LUBRICATION TREATMENT METHOD FOR METAL WIRE MATERIAL

Abstract

 An object is to provide a lubrication treatment method of a metal wire rod, in which not a combination of acid washing/alkaline degreasing and phosphate/soap treatment each causing a large burden on the environment, but shot blast and a coat-type treatment agent are used to allow for a significant reduction in burden on the environment, and a batch manner is applied to allow for practical production efficiency and uniformly form a lubrication coating on a metal wire rod. The object is achieved by a lubrication treatment method of a metal wire rod, which is a method for lubrication treatment of a coiled metal wire rod in a batch manner, including a descaling step of performing shot blast treatment of a coiled metal wire rod, and a lubrication coating formation step of applying a lubricant to the metal wire rod after the descaling step, in which the coiled metal wire rod satisfies L/(d × N) ≥ 1.1 in the descaling step under the assumption that the coil width is L, the wire diameter of the metal wire rod is d, and the number of coil turns is N, and the lubricant contains one or more coating base components (A) selected from the group consisting of an inorganic salt and an organic acid salt, and a lubrication component (B).

Description

TECHNICAL FIELD

[0001] The present invention relates to a lubrication treatment method to be applied in wire drawing processing of various metal wire rods.

BACKGROUND ART

[0002] In general, when metal materials such as iron and steel, and stainless steel are plastically worked, lubrication treatment for production of lubrication coatings on metal surfaces is applied for the purpose of prevention of burning and/or flawing occurring due to metal contact of workpieces and tools. In particular, composite coating treatment (hereinafter, also referred to as "phosphate/soap treatment") of phosphate chemical conversion coatings and soap-based lubrication coatings is widely used as lubrication treatment particularly excellent in processability.

[0003] However, such phosphate/soap treatment has the problem of causing large energy consumption and a large burden on the environment. Thus, environment-friendly coat-type aqueous lubricants have been recently developed.

[0004] Coat-type aqueous lubricants include a plurality of types, including one containing a water-soluble inorganic salt and wax as described in Patent Document 1, and one containing a resin component, an inorganic component, and a solid lubrication component as described in Patent Document 2. Coat-type lubrication treatment is treatment to be performed at a low temperature for a short time, and imposes a small burden on the environment in light of the consumption of energy.

[0005] In the coat-type lubrication treatment, cleaning treatment is performed before coating with aqueous lubricants, for the purpose of removal of a variety of dirt such as oxidized scales and/or oils generated on metal material surfaces due to heat treatment and/or the like. Shot blast, acid washing, alkaline degreasing, and/or the like are/is used for such cleaning treatment. Acid washing and alkaline degreasing in such cleaning treatment use acidic or alkaline high-temperature (generally about 50°C to 80°C) detergents and furthermore require multiple steps and take a significant time for working, and therefore cause a large burden on the environment and a large burden on operators. On the other hand, shot blast does not have such disadvantages.

[0006] Methods for applying coat-type aqueous lubricants to lubrication treatment of metal wire rods include a method for carrying out a metal wire rod covered with a lubrication coating by an in-line system, by continuously performing a process including subjecting a surface of a metal wire rod to cleaning treatment for 20 seconds or less according to any cleaning treatment method selected from shot blast, bending, electrolytic acid washing, and the like, then contacting and coating the surface with a coat-type aqueous lubricant, and then drying the resultant, as proposed in Patent Document 3.

RELATED ART DOCUMENT

PATENT DOCUMENT

[0007] 

Patent Document 1: International Publication No. WO2002/012420

Patent Document 2: International Publication No. WO2011/001653

Patent Document 3: International Publication No. WO2003/035929

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The coat-type lubrication treatment by an in-line system according to Patent Document 3, when used, hardly causes a thick film portion and unevenness in a lubrication coating formed, but has the problem of being low in throughput per hour and being not practical in terms of production efficiency, as compared with that by a batch system. A solution considered for solving the problem is an increase in linear velocity in the in-line system, but is not suitable because the drying time cannot be sufficiently allowed and drying failure occurs, and also uniformity of a lubrication coating is inferior.

[0009] If the shot blast is selected as a cleaning treatment in lubrication treatment to treat a coiled metal wire rod in a batch system, descaling is insufficient, resulting in the problem of no uniform lubrication coating obtained.

