Metallic component production method and cold plastic working device

Abstract

The present invention provides a metallic component production method that makes it possible to suppress the occurrence of surface flaws of a metallic component which is obtained after cold plastic working. The metallic component production method includes a lubricant adhesion step and a cold plastic working step. In the lubricant adhesion step, a lubricant (LU) containing fine bubbles is adhered to at least one of a plastic working tool (2) and a metallic workpiece (W). In the cold plastic working step, after the lubricant (LU) has been adhered to at least one of the surface of the plastic working tool (2) and the surface of the metallic workpiece (W), cold plastic working is performed on the metallic workpiece (W) using the plastic working tool (2) to produce a metallic component.

Description

Metallic material manufacturing method and cold plastic working device

[0001] The present invention relates to a method for manufacturing a metal material and a cold plastic working apparatus used in the manufacturing method.

[0002] There are known methods for manufacturing metallic materials by performing cold plastic working on metallic raw materials, which can be broadly classified into (1) wire drawing, (2) cold drawing, (3) cold extrusion, and (4) cold rolling.

[0003] Metal wires such as steel cords, aluminum wires, copper wires, and titanium wires may have a wire diameter of less than 1 mm. Such ultra-fine metal wires are manufactured by wiredrawing, a type of cold plastic working. In wiredrawing, a metal material is passed through a die and then drawn out of the die to produce a metal wire.

[0004] Metal bars, such as steel bars, aluminum bars, copper bars, and titanium bars, and metal tubes, such as steel pipes, aluminum pipes, copper pipes, and titanium pipes, are manufactured by cold drawing, a type of cold plastic working. In cold drawing, a metal material is passed through a die and then pulled out of the die to produce a metal material (metal bar or metal tube).

[0005] Steel, aluminum, copper, titanium, and other shapes are manufactured by cold extrusion, a type of cold plastic processing. In cold extrusion, a metal material is pushed out of a die using a stem to produce a metal material (metal shape).

[0006] Metal sheets such as steel sheets, aluminum sheets, copper sheets, and titanium sheets are manufactured by cold rolling, which is a type of cold plastic working. The above-mentioned metal wires, metal bars, and metal pipes may also be manufactured by cold rolling. In cold rolling, metal materials (metal sheets, metal wires, metal bars, and metal pipes) are manufactured by cold rolling a metal material using work rolls.

[0007] A number of techniques for manufacturing metal materials using these cold plastic working processes have been proposed. For example, metal wire drawing techniques are disclosed in Japanese Patent Laid-Open No. 2011-147963 (Patent Document 1) and Japanese Patent Laid-Open No. 2014-151357 (Patent Document 2). Patent Document 1 discloses a technique for recycling lubricant whose lubricating performance has deteriorated during wire drawing. Furthermore, Patent Document 2 discloses a technique for efficiently removing plating debris generated during wire drawing of plated wire from the lubricant and reusing the lubricant.

[0008] JP 2011-147963 A JP 2014-151357 A

[0009] However, when a metal material is manufactured by cold plastic working, defects may occur on the surface of the manufactured metal material. For example, when a metal wire is manufactured by wire drawing, the strength of the metal wire decreases as the wire diameter becomes smaller. Therefore, defects are more likely to occur on the surface of the metal wire during wire drawing. Although Patent Documents 1 and 2 disclose techniques related to the reuse of lubricants, they do not consider suppressing surface defects on metal materials after cold plastic working.

[0010] An object of the present invention is to provide a method for manufacturing a metal material that can suppress the occurrence of surface defects on the metal material after cold plastic working, and a cold plastic working apparatus used in the manufacturing method.

[0011] The method for manufacturing a metal material according to this embodiment includes a lubricating liquid application step and a cold plastic working step. In the lubricating liquid application step, a lubricating liquid containing fine bubbles is applied to at least one of the surface of a plastic working tool and the surface of a metal raw material. In the cold plastic working step, the lubricating liquid is applied to at least one of the surface of a plastic working tool and the surface of a metal raw material, and then cold plastic working is performed on the metal raw material using the plastic working tool to manufacture the metal material.

[0012] The cold plastic working apparatus of this embodiment is capable of performing cold plastic working on a metal material. The cold plastic working apparatus includes a plastic working tool, a fine bubble generator, and a lubricant applying device. The fine bubble generator generates a lubricant containing fine bubbles. The lubricant applying device applies the lubricant containing fine bubbles to at least one of the surface of the plastic working tool and the surface of the metal material before or during the cold plastic working.

[0013] The method for manufacturing a metal material according to this embodiment can suppress the occurrence of surface defects on the metal material after cold plastic working. The cold plastic working apparatus according to this embodiment can suppress the occurrence of surface defects on the metal material after cold plastic working.

[0014] FIG. 1 is a schematic diagram showing an example of a cold plastic working apparatus used in the method for producing a metallic material according to the first embodiment. FIG. 2 is a schematic diagram showing an example of a cold plastic working apparatus having a different configuration from that shown in FIG. 1. FIG. 3 is a schematic diagram showing an example of a cold plastic working apparatus having a different configuration from that shown in FIGS. 1 and 2. FIG. 4 is a schematic diagram showing an example of a cold plastic working apparatus having a different configuration from that shown in FIGS. 1 to 3. FIG. 5 is a schematic diagram showing an example of a cold plastic working apparatus used in the method for producing a metallic material according to the second embodiment. FIG. 6 is a schematic diagram showing an example of a cold plastic working apparatus used in the method for producing a metallic material according to the third embodiment. FIG. 7 is a schematic diagram for explaining cold plastic working using the cold plastic working apparatus shown in FIG. 6. FIG. 8 is a schematic diagram for explaining cold plastic working using the cold plastic working apparatus shown in FIG. 8, which is different from that shown in FIG. 6 and is used in the method for producing a metallic material according to the third embodiment. FIG. 9 is a schematic diagram for explaining cold plastic working using the cold plastic working apparatus shown in FIG. 8. FIG. 10 is a schematic diagram showing an example of a cold plastic working apparatus used in the method for manufacturing a metal material according to the fourth embodiment.

[0015] The method for manufacturing a metallic material according to this embodiment includes a lubricating liquid application step and a cold plastic working step. In the lubricating liquid application step, a lubricating liquid containing fine bubbles is applied to at least one of the surface of a plastic working tool and the surface of a metallic raw material. In the cold plastic working step, the lubricating liquid is applied to at least one of the surface of the plastic working tool and the surface of the metallic raw material, and then cold plastic working is performed on the metallic raw material using the plastic working tool to manufacture the metallic material (first configuration).

[0016] When cold plastic working is performed on a metal material, the metal material is constrained by plastic working tools such as dies and work rolls and undergoes plastic deformation. During plastic deformation, a new surface is generated on the surface of the metal material. This new surface is likely to weld to the surface of the plastic working tool. If part of the new surface is welded to the surface of the plastic working tool, the welded part will solidify on the surface of the plastic working tool to form a solidified part. This solidified part will come into contact with the metal material as it passes through the plastic working tool, forming a flaw on the surface of the metal material (metal material).

[0017] In the first method for manufacturing a metal material, a lubricating liquid containing fine bubbles is applied to at least one of the surface of a plastic processing tool and the surface of the metal raw material, and then cold plastic processing is performed. In this case, the fine bubbles in the lubricating liquid are interposed between the surface of the plastic processing tool and the surface of the metal raw material during cold plastic processing. At this time, it is thought that the fine bubbles exert a buffering effect between the surface of the plastic processing tool and the surface of the metal raw material, mitigating direct collision between the surface of the plastic processing tool and the surface of the metal raw material. Due to this buffering effect, the fine bubbles suppress strong contact between the surface of the plastic processing tool and the newly formed surface of the metal raw material. Therefore, the newly formed surface of the metal raw material is less likely to fuse to the surface of the plastic processing tool. As a result, the occurrence of scratches is suppressed on the surface of the metal material after cold plastic processing.

[0018] The method for manufacturing a metal material of the second configuration is the method for manufacturing a metal material of the first configuration, in which the average particle size of the fine bubbles is 0.01 μm or more and 50.00 μm or less.

[0019] In the second method for producing a metal material, the fine bubbles are fine bubbles or ultrafine bubbles. In this case, the fine bubbles can easily be interposed between the surface of the plastic processing tool and the surface of the metal material. As a result, the buffering effect of the fine bubbles interposed between the surface of the plastic processing tool and the surface of the metal material can suppress the occurrence of scratches on the surface of the metal material.

[0020] The manufacturing method of the metal material of the third configuration is the manufacturing method of the metal material of the second configuration, in which the average particle size of the fine bubbles is 0.01 μm or more and less than 1.00 μm.

[0021] In the third method for producing a metal material, the fine bubbles are ultrafine bubbles, which allows the fine bubbles to be more easily interposed between the surface of the plastic processing tool and the surface of the metal material.

[0022] The manufacturing method of the fourth configuration of the metal material is a manufacturing method of the metal material of any one of the first to third configurations, in which the metal material has one of aluminum, steel, titanium, and copper as its main component.

[0023] The fifth configuration of the method for manufacturing a metal material is a method for manufacturing a metal material of any one of the first to fourth configurations, in which the number density of fine bubbles in the lubricating liquid is set to 50 bubbles / mL or more.

[0024] In the fifth method for producing a metal material, the fine bubble density is 50 bubbles / mL or more, so a sufficient amount of fine bubbles is contained in the lubricating liquid. Therefore, during cold plastic working, a sufficient amount of fine bubbles is present between the surface of the plastic working tool and the surface of the metal material. As a result, the occurrence of surface defects can be suppressed in the metal material after cold plastic working.

