JP5776765B2 - Processing lubricant, processing additive and processing method - Google Patents

Description

  The present invention relates to a processing lubricant that enables strong processing of an aluminum-based metal without causing seizure or the like, a processing additive used therefor, and a processing method using them.

  In order to produce high quality members at low cost, high workability is required. For example, when performing cold plastic processing such as forging, ironing, drawing, etc., the quality of the processed surface is maintained while increasing productivity by increasing the amount of deformation per operation, etc. It is required to extend the life. For this purpose, it is important to reduce the coefficient of friction between the processing tool and the workpiece and to improve the seizure resistance. Therefore, conventionally, a hard film that is effective in reducing the friction coefficient is provided on the surface of a processing tool such as a mold, and various processing lubricants (lubricating oils) are used, or they are combined for processing. Has been done.

  However, when a work material made of aluminum or an aluminum alloy (hereinafter, simply referred to as “aluminum alloy” including aluminum as appropriate) is cold-worked (for example, plastic working with a large surface area expansion ratio), Such a lubrication method tends to cause seizure, and it has been difficult to ensure the processing quality and the tool life. This is presumably because aluminum alloys have lower strength and lower ductility than steel materials and the like.

  Conventionally, in order to prevent such seizure, a solid lubricant film (bonded film) is often formed in advance on the surface of an aluminum alloy. However, formation of a solid lubricating film requires a chemical conversion treatment (see Patent Document 1 below), a heat drying step of metal soap, and the like, and is expensive. In addition, the solid lubricating coating often contains environmentally hazardous elements such as P and Zn, and its use is desired to be suppressed due to recent environmental problems.

  Under such circumstances, an aluminum alloy processing lubricant that replaces the solid lubricant film has been proposed. The description regarding these exists in the following patent documents 2-5, for example.

Japanese Patent Laid-Open No. 10-237667 Japanese Patent Publication No. 6-51875 Japanese Patent No. 3812849 JP-A-10-183151 JP 2004-358495 A JP 2010-95792 A

  Patent Document 2 proposes a lubricant for cold forging of an aluminum alloy obtained by adding a fatty acid to mineral oil. However, a lubricant to which a fatty acid having a molecular weight of at most several hundreds is added can cause seizure when the aluminum alloy is strongly processed cold.

  Patent Document 3 provides a lubricating oil suitable for plastic working of an aluminum alloy DI can. Similar to the lubricant disclosed in Patent Document 2, this lubricant also has insufficient seizure resistance. Further, this lubricating oil uses an extreme pressure agent containing sulfur (S) and phosphorus (P), which are environmentally harmful elements, and is not environmentally preferable.

  Patent Document 4 also provides a lubricating oil suitable for plastic working of an aluminum alloy DI can, but uses a water-soluble fatty acid having a molecular weight of 900 to 1300 as an additive. However, the seizure resistance is insufficient as in the case of Patent Document 3.

  Patent Document 5 proposes to form a DLC film on the narrowed portion of the jig and to apply lubricating oil to the narrowed portion during cold drawing of the aluminum alloy. The lubricating oil used here is obtained by adding a low molecular weight fatty acid ester, zinc phosphate or the like to mineral oil. This lubricating oil also contains environmentally hazardous elements P and Zn, which is not environmentally preferable.

  The above-mentioned Patent Document 6 is not a lubricant specialized for processing aluminum alloys, but is combined with a lubricant containing a fatty acid having a relatively low molecular weight and a die coated with a Si-containing amorphous carbon film. It is proposed to process.

  The present invention has been made in view of the circumstances as described above. In other words, processing without causing seizure or the like even when performing cold plastic processing with a high degree of processing on a workpiece made of an aluminum alloy without using an extreme pressure agent or the like that is an environmentally hazardous substance. It is an object to provide a lubricant. Moreover, it aims at providing the processing additive used for preparation of the processing lubricant, and the processing method using them.

  As a result of extensive research and trial and error, the present inventor has made efforts to solve this problem, and as a result, by using a polymer compound having a very large molecular weight that has not been used in a conventional processing lubricant, It was newly found that an aluminum alloy can be strongly processed with a low processing force without causing seizure without using an extreme pressure agent containing an element. By developing this result, the present invention described below has been completed.

《Processing lubricant》
(1) The processing lubricant of the present invention includes a coated surface of a processing tool coated with an amorphous carbon film and a processed surface of a workpiece made of aluminum or an aluminum alloy and processed in contact with the coated surface. The amorphous carbon film is a Si-containing amorphous carbon film containing silicon (Si) and the balance being C and H, and is composed of a carbonyl group and an amino group. 8 to 50% by mass of a high molecular compound having a surface functional group consisting of at least one of a carboxyl group or a hydroxyl group and having a molecular weight of 30,000 to 1,000,000 when the whole is 100% by mass. Features. Further, the processing lubricant of the present invention comprises a coating surface of a processing tool coated with an amorphous carbon film and a processing surface of a workpiece made of aluminum or an aluminum alloy and processed in contact with the coating surface. A processing lubricant interposed therebetween, wherein the amorphous carbon film is a Si-containing amorphous carbon film containing silicon (Si) and the balance being C and H, and includes a carbonyl group, an amino group, and a carboxyl group. 8 to 50% by mass of a water-soluble polymer compound having a surface functional group consisting of at least one of a group or a hydroxyl group and having a molecular weight of 8,000 to 1,000,000, based on 100% by mass as a whole. And

(2) By using the processing lubricant of the present invention, even when the workpiece is made of an aluminum alloy (including aluminum), between the workpiece and the processing tool coated with the amorphous carbon film Thus, high-quality strong processing can be performed with low processing force without causing seizure. Moreover, such an excellent effect is obtained between the coated surface of the processing tool coated with the amorphous carbon film and the processed surface of the workpiece processed by the same (hereinafter, simply “between processed surfaces”). Is obtained by simply interposing the processing lubricant of the present invention, and unlike the case of the solid lubricant film, no chemical conversion treatment, heat drying treatment or the like is required.

