JP2013199563A - Lubricant composition for cold pilgering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition which has excellent seizure resistance even when a content of a chlorine-based compound is reduced, and with which decrease in corrosion resistance of a surface of an alloy tube stock is suppressed.SOLUTION: A lubricant composition contains 10 to 40 mass% of a sulfur-containing compound and 20 to 60 mass% of a calcium-containing compound. The sulfur-containing compound is a sulfur-containing compound having three to five continuously bound sulfur atoms with 12-18C hydrocarbons attached to both terminals thereof. The calcium-containing compound contains a first calcium sulfonate of which the crystal structure of the carbonate is an amorphous type crystal and the total base number is 300 mgKOH/g or more, and a second calcium sulfonate of which the crystal structure of the carbonate is a calcite type crystal and the total base number is 150 mgKOH/g or more, and a ratio of the first calcium sulfonate to the second calcium sulfonate Ris 1/4 to 4.

Description

  The present invention relates to a lubricant composition, and more particularly to a lubricant composition used for cold pilger rolling.

  Cold pilga rolling is used for the production of metal tubes typified by stainless steel. In cold pilger rolling, a lubricant composition is used. The lubricant composition used for cold pilga rolling usually contains an oily agent, an extreme pressure additive, and the like. The oily agent is, for example, fats and oils, fatty acids, esters and the like. The extreme pressure additive is, for example, sulfur, a chlorine-based compound, phosphorus or the like.

  Examples of the chlorinated compound include chlorinated paraffin and chlorinated fatty acid ester. Chlorine-based compounds are less expensive than other extreme pressure additives. Chlorine compounds are further excellent in lubricity and are not easily flammable. Therefore, the conventional lubricant composition contains a chlorine compound.

  However, chlorinated compounds are not preferred for organisms and the environment. Furthermore, when a lubricant containing a chlorinated compound is incinerated, hydrogen chloride and dioxins are generated. These compounds can cause air pollution. Therefore, there is a demand for a lubricant composition that suppresses the content of chlorine-based compounds.

  JP-A-8-333594 (Patent Document 1), JP-A-8-34988 (Patent Document 2), JP-A-6-256784 (Patent Document 3) and JP-A-2006-182809 (Patent Document 4). ) Proposes a lubricant composition for metalworking that does not contain chlorine compounds.

  The die forging lubricant disclosed in Patent Document 1 contains a highly basic alkaline earth metal salt. The lubricant composition disclosed in Patent Document 2 contains a highly basic petroleum sulfonate and an extreme pressure additive typified by a calcium salt of a phosphate ester or sulfur-based fats and oils. The lubricant composition disclosed in Patent Document 3 contains a film enhancer such as ZnDTP or sulfide lard and a carbohydrate such as a starch derivative. The lubricant composition disclosed in Patent Document 4 contains a specific highly basic organometallic salt.

JP-A-8-333594 JP-A-8-34988 JP-A-6-256784 JP 2006-182809 A

  Cold pilga rolling is suitable for processing an alloy material containing a large amount of Cr and Ni. However, when the lubricant composition disclosed in Patent Literature 1 to Patent Literature 4 is used for cold pilger rolling, seizure may occur on the surface of the alloy material or the corrosion resistance of the surface of the alloy material may be reduced.

  An object of the present invention is to provide a lubricant composition that has excellent seizure resistance and can suppress a decrease in corrosion resistance on the surface of an alloy material even when the content of a chlorine-based compound is suppressed.

The lubricant composition according to the present invention is used for cold pilger rolling. The lubricant composition contains 10 to 40% by mass of a sulfur-containing compound and 20 to 60% by mass of a calcium-containing compound. In the sulfur-containing compound, 3 to 5 sulfur atoms continue, and hydrocarbons having 12 to 18 carbon atoms are added to both ends thereof. The calcium-containing compound contains first and second calcium sulfonates. The first calcium sulfonate has an amorphous crystal structure and a total base number of 300 mgKOH / g or more. The calcium carbonate sulfonate has a calcite-type crystal structure of carbonate and a total base number of 150 mgKOH / g or more. The ratio _{RA / C} of the first calcium sulfonate to the second calcium sulfonate is 1/4 to 4.

  The lubricant composition according to the present invention has excellent seizure resistance even when the content of the chlorine compound is suppressed, and suppresses a decrease in corrosion resistance of the alloy material surface.

  Hereinafter, embodiments of the present invention will be described in detail.

