained by adding a hindered ester and an antioxidant to rapeseed oil is used as the lubricant. Things. Rapeseed oil, which is a vegetable oil, is rich in higher fatty acids and therefore excellent in oiliness, and by using a lubricant containing this rapeseed oil as a main component, boundary friction on the surface of metal parts can be reduced. Also,
By adding hindered esters to rapeseed oil, the oiliness of the lubricant can be improved even at high temperatures due to friction during cold forging, further reducing boundary friction on the surface of metal parts and preventing seizure The metal part can be released from the mold smoothly. In addition, rapeseed oil has a low oxidative stability because it contains a large amount of unsaturated fatty acids. However, by adding an antioxidant to rapeseed oil, the oxidative stability of the lubricant can be enhanced.

According to a fifth aspect of the present invention, there is provided a method for cold forging an aluminum-based metal part according to any one of the first to fourth aspects, wherein the base treatment step is performed by etching using an alkali. is there. Therefore, by performing etching using an alkali on the metal surface in the undercoating process to form fine irregularities on the surface, it is possible to prevent the lubricant from adhering to the metal component surface in the film forming process to form a lubricating film. Can be easier.

According to a sixth aspect of the present invention, there is provided a method for cold forging an aluminum-based metal part according to any one of the first to fourth aspects, wherein in the undercoating step, shot peening using steel grains is performed. Things. Therefore, in the undercoating process, the metal particles are sprayed onto the metal surface to form minute irregularities due to the impact of the collision of the steel particles. Can be easily formed.

The cold forging method for an aluminum-based metal part according to a seventh aspect is characterized in that, in the invention according to any one of the first to fourth aspects, in the base treatment step, liquid honing using alumina abrasive grains is performed. Is what you do. Therefore,
In the undercoating process, alumina abrasive grains are sprayed on the metal surface together with pressurized water and pressurized air to form minute irregularities due to the polishing effect. The formation of a coating can be facilitated.

[0020]

Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the present invention is applied to a case where a metal part 1 formed by cutting a bar (for example, a diameter of 30 mm) made of an aluminum alloy into a length of about 2 cm is cold forged. First, an apparatus for cold forging the metal component 1 will be described. A mold 2 for cold forging is provided on a clamp press machine 3, and the mold 2 has a projecting portion 4 projecting downward in a tapered shape and a horizontal contact surface 5 contacting the upper end surface of the metal component 1. Having. After applying a lubricant 6 for forming a lubricating film 6a to the surface of the metal component 1 by spraying, the metal component 1 is extruded from above by means of a mold 2, and as shown in FIG. A tapered recess 7 is formed at the upper end of the component 1, and at this time, the contact surface 5 of the mold 2 contacts the upper end of the metal component 1.

Next, a method of cold forging the metal part 1 will be described. As shown in FIG. 3, the cold forging method includes a base treatment step of performing a base treatment for facilitating formation of a lubricating film 6 a on the surface of the metal component 1;
And a forging step of cold-forging the metal part 1 on which the lubricating coating 6a is formed by applying a lubricant 6 containing a vegetable oil as a main component to the surface of the metal part 1 to form a lubricating coating 6a.

The base treatment step includes an etching step for forming minute irregularities on the surface of the metal component 1, and an ultrasonic cleaning step for removing a product generated on the surface in the etching step by ultrasonic cleaning. I have. In the etching step, the metal component 1 is immersed in an alkali solution (for example, a strong alkali solution such as an aqueous sodium hydroxide solution) for about 10 minutes to form minute irregularities on the surface of the metal component 1 and simultaneously perform degreasing of the surface. In the ultrasonic cleaning step, the metal component 1 is washed with water while applying ultrasonic waves to remove products on the surface.

Next, a film forming step will be described. The lubricant 6 that forms the lubricating film 6a on the surface of the metal component 1
A rapeseed oil, which is a kind of vegetable oil, is a main component, and a hindered ester for improving the oiliness of the lubricant 6 and an antioxidant are added. Rapeseed oil is a higher grade having a polar group such as oleic acid (18 carbon atoms, 1 double bond), linoleic acid (18 carbon atoms, 2 double bonds), erucic acid (22 carbon atoms, 1 double bond). High in fatty acids. The polar groups of these fatty acids are physically adsorbed (electrically adsorbed) on the surface of the metal component 1,
The higher fatty acids are long-chained and have a large molecular weight, so that the adsorption film is firmly held by mutual attraction between molecular chains. This adsorption film is 2
The contact between the two metals can be suppressed, and rapeseed oil, which is the main component of the lubricant 6, can easily form this adsorbing film and thus has excellent oiliness, and the lubricating coating 6a formed by the lubricant 6 has the surface of the metal component 1. Can be significantly reduced. Since rapeseed oil is a vegetable oil, it has very high biodegradability, is easy to treat waste oil, and has very little adverse effect on the environment.