  Therefore, even when cold-working aluminum alloys at a high processing rate, it is possible to simplify the machining process, save energy, and extend the life of processing tools such as molds, which in turn improves productivity and lowers the cost of aluminum alloy products. Can be planned.

  Further, according to the processing lubricant of the present invention, even when an aluminum alloy is strongly processed, an extreme pressure agent containing an environmental load element that has been used so far is not required. According to the description of Toyoda Central R & D Review, Vol.28, No.3, P12-13 (1993.9), the term “strong processing” as used herein refers to a ball-through test using processing oil containing extreme pressure agent. This refers to processing with a surface area reduction rate of 8% (details are shown in the examples) that allow ironing of steel materials without seizure. Therefore, the processing lubricant of the present invention is excellent in environmental properties.

(3) By the way, the mechanism by which the processing lubricant of the present invention exhibits such excellent characteristics is not necessarily clear, but at present, it is considered as follows. The polymer compound contained in the processing lubricant of the present invention has a molecular weight far greater than that of the base oil and additives constituting the conventional processing lubricant. For this reason, the polymer compound according to the present invention has a large physical adsorption force per molecule adsorbed on the coated surface of the processing tool (specifically, on the amorphous carbon film) or the processed surface of the workpiece. Also, the viscosity is high. For this reason, it is considered that an oil film breakage hardly occurs between the processed surfaces even when the aluminum alloy is strongly processed. In addition, the conventional solid lubricating film and the like required a film thickness of about several μm. However, since the polymer compound of the present invention has a large molecular weight, another polymer compound is entangled with the polymer compound adsorbed on the surface. The solid contact between the processed surfaces can be suppressed. Further, since the polymer compound is an adsorption film (liquid film) to the last unlike the solid lubricating film, it is easy to follow plastic deformation during processing, and it is considered that solid contact between the processed surfaces is also easily suppressed in this respect.

  Furthermore, even if the adsorption film (liquid film) by the polymer compound according to the present invention causes local micro-breakage, there is a non-excellence in seizure resistance, abrasion resistance, sliding resistance, etc. between the processed surfaces. There is a crystalline carbon film. This amorphous carbon film functions as a back-up for processing lubricants or polymer compounds, and effectively suppresses seizure (or macroscopic adhesion) due to solid contact between metals and increases in the coefficient of friction. it seems to do.

  Here, the polymer compound is not only physically adsorbed mainly on the coated surface of the processing tool or the work surface of the work material, but also by being chemically adsorbed on the amorphous carbon film. It is thought that it exhibits a large adsorptivity. Thereby, it is considered that the oil film breakage hardly occurs between the processed surfaces. The chemical adsorption occurs because the polymer compound according to the present invention has a surface functional group composed of at least one of a carbonyl group, an amino group, a carboxyl group, and a hydroxyl group. In particular, when the amorphous carbon film is a Si-containing amorphous carbon film (DLC-Si film), the chemical adsorption is caused by the Si-OH (silanol) and polymer surface of Si on the DLC-Si film. It is thought to occur between functional groups.

  In any case, according to the processing lubricant of the present invention, even when a large shearing force is applied between the processed surfaces due to the strong processing of the aluminum alloy, the lubricating film (boundary) composed of a stable polymer compound between the processed surfaces. Film) is maintained, and seizure is prevented and processing force is reduced.

《Processing additive》
The present invention can be grasped not only as a processing lubricant but also as a processing additive comprising the above-described polymer compound used for the preparation thereof.

《Processing method》
Furthermore, the present invention can be grasped not only as a processing lubricant and processing additive but also as a processing method using them. That is, the present invention relates to the processing of a workpiece made of the above-described processing lubricant, which is made of a coating surface of a processing tool coated with an amorphous carbon film and made of aluminum or an aluminum alloy in contact with the coating surface. There may be a processing method characterized in that the workpiece is processed by the processing tool with the processing tool interposed between the processing surface and the surface.

<Others>
Unless otherwise specified, “x to y” in the present specification includes the lower limit value x and the upper limit value y. In addition, a numerical range such as “a to b” can be set as a new lower limit value or upper limit value for a numerical value described in this specification or an arbitrary numerical value in the numerical range described in this specification.

1 is a chart illustrating oil-soluble polymer compounds according to the present invention and their chemical structural formulas. It is the chart which illustrated water-soluble polymer compound and its chemical structural formula concerning the present invention. It is the schematic of a ball pass test device. Sample No. It is a pyrogram by pyrolysis GC / MS concerning A81.

  The present invention will be described in more detail with reference to embodiments of the invention. The contents described in the present specification can be applied not only to the processing lubricant or processing additive according to the present invention but also to a processing method using them. One or more configurations arbitrarily selected from the specification may be added to the configuration of the present invention described above. Moreover, if the structure regarding a processing method is understood as a product-by-process, it may become the structure regarding a thing (processed object). Note that which embodiment is the best depends on the object of use, required performance, and the like.