  The present inventors have investigated and studied a lubricant composition that has excellent seizure resistance even if the content of the chlorine-based compound is suppressed and can suppress a decrease in the corrosion resistance of the alloy material surface. As a result, the present inventors obtained the following knowledge.

  Sulfur-based extreme pressure agents are said to have high adsorptivity to alloy materials typified by stainless steel. However, as a result of the investigation by the present inventors, the following matters have been revealed. Conventional sulfur-based extreme pressure agents are easily adsorbed on Fe base materials exposed on the surface by plastic deformation during cold pilger rolling, or on Fe-rich grain boundaries with low Cr concentration. However, it is difficult to adsorb on an inert oxide film (chromia) formed on the surface of the alloy material. Furthermore, since the adsorptivity to Cr and Ni is low, it is difficult to adsorb on the surface of the alloy material having a large Cr content and Ni content.

  Further, even if the Fe base material is exposed by plastic deformation on the surface of the alloy material, chromia that is an oxide film is rapidly formed on the Fe base material. Specifically, in cold pilger rolling, every time the pilga mill roll rotates, even if the alloy material is rolled, chromia is formed on the surface of the alloy material shortly after the end of rolling. Therefore, it is difficult for the sulfur-based extreme pressure agent to be adsorbed on the surface of the alloy material. Therefore, even if the lubricant composition contains a conventional sulfur extreme pressure agent, seizure may occur.

  If the Cr and Ni contents in the alloy material are further increased, the surface of the alloy material exposed by plastic deformation contains a large amount of Cr and Ni. In this case, even if chromia is not formed on the alloy surface, the sulfur-based extreme pressure agent is difficult to adsorb. Therefore, seizure is likely to occur during cold pilga rolling.

  Furthermore, as described above, conventional sulfur-based extreme pressure agents are easily adsorbed on Fe-rich grain boundaries. Therefore, the boundary lubricant film formed by the lubricant composition containing the conventional sulfur-based extreme pressure agent is difficult to cover the entire alloy material surface. Therefore, seizure is likely to occur in cold pilger rolling with high surface pressure and high workability. In addition, the conventional lubricant composition adsorbed on the grain boundary may erode the grain boundary by a chemical reaction and reduce the corrosion resistance of the alloy material surface.

  The present inventors examined a sulfur-based extreme pressure agent that is easily adsorbed on the surface of an alloy material having a high Cr and Ni content. As a result, the present inventors have found that a sulfur-containing compound in which 3 to 5 sulfur atoms are continuous and a hydrocarbon having 12 to 18 carbon atoms is added to both ends thereof (hereinafter referred to as a specific sulfur-containing compound) is Cr and It has been found for the first time that it easily adsorbs to Cr and Ni in the austenite grains and / or ferrite grains of the alloy containing Ni. The reason for this is not clear, but the following matters are presumed. Attention is paid to the —S—S—S— structure (hereinafter referred to as “S-linked structure”) of the specific sulfur-containing compound. In the S connection structure, the binding energy of S (center S) in which S is bonded to both ends is lower than that of the C—S bond. Therefore, S in which S is bonded to both ends easily reacts with Cr and Ni. Therefore, the specific sulfur-containing compound reacts with Cr and Ni to form a mercaptide reaction coating having an organic chain, a Ni-S inorganic boundary lubricating coating with a broken organic chain, and a Cr-S inorganic with a broken organic chain. It is considered that one of the boundary lubrication films is formed.

  These adsorptions are mainly due to the S-linked structure. However, the chain length of the hydrocarbons connected to both ends of the S-linked structure also affects the adsorption. The hydrocarbon chain becomes a steric hindrance when the S molecule is adsorbed on the alloy surface. Therefore, there is an appropriate range for the carbon chain. If the flash point is a problem, the molecular weight of the hydrocarbon chain may be increased within the appropriate range of the carbon chain.

  The sulfur-based extreme pressure agent reacts in a high temperature range (about 225 ° C. to about 300 ° C.). In cold pilger rolling, the surface temperature of the alloy material on the roll exit side (after one roll rotation) is 200 ° C. or higher. On the other hand, the surface temperature of the alloy material on the roll entry side (at the start of rolling) is approximately room temperature. Therefore, the lubricant composition is required to have seizure resistance in a wide temperature range. In order to obtain seizure resistance in a low temperature range (about 100 ° C. to about 175 ° C.) and a medium temperature range (about 175 ° C. to about 225 ° C.), the conventional lubricant composition is an oily agent or a highly basic organic metal. Contains salt.