[0025] A sixth aspect of the method for manufacturing a metal material is the method for manufacturing a metal material of any one of the first to fifth aspects, in which the plastic processing tool is a die. In the cold plastic processing step, the die is used to perform wire drawing on the metal material to produce a metal wire.

[0026] The seventh configuration of the manufacturing method for a metal material is the sixth configuration of the manufacturing method for a metal material, in which wire drawing is performed using one or more dies, and when the diameter of the through hole of the final die among the one or more dies is d (μm), the average particle size of the fine bubbles is 0.6 dμm or less.

[0027] In the seventh method for producing a metal material, a sufficient amount of fine bubbles can be present between the surface of the through hole of the die and the surface of the metal material, thereby further suppressing the occurrence of surface defects in the metal material after cold plastic working.

[0028] The method for manufacturing a metal material according to an eighth aspect is the method for manufacturing a metal material according to any one of the first to fifth aspects, in which the plastic processing tool is a die. In the cold plastic processing step, the die is used to perform cold drawing on the metal material to produce a metal material that is a metal bar or a metal tube.

[0029] A ninth aspect of the method for manufacturing a metal material is the method for manufacturing a metal material of any one of the first to fifth aspects, in which the plastic processing tool is a die. In the cold plastic processing step, the die is used to perform cold extrusion processing on the metal material to manufacture a metal material that is a metal bar or a metal tube.

[0030] A tenth aspect of the method for producing a metallic material is the method for producing a metallic material of any one of the first to fifth aspects, in which the plastic processing tool is a work roll. In the cold plastic processing step, the work roll is used to cold roll the metallic material to produce one of a metal bar, a metal pipe, and a metal plate.

[0031] An eleventh aspect of the method for manufacturing a metal material is a method for manufacturing a metal material according to any one of the first to fourth aspects, in which the cold plastic working step involves cold plastic working using one or more plastic working tools. When the plastic working tools are dies and the cold plastic working is wire drawing or cold drawing, the area reduction rate of the metal material at each plastic working tool is set to 10.0% or more and less than 23.5%. In the lubricating liquid application step, when the minimum number density N / mL defined by formula (1) is calculated for each cold plastic working performed with each plastic working tool, the number density of fine bubbles in the lubricating liquid is set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 x (P / 100) x V (1) Here, in formula (1), P is substituted with the area reduction rate (%) at the plastic working tool defined by formula (2), and V is substituted with the moving speed V (mpm) of the metal material at the outlet of the plastic working tool. P = {(A0 - A1) / A0} × 100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted, and A1 is the cross-sectional area (mm ２ ) is substituted.

[0032] A twelfth configuration of the method for manufacturing a metal material is a method for manufacturing a metal material according to any one of the first to fourth configurations, in which the cold plastic working step uses a single plastic working tool to perform cold plastic working. When the plastic working tool is a die and the cold plastic working is cold extrusion, the area reduction rate of the metal material at the plastic working tool is set to 50.0% or more and 95.0% or less. In the lubricating liquid application step, when the minimum number density N / mL defined by formula (1) is calculated during cold plastic working with the plastic working tool, the number density of fine bubbles in the lubricating liquid is set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 x (P / 100) x V (1) Here, in formula (1), P is substituted with the area reduction rate (%) at the plastic working tool defined by formula (2), and V is substituted with the moving speed V (mpm) of the metal material at the outlet side of the plastic working tool. P = {(A0 - A1) / A0} × 100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２) is substituted, and A1 is the cross-sectional area (mm ２ ) is substituted.

[0033] A thirteenth configuration of the method for manufacturing a metal material is a method for manufacturing a metal material according to any one of the first to fourth configurations, in which the cold plastic working step involves cold plastic working using one or more plastic working tools. When the plastic working tools are work rolls and the cold plastic working is cold rolling, the total area reduction rate of the metal material due to all of the plastic working tools is set to 50.0% or more and 95.0% or less. In the lubricating fluid application step, when the minimum number density N / mL defined by formula (1) is calculated for each cold plastic working performed with each plastic working tool, the number density of fine bubbles in the lubricating fluid is set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 x (P / 100) x V (1) Here, in formula (1), P is substituted with the area reduction rate (%) of the plastic working tool defined by formula (2), and V is substituted with the moving speed V (mpm) of the metal material at the outlet of the plastic working tool. P = {(A0 - A1) / A0} × 100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted into A1, and the cross-sectional area (mm ２ ) is substituted.

[0034] In the manufacturing method of any one of the eleventh to thirteenth configurations of a metal material, the number density of fine bubbles in the lubricating liquid is set to a maximum value of N bubbles / mL or more. In this case, an appropriate amount of fine bubbles is contained in the lubricating liquid, taking into consideration the type of cold plastic working and the manufacturing conditions. Therefore, during cold plastic working, a sufficient amount of fine bubbles is present between the surface of the plastic working tool and the surface of the metal material. As a result, the occurrence of surface defects can be more effectively suppressed in the metal material after cold plastic working.

[0035] A cold plastic working apparatus of a fourteenth configuration is capable of performing cold plastic working on a metal material. The cold plastic working apparatus includes a plastic working tool, a fine bubble generator, and a lubricant applying device. The fine bubble generator generates a lubricant containing fine bubbles. The lubricant applying device applies the lubricant containing fine bubbles to at least one of the surface of the plastic working tool and the surface of the metal material before or during the cold plastic working.

[0036] In the cold plastic working apparatus of the fourteenth configuration, a fine bubble generator generates a lubricating liquid containing fine bubbles. Furthermore, a lubricating liquid application device applies the lubricating liquid containing fine bubbles to the surface of the plastic working tool or the surface of the metal material. Therefore, during cold plastic working, fine bubbles in the lubricating liquid are present between the surface of the plastic working tool and the surface of the metal material. As a result, the occurrence of surface defects can be suppressed in the metal material after cold plastic working.

[0037] A cold plastic working apparatus of a fifteenth configuration is the cold plastic working apparatus of the fourteenth configuration, in which the lubricant application device includes a nozzle and a supply device. The nozzle discharges the lubricant containing fine bubbles onto at least one of the surface of the plastic working tool and the surface of the metal material. The supply device supplies the lubricant containing fine bubbles to the nozzle.

[0038] The cold plastic processing device of the fifteenth configuration can apply a lubricating liquid containing fine bubbles to the surface of the plastic processing tool and / or the surface of the metal material using a supply device and a nozzle.

[0039] A cold plastic working apparatus of a sixteenth configuration is the cold plastic working apparatus of the fifteenth configuration, in which the nozzle is disposed on the inlet side of the plastic working tool. The nozzle discharges a lubricating liquid containing fine bubbles from the inlet side of the plastic working tool onto at least one of the surface of the plastic working tool and the surface of the metal raw material.

[0040] In the cold plastic working device of the sixteenth configuration, a lubricating liquid containing fine bubbles is discharged from the inlet side of the plastic working tool onto the surface of the plastic working tool and / or the surface of the metal raw material, so that the lubricating liquid containing fine bubbles is applied to the surface of the plastic working tool and / or the surface of the metal raw material before plastic working is performed.

[0041] A cold plastic working apparatus of a seventeenth configuration is the cold plastic working apparatus of any one of the fourteenth to sixteenth configurations, in which the plastic working tool is a die capable of wire drawing or cold drawing the metal material. The cold plastic working apparatus further includes a drawing device. The drawing device draws the metal material from the plastic working tool.

[0042] The cold plastic working apparatus of an eighteenth configuration is the cold plastic working apparatus of the seventeenth configuration, which is capable of performing wire drawing on a metal material. The lubricant application device includes a reservoir tank and an immersion mechanism. The reservoir tank is capable of storing lubricant containing fine bubbles. The immersion mechanism immerses the metal material in the lubricant in the reservoir tank at the entry side of the die before it passes through the die. The die is positioned so that it is immersed in the lubricant in the reservoir tank.

[0043] In the cold plastic working apparatus of the eighteenth configuration, the die is immersed in the lubricating liquid in the reservoir, and the metal material is also immersed in the lubricating liquid in the reservoir at the entry side of the die, so that the lubricating liquid containing fine bubbles can be applied to the surface of the metal material before it passes through the die and to the surface of the through-holes of the die.

[0044] A cold plastic working apparatus of a nineteenth configuration is the cold plastic working apparatus of the eighteenth configuration, further comprising a withdrawal mechanism. The withdrawal mechanism withdraws the metal material after passing through the die from the lubricating liquid in the reservoir at the exit side of the die.

[0045] In the cold plastic working device of the nineteenth configuration, the metal material after cold plastic working is drawn out from the lubricating liquid in the reservoir, so that the metal material can be wound outside the reservoir.

[0046] A cold plastic working apparatus of a twentieth configuration is the cold plastic working apparatus of the fourteenth configuration, in which the plastic working tool is a die capable of cold extrusion working a metal material. The cold plastic working apparatus further includes a container for storing the metal material, and a stem for extruding the metal material stored in the container from the die.

[0047] A cold plastic working apparatus of a twenty-first configuration is the cold plastic working apparatus of any one of the fourteenth to sixteenth configurations, in which the plastic working tool is a work roll capable of cold rolling a metal material.

[0048] Hereinafter, the method for manufacturing a metal material and the cold plastic working apparatus according to the present embodiment will be described with reference to the drawings. In each drawing, the same or corresponding components are designated by the same reference numerals, and the same description will not be repeated.

[0049] [Regarding the manufacturing method of the metal material of this embodiment] The manufacturing method of the metal material of this embodiment includes a lubricating liquid application step and a cold plastic working step. In the lubricating liquid application step, a lubricating liquid containing fine bubbles is applied to at least one of the surface of the plastic working tool and the surface of the metal raw material. In the cold plastic working step, the lubricating liquid is applied to at least one of the surface of the plastic working tool and the surface of the metal raw material, and then cold plastic working is performed on the metal raw material using the plastic working tool to manufacture the metal material.