《Polymer Compound》
(1) The polymer compound according to the present invention has a molecular weight of 8,000 to 1,000,000. If the molecular weight is too small, the above-described effect of the present invention is poor. On the other hand, the molecular weight may be large, but it is not easy to obtain a polymer compound having an excessive molecular weight. Therefore, the molecular weight of the polymer compound is preferably about 10,000 to 900,000, more preferably about 30,000 to 850,000.

  Such a polymer compound can be obtained by a known method. For example, for a polymer compound, a polymer is synthesized by a chemical reaction starting from a so-called monomer. As this synthesis method, it is widely known that the synthesis is generally carried out by polymerization by chain reaction or polycondensation by sequential reaction, polyaddition or addition condensation. The molecular weight of the polymer compound can be arbitrarily adjusted by, for example, selection or control of monomer selection, polymerization temperature, amount of catalyst, amount of chain transfer agent, number of chains, and the like. By such a method, a polymer compound having an arbitrary molecular weight can be obtained. Moreover, at least a part of the polymer compound according to the present invention is commercially available as an industrial product for other uses such as a structural material (solid) and a viscosity modifier (liquid). Therefore, it is easy to procure a high molecular weight compound according to the present invention.

  By the way, the polymer compound according to the present invention has a surface functional group composed of at least one of a carbonyl group, an amino group, a carboxyl group and a hydroxyl group. Depending on the type of surface functional group, the polymer compound can be oil-soluble or water-soluble. Therefore, the polymer compound according to the present invention may be an oil-soluble polymer compound having a carbonyl group and / or an amino group, or a water-soluble polymer compound having a carboxyl group and / or a hydroxyl group.

(2) Typical examples of the oil-soluble polymer compound (main part) include polymethacrylate (PMA), olefin copolymer (OCP), polyisobutylene (PIB) and the like as shown in FIG. In addition, styrene / isoprene block polymer hydride (SDC) is also available. These polymers may be used alone, or a plurality of types may be mixed and used. The polymer is a polymer of a monomer, and the hydrocarbon constituting the monomer may be any of alkane, alkene, alkyne, cycloalkane, aromatic hydrocarbon and the like. The alkyl group bonded to the terminal may be linear (normal), branched (iso), or cyclic.

  Such polymers have not been used in processing lubricants so far, but are known as high viscosity index improvers and the like, and various products are commercially available. Of course, it goes without saying that a polymer not commercially available or a polymer originally developed may be used as the polymer compound of the present invention.

The oil-soluble polymer compound is mainly composed of such a polymer, and a carbonyl group (—C (═O) —), an amino group (—NH ₂ , —NHR, —NRR ′: R, R ′ are hydrocarbons. ), A carboxyl group (—C (═O) —OH), or a surface functional group such as a hydroxyl group (—OH). There may be at least one or more such surface functional groups, but there may be a plurality or a plurality of types. The carbonyl group may be in any form such as aldehyde, ketone, carboxylic acid, ester and amide. As described above, such a surface functional group is considered to enhance the adsorptivity of the oil-soluble polymer compound, particularly the chemical adsorptivity.

  Here, when the polymer compound according to the present invention is an oil-soluble polymer compound having a carbonyl group, the molecular weight is preferably 60,000 to 1,000,000, 80,000 to 800,000, or even 100,000 to 600,000. Further, when the polymer compound according to the present invention is an oil-soluble polymer compound having a carbonyl group and an amino group, the molecular weight is preferably 30,000 to 1,000,000, 50,000 to 500,000, or even 80,000 to 350,000. is there.

(3) As an example of the water-soluble polymer compound (main part), polyacrylic acid (PA), sodium polyacrylate, polyvinyl alcohol (PVA) and the like as shown in FIG. 2 are representative. These polymers may be used alone or as a mixture of plural kinds. In this case, the monomer constituting the polymer may be any of alkane, alkene, alkyne, cycloalkane, aromatic hydrocarbon and the like. The alkyl group bonded to the terminal may be linear (normal), branched (iso), or cyclic.

  A variety of water-soluble polymer compounds are commercially available in the same manner as oil-soluble polymer compounds, and desired water-soluble polymer compounds having various molecular weights can be obtained at a relatively low cost. Of course, a polymer not commercially available or a polymer originally developed may be used as the water-soluble polymer compound of the present invention.

  The water-soluble polymer compound also has a surface functional group such as a carboxyl group, a hydroxyl group, a carbonyl group or an amino group as described above, with such a polymer as a main part. There may be at least one or more such surface functional groups, but there may be a plurality or a plurality of types.

  When the molecular compound according to the present invention is a water-soluble polymer compound having a carboxyl group and / or a hydroxyl group, the molecular weight is preferably 8,000 to 1,000,000, 20,000 to 900,000, or even 100,000 to 850,000.

(4) Various polymers can be used for the polymer compound according to the present invention, and the constituent elements thereof are not limited. However, it is preferable that the polymer compound does not contain an environmental load element (Cl, P, S, etc.). That is, the polymer compound according to the present invention is composed of only elements such as carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and preferably does not include other elements. Any of the polymer compounds (polymers) according to the present invention already exemplified are composed of C, H, O, N, etc. and do not contain an environmental load element.