  Organometallic salts represented by calcium sulfonate include fine particles of calcium carbonate. The calcium carbonate fine particles are adsorbed on the surface of the alloy material (during cold pilger rolling) to suppress metal contact between the roll surface and the surface of the alloy material. Therefore, seizure hardly occurs in a low temperature range and a middle temperature range. In particular, calcium sulfonates composed of amorphous calcium carbonate (hereinafter referred to as A calcium sulfonates) include fine calcium carbonate particles having a smaller particle size than other calcium sulfonates. If the A calcium sulfonate is basified, the content of the above-mentioned calcium carbonate fine particles is increased, and the seizure resistance is enhanced.

  However, in the case of calcium carbonate having an amorphous structure, since the particles are brittle, they are easily pulverized, and very fine calcium carbonate particles are easily formed. Such fine calcium carbonate fine particles selectively grind grain boundaries having a low Cr concentration in the alloy material surface. This is because the grain boundaries are more easily cut than in the grains. Such selective grinding reduces the corrosion resistance of the alloy material.

  In calcium sulfonates containing calcium carbonate having a calcite type crystal structure (hereinafter referred to as C calcium sulfonate), the calcium carbonate is larger than the calcium carbonate fine particles of A calcium sulfonate. In addition, calcium carbonate of C calcium sulfonate has a scaly layered structure, and is unlikely to be refined like A calcium sulfonate. Therefore, the calcium carbonate of C calcium sulfonate is less likely to grind grain boundaries than the A calcium sulfonate, and it is easy to suppress a decrease in corrosion resistance of the alloy material surface. However, the calcium carbonate of the C calcium sulfonate is larger than the calcium carbonate of the A calcium sulfonate and the shape is scale-like. Therefore, the seizure resistance of A calcium sulfonate is superior to that of C calcium sulfonate.

Therefore, it is effective to contain A calcium sulfonate and C calcium sulfonate in a specific ratio in order to increase the corrosion resistance of the alloy material surface and increase the seizure resistance in the low temperature range and the medium temperature range. . Specifically, in the lubricant composition, the ratio R _{A / C} of A calcium sulfonate having a total base number (Total Base Number: TBN) of 300 mgKOH / g or more to C calcium sulfonate having a TBN of 150 mgKOH / g or more. If it is 1/4 to 4, the seizure resistance in the low temperature range and the medium temperature range is enhanced, and the corrosion resistance of the alloy material surface is enhanced.

  The lubricant composition of the present invention may further contain a fatty acid ester. Fatty acid esters are a type of oily agent. Similar to calcium sulfonate, the oil-based agent is adsorbed on the surface in a low temperature region and a medium temperature region to suppress seizure. The oily agent has a polar group in the molecule. Among the oily agents, fatty acid esters are firmly adsorbed on the surface of an alloy containing a large amount of Cr and Ni to suppress seizure resistance.

  However, fatty acid esters may be polymerized by reacting with a specific sulfur-containing compound having an S-linked structure under the influence of processing heat, and may increase the viscosity of the entire lubricating oil over time.

  Among the fatty acid esters, fatty acid monoesters having 14 to 18 carbon atoms in the fatty acid and 3 to 8 carbon atoms in the alcohol part and having no unsaturated bond (hereinafter referred to as specific fatty acid esters) contain specific sulfur. It is difficult to increase viscosity even when used in combination with a compound.

  Based on the above knowledge, the following lubricant composition of the present embodiment was completed.

The lubricant composition according to the present embodiment is used for cold pilger rolling. The lubricant composition contains 10 to 40% by mass of a sulfur-containing compound and 20 to 60% by mass of a calcium-containing compound. The sulfur-containing compound has an S-linked structure in which 3 to 5 sulfur atoms are continuous, and adds a hydrocarbon having 12 to 18 carbon atoms to both ends of the S-linked structure. The calcium-containing compound contains a first calcium sulfonate and a second calcium sulfonate. Ferrous calcium sulfonate has a crystal structure of an amorphous crystal and a total base number (TBN) of 300 mgKOH / g or more. The calcium carbonate sulfonate has a calcite crystal structure and a total base number (TBN) of 150 mgKOH / g or more. The ratio _{RA / C} of the first calcium sulfonate to the second calcium sulfonate is 1/4 to 4.