The hindered ester (for example, an ester of trimethylolpropane and higher fatty acid) added to improve the oiliness of the lubricant 6 has a polar group and a large molecular weight, is excellent in oiliness, and is further heated. Even when the surface of the metal component 1 is brought to a high temperature state due to frictional heat during cold forging, the oiliness of the lubricant 6 can be improved because olefin is not generated by dehydration. . On the other hand, most of the higher fatty acids contained in the rapeseed oil are unsaturated fatty acids having a double bond as described above and have poor oxidative stability.
To prevent deterioration of lubrication performance due to deterioration of
An antioxidant is added to the lubricant 6 to enable long-term storage of the lubricant.

As shown in FIG. 3, in the lubricant spraying step as a film forming step, the lubricant 6 is applied to the surface of the metal component 1 by spraying. At this time, since fine irregularities are formed on the surface of the metal component 1 in the base treatment step, the sprayed lubricant 6 easily adheres to the surface of the metal component 1 to form a lubricating film 6a.

As shown in FIG. 2, after forming a lubricating film 6a on the surface of the metal part 1, in the cold forging step of the forging step, the die 2 is lowered to perform cold forging on the metal part 1. Lubricant 6
Is excellent in oiliness, so that the formed friction coating 6a can reduce the boundary friction of the surface of the metal component 1;
Seizure does not occur on the inner surface of the concave portion 7 of the metal component 1, and the metal component 1 can be released from the mold 2 smoothly. Further, since the lubricating coating 6a is formed of the lubricant 6, a step of removing the lubricating coating 6a after cold forging the metal component 1 is unnecessary.

According to the method for cold forging aluminum-based metal parts described above, the lubricant 6 containing rapeseed oil as a main component and added with a hindered ester and an antioxidant is applied to the surface of the metal part 1 in the film forming step. To form a lubricating coating 6a. Since the lubricant 6 has excellent oiliness even when the surface of the metal component 1 due to frictional heat is at a high temperature, boundary friction on the surface is reduced, seizure is prevented and metal The component 1 can be released from the mold 2 smoothly. Therefore, the inner surface of the concave portion 7 of the metal component 1 can be finished to a mirror-like shape, and its gloss can be improved. Further, by adding an antioxidant to the lubricant 6, the oxidative stability of the lubricant 6 can be improved, and deterioration of the lubricant 6 in a high temperature state during cold forging and oxidation during storage can be prevented.

In the film forming step, the lubricating film 6a can be formed only by applying the lubricant 6 to the surface of the metal component 1, so that the number of work steps in the film forming step can be remarkably reduced, and the film is formed. This is advantageous in terms of equipment economics because the equipment for performing this can be simplified. Further, the lubricating coating 6a
Need not be removed, so that a post-processing step in the forging step for the removal becomes unnecessary.

In the base treatment step and the film formation step,
The use of acid or alkali is only the etching step using alkali, so the amount of alkali used is small, the number of work steps for waste liquid treatment can be reduced, and equipment for waste liquid treatment is also simplified. It is possible.

Since the lubricant 6 containing rapeseed oil, which is a kind of vegetable oil, as a main component was used to form the lubricating film 6a, the lubricant 6 is extremely excellent in biodegradability, and is easy to treat waste oil. There is little adverse effect on the environment.

Next, a description will be given of modified embodiments obtained by adding various changes to the above-described embodiment. 1) In the base treatment step, the metal part 1 may be subjected to a base treatment using shot peening in which steel grains are sprayed on the surface of the metal part 1 to form irregularities. Alternatively, the metal component 1 may be subjected to a base treatment by using liquid honing in which alumina abrasive grains are sprayed on the surface of the metal component 1 together with pressurized water and pressurized air to form irregularities by the polishing effect.
When the base treatment is performed by these methods, acid and alkali are not used, so that waste liquid treatment and equipment for waste liquid treatment become unnecessary, and a product due to use of acid or alkali is generated on the surface of the metal component 1. Since there is no ultrasonic cleaning, ultrasonic cleaning is unnecessary.

2) The lubricant 6 may be applied directly to the surface of the metal component 1 by brushing or the like. In this case, it is desirable to apply the coating with substantially the same thickness so as not to cause unevenness. 3) It goes without saying that the present invention can be applied to cold forging of metal parts made of aluminum or aluminum alloy having different sizes and shapes from the present embodiment.

[0033]

According to the first aspect of the present invention, a cold forging method for an aluminum-based metal part includes a base treatment step of performing a base treatment for facilitating formation of a lubricating film on the surface of the metal part; Since the method includes a film forming step of forming a lubricating film by applying a lubricant containing vegetable oil as a main component on the surface of the metal part, and a forging step of cold forging the metal part having the lubricating film formed thereon, the following effects can be obtained.

When cold forging a metal part made of aluminum or an aluminum alloy, first, a base treatment for facilitating the formation of a lubricating film on the surface of the metal part is performed in a base treatment step. A lubricant mainly composed of vegetable oil is applied to the surface of the metal component to form a lubricating film, and the metal component is cold forged by a forging process. Vegetable oil is rich in higher fatty acids and therefore excellent in oiliness. By using a lubricant containing the vegetable oil as a main component, boundary friction on the metal surface is reduced, seizure is prevented, and metal parts are smoothly removed from the mold. Can be released. Accordingly, the surface of the metal component can be mirror-finished to improve its gloss.