《Processing lubricant》
(1) The processing lubricant of the present invention may be composed of only the above-described polymer compound. However, a polymer compound having a large molecular weight usually has high viscosity and is difficult to handle as it is as a processing lubricant. . Therefore, it is preferable to use a base oil or water having an appropriate viscosity to which a polymer compound is added as a processing lubricant. For oil-soluble polymer compounds, base oil should be used as a solvent, and for water-soluble polymer compounds, water should be used as a solvent.

  The amount of polymer compound added to the solvent (mixing amount) includes the processing lubricant supply method between processing surfaces, the type and characteristics of the solvent and polymer compound, as well as the processing conditions (deformation amount, processing force, temperature). Depending on the processing atmosphere, the type and characteristics of the processing tool or workpiece, the properties of the amorphous carbon film and the surface to be processed, etc.).

  However, it is preferable that the polymer compound is contained in an amount of 8 to 50% by mass, 15 to 45% by mass, and further 25 to 40% by mass when the entire processing lubricant is 100% by mass. When the amount of the polymer compound is too small, the effect is poor. When the amount is too large, the viscosity of the processing lubricant is increased and the handling property is lowered. Note that the processing lubricant may be supplied between the processing surfaces by spraying or pouring the processing lubricant, immersing the processing tool or workpiece in the processing lubricant, or the like.

If the way the base oil in the oil-soluble polymer compound processing lubricant added, kinematic viscosity at 40 ° C. is ^{5~300mm 2 / s, 10~250mm 2 /} s and even more so as to be as about 15~200mm ² / s It is preferable to adjust to.

(2) The base oil used for the processing lubricant is not particularly limited, and mineral oils, synthetic oils, fats and the like can be used alone or in combination. Mineral oil includes, for example, paraffinic and naphthenic. Synthetic oils include, for example, poly-α-olefin, poly-α-olefin hydride, isobutene oligomer, hydride of isobutene oligomer, isoparaffin, alkylbenzene, alkylnaphthalene, diester, polyol ester, polyoxyalkylene glycol, dialkyldiphenyl ether And polyphenyl ether. A base oil obtained by appropriately mixing different kinds of mineral oil or synthetic oil may be used. In addition, the base oil itself is so preferable that it does not contain an environmental load element. That is, it is preferable that the base oil is composed of C and H in the main part and only O or N in the remaining part.

(3) It is preferable that the processing lubricant of the present invention is composed of only a solvent and a polymer compound, since the cost can be reduced. However, additives other than the polymer compound may optionally be included for the purpose of further improving the workability and the specific function. Such additives include, for example, an extreme pressure agent and an antiwear agent, and any of them does not contain an environmental load element such as Cl, S, P, and Mo.

《Processing tool》
The processing tool is formed by forming an amorphous carbon film on the surface of a base material.

(1) Base material The base material of a processing tool selects the material, shape, etc. suitable for the kind of process. For example, as long as an amorphous carbon film can be formed on the surface, the material may be made of metal such as carbon steel, alloy steel, cast iron, aluminum alloy, or ceramics such as alumina, silicon nitride, silicon carbide, cemented carbide. But you can.

(2) Amorphous carbon film The amorphous carbon film formed on the substrate of the processing tool is a so-called diamond-like carbon film (hereinafter referred to as “DLC film”). The composition, film formation method, and characteristics (hardness, Young's modulus, peel resistance, etc.) of the DLC film formed on the surface of the processing tool are not questioned. It is preferable to provide.

Here, the characteristics of the DLC film are affected by the composition and manufacturing method. For example, the content of C, H and Si, and the C atom (hereinafter referred to as “Csp ² ”) whose electron orbit takes a sp ² hybrid orbital and the C atom whose electron orbit takes a sp ³ hybrid orbit (hereinafter “Csp ³ ”). The characteristics of the DLC film can change depending on the abundance ratio.

  The DLC film is preferably a Si-containing amorphous carbon film containing Si (hereinafter referred to as “DLC-Si film”). The DLC-Si film is a hard film and has excellent frictional sliding characteristics. Therefore, it is preferable that the surface of the processing tool is covered with a DLC-Si film because seizure resistance is improved, processing force is reduced, and the life of the processing tool is increased.

  An example of the composition of the DLC film (hereinafter, including the DLC-Si film) is as follows: H: 0 to 40 atomic%, 5 to 35 atomic%, and further 10 to 30 when the entire film is 100 atomic%. It is preferable that it contains atomic% and the balance is C. In the case of a DLC-Si film, it is preferable to further contain Si: 2 to 30 atomic%, further 4 to 20 atomic%.

  H can increase the toughness of the DLC film and improve the adhesion to the substrate. However, if H is too small, the effect is poor, and if H is excessive, the DLC film softens on the contrary, and the life and frictional sliding characteristics of the processing tool may be reduced. Si is effective for hardening the DLC film and forming silanol (-Si-OH) that enhances the adsorptivity of the polymer compound. If the amount of Si is too small, the effect is poor. If the amount of Si is excessive, the DLC film is hardened too much, and conversely, the frictional sliding characteristics can be lowered.

The ratio of Csp ² to Csp ^{3 in} C is preferably 20 to 90%, more preferably 60 to 75%, with Csp ² being 100% when the total number of C atoms in the DLC film is 100%. The presence of Csp ² can increase the toughness of the DLC film and improve the frictional sliding characteristics. However, if Csp ² is too small, the effect is poor, and if it is excessive, the DLC film softens, which is not preferable.