[0050] Here, the cold plastic working includes (1) wire drawing, (2) cold drawing, (3) cold extrusion, and (4) cold rolling. In the first embodiment, the method for manufacturing a metal material of this embodiment will be described using an example in which the cold plastic working is wire drawing.

[0051] [First embodiment] [Regarding cold plastic working apparatus] Fig. 1 is a schematic diagram showing an example of a cold plastic working apparatus used in the manufacturing method of a metal material of this embodiment. Referring to Fig. 1, the cold plastic working apparatus includes a plastic working tool 2, a fine bubble generator 4, and a lubricant application device 5. The cold plastic working apparatus shown in Fig. 1 is a wire drawing apparatus. Each component will be described below.

[0052] [Regarding the plastic processing tool 2] In FIG. 1 , the plastic processing tool 2 is a die. In the first embodiment, the plastic processing tool 2 will also be referred to as the die 2 in the following description. The die 2 has a through hole in the center. The die 2 may have a known configuration. The through hole of the die 2 includes, for example, an approach and reduction section, a bearing section, and a back relief section, in that order from the entry side to the exit side of the die 2. The inner diameters of the approach and reduction sections decrease from the entry side to the exit side of the die 2. The approach and reduction sections serve to introduce the metal material W, which is a metal wire, into the die 2 and reduce the diameter of the metal material W. The inner diameter of the bearing section is constant. The inner diameter of the bearing section corresponds to the die diameter. The bearing section restrains the metal material W to keep the outer diameter of the metal material W constant. The inner diameter of the back relief section increases from the entry side to the exit side of the die 2. The back relief portion prevents the die 2 from being damaged by the metal material W.

[0053] When the cold plastic working apparatus is a wire drawing apparatus, the cold plastic working apparatus further includes a drawing apparatus 3. The drawing apparatus 3 draws the metal material W from the die 2. The drawing apparatus 3 includes a winding apparatus 32 and a support reel 33. The unwinding apparatus 31 unwinds the coil-shaped metal material W. The winding apparatus 32 draws the metal material W, which has been unwound from the unwinding apparatus 31 and passed through the die 2, from the die 2. The winding apparatus 32 further winds up the metal material W drawn from the die 2 into a coil. The support reel 33 is arranged on the inlet side and / or outlet side of the die 2, and supports the metal material W during wire drawing. The drawing apparatus 3 does not have to include the support reel 33.

[0054] The drawing device 3 is not limited to the above configuration, and may have a configuration other than the above configuration as long as it is configured to draw the metal material W from the die 2.

[0055] [Fine Bubble Generator 4] The fine bubble generator 4 generates lubricating liquid LU containing fine bubbles. The fine bubble generator 4 is arranged outside the storage tank 511 in which the lubricating liquid LU is stored. In FIG. 1, one fine bubble generator 4 is arranged. However, the arrangement position and number of fine bubble generators 4 are not particularly limited. There may be one or more fine bubble generators 4.

[0056] The fine bubble generator 4 includes a pipe 41, a pipe 42, and a fine bubble generator 43. The pipes 41 and 42 connect a storage tank 511 and the fine bubble generator 43. The lubricating liquid LU from the storage tank 511 is introduced into the fine bubble generator 43 via the pipe 41. The fine bubble generator 43 generates fine bubbles in the lubricating liquid LU.

[0057] The method of generating fine bubbles by the fine bubble generator 43 is not particularly limited. The fine bubble generator 43 may generate fine bubbles using dissolved gas in the lubricating liquid LU using a swirling liquid flow system. The fine bubble generator 43 may employ any of an ejector system, a Venturi system, a pressurized dissolution system, and a fine hole system to generate fine bubbles by introducing external gas into the lubricating liquid LU. The fine bubble generator 43 can be appropriately selected from known fine bubble generators. The lubricating liquid LU containing the fine bubbles is returned to the storage tank 511 via the pipe 42.

[0058] The lubricating liquid LU contains water and a surfactant. That is, the lubricating liquid LU used in the manufacturing method of this embodiment is an aqueous lubricating liquid. The surfactant may be a well-known surfactant. For example, the surfactant may be one or more selected from the group consisting of a nonionic surfactant, an anionic surfactant, an amphoteric surfactant, and a cationic surfactant.

[0059] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxy(ethylene and / or propylene) alkylphenyl ethers, polyoxyethylene alkyl esters composed of polyethylene glycol or ethylene oxide and higher fatty acids (e.g., having 12 to 18 carbon atoms), and polyoxyethylene sorbitan alkyl esters composed of sorbitan, polyethylene glycol, and higher fatty acids (e.g., having 12 to 18 carbon atoms). Examples of anionic surfactants include fatty acid salts, sulfate ester salts, sulfonate salts, phosphate ester salts, and dithiophosphate ester salts. Examples of amphoteric surfactants include amino acid-type and betaine-type carboxylate salts, sulfate ester salts, sulfonate salts, and phosphate ester salts. Examples of cationic surfactants include aliphatic amine salts and quaternary ammonium salts.

[0060] The lubricating fluid LU may contain other components in addition to water and surfactants, such as extreme pressure additives, rust inhibitors, preservatives, and friction reducers.

[0061] In this specification, fine bubbles refer to fine bubbles with a particle size of less than 100 μm as defined in JIS B 8741-1:2019. Microbubbles refer to fine bubbles with a particle size of 1.00 μm or more and less than 100.00 μm. Ultrafine bubbles refer to fine bubbles with a grain boundary of 0.01 μm or more and less than 1.00 μm.

[0062] [Lubricant Application Device 5] The lubricant application device 5 applies a lubricant LU containing fine bubbles to the surface of the metal material W before it passes through the die 2. In Figure 1, the lubricant application device 5 includes a supply device 51 and a lubricant nozzle 52.

[0063] The supply device 51 includes a storage tank 511, a pipe 512, and a drive source 513. The storage tank 511 is capable of storing lubricating liquid LU containing fine bubbles. One end of the pipe 512 is immersed in the lubricating liquid stored in the storage tank 511. The other end of the pipe 512 is connected to the lubricating liquid nozzle 52. The drive source 513 supplies the lubricating liquid LU in the storage tank 511 to the lubricating liquid nozzle 52 via the pipe 512. The drive source 513 is, for example, a pump.

[0064] The lubricating liquid nozzle 52 is disposed on the inlet side of the die 2. The lubricating liquid nozzle 52 receives a supply of lubricating liquid LU containing fine bubbles from a pipe 512. The lubricating liquid nozzle 52 then discharges the lubricating liquid LU containing fine bubbles to the outside, causing the lubricating liquid LU to adhere to the surface of the metal material W before it passes through the die 2.

[0065] The cold plastic working apparatus may further include a lubricating liquid recovery device 6. The lubricating liquid recovery device 6 includes a recovery pan 61 and a recovery pipe 62. The recovery pan 61 functions as a tray for recovering the lubricating liquid LU discharged from the lubricating liquid nozzle 52. The recovery pipe 62 discharges the lubricating liquid LU stored in the recovery pan 61 into a storage tank 511. The lubricating liquid recovery device 6 allows the lubricating liquid LU to be circulated and reused. Note that the cold plastic working apparatus does not necessarily have to include the lubricating liquid recovery device 6.

[0066] [Method for manufacturing a metal material using a cold plastic working apparatus] In the method for manufacturing a metal material of this embodiment, the above-mentioned cold plastic working apparatus is used to perform cold plastic working on a metal raw material W. Hereinafter, the method for manufacturing a metal material of this embodiment will be described.

[0067] In the method for manufacturing a metal material according to this embodiment, a lubricating liquid LU containing fine bubbles is prepared. As described above, the lubricating liquid LU containing fine bubbles is generated by the fine bubble generator 4.

[0068] Furthermore, a metal material W to be subjected to cold plastic working is prepared. There are no particular limitations on the metal material W, as long as it is made of a metal. For example, the metal material W is made of a metal whose main component is any one selected from the group consisting of aluminum, steel, titanium, and copper. Here, "main component" means that the component is contained in an amount of 50% or more by mass.

[0069] The metal material W containing aluminum as a main component is, for example, a material made of aluminum or a material made of an aluminum alloy.

[0070] In this embodiment, the metal material W is a wire rod. Therefore, the prepared metal material W is attached to the unwinding device 31 in a state where it is wound around a reel in a coil shape, for example.

[0071] After the above preparations have been made, cold plastic working (wire drawing) is performed on the metallic material W. At this time, the lubricating liquid LU containing fine bubbles is applied to at least one of the surface of the metallic material W before cold plastic working and the surface of the die 2 (the surface of the through hole, i.e., the inner surface of the die). Specifically, at the inlet side of the die 2, the lubricating liquid LU containing fine bubbles is discharged from the lubricating liquid nozzle 52 of the lubricating liquid application device 5, and the lubricating liquid LU is applied to the surface of the metallic material W before it passes through the die 2 and / or the surface (inner surface) of the die 2.

[0072] After the lubricating liquid LU containing fine bubbles is adhered to the surface of the metal material W and / or the surface (inner surface) of the die 2, the metal material W is passed through the die 2 to be subjected to cold plastic working (wire drawing). Specifically, the metal material W is drawn from the entry side to the exit side of the die 2 by the drawing device 3. In this case, the metal material W passes through the die 2 with the lubricating liquid LU containing fine bubbles adhered to its surface. Through the above steps, the manufacturing method of this embodiment performs cold plastic working on the metal material W. As a result, the occurrence of surface defects is significantly suppressed in the manufactured metal material (metal wire).