  The lubricant composition according to the present embodiment has excellent seizure resistance even when the content of the chlorine-based compound is suppressed, and suppresses a decrease in the corrosion resistance of the alloy material surface.

  The above-described lubricant composition may further contain a fatty acid monoester. In the present specification, the fatty acid monoester has 14 to 18 carbon atoms in the fatty acid, 3 to 8 carbon atoms in the alcohol part, and 10% by mass or less of the fatty acid ester having an unsaturated bond. The fatty acid ester having an unsaturated bond is an unsaturated fatty acid ester and a diester, triester, polyol ester or the like having a saturated or unsaturated fatty acid.

  In this case, the seizure resistance of the lubricant composition is increased.

  The alloy material to be cold pilger rolled is, for example, a Cr alloy, a Ni alloy, or a Ni-based alloy containing 12 mass% or more of Cr and Ni in total.

  The above-described lubricant composition is effective for the above-described alloy.

  The method for manufacturing a metal pipe according to the present embodiment includes a step of preparing an alloy base pipe containing 12 mass% or more of Cr and Ni in total, and using the above-described lubricant composition, And pilga rolling.

  In this case, seizure is suppressed and an alloy pipe excellent in corrosion resistance is manufactured.

  Hereinafter, the details of the lubricant composition according to the present embodiment will be described.

[Composition of lubricant composition]
The lubricant composition according to the present embodiment contains a specific sulfur-containing compound and a specific calcium-containing compound.

[Specific sulfur-containing compounds]
The specific sulfur-containing compound contains a structure in which 3 to 5 sulfur elements are continuously arranged (referred to as S-linked structure) and a hydrocarbon having 12 to 18 carbon atoms added to both ends of the structure. The specific sulfur-containing compound is adsorbed on the surface of the alloy material in a high temperature range. For this reason, the seizure resistance of the alloy material and the corrosion resistance of the surface of the alloy material are mainly enhanced at high temperatures.

  The upper limit of the carbon number of the hydrocarbon is preferably 18 from the viewpoint of easy substance selection. On the other hand, the lower limit of the carbon number is 12. When the number of carbon atoms is less than 12, the molecular weight becomes small. If the molecular weight is small, it tends to evaporate or volatilize. Therefore, the lubricant composition cannot maintain the initial composition, and the lubricity is lowered.

  The preferred carbon number of the hydrocarbon is 16-18. In this case, the flash point of the sulfur-containing compound can be increased.

  When the number of S elements in the S-linked structure of the specific sulfur-containing compound is less than 3, the specific sulfur-containing compound is difficult to adsorb on the alloy material surface. This is presumed to be due to the lack of weak energy bonds in the structure of the specific sulfur-containing compound. On the other hand, when the number of S elements in the S-linked structure exceeds 5, the S—S bond becomes unstable and is easily excluded from the molecule. As a result, sulfur crystals are likely to be precipitated. Therefore, the number of S elements in the S connection structure of the specific sulfur-containing compound is 3-5.

  The content of the specific sulfur-containing compound in the lubricant composition is 10 to 40% by mass. If the content of the specific sulfur-containing compound is too small, seizure is likely to occur at high temperatures. On the other hand, if there is too much content of a sulfur containing compound, the corrosion resistance of the alloy raw material surface will fall.

  When the content of the specific sulfur-containing composition is 10 to 40% by mass, the lubricant composition exhibits excellent seizure resistance, particularly in a high temperature range, and maintains the corrosion resistance of the alloy material surface.

  The specific sulfur-containing compound is, for example, ditashalide decyl trisulfide, ditashalide decyl pentasulfide, dihexadecyl tetrasulfide, dioctadecyl tetrasulfide.

[Specific calcium-containing compounds]
The specific calcium-containing compound increases the seizure resistance in a low temperature range to a medium temperature range, and increases the corrosion resistance of the alloy material surface. The specific calcium-containing compound contains A calcium sulfonate and C calcium sulfonate.

[A calcium sulfonate]
The crystal structure of A calcium sulfonate carbonate (calcium carbonate) is an amorphous crystal structure, and the total base number (TBN) is 300 mgKOH / g or more. The carbonate in A calcium sulfonate is a fine particle. The carbonate adsorbs on the friction surface (the surface of the alloy material at the time of cold pilger rolling) and suppresses metal contact between the roll surface and the surface of the alloy material. Therefore, A calcium sulfonate suppresses the occurrence of seizure. The seizure resistance of A calcium sulfonate is superior to C calcium sulfonate.