[0010] The present invention is to find out and solve the problems of the above background art, and an object thereof is to provide a lubrication treatment method of a metal wire rod, in which shot blast and a coat-type aqueous lubricant are applied in consideration of global environmental conservation, to result in a reduction in burden on the environment, and a batch manner is applied to allow for practical production efficiency and uniformly form a lubrication coating.

MEANS FOR SOLVING THE PROBLEMS

[0011] The present inventors have made intensive studies in order to achieve the above object, and as a result, have found that the above object can be achieved by lubrication treatment of a metal wire rod in a batch manner, including descaling a coiled metal wire rod by shot blast treatment in a state where a proper gap is provided between such wire rods, and subsequently applying a lubricant to the wire rod, to form a lubrication coating, and thus have completed the present invention. The present invention can encompass the following.

(1): A lubrication treatment method of a metal wire rod, which is a method for lubrication treatment of a coiled metal wire rod in a batch manner, including

a descaling step of performing shot blast treatment of a coiled metal wire rod, and a lubrication coating formation step of applying a lubricant to the metal wire rod after the descaling step, wherein

the coiled metal wire rod satisfies L/(d × N) ≥ 1.1 in the descaling step under the assumption that the coil width is L, the wire diameter of the metal wire rod is d, and the number of coil turns is N, and

the lubricant contains one or more coating base components (A) selected from the group consisting of an inorganic salt and an organic acid salt, and a lubrication component (B).

(2): The lubrication treatment method of a metal wire rod according to (1), wherein the lubricant has a viscosity at 25°C of 5 to 50 mPa·s.

(3): The lubrication treatment method of a metal wire rod according to (1) or (2), wherein the solid weight ratio (B)/{(A)+(B)} between the coating base component(s) (A) and the lubrication component (B) in the lubricant is within a range of 0.05 to 0.90.

(4): The lubrication treatment method of a metal wire rod according to any of (1) to (3), including a preliminary heating step of heating the metal wire rod before the lubrication coating formation step.

EFFECT OF THE INVENTION

[0012] According to the present invention, not a combination of acid washing/alkaline degreasing and phosphate/soap treatment each causing a large burden on the environment, but shot blast and a coat-type treatment agent are used to allow for a significant reduction in burden on the environment, and furthermore a batch manner is applied to provide practical production efficiency, thereby allowing for a significant reduction in production energy. Additionally, a lubrication treatment method of a metal wire rod can be provided in which a lubrication coating is uniformly formed on a metal wire rod.

BRIEF DESCRIPTION OF DRAWING

[0013] [Fig. 1] A schematic view showing the coil width L, the wire diameter d of a metal wire rod, and the number N of coil turns, of a coiled metal wire rod.

MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, the content of the present invention is described in detail. A lubrication treatment method of a metal wire rod according to an embodiment of the present invention is to be used for wire drawing processing. The wire drawing processing is drawing processing involving allowing a metal wire rod to pass through a conical hole die having a broad inlet port and a narrow outlet port, thereby respectively decreasing the diameter and elongating the the length of the metal wire rod.

[0015] The type of metal of the metal wire rod to which the lubrication treatment method of the present embodiment can be applied is not particularly restricted, and examples include iron, steel, stainless steel, aluminum, an aluminum alloy, magnesium, a magnesium alloy, titanium, a titanium alloy, copper, and a copper alloy. The wire diameter of the metal wire rod is not particularly restricted as long as the metal wire rod can be wound in a coiled manner.

[0016]  The lubrication treatment method of the present embodiment includes a descaling step of performing shot blast treatment of a metal wire rod wound into a coil shape, and a lubrication coating formation step of applying a lubricant to the metal wire rod after the descaling step. The lubrication coating formation step may include a drying step of drying the lubricant applied. The lubrication treatment method of the present embodiment is made by a batch system in which such a coil-shaped metal wire rod is treated with being directly travelled stepwise in treatment equipment. A water-washing step may be provided before application of the lubricant in the lubrication coating formation step, for the purpose of removal of residues such as shot grains attached onto a metal wire rod surface in the descaling step.