[0073] The reason why the manufacturing method of this embodiment significantly reduces surface defects in the manufactured metal wire is thought to be as follows.

[0074] When cold plastic working is performed on the metallic material W, the metallic material W is constrained all around by the die 2. The metallic material W is subjected to cold plastic deformation (diameter reduction) by receiving an external force from the die 2 all around. In other words, cold plastic working is performed in a state where the entire circumference is substantially constrained, unlike working such as cutting, in which an external force is applied to a portion of the entire circumference of the workpiece.

[0075] In this way, in cold plastic working, plastic deformation occurs under harsh conditions where the entire periphery is constrained by the die 2, and as a result of the plastic working, a new surface is generated on the surface of the metallic material W. Because the new surface is in an active state, it is prone to welding to the inner surface of the through hole of the die 2. If a portion of the new surface is welded to the inner surface of the die 2, the welded portion solidifies and forms a convex solidified portion. When the metallic material W passes through the die 2 during wire drawing, it comes into contact with the solidified portion formed by welding, and linear scratches extending in the axial direction of the metallic material W are formed on the surface of the metallic material W.

[0076] In this embodiment, as described above, the lubricating liquid LU containing fine bubbles is applied to the surface of the metal material W or the inner surface of the die 2 on the entry side of the die 2. In this case, the lubricating liquid LU containing fine bubbles is interposed between the entire surface of the through hole of the die 2 and the entire surface of the metal material W. At this time, the fine bubbles provide a buffering effect between the surface of the through hole of the die 2 and the surface of the metal material W. Due to this buffering effect, the fine bubbles prevent strong contact between the surface of the through hole of the die 2 and the surface of the metal material W. The fine bubbles also have the effect of aggregating surfactants in the lubricating liquid LU. Due to this aggregating effect, the fine bubbles increase the adsorption of the surfactant on the surface of the through hole of the die 2 and the surface of the metal material W.

[0077] Due to the above two actions, the fine bubbles in the lubricating liquid LU prevent the newly formed surface of the metal material W, which is generated by the strong constraint of the die 2, from coming into strong contact with the surface of the through hole of the die 2. This makes it difficult for the newly formed surface of the metal material W to fuse to the surface of the through hole of the die 2, and makes it difficult for a solidified portion to form on the surface of the through hole of the die 2. As a result, the occurrence of defects on the surface of the metal material after cold plastic working is significantly suppressed.

[0078] 1, the cold plastic working apparatus includes one plastic working tool (die) 2. However, the cold plastic working apparatus may include a plurality of plastic working tools (dies) 2.

[0079] Fig. 2 is a schematic diagram of an example of a cold plastic working apparatus having a different configuration from that of Fig. 1. Referring to Fig. 2, the cold plastic working apparatus includes a plurality of dies 2. The plurality of dies 2 are arranged in a row. The other configurations of the cold plastic working apparatus are the same as those of the cold plastic working apparatus of Fig. 1.

[0080] The method for producing a metal material using the cold plastic working apparatus of Figure 2 is the same as the method for producing a metal material using the cold plastic working apparatus of Figure 1. Specifically, at the entry side of the die 2, a lubricating liquid nozzle 52 applies a lubricating liquid LU containing fine bubbles to the surface of the metal material W and / or the inner surface of the die 2. After the lubricating liquid LU containing fine bubbles has been applied to the surface of the metal material W and / or the inner surface of the die 2, the metal material W is passed through multiple dies 2 for cold plastic working (wiredrawing). As described above, even when the cold plastic working apparatus includes multiple dies 2, applying the lubricating liquid LU containing fine bubbles to the surface of the metal material W and / or the inner surface of the die 2 can utilize the buffering and coagulating effects of the fine bubbles. As a result, the occurrence of defects on the surface of the metal material after wiredrawing is suppressed.

[0081] When the cold plastic working apparatus is equipped with a plurality of plastic working tools (dies) 2, preferably, as shown in Fig. 3, a lubricating liquid nozzle 52 is provided on the inlet side of each plastic working tool (die) 2. In this case, a sufficient amount of lubricating liquid LU containing fine bubbles can be applied to the surface of the metal material W before it is inserted into each plastic working tool (die) 2 and / or to the surface (inner surface) of the plastic working tool (die) 2. Therefore, the occurrence of defects on the surface of the metal material after cold plastic working is more effectively suppressed.

[0082] [Preferred average particle size D of fine bubbles] In the manufacturing method of a metal material (metal wire) of this embodiment, the diameter (smallest inner diameter) of the through-hole of the final die 2 among one or more dies 2 is d (μm). In this case, the average particle size D of the fine bubbles is preferably 0.6 dμm or less. Here, the smallest inner diameter d (μm) of the through-hole of the die 2 is, for example, the inner diameter of the bearing portion of the through-hole of the die 2.

[0083] As described above, the fine bubbles exert a buffering effect and aggregating effect by being present between the inner surface of the through holes of the die 2 and the surface of the metal material W. Therefore, it is preferable that the fine bubbles have a size that allows them to penetrate between the inner surface of the through holes of the die 2 and the surface of the metal material W. As described above, the smaller the wire diameter of the metal material W, the lower the strength of the metal material W. Therefore, the smaller the wire diameter of the metal material W, the more likely it is that defects will occur. Therefore, when wiredrawing is performed continuously using one or more dies 2, it is preferable to adjust the average particle size of the fine bubbles to a size that allows them to be inserted between the inner surface of the through holes of the die 2 that will perform the final wiredrawing and the surface of the metal material W to be wiredrawn by that die 2.

[0084] If the average particle size D of the fine bubbles is 0.6 dμm or less, it is sufficiently small compared to the minimum inner diameter d of the through-holes of the die 2. Therefore, the fine bubbles can easily penetrate between the inner surface of the through-holes of the die 2 and the surface of the metal material W. As a result, the buffering and coagulating effects of the fine bubbles interposed between the inner surface of the through-holes of the die 2 and the surface of the metal material W can suppress the occurrence of defects even in metal material W with a small wire diameter.

[0085] The lower limit of the average particle size of the fine bubbles is not particularly limited, and the preferred lower limit of the average particle size of the fine bubbles is 0.01 μm.

[0086] [Preferred Number Density ND of Fine Bubbles (Part 1)] In the method for manufacturing a metal material of this embodiment, the number density of fine bubbles in the lubricating liquid LU is not particularly limited. Preferably, the number density ND of fine bubbles in the lubricating liquid LU is 50 bubbles / mL or more.

[0087] If the number density ND of the fine bubbles is 50 bubbles / mL or more, a sufficient amount of fine bubbles is contained in the lubricating liquid LU. Therefore, during cold plastic working, a sufficient amount of fine bubbles is present between the inner surface of the through hole of the die 2 and the surface of the metal material W. As a result, the occurrence of defects in the metal wire after cold plastic working can be more effectively suppressed.

[0088] The preferred lower limit of the fine bubble number density ND is 60 bubbles / mL, more preferably 70 bubbles / mL, even more preferably 80 bubbles / mL, even more preferably 90 bubbles / mL, and even more preferably 100 bubbles / mL. The upper limit of the fine bubble number density ND is not particularly limited. The upper limit of the fine bubble number density ND is, for example, 60,000 bubbles / mL, for example, 50,000 bubbles / mL, or for example, 40,000 bubbles / mL.

[0089] [Method for Measuring the Average Particle Size D and Number Density ND of Fine Bubbles] The average particle size D (μm) and number density ND (number / mL) of fine bubbles are measured using the following method. 10 mL of lubricating fluid LU containing fine bubbles is collected. The particle size distribution of the fine bubbles in the collected lubricating fluid LU is determined using a quantitative laser diffraction / scattering method with a particle size distribution measuring device. A laser is irradiated onto the fine bubbles, and the scattered light is detected using a forward scattered light sensor, a side scattered light sensor, and a back scattered light sensor. The particle size distribution of the fine bubbles is determined from the light intensity distribution pattern, and the median diameter of the obtained particle size distribution is defined as the average particle size D (μm). Furthermore, in the quantitative laser diffraction / scattering method, calibration is performed using polystyrene latex standard particles with a known number density, and the difference in refractive index between the fine bubbles (air) and polystyrene latex is corrected using Mie scattering theory. The number density ND (number / mL) of the fine bubbles is determined using the above method.

[0090] [Preferred Number Density ND of Fine Bubbles (Part 2)] In the manufacturing method of this embodiment, preferably, cold plastic working is performed using one or more plastic working tools (dies) 2, and further, the area reduction rate of the metallic material W at each plastic working tool (die) 2 during wire drawing is set to 10.0% or more and less than 23.5%. In this case, when the minimum number density N / mL defined by formula (1) is calculated for each plastic working tool (die) 2, preferably, the number density ND of the fine bubbles in the lubricating liquid LU is set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 × (P / 100) × V (1) Here, in formula (1), P is substituted with the area reduction rate (%) at the plastic working tool (die) 2 defined by formula (2), and V is substituted with the moving speed V (mpm) of the metallic material W at the outlet side of the plastic working tool (die) 2. P = {(A0 - A1) / A0} × 100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted, and A1 is the cross-sectional area (mm ２ ) is substituted.

[0091] More specifically, the number density ND of fine bubbles is determined as follows: When a metal material is manufactured by cold plastic processing (wire drawing) using only one plastic processing tool (die) 2, the minimum number density N / mL in the cold plastic processing (die) 2 is determined based on formulas (1) and (2). The obtained minimum number density N / mL is set as the lower limit of the preferable number density ND of fine bubbles.