  The preferred TBN of the A calcium sulfonate is 400 mg KOH / g or more. A calcium sulfonate is produced by a known production method. A method for producing A calcium sulfate is disclosed in, for example, “Development of petroleum product additives” by Heihachiro Okabe et al., CMC Publishing Co., Ltd.

A calcium sulfonate is, for example, Hybase C-311 (TBN 305 mgKOH / g), Hybase C-401 (TBN 418 mgKOH / g), Hybase C-500 (TBN 495 mgKOH / g) manufactured by Chemtura Corporation, HiTEC611 (TBN300 mgKOH) manufactured by Afton Chemical / L), Lubrizol Corporation LUBLIZOL 5347 (TBN400mgKOH / g), SOLTEX AmorCal ^TM 400M (TBN400mgKOH / g), AmorCal ^TM 800 (TBN400mgKOH / g), PCAS ARCOT 642N (TBN 380mgKOH / g), ARCOT 644 (TBN 410 mg KOH / g).

[C calcium sulfonate]
The crystal structure of carbonate of C calcium sulfonate (calcium carbonate) is a calcite type crystal structure, and TBN is 150 mgKOH / g or more. Carbonate of C calcium sulfonate is larger than carbonate of A calcium sulfonate. Carbonate of C calcium sulfonate has a scaly layered structure. Therefore, the carbonate of C calcium sulfonate is harder to grind the grain boundaries on the surface of the alloy material than the carbonate of A calcium sulfonate. Accordingly, it is possible to suppress a decrease in the corrosion resistance of the alloy material.

  The preferred TBN of C calcium sulfonate is 200 mg KOH / g or more. Methods for producing C calcium sulfonate are well known. The production method of C calcium sulfonate is disclosed in, for example, US Pat. No. 3,420,279, US Pat. No. 3,376,222, US Pat. No. 4,560,489, US Pat. No. 4,597,880, US Pat. ing.

  C calcium sulfonate is, for example, Hybase C-231 (TBN 285 mgKOH / g), Calcinate C-400W (TBN 385 mgKOH / g) manufactured by Chemtura Corporation, ARCOT 645 (TBN170 mgKOH / g), ARCOT 649 (TBN250 mgKOH / g) manufactured by PCAS Etc.

[Content of specific calcium-containing compound]
Content of the specific calcium containing compound in the lubricant composition by this embodiment is 20-60 mass%. When the content of the specific calcium-containing compound is too small, seizure is likely to occur in a low temperature range and a middle temperature range. On the other hand, when the content of the specific calcium-containing compound is too large, the grain boundaries on the surface of the alloy material are scraped off by the A calcium sulfonate and the C calcium sulfonate, and the corrosion resistance on the surface of the alloy material tends to decrease.

  When the content of the specific calcium-containing compound is 20 to 60% by mass, the lubricant composition exhibits excellent seizure resistance in the low temperature range and the medium temperature range, and maintains the corrosion resistance of the alloy material surface.

As described above, A calcium sulfonate is excellent in seizure resistance, and C calcium sulfonate suppresses a decrease in corrosion resistance on the surface of the alloy material. In order to increase the corrosion resistance of the alloy material surface and to enhance the seizure resistance in the low temperature range and the medium temperature range, the ratio R _{A / C} of the _A calcium sulfonate to the C calcium sulfonate may be contained at a specific ratio. It is valid. Specifically, the ratio _{RA / C} is 1/4 to 4.

When the ratio _{RA / C} is less than 1/4, the ratio of A calcium sulfonate in the specific calcium-containing compound is too small. In this case, seizure resistance is reduced.

When ratio _{RA / C} exceeds 4, the ratio of A calcium sulfonate in a specific calcium containing compound is too much. In this case, the grain boundary on the surface of the alloy material is scraped, and the corrosion resistance of the surface of the alloy material is reduced.

If ratio _{RA / C} is 1 / 4-4, it will be excellent in the seizure resistance in a low temperature range and a middle temperature range, and the fall of the corrosion resistance of the alloy raw material surface will also be suppressed.

[Other additives for lubricant composition]
The lubricant composition according to the present embodiment may contain well-known additives contained in conventional plastic working fluids in addition to the above-described specific sulfur-containing compound and specific calcium-containing compound. Known additives include, for example, mineral oils, base oils such as poly-alpha olefins, oils and fats, hindered esters, alkylamines and other oily agents, polysulfides, sulfurized fats and other organic sulfur compounds, (sub) phosphate esters and ) Extreme pressure additives such as organophosphorus compounds such as phosphate esters (excluding chlorine-based ones), organic metal salts such as zinc dithiophosphate and molybdenum dithiocarbamate, graphite, molybdenum disulfide, nanocarbon particles, etc. Solid lubricants, antioxidants, rust inhibitors, anticorrosives, and the like.