Incidentally, the amount of C and Si in the DLC film can be quantified by electron beam microanalyzer (EPMA), X-ray photoelectron spectroscopy (XPS), Rutherford backscattering method (RBS) or the like. The amount of H can be quantified by elastic recoil detection method (ERDA). ERDA is a method of measuring the hydrogen concentration in the film by irradiating the surface of the film with a 2 MeV helium ion beam, detecting hydrogen ions ejected from the film with a semiconductor detector. Further, the amount of Csp ^{2 and the} amount of Csp ³ can be quantified by a high-power decoupling method (HD-MAS) in which magic angle spinning with quantitativeness is performed by solid-state NMR.

As a method for forming the DLC film, for example, a CVD method or a PVD method such as a plasma CVD method, an ion plating method, or a sputtering method can be used. As an example, the case of using the DC plasma CVD method will be described. First, a reaction gas and a carrier gas are introduced into a vacuum furnace in which a processing tool (base material) is arranged. Next, plasma is generated by discharging in the vacuum furnace. And plasma ionized C, CH, Si, etc. are made to adhere to the covering surface of a processing tool. Thereby, a hard DLC film is formed. Examples of the reaction gas used at this time include hydrocarbon gases such as methane (CH ₄ ), acetylene (C ₂ H ₂ ), and benzene (C ₆ H ₆ ). In the case of forming a DLC-Si film, a silicon compound gas such as Si (CH ₃ ) ₄ [TMS], SiH ₄ , SiCl ₄ , SiH ₂ F ₄ and hydrogen gas may be further used. An inert gas such as argon gas may be used as the carrier gas.

  By the way, when the amorphous carbon film is a Si-containing amorphous carbon film, a silanol layer is formed on the surface of the amorphous carbon film, so that the polymer compound having the above-described polar surface functional group becomes a Si-containing amorphous film. The surface of the carbonaceous film becomes more strongly bonded or adsorbed. The polymer compound is not limited to a water-soluble polymer compound but may be an oil-soluble polymer compound. In the case of the oil-soluble polymer compound having a surface functional group described above, if a slight amount of moisture is contained in the processing lubricant, a silanol layer is easily formed on the Si-containing amorphous carbon film. In addition, it is preferable that the water | moisture content in a process lubricant is 10 ppm or more when the whole is 100 mass%.

  The film thickness of the DLC film (including the DLC-Si film) is preferably 0.1 to 6 μm, and more preferably 0.3 to 3 μm. If the film thickness is too small, the durability of the DLC film is lowered, and if the film thickness is too large, the adhesion to the substrate and the peel resistance are lowered. The hardness of the DLC film is preferably 10 GPa or more, 15 GPa or more, and further 20 GPa or more. If the hardness is too small, the durability of the DLC film is lowered, which is not preferable.

《Processing method》
The processing referred to in the present invention is preferably plastic processing such as forging, ironing, drawing, pressing, rolling, extrusion, drawing, and rolling. In particular, it is preferable to use the present invention for plastic working such as ironing, drawing, forging, etc., where the working rate and area expansion rate are large (for example, the area reduction ratio: 5 to 15%). In addition, the processing referred to in the present invention may be processing such as cutting, shearing or drilling. In addition, the processing tool should just respond | correspond to the kind of process, and may be various dies (a punch, a die etc. are included), a cutting tool, etc.

  The processing referred to in the present invention may be cold or warm. The processing temperature is not limited as long as the DLC film and the processing lubricant do not change so much (for example, room temperature to 200 ° C.). The material to be processed may be a raw material, an intermediate material, or a final product regardless of its form.

  The present invention will be described more specifically with reference to examples.

<Preparation of processing lubricant>
(1) Sample No. A00-A111 (Oil-based processing lubricant)
As shown in Table 1, various oil-soluble polymer compounds (additives) were added to the base oil (sample No. A00) to prepare a plurality of processing lubricants for aluminum alloys.

As the base oil, additive-free mineral oil (Thamper 110 / manufactured by Nippon Sun Oil Co., Ltd.) was used. The kinematic viscosity of this base oil was 20.2 mm ² / sec at 40 ° C. The structure (main part and functional group) and molecular weight (Mw) of the oil-soluble polymer compound of each sample are shown together in Table 1. The chemical structure of the polymethacrylate or olefin copolymer which is the main part of the oil-soluble polymer compound is as shown in FIG.

  The amount of the oil-soluble polymer compound added to the base oil is also shown in Table 1 with 100% by mass of the entire processing lubricant. In Table 1, sample No. A00 and sample no. A01 is the same processing lubricant. A60 and sample no. A61 is the same processing lubricant.

  The type, number and molecular weight of the functional group of the oil-soluble polymer compound were adjusted and specified as follows. First, the molecular weight of the oil-soluble polymer compound was measured by the weight average molecular weight by gel permeation chromatography (GPC). The equipment used and measurement conditions at this time are as follows.

Apparatus: LC-20AD (manufactured by Shimadzu Corporation)
Column: Shodex KF-806 x 2 and KF-802 x 1
Or K-806 × 2 K-802 × 1 Measurement temperature: Room temperature to 40 ° C.
Sample solution: 0.2 mass% THF solution or 0.3 mass% chloroform Solution injection amount: 150 μl
Detector: Refractive index detector Standard: Polystyrene

  Next, the functional groups (carbonyl group, amino group, hydroxyl group) of the oil-soluble polymer compound were identified by infrared spectroscopic analysis and nuclear magnetic resonance (NMR).