[0092] On the other hand, when a metal material is manufactured by performing cold plastic processing (wire drawing) once in succession using a plurality of plastic processing tools (dies) 2, that is, when wire drawing is performed using a plurality of plastic processing tools (dies) 2 while the metal material W unwound from the unwinding device 31 is being wound onto the winding device 32, the lower limit of the preferable number density ND of the fine bubbles is determined by the following method. The minimum number density N / mL for each plastic processing tool (die) 2 is determined based on formulas (1) and (2). The maximum value of the obtained minimum number densities N / mL is set as the lower limit of the preferable number density ND of the fine bubbles.

[0093] In cold plastic working, the higher the area reduction rate P, the more easily the newly formed surface of the metal material W passing through the plastic working tool (die) 2 fuses with the inner surface of the through hole of the plastic working tool (die) 2. Furthermore, the faster the moving speed V, the more easily the newly formed surface of the metal material W passing through the plastic working tool (die) 2 fuses with the inner surface of the through hole of the plastic working tool (die) 2. Therefore, the preferable number density ND of fine bubbles varies depending on the area reduction rate P and the moving speed V of the metal material W. Furthermore, when wire drawing is performed once using multiple plastic working tools (dies) 2, the preferable number density ND of fine bubbles also varies depending on the area reduction rate P of each plastic working tool (die) and the moving speed V of the metal material W.

[0094] If the number density ND of the fine bubbles in the lubricating liquid LU is equal to or greater than the maximum value of the minimum number density N / mL, then an appropriate amount of fine bubbles is contained in the lubricating liquid LU, taking into consideration the most severe manufacturing conditions of cold plastic working. Therefore, during cold plastic working, a sufficient amount of fine bubbles is present between the inner surface of the through-hole of the plastic working tool (die) 2 and the surface of the metal material W. As a result, the occurrence of defects in the metal material after cold plastic working can be more effectively suppressed.

[0095] The moving speed V (mpm) of the metal material at the exit side of the plastic processing tool can be determined by a speedometer arranged at the exit side of the plastic processing tool.

[0096] 1 to 3, the lubricating liquid application device 5 of the cold plastic working device includes a plurality of lubricating liquid nozzles 52, and the lubricating liquid nozzles 52 apply the lubricating liquid LU to the surface of the metal material W before the wiredrawing process. However, the lubricating liquid application device 5 may have another configuration.

[0097] Figure 4 is a schematic diagram of an example of another cold plastic working apparatus (wire drawing apparatus) having a different configuration from those of Figures 1 to 3. Referring to Figure 4, the cold plastic working apparatus (wire drawing apparatus) of this example differs from those of Figures 1 to 3 in the configuration of the lubricating liquid application device 5. The other configurations of the cold plastic working apparatus of this example are the same as those of the cold plastic working apparatus of Figures 1 to 3.

[0098] The lubricant application device 5 includes a reservoir 511, an immersion mechanism 53, a draw-out mechanism 54, and a support reel 55. The reservoir 511 is capable of storing a lubricant LU containing fine bubbles. The die 2 is immersed in the reservoir 511.

[0099] The immersion mechanism 53 immerses the metallic material W in the lubricating liquid LU in the reservoir 511 at the entry side of the die 2 before it passes through the die 2. The immersion mechanism 53 includes, for example, direction-changing reels 531 and 532. The immersion mechanism 53 changes the traveling direction of the metallic material W unwound from the unwinding device 31 so that it proceeds to the entry side of the die 2 immersed in the reservoir 511. Specifically, the direction-changing reel 531 changes the traveling direction of the metallic material W unwound from the unwinding device 31 so that it is immersed in the lubricating liquid LU in the reservoir 511 at the entry side of the die 2. Furthermore, the direction-changing reel 532 changes the traveling direction of the metallic material W so that the central axis of the metallic material W immersed in the lubricating liquid LU is coaxial with the central axis of the through hole of the die 2. Cold plastic working (wire drawing) is performed in a state where the lubricating liquid LU is sufficiently adhered to the surface of the metal material W and the die 2 immersed in the lubricating liquid LU in the reservoir 511 by the immersion mechanism 53.

[0100] The drawing-out mechanism 54 draws out the metal material W that has passed through the die 2 from the lubricating liquid LU in the storage tank 511. The drawing-out mechanism 54 includes, for example, direction-changing reels 541 and 542. The drawing-out mechanism 54 changes the direction of travel of the metal material W that has passed through the die 2 so that it proceeds out of the lubricating liquid LU in the storage tank 511. Specifically, the direction-changing reel 541 changes the direction of travel of the metal material W at the outlet side of the die 2 so that the metal material W that has passed through the die 2 is drawn out of the lubricating liquid LU in the storage tank 511. Furthermore, the direction-changing reel 542 changes the direction of travel of the metal material W so that the metal material W drawn out of the lubricating liquid LU in the storage tank 511 moves toward the winding device 32. The metal material W drawn out of the lubricating liquid LU in the storage tank 511 by the drawing-out mechanism 54 is wound onto the winding device 32.

[0101] The support reel 55 is disposed on the inlet side and / or outlet side of the die 2 to support the metal material W during cold plastic working. The lubricating liquid application device 5 does not necessarily have to include the support reel 55.

[0102] In the cold plastic working apparatus of this example, the die 2 is immersed in the lubricating liquid LU in the reservoir 511, and further, the metal material W before passing through the die 2 is also immersed in the lubricating liquid LU in the reservoir 511 at the inlet side of the die 2. Therefore, during wire drawing, a sufficient amount of lubricating liquid LU can be adhered to the surface of the through hole of the die 2 and the surface of the metal material W. Therefore, during cold plastic working, the buffering and coagulating effects of the fine bubbles in the lubricating liquid LU can be fully utilized. As a result, the occurrence of defects in the metal wire after cold plastic working can be more effectively suppressed.

[0103] The cold plastic working apparatus in Fig. 4 includes one die 2. However, the cold plastic working apparatus in Fig. 4 may include multiple dies 2. In this case, the multiple dies 2 are arranged immersed in the lubricating liquid LU in the reservoir 511.

[0104] [Second embodiment] In the first embodiment, a method for manufacturing a metallic material in which the cold plastic working is wire drawing has been described. However, the method for manufacturing a metallic material of this embodiment is also applicable to cold plastic working other than wire drawing. In the second embodiment, a method for manufacturing a metallic material in which the cold plastic working is cold drawing will be described.

[0105] Fig. 5 is a schematic diagram showing an example of a cold plastic working apparatus used in the method for producing a metal material according to the second embodiment. Referring to Fig. 5, the cold plastic working apparatus includes a plastic working tool 2, a fine bubble generator 4, and a lubricant application device 5. The cold plastic working apparatus shown in Fig. 5 is a cold drawing apparatus. Each component will be described below.

[0106] In Figure 5, the plastic processing tool 2 is a die. The cold plastic processing apparatus of Figure 5 further includes a drawing device 3. The drawing device 3 of this example includes a chuck 36. The chuck 36 grips the tip of the metal material W. In the cold plastic processing apparatus of Figure 5, the drawing device 3 performs drawing by pulling out the metal material W gripped by the chuck 36. The cold plastic processing apparatus of Figure 5 further includes a plug 7. The plug 7 is placed inside the metal material W, which is a metal tube, and fixed at a predetermined position. The plug 7 maintains a constant inner diameter of the metal material (metal tube) after cold drawing during cold drawing. The drawing device 3 and plug 7 shown in Figure 5 are well-known in construction.

[0107] The configuration of the fine bubble generator 4 of the cold plastic working apparatus in Fig. 5 is the same as the configuration of the fine bubble generator 4 shown in Fig. 1 to Fig. 4. In addition, the configuration of the lubricating liquid application device 5 of the cold plastic working apparatus in Fig. 5 is the same as the configuration of the lubricating liquid application device 5 shown in Fig. 1.

[0108] 5 shows a cold plastic working apparatus (cold drawing apparatus) for use when the metallic material W is a metal pipe, but in the manufacturing method of this embodiment, the metallic material W may be a metal bar. In this case, the plug 7 in the cold plastic working apparatus is omitted.

[0109] The method for manufacturing a metal material of this embodiment also includes the same steps as those of the first embodiment. Specifically, a lubricating liquid LU containing fine bubbles generated by a fine bubble generator 4 is applied to at least one of the surface of a metal material W and a plastic processing tool (die) 2 using a lubricating liquid application device 5. After the application of the lubricating liquid LU containing fine bubbles, the metal material is subjected to cold plastic processing (cold drawing) using the plastic processing tool (die) 2 to manufacture a metal material (metal bar or metal tube). Note that the [preferable average particle size D of the fine bubbles], [preferable number density ND (part 1) of the fine bubbles], and [preferable number density ND (part 2) of the fine bubbles] described in the first embodiment can also be used in this embodiment.

[0110] However, in [Preferred number density ND of fine bubbles (part 2)], the area reduction rate of the metal material W at each plastic processing tool (die) 2 during cold drawing is set to 10.0% or more and 23.5% or less. In this case, when the minimum number density N / mL defined by formula (1) is determined for each plastic processing tool (die) 2, the number density ND of the fine bubbles in the lubricating liquid LU is preferably set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 × (P / 100) × V (1) Here, the area reduction rate (%) at the plastic processing tool (die) 2 defined by formula (2) is substituted for P in formula (1), and the moving speed V (mpm) of the metal material W at the plastic processing tool (die) 2 is substituted for V. P = {(A0 - A1) / A0} × 100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted, and A1 is the cross-sectional area (mm ２ ) is substituted.

[0111] More specifically, the number density ND of fine bubbles is determined as follows: When a metal material is manufactured by cold plastic processing (cold drawing) using only one plastic processing tool (die) 2, the minimum number density N / mL in the cold plastic processing (die) 2 is determined based on formulas (1) and (2). The obtained minimum number density N / mL is set as the lower limit of the preferable number density ND of fine bubbles.