[0017] The metal wire rod in the lubrication treatment method of the present embodiment has a coil shape helically wound. In the present embodiment, the coiled metal wire rod satisfies L/(d × N) ≥ 1.1 under the assumption that the coil width is L, the wire diameter of the metal wire rod is d, and the number of coil turns is N. Fig. 1 illustrates a specific example, in which L/(d × N) represents the degree of coil separation and the value thereof is set to 1.1 or more, to allow shot grains to be spread throughout the metal wire rod surface and thus allow sufficient descaling to be performed, and as a result, unevenness of a lubrication coating formed can be suppressed. The value is preferably 1.2 or more, more preferably 1.3 or more. The upper limit is not particularly limited, and is usually 3.0 or less, preferably 2.0 or less, from the viewpoint of production efficiency.

[0018] In a case where L/(d × N) is less than 1.1, shot grains are not sufficiently projected onto the metal wire rod surface, and dirt such as oxidized scales and/or oils cannot be sufficiently removed in the descaling step. As a result, cissing occurs during application of the lubricant, and unevenness occurs on a lubrication coating formed by subsequent drying, leading to deterioration in lubricity. If oxidized scales remain, deterioration in lubricity may be caused also by deterioration in adhesiveness between the wire rod surface and the lubrication coating.

[0019] Fig. 1 illustrates a schematic view representing the coil width L, the wire diameter d of the metal wire rod, and the number N of coil turns, of the coiled metal wire rod.

[0020] The coil width L is appropriately set depending on the equipment for performing lubrication treatment, and is usually 1 m or more, or may be 2 m or more, or may be 3 m or more. The upper limit is usually 10 m or less, or may be 8 m or less, or may be 5 m or less.

[0021] The wire diameter d of the metal wire rod is appropriately set depending on the type and use of the metal wire rod, and is usually 1 mm or more, or may be 5 mm or more, or may be 8 mm or more. The upper limit is usually 5 cm or less, or may be 4 cm or less, or may be 2 cm or less.

[0022] The number N of coil turns is appropriately set depending on the equipment for performing lubrication treatment, and is usually 30 or more, or may be 100 or more, or may be 200 or more. The upper limit is usually 5000 or less, or may be 2000 or less, or may be 1000 or less.

[0023] The shot blast used in the descaling step is a method for physical and/or mechanical removal of oxidized scales on the metal wire rod surface by projection and collision of shot grains such as steel balls or cut wires to the metal wire rod surface with compressed air or centrifugal force. A known method can be used in the shot blast, and is not particularly restricted. The shot blast may also be performed with rotation of the coiled metal wire rod, for the purpose of shortening of the time necessary for descaling.

[0024] The lubrication treatment method of the present embodiment includes a lubrication coating formation step of subjecting the coiled metal wire rod to the descaling treatment, then contacting the metal wire rod and the lubricant, and applying the lubricant to the metal wire rod. The method preferably includes a preliminary heating step of preliminarily heating the metal wire rod before contact of the metal wire rod and the lubricant. The preliminary heating can promote drying of the lubricant applied to the metal wire rod. Such drying of the lubricant can be promoted, to suppress dripping onto the wire rod surface and form a uniform lubrication coating having less unevenness.

[0025] The preliminary heating method is not particularly limited, hot water washing/heating, high-frequency heating, hot air heating, steam heating, or the like can be adopted, and hot water washing/heating is preferable in the present embodiment. The hot water washing/heating may be performed so as to also serve as water-washing for the purpose of removal of residues such as shot grains attached onto the wire rod surface in the descaling step. The temperature of the preliminary heating is not particularly limited, and the preliminary heating is preferably performed so that the temperature of the metal wire rod is 70 to 150°C. The preliminary heating can be performed in this temperature range, to provide a uniform and high-quality lubrication coating.

[0026] The method for contacting the metal wire rod and the lubricant is not particularly limited, and, for example, an immersion method, a spraying method, or a pouring method from a coil upper portion can be applied. The metal wire rod and the lubricant may be contacted so that the metal wire rod surface is sufficiently covered with the lubricant, and the contacting time is not particularly restricted. When the metal wire rod and the lubricant are contacted, the coil width of the coiled metal wire rod may be appropriately elongated depending on the method for contacting the lubricant. The expression of L/(d × N) ≥ 1.1 may or may not be satisfied during such contacting. The lubricant may be warmed to 40 to 70°C and then contacted with the metal wire rod in order to increase the drying speed.