Since a lubricating film can be formed only by applying a lubricant containing a vegetable oil as a main component to the surface of a metal part, the film processing step for forming the lubricating film can be remarkably shortened, and the lubricating film is removed after the forging step. Is also unnecessary,
This is advantageous in terms of the production cost of metal parts. Since the equipment for forming the coating can be simplified, the equipment is economically advantageous. In addition, lubricants are very biodegradable,
Waste oil treatment is easy and adverse effects on the environment can be suppressed.

According to the second aspect of the present invention, since a rapeseed oil-based lubricant is used as a lubricant, rapeseed oil, which is a vegetable oil, is rich in higher fatty acids and therefore excellent in oiliness. By using the lubricant, the boundary friction on the metal surface can be reduced, seizure can be prevented, and the metal component can be smoothly released from the mold. Other effects are the same as those of the first aspect.

According to the third aspect of the present invention, a rapeseed oil containing a hindered ester is added to a rapeseed oil as a lubricant. Therefore, rapeseed oil, which is a vegetable oil, is rich in higher fatty acids and thus has excellent oiliness. By using the lubricant described above, the boundary friction on the metal surface can be reduced.
In addition, by adding a hindered ester that is excellent in oiliness and has good heat resistance to rapeseed oil, the oiliness of the lubricant can be improved even in a high temperature state due to frictional heat during cold forging, and the surface of the metal part of the lubricant can be improved. Friction can be further reduced, seizure can be prevented, and the metal component can be smoothly released from the mold. Other effects are the same as those of the first aspect.

According to the fourth aspect of the present invention, a rapeseed oil containing a hindered ester and an antioxidant added to rapeseed oil is used as a lubricant. By using a lubricant containing rapeseed oil as a main component, boundary friction on the metal surface can be reduced. In addition, by adding a hindered ester that is excellent in oiliness and has good heat resistance to rapeseed oil, the oiliness of the lubricant can be improved even in a high temperature state due to frictional heat during cold forging, and the surface of the metal part of the lubricant can be improved. Friction can be further reduced, seizure can be prevented, and the metal component can be smoothly released from the mold. Further, by adding an antioxidant to rapeseed oil, the oxidative stability of the lubricant can be increased. Other effects are the same as those of the first aspect.

According to the fifth aspect of the present invention, since the etching using an alkali is performed in the undercoating process, the etching using the alkali is performed on the surface of the metal component to form irregularities on the surface, and the lubrication is performed in the film forming process. The agent can easily adhere to the surface of the metal component to form a lubricating film. In addition, it has the same effect as any one of the first to fourth aspects.

According to the sixth aspect of the present invention, in the undercoating step, shot peening using steel grains is performed, so that the steel grains are sprayed on the surface of the metal component to form irregularities, and the lubricant is removed in the film forming step. It is easy to form a lubricating film by attaching to the surface of the metal component. Further, since no acid or alkali is used, waste liquid treatment is unnecessary. In addition, it has the same effect as any one of the first to fourth aspects.

According to the seventh aspect of the present invention, in the undercoating process, liquid honing using alumina abrasive grains is performed, so that the alumina abrasive grains are sprayed on the surface of the metal component together with pressurized water and pressurized air to form irregularities. However, the lubricant can be easily attached to the surface of the metal component to form a lubricating film in the film forming step. Further, since no acid or alkali is used, waste liquid treatment is unnecessary. In addition, claim 1
4 has the same effect.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a cold forging method (before a forging step) of an aluminum-based metal component in an embodiment according to the present invention.

FIG. 2 is an explanatory diagram of a cold forging method (forging step) of an aluminum-based metal part.

FIG. 3 is a view showing work steps of a cold forging method of an aluminum-based metal part.

FIG. 4 is a view showing working steps of a conventional cold forging method for aluminum-based metal parts.

FIG. 5 is a table showing a base treatment step and a film formation step of a known aluminum-based metal component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal part 2 Die 6 Lubricant 6a Lubricant coating

Claims (7)

[Claims] 1. A method for cold forging a metal part made of aluminum or an aluminum alloy, wherein a base treatment step for performing a base treatment for facilitating formation of a lubricating film on a surface of the metal part; A forging step of applying a lubricant containing vegetable oil as a main component to form a lubricating film, and a forging step of cold forging the metal component having the lubricating film formed thereon. Method. 2. The method according to claim 1, wherein a lubricant containing rapeseed oil as a main component is used as the lubricant. 3. The method according to claim 1, wherein a lubricant obtained by adding a hindered ester to rapeseed oil is used as the lubricant. 4. The method according to claim 1, wherein a lubricant obtained by adding a hindered ester and an antioxidant to rapeseed oil is used as the lubricant. 5. The cold forging method for an aluminum-based metal part according to claim 1, wherein in the base treatment step, etching using an alkali is performed. 6. The method according to claim 1, wherein in the base treatment step, shot peening using steel grains is performed.
The cold forging method for an aluminum-based metal part according to any one of the above. 7. The cold forging method for an aluminum-based metal component according to claim 1, wherein in the base treatment step, liquid honing using alumina abrasive grains is performed.