[0112] On the other hand, when a metal material is manufactured by performing cold plastic working (cold drawing) once in succession using a plurality of plastic working tools (dies) 2, the lower limit of the preferable number density ND of fine bubbles is determined by the following method. The minimum number density N / mL for each plastic working tool (die) 2 is determined based on formulas (1) and (2). The maximum value of the obtained minimum number densities N / mL is set as the lower limit of the preferable number density ND of fine bubbles.

[0113] [Third embodiment] The method for manufacturing a metal material according to this embodiment is applicable to cold plastic working other than wire drawing and cold drawing. In the third embodiment, a method for manufacturing a metal material in the case where the cold plastic working is cold extrusion will be described.

[0114] Figure 6 is a schematic diagram showing an example of a cold plastic working apparatus used in the manufacturing method of a metal material according to the third embodiment. Referring to Figure 6, the cold plastic working apparatus includes a plastic working tool 2, a fine bubble generator 4, and a lubricant application device 5. The plastic working tool 2 is a die. The cold plastic working apparatus further includes a container 70 and a stem 80. The container 70 and stem 80 shown in Figure 6 have well-known configurations. The cold plastic working apparatus shown in Figure 6 is a direct extrusion cold plastic working apparatus. The cold plastic working apparatus may further include a lubricant recovery device 6, as shown in Figure 6.

[0115] The configuration of the fine bubble generator 4 of the cold plastic working apparatus in Fig. 6 is the same as the configuration of the fine bubble generator 4 shown in Fig. 1 to Fig. 4. In addition, the configuration of the lubricating liquid application device 5 of the cold plastic working apparatus in Fig. 6 is the same as the configuration of the lubricating liquid application device 5 shown in Fig. 1.

[0116] 6, the lubricating liquid application device 5 uses a lubricating liquid nozzle 52 to apply lubricating liquid LU containing fine bubbles to the surface of the metal material W before it is inserted into the container 70. The lubricating liquid application device 5 further uses the lubricating liquid nozzle 52 to apply lubricating liquid LU containing fine bubbles to the inner surface of the plastic processing tool (die) 2 before cold extrusion.

[0117] After a lubricating liquid LU containing fine bubbles is applied to the surface of the metal material W and the inner surface of the plastic processing tool (die) 2, the metal material W is inserted into a container 70, and pressure is applied to the metal material W by a stem 80 to perform cold extrusion, as shown in Figure 7. In this cold plastic processing device, the metal material W is extruded in the direction in which the stem 80 advances.

[0118] 6, the lubricating liquid application device 5 uses a lubricating liquid nozzle 52 to apply lubricating liquid LU containing fine bubbles to the surface of the metal material W before cold extrusion. However, the lubricating liquid application device 5 may have a configuration different from that of the lubricating liquid nozzle 52. For example, the lubricating liquid application device 5 may include a storage tank for storing the lubricating liquid LU containing fine bubbles. In this case, the lubricating liquid application device 5 immerses the metal material W before cold extrusion in the storage tank and applies the lubricating liquid LU containing fine bubbles to the surface of the metal material W.

[0119] The cold plastic processing apparatus for performing cold extrusion is not limited to those shown in FIGS. 6 and 7 . FIG. 8 is a schematic diagram showing another example of a cold plastic processing apparatus for performing cold extrusion, having a different configuration from that shown in FIG. 6 . The cold plastic processing apparatus shown in FIG. 8 is an indirect extrusion cold plastic processing apparatus. The cold plastic processing apparatus of FIG. 8 includes a plastic processing tool 2, a fine bubble generator 4, and a lubricating liquid application device 5. The plastic processing tool 2 is a die. The cold plastic processing apparatus further includes a container 70 and a stem 80. The plastic processing tool (die) 2 is attached to the end of the stem 80. The stem 80 has a through hole. The through hole of the stem 80 is arranged coaxially with the through hole of the plastic processing tool (die) 2. The cold plastic processing apparatus may further include a lubricating liquid recovery device 6, as shown in FIG. 8 .

[0120] The configuration of the fine bubble generator 4 of the cold plastic working apparatus in Fig. 8 is the same as the configuration of the fine bubble generator 4 shown in Fig. 1 to Fig. 4. In addition, the configuration of the lubricating liquid application device 5 of the cold plastic working apparatus in Fig. 8 is the same as the configuration of the lubricating liquid application device 5 shown in Fig. 1.

[0121] In the cold plastic working apparatus shown in Fig. 8, the lubricating liquid application device 5 uses a lubricating liquid nozzle 52 to apply lubricating liquid LU containing fine bubbles to the surface of the metal material W before it is inserted into the container 70. The lubricating liquid application device 5 further uses the lubricating liquid nozzle 52 to apply lubricating liquid LU containing fine bubbles to the inner surface of the plastic working tool (die) 2 before cold extrusion. As shown in Fig. 8, the lubricating liquid application device 5 may also use the lubricating liquid nozzle 52 to apply lubricating liquid LU to the inner surface of the through-hole of the stem 80.

[0122] After a lubricating liquid LU containing fine bubbles is applied to the surface of the metal material W and the inner surface of the plastic processing tool (die) 2, the metal material W is inserted into a container 70, and pressure is applied to the metal material W by a stem 80 to perform cold extrusion, as shown in Figure 9. In this cold plastic processing device, the metal material W is extruded in the direction opposite to the direction in which the stem 80 advances.

[0123] In the cold plastic processing device for cold extrusion described above, a lubricating liquid LU containing fine bubbles is applied to the surface of the metal material W and the inner surface of the plastic processing tool (die) 2 before cold extrusion, and then cold extrusion is performed. This makes it possible to more effectively suppress the occurrence of defects in the metal material after hot extrusion.

[0124] In this embodiment, the [preferable average particle size D of fine bubbles], [preferable number density ND (part 1)], and [preferable number density ND (part 2)] described in the first embodiment can also be adopted.

[0125] However, in the manufacturing method of this embodiment, the metal material is produced by cold extrusion using only one plastic processing tool (die) 2. Therefore, in [Preferred Fine Bubble Number Density ND (Part 2)], the area reduction rate of the metal material W at the plastic processing tool (die) 2 during cold extrusion is set to 50.0% or more and 95.0% or less. In this case, when the minimum number density N / mL defined by Equation (1) is calculated during cold extrusion with the plastic processing tool (die) 2, the number density ND of the fine bubbles in the lubricating liquid LU is preferably set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 × (P / 100) × V (1) Here, the area reduction rate (%) at the plastic processing tool (die) 2 defined by Equation (2) is substituted for P in Equation (1), and the moving speed V (mpm) of the metal material W at the plastic processing tool (die) 2 is substituted for V. P = {(A0 - A1) / A0} × 100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted, and A1 is the cross-sectional area (mm ２) is substituted.

[0126] More specifically, the number density ND of fine bubbles is calculated as follows. In this embodiment, cold plastic processing (cold extrusion) is performed using only one plastic processing tool (die) 2 to produce a metal material. In this case, the minimum number density N / mL in the cold plastic processing (die) 2 is calculated based on formulas (1) and (2). The obtained minimum number density N / mL is set as the lower limit of the preferable number density ND of fine bubbles. In the cold plastic processing (cold extrusion) of this embodiment, the area reduction rate P defined by formula (2) is the area reduction rate due to one plastic processing tool (die) 2, and as described above, this area reduction rate is preferably 50.0% or more and 95.0% or less.

[0127] [Fourth embodiment] The method for manufacturing a metal material according to this embodiment is applicable to cold plastic working other than wire drawing, cold drawing, and cold extrusion. In the fourth embodiment, a method for manufacturing a metal material in the case where the cold plastic working is cold rolling will be described.

[0128] Fig. 10 is a schematic diagram showing an example of a cold plastic working apparatus used in the manufacturing method of a metal material according to the fourth embodiment. Referring to Fig. 10, the cold plastic working apparatus includes a plastic working tool 2, a fine bubble generator 4, and a lubricant application device 5. The cold plastic working apparatus shown in Fig. 10 is a cold rolling apparatus. Each component will be described below.

[0129] In Fig. 10, the plastic processing tool 2 is a work roll. Specifically, in Fig. 10, a pair of work rolls is arranged as the plastic processing tool 2. Each of the pair of work rolls 2 is supported by a corresponding support roll 20. The configuration of the fine bubble generator 4 of the cold plastic processing apparatus in Fig. 10 is the same as the configuration of the fine bubble generator 4 shown in Figs. 1 to 4. Furthermore, the configuration of the lubricating liquid application device 5 of the cold plastic processing apparatus in Fig. 10 is the same as the configuration of the lubricating liquid application device 5 shown in Fig. 1.

[0130] FIG. 10 shows a cold plastic working apparatus (cold rolling apparatus) for a case where the metal material W is a metal plate. However, in the manufacturing method of this embodiment, the metal material W may be any of a metal wire, a metal bar, and a metal tube. In these cases, a caliber is formed on a pair of work rolls, and a groove is formed by the pair of work rolls. When the metal material W is any of a metal wire, a metal bar, and a metal tube, the cold plastic working apparatus may include three or more work rolls. That is, the number of plastic working tools (work rolls) may be one or two or more. When the cold plastic working apparatus includes three work rolls, the work rolls are arranged at 120° intervals around the central axis of the metal material W. In this case, the groove is formed by the three work rolls. When the cold plastic working apparatus includes four work rolls, the work rolls are arranged at 90° intervals around the central axis of the metal material W. In this case, the groove is formed by the four work rolls.