[0027] The lubricant is an aqueous lubricant containing one or more coating base components (A) selected from an inorganic salt and an organic acid salt and a lubrication component (B) as main components in an aqueous medium. In the present embodiment, a lubrication coating formed from the lubricant containing the coating base component(s) (A) and the lubrication component (B) is favorable in followability during wire drawing processing, has hardness and strength against burning with a die tool, is favorable in slippability, and can be reduced in friction coefficient.

[0028] The aqueous medium is not particularly limited as long as it is a mixture of water or a water-miscible organic solvent. The content of water in the mixture, as expressed by "% by mass", may be 50% by mass or more, and is more preferably 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more in the listed order.

[0029] The water-miscible organic solvent is not particularly limited as long as it is miscible with water, and examples include ketone-based solvents such as acetone and methyl ethyl ketone; amide-based solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol-based solvents such as methanol, ethanol and isopropanol; ether-based solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone-based solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone. One of such water-miscible organic solvents may be mixed with water, or two or more kinds thereof may be mixed with water.

[0030] Examples of the inorganic salt serving as the coating base component (A) include silicate, borate, phosphate, carbonate, sulfate, nitrate, tungstate, molybdate, and vanadate. Examples of the constituent salt therefor include alkali metal salts (sodium salt, potassium salt, lithium salt, and the like), alkaline earth metal salts (magnesium salt, calcium salt, and the like), ammonium salts, and amine salts (ethylamine salt and the like). Such salts may be soluble or insoluble in water, as long as followability of a lubrication coating is obtained in wire drawing processing.

[0031] Specific examples can include sodium silicate, lithium borate (lithium tetraborate), sodium borate (sodium tetraborate), potassium borate (potassium tetraborate), sodium phosphate, calcium phosphate, sodium tripolyphosphate, sodium carbonate, magnesium carbonate, potassium sulfate, calcium sulfate, and sodium tungstate. These inorganic salts may be used singly or in combination of two or more kinds thereof.

[0032] Examples of the organic acid salt serving as the coating base component (A) include aliphatic carboxylate, aromatic carboxylate, and organic phosphonate. Such aliphatic carboxylate may have two or more carboxyl groups and/or one or more hydroxyl groups in its molecule, and preferably has two to eight carbon atoms. Examples include oxalate, maleate, malate, tartrate, gluconate, citrate, and glutarate. Such aromatic carboxylate may have two or more carboxyl groups and/or one or more hydroxyl groups in its molecule. Examples include benzoate, phthalate, isophthalate, terephthalate, and salicylate. Such organic phosphonate may have two or more phosphone groups and/or one or more hydroxyl groups in its molecule. Examples include octylphosphonate and 1-hydroxyethane-1,1-diphosphonate.

[0033] Examples of the constituent salt therefor include alkali metal salts (sodium salt, potassium salt, lithium salt, and the like), alkaline earth metal salts (magnesium salt, calcium salt, and the like), ammonium salts, amine salts (ethylamine salt and the like). Such salts may be soluble or insoluble in water, as long as followability of a lubrication coating is obtained in wire drawing processing.

[0034] Specific examples can include lithium oxalate, sodium malate, sodium tartrate, potassium gluconate, calcium citrate, magnesium glutarate, sodium benzoate, sodium salicylate, sodium 1-hydroxyethane-1,1-diphosphonate. These organic acid salts may be used singly or in combination of two or more kinds thereof.

[0035] Examples of the lubrication component (B) can include oil, wax, soap, molybdenum disulfide, graphite, fluororesins such as polytetrafluoroethylene (PTFE), hopeite (zinc phosphate), and an extreme pressure agent. Examples of the wax include polyethylene wax, microcrystalline wax, polypropylene wax, and carnauba wax, and polyethylene wax is most preferred. Examples of the soap include a metal salt of fatty acid, and more specific examples thereof can include respective metal salts of saturated or unsaturated fatty acids each having 8 to 22 carbon atoms, such as octanoic acid, lauric acid, palmitic acid, oleic acid, and stearic acid. Examples of such metal salts can include not only alkali metal salts such as a sodium salt and a potassium salt, but also polyvalent metal salts such as a calcium salt, a zinc salt, a magnesium salt, and a barium salt. A so-called solid lubricant including solid particles of molybdenum disulfide, graphite, polytetrafluoroethylene, hopeite, or the like is not particularly restricted in terms of the average particle size, the molecular weight, and the like. Examples of the extreme pressure agent can include a sulfur-based extreme pressure agent, an organic molybdenum-based extreme pressure agent, and a phosphorus-based extreme pressure agent. More specific examples include sulfurized olefin, molybdenum dithiophosphate (MoDTP), and phosphate ester. These lubrication components may be used singly or in combination of two or more kinds thereof.