  Note that the lubricant composition according to this embodiment does not contain a chlorine compound, and even if it does not contain a chlorine compound, the lubricant composition according to this embodiment has excellent seizure resistance and is an alloy material. Suppresses surface corrosion resistance.

[Specific fatty acid ester]
The lubricant composition may further contain a specific fatty acid ester. Specifically, the fatty acid ester has 14 to 18 carbon atoms in the fatty acid, 3 to 8 carbon atoms in the alcohol part, and 10% by mass or less of the fatty acid ester having an unsaturated bond ( Hereinafter, the specific fatty acid ester).

  As described above, the specific fatty acid ester is strongly adsorbed on the surface of the alloy material containing a large amount of Cr and Ni to enhance the seizure resistance. Furthermore, since the fatty acid ester having an unsaturated bond is 10% by mass or less, even when used in combination with the above-described specific sulfur-containing compound, the lubricant composition is difficult to increase in viscosity.

  If the specific fatty acid ester in the lubricant composition is contained even a little, the above-described effects can be obtained. On the other hand, if the content of the specific fatty acid ester is too large, the adsorption and reaction of other additives may be inhibited. The lower limit of the preferred specific fatty acid ester is 5%. A preferable upper limit of the specific fatty acid ester is 40%.

  Specific fatty acid esters are, for example, butyl stearate, octyl palmitate, butyl myristate, isopropyl myristate, 2-ethylhexyl palmitate, butyl stearate, 2-ethylhexyl stearate, isopropyl isostearate and the like.

[Metal tube manufacturing method]
The lubricant composition according to the present embodiment is used for manufacturing a metal tube by cold pilger rolling. Hereinafter, the manufacturing method of the metal pipe by cold pilger rolling is demonstrated.

[Preparation of alloy material]
First, an alloy material to be rolled is prepared. The alloy material is a Cr alloy, a Cr—Ni alloy, or a Ni-based alloy in which the total of the Cr content and the Ni content is 12% by mass or more. Alloy materials include, for example, austenitic stainless steels such as SUS201, SUS202, SUS304, and SUS316, ferritic stainless steels such as SUS430 and SUSxm8, martensitic stainless steels such as SUS403, SUS410, SUS416, SUS420J2, and SUS630, SUS631, etc. And nickel superalloys such as NCF600 and NCF690.

  The lubricant composition of this embodiment is suitable for cold pilger rolling of a Cr alloy, a Cr—Ni alloy, and a Ni-based alloy having a total of Cr content and Ni content of 25% or more.

[Manufacture of alloy pipes]
An alloy pipe is manufactured from the prepared alloy material. The alloy pipe is manufactured by a known method. For example, an alloy pipe is manufactured by hot extrusion represented by the Eugene Sejurune method. An alloy base tube may be manufactured by forming a through hole in the center of the alloy base tube by machining from an alloy material of a round bar.

[Cold Pilga Rolling]
Using the manufactured alloy base pipe, cold pilger rolling is performed to manufacture a metal pipe. Cold pilga rolling is a well-known rolling method. For cold pilga rolling, a pilga mill is used. The pilgamill includes a pair of rolls having a special hole shape, a mandrel, and a propulsion device.

  Insert the mandrel into the alloy tube. Thereafter, the alloy pipe is sandwiched between a pair of rolls. When the pair of rolls are rotated once, a region of the alloy base tube that is in contact with the hole mold of the roll is rolled. When the pair of rolls are rotated once, the alloy base tube is separated from the hole mold of the rolls. The propulsion device advances the alloy base pipe away from the hole mold by a predetermined distance. At this time, the propulsion device rotates the mandrel and the alloy base tube 60 to 90 degrees around the central axis. Thereafter, the alloy base pipe is sandwiched again between the pair of rolls, and the roll is rotated once again to roll the alloy base pipe. Roll rolling for each rotation is repeated, and the alloy tube is cold-rolled to produce a metal tube.

  During cold pilger rolling, the lubricant composition of the present embodiment is supplied to the inner and outer surfaces of the alloy pipe. For example, the lubricant composition is sprayed on the inner and outer surfaces of the alloy base pipe using a spray. The lubricant composition is recovered and circulated through a large tank arranged around the Pilgamil.