[0131] The method for manufacturing a metal material of this embodiment also includes the same steps as those of the first embodiment. Specifically, a lubricating liquid LU containing fine bubbles generated by a fine bubble generator 4 is applied to at least one of the surface of a metal material W and a plastic processing tool (work roll) 2 using a lubricating liquid application device 5. After the application of the lubricating liquid LU containing fine bubbles, the metal material W is subjected to cold plastic processing (cold rolling) using the plastic processing tool (work roll) 2 to manufacture the metal material. Note that the [preferable average particle size D of the fine bubbles], [preferable number density ND (part 1) of the fine bubbles], and [preferable number density ND (part 2) of the fine bubbles] described in the first embodiment can also be used in this embodiment.

[0132] However, in the manufacturing method of this embodiment, cold rolling is performed using one or more plastic processing tools (work rolls) 2 to produce a metallic material. Therefore, in [Preferred Fine Bubble Number Density ND (Part 2)], the area reduction rate of the metallic material W at the plastic processing tool (work roll) 2 during cold rolling is set to 50.0% or more and 95.0% or less. In this case, when the minimum number density N / mL defined by Equation (1) is calculated for each plastic processing tool (work roll) 2, the number density ND of the fine bubbles in the lubricating liquid LU is preferably set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 × (P / 100) × V (1) Here, the area reduction rate (%) at the plastic processing tool (work roll) 2 defined by Equation (2) is substituted for P in Equation (1), and the moving speed V (mpm) of the metallic material W at the plastic processing tool (work roll) 2 is substituted for V. P = {(A0 - A1) / A0} × 100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted into A1, and the cross-sectional area (mm ２ ) is substituted.

[0133] More specifically, the number density ND of fine bubbles is determined as follows: When a metal material is produced by cold plastic processing (cold rolling) using only one plastic processing tool (work roll) 2, the minimum number density N / mL in the cold plastic processing (work roll) 2 is determined based on formulas (1) and (2). The obtained minimum number density N / mL is set as the lower limit of the preferable number density ND of fine bubbles.

[0134] On the other hand, when cold plastic working (cold rolling) is performed continuously using multiple plastic working tools (work rolls) 2 to produce a metal material, the lower limit of the preferred fine bubble number density ND is determined by the following method. The minimum number density N / mL for each plastic working tool (work roll) 2 is determined based on formulas (1) and (2). The maximum value of the obtained minimum number densities N / mL is set as the lower limit of the preferred fine bubble number density ND. In the cold plastic working (cold rolling) of this embodiment, the area reduction rate P defined by formula (2) is the total area reduction rate for all plastic working tools (work rolls) 2, and as described above, this total area reduction rate is preferably 50.0% or more and 95.0% or less. The travel speed V (mpm) substituted into formula (1) is the average travel speed during cold plastic working using all plastic working tools (work rolls) 2.

[0135] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0136] Wiredrawing was carried out using a lubricating liquid containing fine bubbles and a lubricating liquid not containing fine bubbles for the metal wires (metallic materials) with the test numbers shown in Table 1. Hereinafter, the wiredrawing process using a lubricating liquid containing fine bubbles will be referred to as "wiredrawing process A." Furthermore, the wiredrawing process using a lubricating liquid not containing fine bubbles will be referred to as "wiredrawing process B."

[0137]

[0138] The "Metallic Material" column in Table 1 indicates the type of metal wire used for each test number. "Al" means that the metal wire was a metal wire whose main component was aluminum. "Fe" means that the metal wire was a steel wire. "Cu" means that the metal wire was a metal wire whose main component was Cu. "Ti" means that the metal wire was a metal wire whose main component was Ti.

[0139] For each test number, the wiredrawing process A used a wiredrawing process device having the configuration shown in Fig. 4. The wiredrawing process B used a wiredrawing process device having the configuration shown in Fig. 4, but the fine bubble generator 4 was stopped.

[0140] The lubricating liquid in both wire drawing process A and wire drawing process B contained water and a surfactant. Polyoxyethylene alkyl ether (3 mass%) was used as the surfactant in both cases. The concentration of the surfactant in the lubricating liquid was the same for all test numbers, and was also the same for wire drawing process A and wire drawing process B for each test number.

[0141] In wire drawing process A, fine bubbles having the average particle diameter shown in the "Average particle diameter D (μm)" column of Table 1 were added to the lubricating liquid using a fine bubble generator 4, at the number density shown in the "Number density ND (pieces / mL)" column of Table 1.

[0142] In each test number, in both wiredrawing process A and wiredrawing process B, the metal wire was drawn multiple times using one or more dies 2 to obtain a metal wire having a diameter shown in the "Diameter after wiredrawing (μm)" column in Table 1. For each test number, the diameter d (μm) of the through hole of the final die 2 was the same as the diameter shown in the "Diameter after wiredrawing (μm)" column in Table 1. The number of dies used for each test number is shown in the "Number of dies used" column in Table 1. When wiredrawing was performed multiple times, after one wiredrawing was performed in the wiredrawing apparatus of FIG. 4, the die 2 was replaced and the next wiredrawing was performed. The area reduction rate for each die was set to 10.0% or more and less than 23.5%.

[0143] For each test number, the area reduction rate and travel speed for each die were the same for both wiredrawing A and wiredrawing B. The "Area Reduction Rate P (%) at Maximum N" and "Travel Speed ​​V (mpm at Maximum N)" columns in Table 1 show the area reduction rate P (%) and travel speed V (mpm) at maximum N, respectively, for the wiredrawing for each test number. Here, "maximum N" means the wiredrawing time at which the maximum number density N / mL was obtained among the multiple minimum number densities N / mL obtained for each die when the minimum number density N / mL defined by Equation (1) was calculated for each wiredrawing with each die. The "Maximum N" column also shows the maximum value among the multiple minimum number densities N / mL obtained for each die.

[0144] Under the above conditions, wiredrawing A and wiredrawing B were performed for each test number. A 10-m-long sample was taken from the metal wire produced by each wiredrawing. The number of defects 50 μm or longer in the axial direction of the metal wire was counted on the surface of the sample. The defects were confirmed by observation with an optical microscope at 100x magnification. The defect density per meter (defects / m) was calculated based on the number of confirmed defects. For each test number, the defect density of the metal wire obtained by wiredrawing A and the defect density of the metal wire obtained by wiredrawing B were calculated. Based on the obtained defect density, the defect density ratio X was calculated using the following formula: defect density ratio X = defect density in wiredrawing A / defect density in wiredrawing B. The obtained defect density ratios are shown in the "defect density ratio X" column of Table 1.

[0145] [Evaluation Results] Referring to Table 1, the defect density ratio was less than 1.0 for all test numbers. In other words, by performing wiredrawing using a lubricating liquid containing fine bubbles, the occurrence of defects in the manufactured metal wire was suppressed compared to wiredrawing using a lubricating liquid not containing fine bubbles.

[0146] In addition, the average particle size of the fine bubbles was outside the range of 0.6 dμm or less in test numbers 1, 13, 21, and 33. In addition, the number density ND of the fine bubbles was less than 50 bubbles / mL in test numbers 8, 9, 12, 20, 28, 29, 32, and 40. Therefore, in the manufacturing methods of these test numbers, the occurrence of defects in the metal wire was suppressed more than in wire drawing using a lubricating liquid containing no fine bubbles, but the defect number density ratio was higher than in other test numbers.

[0147] In test numbers 11, 18, 19, 31, 38, and 39, the average particle size of the fine bubbles was 0.6 dμm or less, and the number density ND of the fine bubbles was 50 bubbles / mL or more, but the number density ND of the fine bubbles was less than the maximum value of the minimum number density N. Therefore, the flaw number density ratio was higher than in test numbers 2 to 4, 7, 10, 14, 15, 22 to 24, 27, 30, 34, 35, and 41 to 44, in which the average particle size of the fine bubbles was 0.6 dμm or less, the number density ND of the fine bubbles was 50 bubbles / mL or more, and the number density ND of the fine bubbles was equal to or greater than the maximum value of the minimum number density N.

[0148] In test numbers 5, 6, 16, 17, 25, 26, 36, and 37, the average particle size of the fine bubbles was less than 1.00 μm, which meant that they were ultrafine bubbles. Therefore, the flaw number density ratio was significantly lower than that of the other test numbers.

[0149] Cold extrusion was carried out using a lubricating liquid containing fine bubbles and a lubricating liquid not containing fine bubbles on metal bars (metal materials) with test numbers shown in Table 2. Hereinafter, the cold extrusion process using a lubricating liquid containing fine bubbles will be referred to as "cold extrusion process A." Furthermore, the cold extrusion process using a lubricating liquid not containing fine bubbles will be referred to as "cold extrusion process B."

[0150]

[0151] The "Metallic Material" column in Table 2 indicates the type of metal rod (metallic material) used for each test number. For each test number, cold extrusion processing A used a cold extrusion apparatus with the configuration shown in Figure 6. For cold extrusion processing B, a cold extrusion apparatus with the configuration shown in Figure 6 was used, but the fine bubble generator 4 was stopped.

[0152] The lubricating liquid for both cold extrusion processing A and cold extrusion processing B contained water and a surfactant. Polyoxyethylene alkyl ether (3 mass%) was used as the surfactant in both cases. The concentration of the surfactant in the lubricating liquid was the same for all test numbers, and was also the same for cold extrusion processing A and cold extrusion processing B for each test number.

[0153] In cold extrusion processing A, fine bubbles having the average particle diameter shown in the "Average particle diameter D (μm)" column in Table 1 were added to the lubricating liquid using a fine bubble generator 4, at the number density shown in the "Number density ND (pieces / mL)" column in Table 2.

[0154] For each test number, in both cold extrusion process A and cold extrusion process B, cold extrusion was carried out once using die 2 on a metal material (metal bar).