[0036] The content ratio between the coating base component(s) (A) and the lubrication component (B) in the lubricant is here described. The solid weight ratio [(B)/{(A)+(B)}] between the coating base component(s) (A) and the lubrication component (B) is preferably within a range of 0.05 to 0.90, more preferably within a range of 0.15 to 0.65. When the [(B)/{(A)+(B)}] is within the above range, the effect of friction reduction, expected to be derived from the lubrication component (B), is sufficiently exerted, to allow for favorable followability of a lubrication coating.

[0037] The total content of the component(s) (A) and the component (B) in the lubricant is not particularly limited, and the total amount of the component(s) (A) and the component (B) in the lubricant is usually within a range of 1 to 50% by weight, preferably within a range of 5 to 20% by weight.

[0038] The viscosity of the lubricant is not particularly limited, and is preferably 5 to 50 mPa·s, more preferably 10 to 40 mPa·s at 25°C. When the viscosity of the lubricant is within the above range, a lubrication coating having less unevenness and high uniformity is formed after drying of the lubricant, and excellent lubricity is exhibited on the coating. The viscosity is herein a measurement value with a B-type viscometer (Brookfield-type viscometer). The B-type viscometer is to calculate the viscosity by measurement of the flow resistance (torque) in immersion of a rotor called spindle in a liquid and rotation of the spindle. Measurement conditions are as follows, and a measurement value after 1 minute from the start of rotation of the spindle is here adopted.

<Measurement conditions of viscosity>

[0039] 

Instrument: TVB-10M, TOKISANGYO

Spindle: 25 mm in diameter, 90 mm in height

Rotational speed: 50 rpm

[0040] A viscosity modifier (C) may be compounded for the purpose of adjusting the viscosity of the lubricant within a desired range. The viscosity modifier is not particularly restricted and examples thereof include an aqueous resin and an inorganic clay mineral. Examples of the aqueous resin include vinyl resins, acrylic resins, epoxy resins, urethane resins, phenol resins, cellulose derivatives (CMC: carboxymethylcellulose, and the like), polymaleic acid-based resins, and polyolefin-based resins (PVA: polyvinyl alcohol, and the like). Examples of the inorganic clay mineral include smectite-based clay minerals such as montmorillonite, sauconite, beidellite, saponite, and hectorite. These may be compounded singly or in combination of two or more kinds thereof.

[0041] The content of the viscosity modifier (C) in the lubricant is not particularly limited, and the content in the lubricant is usually within a range of 0.1 to 10% by weight, preferably within a range of 0.5 to 5% by weight.

[0042] A rust-proofing component may be compounded to the lubricant, for the purpose of suppression of rusting on the metal wire rod after lubrication coating formation, as long as the effects of the present invention are not impaired. The rust-proofing component here used is a corrosion inhibitor for suppression of rusting on a metal material, and is a component acting as an inhibitor for suppression of redox reaction on a metal surface. The rust-proofing component here used can be any known component such as nitrite, phosphite, an amine compound, an azole compound, a benzotriazole compound, or a chelate compound. When a surfactant is needed in order to disperse the lubrication component in the lubricant, any surfactant of a non-ionic surfactant, an anionic surfactant, an amphoteric surfactant, and a cationic surfactant can be used.

[0043] Drying of the lubricant applied to the metal wire rod can be performed by drying with heating, air drying, or the like. The drying temperature is not particularly restricted, and such drying is preferably performed at an atmosphere temperature of 60 to 150°C.

[0044] The weight of attachment of a lubrication coating formed by the lubrication treatment method according to the present embodiment may be appropriately adjusted depending on the level of difficulty of processing, and the like, and the weight of a dry coating is preferably 1 g/m² or more, more preferably within a range of 2 to 18 g/m² from the viewpoint of prevention of burning and/or flawing, friction reduction, and/or suppression of scum generation in wire drawing processing. The weight of attachment of the lubrication coating can be adjusted by appropriately controlling the concentration of the lubricant applied. The weight of attachment can be determined by cutting out the metal wire rod subjected to lubrication treatment, to a certain length, measuring the weight of a product cut out, then releasing a coating and measuring the weight of a single metal wire rod, to determine the difference in weight, and performing calculation with the difference in weight and the surface area (calculated from the length cut out). The coating can be here released by, for example, immersion in hot water at 60°C for 1 minute.