  Sample No. None of the processing lubricants of 00 to A111 contains an environmental load substance. That is, these processing lubricants are substantially composed only of C, H, O, or N, and do not include metals (such as Zn), heavy metals (such as Mo), S, P, and Cl that are environmentally hazardous elements.

(2) Sample No. B11-B51 (lubricant for aqueous processing)
As shown in Table 2, various water-soluble polymer compounds (additives) were added to distilled water to prepare a plurality of processing lubricants for aluminum alloys.

  The structure (main part and functional group) and molecular weight (Mw) of each water-soluble polymer compound are shown together in Table 2. The chemical structure of polyacrylic acid, sodium polyacrylate or polyvinyl alcohol, which is the main part of the water-soluble polymer compound, is as shown in FIG.

  The amount of the water-soluble polymer compound added to distilled water is also shown in Table 2 with the entire processing lubricant as 100% by mass. In Table 2, sample No. B20 and sample no. B21 is the same processing lubricant.

  The type, number and molecular weight of the functional group of the water-soluble polymer compound were also adjusted and specified in the same manner as described above. However, in the measurement of the weight average molecular weight of the water-soluble polymer compound by GPC, column: Shodex O Hpak (SB-G + SB-803HQ + SB-802HQ), sample solution: 0.2 mass% NaCl aqueous solution, solution injection amount: 100 μl .

  Sample No. None of the processing lubricants B11 to B51 contains an environmental load substance. That is, these processing lubricants are substantially composed only of C, H, O, or Na, and do not include metals (such as Zn), heavy metals (such as Mo), S, P, and Cl that are environmentally hazardous elements.

(3) Sample No. C11-C21 and Sample No. D10-20
Conventional lubricating oils with relatively low molecular weight and commercially available processing lubricating oils were also prepared. These are shown in Table 3. Sample No. C20 and sample no. C21 is the same lubricating oil for processing. Sample No. The commercial oil indicated by D10 is a lubricating oil for cold forging (product name: FW439A, manufacturer: Nippon Oil Corporation). Sample No. The commercial oil shown in D20 is a lubricating oil for cold forging (product name: Titan Homer CCD220, manufacturer: Toyota Chemical Engineering Co., Ltd.).

(4) Sample No. E10 and E11
Samples relating to the solid lubricating coating were also prepared. The solid lubricant film is not a fluid film (liquid film) formed by a processing lubricant applied to a mold (processing tool) or the like, but a non-fluid film fixed to the surface of the workpiece. This is also shown in Table 3.

  This solid lubricating film was formed as follows. First, a chemical conversion treatment film made of aluminum fluoride is formed on the outermost surface (inner peripheral surface) of a workpiece (base material) made of an aluminum alloy by using a silicofluorination method. On top of this, a zinc phosphate metal soap film and a sodium stearate metal soap film were sequentially formed while heating and drying. In this way, a solid lubricating film having a three-layer structure was formed on the surface of the workpiece. Incidentally, this solid lubricating coating is well known as a lubricating method capable of cold forging an aluminum alloy even under severe conditions difficult to cope with with conventional lubricating oils.

<Processing evaluation method>
(1) Ball threading test In this example, a ball threading test that can alternatively evaluate the frictional resistance (working force) and seizure resistance between the mold and the workpiece when performing ironing, etc. The lubricity (workability) of each processing lubricant was evaluated. FIG. 3 shows an outline of the test apparatus 10 used for this ball-through test. The test apparatus 10 includes a container 1, a punch 2, a knockout punch 3 and a ball 5. The container 1 is a steel (JIS SKH51) female die (die) provided with a through hole 1a having a diameter of 30 mm. A cylindrical workpiece 4 to be ironed can be inserted or inserted into the through hole 1a. The punch 2 pushes the male ball 5 into the inner cylinder portion 4 a of the workpiece 4 set in the container 1. When the punch 2 moves, the workpiece 4 is ironed by the balls 5. The knockout punch 3 supports the workpiece 4 pushed by the punch 2 from below and holds the workpiece 4 in a predetermined position.

  Incidentally, a load meter (not shown) for measuring the pushing force (working force) applied to the punch 2 is installed above the punch 2. Further, a displacement meter (not shown) for measuring the amount of movement is installed above the punch 2. In this way, the processing force and the displacement when the workpiece 5 is ironed by pushing the ball 5 are simultaneously measured via the punch 2.

(2) Work material (workpiece)
As the workpiece 4, an aluminum alloy (JIS A6061) cylindrical material having an outer diameter: φ29.9 mm, an inner diameter: φ15.0 mm, and a height of 50 mm (of which the ironing length is 38 mm) was prepared. The workpiece subjected to the test was subjected to an annealing treatment heated at 410 ° C. for 2 hours in an Ar atmosphere.

(3) Ball (processing tool)
A steel ball (high speed tool steel: AISI M50) having a diameter of 16.67 mm was prepared as the ball 5 described above. Hereinafter, this is referred to as “unprocessed ball”. A non-treated ball formed with a DLC-Si film (hereinafter referred to as “DLC-Si film ball”) was also prepared. The DLC-Si film was formed by performing plasma discharge in a mixed gas (raw material gas) of methane (CH ₄ ) and tetramethylsilane (TMS) using a DC plasma CVD apparatus. The flow ratio at that time was CH ₄ : TMS = 1: 100 (total pressure: 500 Pa). Thus, a DLC-Si film having a thickness of 2 μm was obtained. The composition of this DLC-Si film was C: 66 atomic%, H: 30 atomic%, and Si: 4 atomic%. The Si content in the film was quantified by an electron probe microanalysis method (EPMA). Moreover, H content was quantified by the elastic recoil detection method (ERDA).