  Cold pilger rolling may be performed while the oxide scale generated after the hot extrusion process is adhered to the surface of the alloy tube. Cold pilger rolling may be performed after removing the oxide scale attached to the surface of the alloy tube before cold pilger rolling. Shot blasting may be performed on the surface of the alloy base pipe to give iron to the surface of the alloy base pipe, and then cold pilger rolling may be performed. In this case, the lubricant composition is easily held on the surface of the alloy base tube, and the lubricant composition and the surface of the alloy base tube are easily reacted. The roughness of the alloy base pipe surface may be increased to facilitate the retention of the lubricant composition on the alloy base pipe surface. The preferable roughness of the alloy base tube surface is 0.01 μm to 3 μm in terms of arithmetic average roughness Ra defined by JIS B0601 (2001). In this case, the lubricant composition is easily held and is easily drawn between the roll and the surface of the alloy base tube.

  The alloy base tube may be subjected to oxalate conversion treatment or borate conversion treatment. In this case, the lubricity of the alloy base tube is increased.

  Lubricant compositions with test numbers 1 to 21 shown in Table 1 were prepared.

  Referring to Table 1, the “structure” column describes the structure of the component (compound) described in the “component” column. The numerical value in each test number column means mass%. For example, “30” means 30%. “-” Means that the corresponding component is not contained.

[Lubricity evaluation test]
The lubricity (seizure resistance) of the lubricant composition was evaluated by a ball-on-disk wear test. The ball-on-disk wear test was performed by the following method. The disk as a test piece for the ball-on-disk wear test had a diameter of 110 mm and a thickness of 10 mm. Four types of disc materials were prepared: JIS standard SUJ420J, SUS304, SUS329J4L, and NCF690. The ball was 3/4 inch diameter and the material was SUJ2.

  The lubricant compositions of Test Nos. 1 to 21 were applied to the test surface of each disk 30 seconds before the test, and were not applied thereafter. The worn part of the disk was 45 mm from the center of the disk. The load was 200 kgf and the test time was 60 seconds. The torque applied to the disk under test was measured with a torque meter, and the friction coefficient was calculated from the measured value and the load. The test was carried out by holding the disk at 150 ° C. (assuming a low temperature region), 200 ° C. (assuming a medium temperature region), and 250 ° C. (assuming a high temperature region) by high frequency induction heating.

  The test surface of the disc after the test was visually observed to investigate the occurrence of seizure. When seizure occurs in one or more of the above four types of materials and tests in three temperature ranges (4 types of materials x 3 temperature ranges = 12 conditions for each test number) Since the seizure resistance is low, it was judged as “impossible”. When no seizure occurred under any of the conditions, the average of the friction coefficients under all conditions (hereinafter referred to as the average friction coefficient) was obtained. When the average coefficient of friction was larger than 0.15, it was judged as “possible”. When the average coefficient of friction was 0.10 to 0.15, it was judged as “good”. When the average coefficient of friction was less than 0.10, it was judged as “excellent”. In the case of “possible”, “good”, “excellent”, it was judged that the seizure resistance was high.

[Corrosion resistance evaluation test]
Using the discs after the lubricity evaluation test (for each test number, 4 types of materials × 3 types of temperature ranges = 12 discs), a corrosion resistance evaluation test was performed. From the disc after the lubricity evaluation test, a 10 mm square block test piece including a worn part was collected. Using the block test piece, the test was conducted in accordance with the oxalic acid etching test method defined in JIS G0571 (2003). The evaluation of the etching structure after the test was judged based on the classification table indicating the state of the grain boundary in the JIS standard. Specifically, of at least one of the test number disks (12), when at least one etching structure is a grooved structure (symbol C in the table of JIS standard), the corrosion resistance is low, and “impossible” It was judged. When none of the etching structures of the 12 disks was a groove structure and at least one was a mixed structure (symbol B in the JIS standard table), the corrosion resistance was judged as “good”. When any of the 12 discs had a stepped structure (symbol A in the JIS standard table), the corrosion resistance was judged as “excellent”. When it was “good” or “excellent”, it was judged that the corrosion resistance was high.

[Test results]
Table 1 shows the test results. Referring to Table 1, the lubricant compositions of test numbers 1 to 13 had high seizure resistance and corrosion resistance.