EXAMPLES

[0045]  Hereinafter, the present invention is further specifically described together with the effects thereof with reference to Examples and Comparative Examples. The scope of the present invention is not restricted by these Examples.

(1) Preparation of aqueous lubricants

[0046] Preparation methods of various aqueous lubricants in Examples, and Comparative Examples are shown below.

[0047] First, a combination of a component (A) and a component (B) shown in Table 1 was added to water at a predetermined ratio. Here, the weight ratio between the total solid content of the component (A) and the component (B), and water was set to 10:90. Next, a viscosity modifier (C) shown in Table 1 was added so that a predetermined viscosity was obtained, and thus various aqueous lubricants were prepared. Here, all of such aqueous lubricants each contained an aqueous 0.5% fluorescent dye (bistriazinylstilbene disulfonic acid derivative) on a solid content basis in order to evaluate the appearance of a lubrication coating described below.

(2) Lubrication treatment for drawing processing test

[0048] A metal wire rod for a drawing processing test was subjected to lubrication treatment with shot blast of a metal wire rod having a degree of separation (L/(d × N)) shown in Table 1 by an aqueous lubricant combination shown in Table 1 with or without preliminary heating shown in Table 1. The metal wire rod here used was a SCM435 steel wire rod (ϕ13.0 mm, length 200 m). The metal wire rod was formed into a coil so that the coil diameter was 1.3 m, and the coil width L (the distance between both ends of the wire rod), the wire diameter d and the number N of coil turns were respectively values of (L/(d × N)) shown in Table 1. The details of shot blast and lubrication treatment are shown below.

(2-1) Shot blast

<Descaling treatment in Examples 1 to 31 and Comparative Examples 1 to 7: shot blast>

[0049] Shot conditions: shot ball (steel ball, hardness: HRC 40 to 50, ϕ0.5 mm), time 10 minutes, pressure 7 kgf/cm²

(2-2) Preliminary heating

[0050] In Examples and Comparative Examples in which preliminary heating was performed, washing with hot water was carried out after descaling treatment and before lubrication treatment (application of aqueous lubricant).
Conditions of washing with hot water: tap water, 80°C, 1 minute, immersion

(2-3) Lubrication treatment

[0051] In Examples and Comparative Examples in which descaling treatment and preliminary heating were performed, an aqueous lubricant was applied to the metal wire rod surface after preliminary heating, thereafter moisture was evaporated by drying, and thus a lubrication coating was formed. The metal wire rod was partially cut out after lubrication treatment and the lubrication coating was released, and thus the weight of attachment of the lubrication coating was calculated. The coating was here released by immersion in hot water at 60°C for 1 minute.

Application of lubricant: various aqueous lubricants, 60°C, 1 minute, immersion

Drying: drying with heating, 100°C, 10 minutes

(3) Evaluation of uniformity of lubrication coating

[0052] The uniformity of the lubrication coating formed in each lubrication treatment in (2) was evaluated. The evaluation was performed according to a procedure according to the invention of JP 5046545 B2. Light was emitted on the lubrication coating by irradiation with ultraviolet light by a black light in a dark place and the formation state of the coating was visually observed, and thus the uniformity was evaluated according to the following evaluation criteria. B or higher score was determined to correspond to uniformity at a practical level.

<Evaluation criteria>

[0053] 

S: coating attached on the entire surface and uniformly formed.

A: coating attached on the entire surface, but one portion thereof ununiformly formed.

B: coating attached on the entire surface, but the whole thereof ununiformly formed.

C: coating not partially formed.

(4) Drawing processing test

[0054] In order to evaluate the lubrication performance of the metal wire rod subjected to each lubrication treatment in (2), drawing processing was performed, and the lubricity and the scum generation state during drawing processing were evaluated according to the following evaluation criteria. Such drawing processing was performed by drawing the metal wire rod with an R die (ϕ12.0 mm).

<Evaluation criteria of lubricity>

[0055] If lubricity during drawing processing is insufficient, the wire rod and the R die are directly contacted due to lubrication coating loss, thereby causing burning and/or flaws. B or higher scores were determined to correspond to performance at a practical level.