(4) Test conditions The various processing lubricants described above were applied to a processing tool (ball 5), and a ball passing test was performed. In addition, a ball penetration test was similarly performed on a workpiece on which a solid lubricant film was formed. At this time, the area reduction rate of the workpiece 4 is 8%. The reduction of area: 8% is a severe process that usually causes seizure. Specifically, if the above-described solid lubricant film is not formed on the inner peripheral surface of the workpiece 4, the conventional process is severe enough to cause seizure. Incidentally, the area reduction ratio (R) is a ratio at which the cross-sectional area of the workpiece 4 decreases with processing, and is obtained as follows (see FIG. 3).

Area reduction ratio R = (Db ² −Di ² ) × 100 / (Dc ² −Di ² )
Db: outer diameter of the ball 5
Dc: inner diameter of container 1
Di: Inner diameter of workpiece 4 (before processing)

  Supply of the processing lubricant in the ball threading test was performed as follows (the same applies to all tests using the processing lubricant). First, the balls 5 and the workpiece 4 were ultrasonically cleaned in a mixed solution of 50% acetone and 50% hexane and degreased and dried. Thereafter, a processing lubricant was dropped from the upper part of the inner peripheral surface of the workpiece 4. This workpiece 4 was inserted into the container 1. Next, the processing lubricant was dropped on the ball 5 from the top with a dropper. The ball 5 was placed on the inner peripheral surface of the workpiece 4. Thus, the processing lubricant was supplied between the processing surfaces.

  In the above test, the indentation length (squeezing length) of the ball 5 was 38 mm, and the indentation speed (test speed) of the ball 5 was an initial speed of 200 mm / s. The indentation speed was reduced to a final speed of 180 mm / s due to deformation resistance generated when the ball 5 passed through the workpiece 4 (the same applies to all tests).

"test"
Tables 1 to 3 also show the results obtained by performing the above-described ball threading test on each sample in which a processing lubricant or a solid lubricating coating and a DLC-Si film ball or an untreated ball are combined. . “Maximum load” in the table is the maximum ball indentation load acting on the punch 2. In either case, the ball as the processing tool passed without stopping on the way. However, when the balls or workpieces after the ball pass test were observed, there were some seizures. The cases where seizure was not observed were shown in Tables 1 to 3 by ○ (no seizure) and x (there was seizure) when seizure was observed. Even if seizure occurred during the test, the ball penetrated because a part of the workpiece was sheared while adhering to the ball.

<Evaluation>
(1) Conventional processing lubricant, etc. As shown in C11 to D20, when the conventional processing lubricant was used, the maximum load at the time of pressing the ball was 50 kN or more, and seizure occurred. This was the same not only when the surface of the processing tool (ball 5) was untreated but also when there was a DLC-Si film on the surface.

  On the other hand, sample No. E10 and sample no. As shown in E11, when a solid lubricant film was formed on the surface of the workpiece, none of the seizures occurred at a maximum load of about 40 kN. This was true even when the DLC-Si film was present on the surface of the processing tool (ball 5) as well as when the surface was untreated. This is because the solid lubricating film is firmly bonded to the surface of the work piece and has ductility, unlike the conventional lubricating layer made of a processing lubricant (liquid), it is difficult for the lubricating film to break. This is probably because solid contact between the material and the processing tool was effectively suppressed.

  In this way, when the aluminum alloy is strongly processed cold, it can be seen that the conventional processing lubricant causes seizure. This is the same even when a DLC-Si film having an effect on seizure resistance and friction reduction is formed on the surface of the processing tool, or when the processing lubricant has a functional group that is easily adsorbed on the surface of the processing tool. Met. Therefore, until now, it can be understood that a solid lubricating film was formed on the surface of the workpiece and the aluminum alloy was strongly processed.

(2) In the case of oil-based processing lubricants From the results shown in Table 1, when a processing lubricant in which an oil-soluble polymer compound having a large molecular weight is added to the base oil is used, the maximum load when the ball is pushed in It was clarified that the occurrence of seizure could be avoided (sample No. A41, sample No. A51, A61 and A81 to A101).

  These are all cases where an amorphous carbon film (DLC-Si film) is formed on the surface of the processing tool, and the processing lubricant has a surface functional group and an oil-soluble polymer having a molecular weight of 30,000 or more. This was the case where the compound contained 8% by mass or more. In particular, when the surface functional group of the oil-soluble polymer compound is a carbonyl group, when the molecular weight is 60,000 or more and 100,000 or more, the maximum load is remarkably reduced and seizure does not occur. Further, when the surface functional groups of the oil-soluble polymer compound were a carbonyl group and an amino group, when the molecular weight was 30,000 or more, further 50,000 or more, the maximum load was remarkably reduced and no seizure occurred.

  Sample No. A11-A62 and sample no. Comparing A71 to A101, if the molecular weight is the same, the maximum load can be further reduced by using an oil-soluble polymer compound having an amino group in addition to the carbonyl group. FIG. 4 shows a pyrogram (decomposition temperature: 550 ° C.) by pyrolysis GC / MS of the polymer used for sample A81. Two types of carbonyl groups (I and IV in the figure) and two amino groups (II and III in the figure) were observed, indicating that there are many adsorption points in the polymer. The presence of many type III amino groups in the two types of amino groups is considered to be a factor that strengthens the boundary membrane. This is considered to be because the adsorbability of the oil-soluble polymer compound to the processing tool (particularly the DLC-Si film) is improved by the coexistence of both of the carbonyl group and the amino group. Therefore, when there is no aluminum base, the adsorption point can be reduced and the lubricating performance can be lowered.