  In test numbers 3 and 5, the TBN of A calcium sulfonate was 400 mgKOH / g or more, and the TBN of C calcium sulfonate was 200 mgKOH / g or more. Therefore, both lubricity and corrosion resistance were higher than those of test numbers 1 and 2.

The ratio _{RA / C} of test number 4 was in the range of 1/3 to 3. Therefore, both lubricity and corrosion resistance were higher than those of test numbers 1 and 2.

  The lubricant composition of test number 6 contained a specific fatty acid ester. Therefore, both lubricity and corrosion resistance were higher than those of test numbers 1 and 2.

  Test No. 7 contained 40% by mass of octyl palmitate, which is a specific fatty acid ester. Therefore, the lubricity was “excellent”.

The lubricating compositions of Test Nos. 8 to 13 contain a specific fatty acid ester, and the TBN of A calcium sulfonate is 400 mgKOH / g or more, and the TBN of C calcium sulfonate is 200 mgKOH / g or more. It was. Furthermore, the ratio _{RA / C} was in the range of 1/3 to 3. Therefore, both lubricity and corrosion resistance were “excellent”.

  On the other hand, since the lubricant compositions of test numbers 14 to 21 were outside the scope of the present invention, the lubricity or corrosion resistance was low. Specifically, Test No. 14 did not contain a specific sulfide-containing compound. Therefore, the lubricity was “impossible”.

  The content of the specific sulfide-containing compound of test number 15 exceeded the upper limit of the present invention. Therefore, the corrosion resistance was “impossible”.

  The carbon number of the hydrocarbon of the specific sulfide-containing compound of test number 16 was less than 12. Therefore, the lubricity was “good”. However, as a result of performing the lubricity evaluation test again after 3 hours, the lubricity became “impossible”. It is presumed that because the molecular weight is small, it easily evaporates or volatilizes, and the lubricant composition can no longer maintain the initial composition.

  Content of the specific calcium containing compound of the test number 17 was less than the minimum of this invention. Therefore, the lubricity was “impossible”.

  The content of the specific calcium-containing compound of test number 18 exceeded the upper limit of the present invention. Therefore, the corrosion resistance was “impossible”.

The ratio R _{A / C} of test number 19 exceeded 4. Therefore, the corrosion resistance was “impossible”.

The ratio R _{A / C} of test number 20 was less than ¼. Therefore, the lubricity was “impossible”.

  The lubricant composition of Test No. 21 did not contain the specific sulfide-containing compound and the specific calcium-containing compound. Therefore, both lubricity and corrosion resistance were “impossible”.

  While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

  The lubricant composition in the present embodiment is widely applicable to metal processing. In particular, it is suitable for metal processing by cold pilga rolling.

Claims (6)

A lubricant composition used for cold pilga rolling,
10 to 40% by mass of a sulfur-containing compound and 20 to 60% by mass of a calcium-containing compound,
The sulfur-containing compound is a sulfur-containing compound in which 3 to 5 sulfur atoms are continuous and hydrocarbons having 12 to 18 carbon atoms are added to both ends thereof.
The calcium-containing compound includes a first calcium sulfonate having a carbonate crystal structure of an amorphous type crystal and a total base number of 300 mgKOH / g or more, and a carbonate crystal structure of a calcite type crystal having a total base number. Containing a second calcium sulfonate having a ratio R _{A / C} of the first calcium sulfonate to the second calcium sulfonate of 1/4 to 4 . The lubricant composition of claim 1, further comprising:
A lubricant composition containing a fatty acid monoester having a carbon number of 14-18, a carbon number of an alcohol part of 3-8, and having no unsaturated bond. The lubricant composition according to claim 1 or 2, wherein
The total base number of the first calcium sulfonate is 350 mgKOH / g or more, and the total base number of the second calcium sulfonate is 200 mgKOH / g or more. The lubricant composition according to any one of claims 1 to 3, wherein
The lubricant composition, wherein the ratio _{RA / C} is 1/3 to 3. The lubricant composition according to any one of claims 1 to 4, wherein
The alloy pipe to be cold pilger-rolled is a lubricant composition that is a Cr alloy, a Ni alloy, or a Ni-based alloy containing 12 mass% or more of Cr and Ni in total. Preparing an alloy pipe containing 12% by mass or more of Cr and Ni in total;
The manufacturing method of a metal pipe provided with the process of carrying out the cold pilger rolling of the said alloy base pipe using the lubricant composition of any one of Claims 1-4.