S: extremely favorable lubricity, and no burning, flaws, and the like observed on the wire rod surface and the R die at all.

A: favorable lubricity, and slight burning, flaws, and the like observed in a region corresponding to an area ratio of less than 5% on the wire rod surface and the R die.

B: fair lubricity, and slight burning, flaws, and the like observed in a region corresponding to an area ratio of 5% or more and less than 10% on the wire rod surface and the R die.

C: inferior lubricity, and burning, flaws, and the like observed in a region corresponding to an area ratio of 10% or more on the wire rod surface and the R die, or the wire rod broken due to insufficient lubrication during drawing processing.

<Evaluation criteria of scum generation state>

[0056] If the amount of scum generated is large in the lubrication coating during drawing processing, clogging due to lubrication scum may occur in the R die, resulting in the occurrence of a mark of compression on the wire rod surface and deterioration in surface quality. In addition, scum is scattered and deposited around the R die, thereby worsening the working environment. B or higher scores were determined to correspond to performance at a practical level.

S: almost no scum generation observed: an amount of scum generated of less than 10% relative to the amount of the lubrication coating.

A: a small amount of scum generated: an amount of scum generated of 10% or more and less than 20% relative to the amount of the lubrication coating.

B: a slightly large amount of scum generated: an amount of scum generated of 20% or more and less than 40% relative to the amount of the lubrication coating.

C: a large amount of scum generated: an amount of scum generated of 40% or more relative to the amount of the lubrication coating.

[0057]  The test results are shown in Table 2. As clear from Table 2, the lubrication coating formed in each of Examples 1 to 31 exhibited practical levels of coating uniformity, lubricity in the drawing processing test, and scum generation state in evaluations thereof.

[0058] On the other hand, that in each of Comparative Examples 1 to 4, in which the degree of coil separation of the metal wire rod in the descaling step (shot blast) was low, exhibited inferior lubricity and scum generation state.

[0059] In addition, that in each of Comparative Examples 5 to 7, having an aqueous lubricant composition containing only any of the coating base component (A) and the lubrication component (B), exhibited inferior lubricity in the drawing processing test.

[Table 1-1]

		Shot blast	Preliminary heating	Aqueous lubricant
		L/(d×N)	(Hot water -washing)	Coating base component (A)		Lubrication component (B)	B/(A + B)	Viscosity modifier (C)	Viscosity [mPa · s]
				Inorganic salt	Organic acid salt
	1	1.4	No	Na silicate	-	Polyethylene wax	0.3	CMC	10
	2	1.1	No	Na silicate	-	Polyethylene wax	0.3	CMC	10
	3	1.4	No	Na silicate	-	Polyethylene wax	0.3	CMC	6
	4	1.4	No	Na silicate	-	Polyethylene wax	0.3	CMC	42
	5	1.1	No	Na silicate	-	Polyethylene wax	0.3	CMC	6
	6	1.1	No	Na silicate	-	Polyethylene wax	0.3	CMC	42
	7	1.4	No	Na silicate	-	Ca stearate	0.3	CMC	10
	8	1.4	No	Na silicate	-	Polyethylene wax	0.12	CMC	10
	9	1.4	No	Na silicate	-	Polyethylene wax	0.6	CMC	10
	10	1.4	No	Na silicate	-	Polyethylene wax	0.8	CMC	10
	11	1.4	No	K tetraborate	-	Polyethylene wax	0.6	CMC	15
	12	1.4	No	K tetraborate	-	Hopeite	0.2	CMC	15
	13	1.4	No	K tetraborate	-	Polyethylene wax	0.6	Synthetic hectorite	6
	14	1.4	No	K tetraborate	-	Polyethylene wax	0.6	CMC	42
	15	1.4	No	Ca sulfate	-	Polyethylene wax	0.5	PVA	15
	16	1.4	No	-	Na tartrate	Polyethylene wax	0.3	CMC	10
Examples	17	1.4	No	-	Ca citrate	Polyethylene wax	0.5	CMC	10

[Table 1-2]