(3) In the case of a water-based processing lubricant Further, from the results shown in Table 2, even when a processing lubricant obtained by adding a water-soluble polymer compound having a large molecular weight to distilled water is used, It became clear that it can be made lower than in the case of the above-mentioned solid lubricating coating, and the occurrence of seizure can be avoided (Sample Nos. B11 and B21 to B51). Similarly, in these cases, an amorphous carbon film (DLC-Si film) is formed on the surface of the processing tool, and the processing lubricant has a molecular weight of 8000 or more and 10,000 or more having a carboxyl group or a hydroxyl group. This was a case where 8% by mass or more of the water-soluble polymer compound was contained.

(4) Sample No. A60 and sample no. A61 or sample no. B20 and sample no. As can be seen by comparing B21, even when processing using the same processing lubricant, the occurrence of seizure and the maximum load greatly changed depending on whether or not the DLC-Si film was present on the surface of the processing tool. . This is considered as follows. When the DLC-Si film exists on the surface of the processing tool, a strong bonding force is generated between the DLC-Si film and the surface functional group of the polymer compound, and the polymer compound is firmly adsorbed on the DLC-Si film. Thus, a stable lubricating film that does not break during processing is formed between the processed surfaces. And even if the lubricating film is locally interrupted, it is considered that the DLC-Si film having excellent seizure resistance and the like has been backed up.

  Sample No. B11 and sample no. As can be seen from comparison with B51, when the molecular weight of the polymer compound is increased, the maximum load can be reduced even if the addition amount is decreased. In other words, even with a polymer compound having a relatively small molecular weight, increasing the addition amount can reduce the maximum load and avoid the occurrence of seizure. However, from a comparison between the two, it is considered that an increase in the molecular weight of the polymer compound is particularly effective for efficiently reducing the maximum load and avoiding seizure.

(5) Sample No. A01 and Sample No. Using a processing lubricant according to A81 and a processing tool (ball 5) whose surface coating was changed from a DLC-Si film to a DLC film, a ball-through test was conducted in the same manner to evaluate workability. The results are shown in Table 4. In Table 4, sample No. A01 and sample no. Corresponding to A81, sample No. A02 and sample no. A82. The DLC film is a hydrogen-containing DLC film (H content: 26%) formed by a commercially available DLC coating treatment (Japan IT Corporation, Diascoat HT).

  Sample No. A02 and sample no. The maximum loads of A82 were 80 kN and 29 kN. These are respectively sample Nos. A01 and Sample No. It was almost the same as the maximum load of A81. From this, it was confirmed that substantially the same lubricating performance was obtained even when the surface of the processing tool was changed from the DLC-Si film to the DLC film.

1 container 1
2 Punch 2
3 Knockout punch 4 Work material 5 Ball

Claims (10)

A processing lubricant that is interposed between a coated surface of a processing tool coated with an amorphous carbon film and a processed surface of a workpiece made of aluminum or an aluminum alloy and in contact with the coated surface. And
The amorphous carbon film is a Si-containing amorphous carbon film containing silicon (Si) and the balance being C and H,
8 to 50 when a polymer compound having a surface functional group consisting of at least one of carbonyl group, amino group, carboxyl group or hydroxyl group and having a molecular weight of 30,000 to 1,000,000 is 100% by mass as a whole. A processing lubricant characterized by containing a mass%. A processing lubricant that is interposed between a coated surface of a processing tool coated with an amorphous carbon film and a processed surface of a workpiece made of aluminum or an aluminum alloy and in contact with the coated surface. And
The amorphous carbon film is a Si-containing amorphous carbon film containing silicon (Si) and the balance being C and H,
A water-soluble polymer compound having a surface functional group composed of at least one of a carbonyl group, an amino group, a carboxyl group or a hydroxyl group and having a molecular weight of 8000 to 1,000,000 is 8 to A processing lubricant comprising 50% by mass. The processing lubricant according to claim 1 or 2 , which does not contain an environmentally hazardous substance having one or more of chlorine (Cl), phosphorus (P), or sulfur (S). The processing lubricant according to any one of claims 1 to 3, comprising only one or more of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). The water-soluble polymer compounds, processing lubricant according to 請 Motomeko 2 that having a carboxyl group and / or hydroxyl groups. The polymer compound is an oil-soluble polymer compound having a carbonyl group,
The processing lubricant according to any one of claims 1 to 3, wherein the molecular weight is 60,000 to 1,000,000. The polymer compound according to claim 1 which is oil-soluble polymer compound having a carbonyl group and an amino group, 3, 4 or processing lubricant according to any one of 6.   A processing additive comprising a polymer compound used in the processing lubricant according to any one of claims 1 to 7.   The processing lubricant according to any one of claims 1 to 7, comprising a coated surface of a processing tool coated with an amorphous carbon film and aluminum or an aluminum alloy and processed in contact with the coated surface. A processing method, comprising: interposing between a processing surface of a material and processing the material with the processing tool.   The processing method according to claim 9, wherein the processing is cold plastic processing.

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