	18	1.4	No	-	Ca citrate	Polyethylene wax	0.5	CMC	6
	19	1.4	No	-	Ca citrate	Polyethylene wax	0.5	CMC	42
	20	1.4	No	-	Ca citrate	Polyethylene wax	0.08	CMC	10
	21	1.4	No	-	Ca citrate	Polyethylene wax	0.8	CMC	10
	22	1.4	No	-	Mg glutarate	Polyethylene wax	0.5	PVA	15
	23	1.4	Yes	Na silicate	-	Polyethylene wax	0.3	CMC	10
	24	1.1	Yes	Na silicate	-	Polyethylene wax	0.3	CMC	10
	25	1.4	Yes	Na silicate	-	Polyethylene wax	0.3	CMC	6
	26	1.4	Yes	Na silicate	-	Polyethylene wax	0.3	CMC	42
	27	1.1	Yes	Na silicate	-	Polyethylene wax	0.3	CMC	6
	28	1.1	Yes	Na silicate	-	Polyethylene wax	0.3	CMC	42
	29	1.4	Yes	-	Ca citrate	Polyethylene wax	0.5	CMC	10
	30	1.4	Yes	-	Ca citrate	Polyethylene wax	0.5	CMC	6
	31	1.4	Yes	-	Ca citrate	Polyethylene wax	0.5	CMC	42
Comparative Examples	1	1.0	No	Na silicate	-	Polyethylene wax	0.3	CMC	10
	2	1.0	No	K tetraborate	-	Polyethylene wax	0.6	CMC	15
	3	0.6	No	Na silicate	-	Polyethylene wax	0.3	CMC	10
	4	1.0	Yes	Na silicate	-	Polyethylene wax	0.3	CMC	10
	5	1.4	No	-	-	Polyethylene wax	(1.0)	CMC	10
	6	1.4	No	Na silicate	-	-	-	CMC	10
	7	1.4	No	-	Ca citrate	-	-	CMC	10

[Table 2]

[0060] 

Table 2

		Amount of attachment [g/m2]	Uniformity of lubrication coating	Drawing processing test
				Lubricity	Scum generation state
	1	6	A	S	S
	2	6	A	S	S
	3	3	B	B	A
	4	12	B	A	B
	5	3	B	B	A
	6	13	B	A	B
	7	7	A	A	A
	8	5	A	B	S
	9	7	A	A	B
	10	7	A	B	B
	11	7	A	A	B
	12	6	A	S	S
	13	3	B	B	A
	14	13	B	A	B
	15	8	A	A	A
Examples	16	6	A	A	A
	17	6	A	S	S
	18	3	B	B	S
	19	12	B	A	B
	20	7	A	B	S
	21	7	A	B	B
	22	7	A	A	A
	23	7	S	S	S
	24	6	S	S	S
	25	3	A	A	A
	26	14	A	A	B
	27	3	A	A	A
	28	13	A	A	B
	29	7	S	S	S
	30	3	A	A	S
	31	13	A	A	B
Comparative Examples	1	6	B	C	C
	2	8	B	C	C
	3	10	C	C	C
	4	6	B	C	C
	5	5	B	C	C
	6	5	A	C	A
	7	6	A	C	B

[0061] The present invention is described in detail with reference to specific Examples, but it is obvious to those skilled in the art that the present invention can be variously modified and altered without departing from the gist and scope thereof.

Claims

1. A lubrication treatment method of a metal wire rod, which is a method for lubrication treatment of a coiled metal wire rod in a batch manner, comprising

a descaling step of performing shot blast treatment of a coiled metal wire rod, and a lubrication coating formation step of applying a lubricant to the metal wire rod after the descaling step, wherein

the coiled metal wire rod satisfies L/(d × N) ≥ 1.1 in the descaling step under the assumption that the coil width is L, the wire diameter of the metal wire rod is d, and the number of coil turns is N, and

the lubricant contains one or more coating base components (A) selected from the group consisting of an inorganic salt and an organic acid salt, and a lubrication component (B).

2. The lubrication treatment method of a metal wire rod according to claim 1, wherein the lubricant has a viscosity at 25°C of 5 to 50 mPa·s.

3. The lubrication treatment method of a metal wire rod according to claim 1 or 2, wherein the solid weight ratio (B)/{(A)+(B)} between the coating base component(s) (A) and the lubrication component (B) in the lubricant is within a range of 0.05 to 0.90.

4. The lubrication treatment method of a metal wire rod according to any one of claims 1 to 3, comprising a preliminary heating step of heating the metal wire rod before the lubrication coating formation step.

Drawing