[0155] For each test number, the area reduction rate and travel speed at each die were the same for both cold extrusion A and cold extrusion B. The "area reduction rate P (%)" and "travel speed V (mpm)" columns in Table 2 show the area reduction rate P (%) and travel speed V (mpm) for one cold extrusion run for each test number.

[0156] Under the above conditions, cold extrusion processing A and cold extrusion processing B were performed for each test number to produce a metal bar. A sample 500 mm long in the axial direction was taken from the produced metal bar. The number of defects 50 μm or longer in the axial direction of the metal bar was counted on the surface (outer peripheral surface) of the sample. Defects were confirmed by observation at 100x magnification using an optical microscope. Based on the number of confirmed defects, the defect number density per meter (defects / m) was calculated. For each test number, the defect number density of the metal bar obtained by cold extrusion processing A and the defect number density of the metal bar obtained by cold extrusion processing B were calculated. Based on the obtained defect number densities, the defect number density ratio X was calculated using the following formula. Defect density ratio X=defect density in cold extrusion A / defect density in cold extrusion B. The obtained defect density ratios are shown in the "defect density ratio X" column of Table 2.

[0157] [Evaluation Results] Referring to Table 2, the defect density ratio was less than 1.0 for all test numbers. In other words, by performing cold extrusion using a lubricating liquid containing fine bubbles, the occurrence of defects in the manufactured metal bar was suppressed compared to cold extrusion using a lubricating liquid not containing fine bubbles.

[0158] In test number 1, the average particle size of the fine bubbles exceeded 50.00 μm. In test numbers 8, 9, 12, and 20, the number density ND of the fine bubbles was less than 50 bubbles / mL. Therefore, in the manufacturing methods of these test numbers, the occurrence of defects in the metal rod was suppressed more than in cold extrusion processing using a lubricating liquid containing no fine bubbles, but the defect number density ratio was higher than in other test numbers.

[0159] In test numbers 11, 18, and 19, the number density ND of fine bubbles was 50 bubbles / mL or more, but the number density ND of fine bubbles was less than the maximum value of the minimum number density N. Therefore, the flaw number density ratio was higher than in test numbers 2 to 7, 10, and 13 to 17, in which the average particle size of fine bubbles was 50.00 μm or less, the number density ND of fine bubbles was 50 bubbles / mL or more, and the number density ND of fine bubbles was equal to or greater than the maximum value of the minimum number density N.

[0160] In test numbers 5, 6, 16, and 17, the average particle size of the fine bubbles was less than 1.00 μm, which meant they were ultrafine bubbles. Therefore, the flaw density ratio was significantly lower than that of the other test numbers.

[0161] Cold rolling was carried out using a lubricating liquid containing fine bubbles and a lubricating liquid not containing fine bubbles on metal plates (metal materials) with test numbers shown in Table 3. Hereinafter, cold rolling using a lubricating liquid containing fine bubbles will be referred to as "cold rolling A." Furthermore, cold rolling using a lubricating liquid not containing fine bubbles will be referred to as "cold rolling B."

[0162]

[0163] The "Metallic Material" column in Table 3 indicates the type of metal plate (metallic material) used for each test number. For each test number, cold rolling A used a cold rolling mill with the configuration shown in Fig. 10. For cold rolling B, a cold rolling mill with the configuration shown in Fig. 10 was used, but the fine bubble generator 4 was stopped.

[0164] The lubricating liquid in both cold rolling A and cold rolling B contained water and a surfactant. Polyoxyethylene alkyl ether (3 mass%) was used as the surfactant in both cases. The concentration of the surfactant in the lubricating liquid was the same for all test numbers, and was also the same for cold rolling A and cold rolling B of each test number.

[0165] In cold rolling A, fine bubbles having the average particle diameter shown in the "Average particle diameter D (μm)" column of Table 3 were added to the lubricating liquid using a fine bubble generator 4, at the number density shown in the "Number density ND (pieces / mL)" column of Table 3.

[0166] For each test number, in both cold rolling A and cold rolling B, the metal material (metal plate) was subjected to six cold rolling passes using the work rolls 2. In this case, after one cold rolling pass was performed in the cold rolling mill shown in Figure 10, the distance between the work rolls 2 was changed and the next cold rolling pass was performed.

[0167] For each test number, the area reduction rate and travel speed for each work roll were the same for both cold rolling A and cold rolling B. The "area reduction rate P (%)" and "travel speed V (mpm)" columns in Table 3 show the total area reduction rate P (%) for all six cold rolling passes and the average travel speed V (mpm) for all of the cold rolling passes for each test number, respectively.

[0168] Under the above conditions, cold rolling A and cold rolling B were performed for each test number to produce a metal plate. A sample 500 mm long in the rolling direction was taken from the produced metal plate. The number of defects 50 μm or longer in the rolling direction of the metal plate was counted on the surface (outer peripheral surface) of the sample. The defects were confirmed by observation at 100x magnification using an optical microscope. Based on the number of confirmed defects, the defect number density per meter (defects / m) was calculated. For each test number, the defect number density of the metal plate obtained by cold rolling A and the defect number density of the metal plate obtained by cold rolling B were calculated. Based on the obtained defect number densities, the defect number density ratio X was calculated using the following formula. Defect number density ratio X=defect number density in cold rolling A / defect number density in cold rolling B The obtained defect number density ratios are shown in the "defect number density ratio X" column of Table 3.

[0169] [Evaluation Results] Referring to Table 3, the defect density ratio was less than 1.0 for all test numbers. In other words, by performing cold rolling using a lubricating liquid containing fine bubbles, the occurrence of defects in the manufactured metal sheet was suppressed compared to cold rolling using a lubricating liquid not containing fine bubbles.

[0170] In test number 1, the average particle size of the fine bubbles exceeded 50.00 μm. In test numbers 8, 9, and 12, the number density ND of the fine bubbles was less than 50 bubbles / mL. Therefore, in the manufacturing methods of these test numbers, the occurrence of defects in the metal sheet was suppressed more than in cold rolling using a lubricating liquid containing no fine bubbles, but the defect number density ratio was higher than in other test numbers.

[0171] In test numbers 2 to 7 and 11, the number density ND of fine bubbles was 50 bubbles / mL or more, but the number density ND of fine bubbles was less than the maximum value of the minimum number density N. Therefore, the flaw number density ratio was higher than in test numbers 10 and 13 to 17, in which the average particle size of fine bubbles was 50.00 μm or less, the number density ND of fine bubbles was 50 bubbles / mL or more, and the number density ND of fine bubbles was equal to or greater than the maximum value of the minimum number density N.

[0172] In test numbers 16 and 17, the average particle size of the fine bubbles was less than 1.00 μm, which meant they were ultrafine bubbles. Therefore, the flaw density ratio was significantly lower than that of the other test numbers.

[0173] The embodiments of the present disclosure have been described above. However, the above-described embodiments are merely examples for implementing the present disclosure. Therefore, the present disclosure is not limited to the above-described embodiments, and can be implemented by appropriately modifying the above-described embodiments within the scope of the present disclosure.

[0174] 2 Plastic processing tool 3 Drawing device 4 Fine bubble generator 5 Lubricant application device 53 Immersion mechanism 54 Pull-out mechanism

Claims

1. A method for manufacturing a metal material, comprising: a lubricating liquid application step of applying a lubricating liquid containing fine bubbles to at least one of the surface of a plastic processing tool and the surface of a metal raw material; and a cold plastic processing step of applying the lubricating liquid to at least one of the surface of the plastic processing tool and the surface of the metal raw material, and then performing cold plastic processing on the metal raw material using the plastic processing tool to manufacture the metal material.

2. A method for manufacturing a metal material according to claim 1, wherein the average particle size of the fine bubbles is 0.01 μm or more and 50.00 μm or less.

3. A method for manufacturing a metal material according to claim 2, wherein the average particle size of the fine bubbles is 0.01 μm or more and less than 1.00 μm.

4. A method for manufacturing a metal material according to claim 1, wherein the metal material is primarily composed of one of aluminum, steel, titanium, and copper.

5. A method for manufacturing a metal material according to claim 1, wherein the number density of the fine bubbles in the lubricating liquid is set to 50 bubbles / mL or more.

6. A method for manufacturing a metal material according to any one of claims 1 to 5, wherein the plastic processing tool is a die, and in the cold plastic processing step, the die is used to perform wire drawing on the metal material to produce the metal material in the form of a metal wire.

7. A method for manufacturing a metal material as set forth in claim 6, wherein the wire drawing is carried out using one or more of the dies, and when the diameter of the through hole of the final die among the one or more of the dies is d (μm), the average particle size of the fine bubbles is 0.6 dμm or less.

8. A method for manufacturing a metal material according to any one of claims 1 to 5, wherein the plastic processing tool is a die, and in the cold plastic processing step, cold drawing is performed on the metal material using the die to manufacture the metal material in the form of a metal bar or a metal tube.

9. A method for manufacturing a metal material according to any one of claims 1 to 5, wherein the plastic processing tool is a die, and in the cold plastic processing step, cold extrusion processing is performed on the metal material using the die to manufacture the metal material in the form of a metal bar or a metal tube.

10. A method for manufacturing a metal material according to any one of claims 1 to 5, wherein the plastic processing tool is a work roll, and in the cold plastic processing step, the work roll is used to cold roll the metal material, thereby manufacturing the metal material, which is one of a metal bar, a metal pipe, and a metal plate.

11. A method for producing a metallic material according to any one of claims 1 to 4, wherein in the cold plastic working step, the cold plastic working is carried out using one or more of the plastic working tools, and when the plastic working tool is a die and the cold plastic working is wire drawing or cold drawing, the area reduction rate of the metallic material for each of the plastic working tools is set to 10.0% or more and less than 23.5%, and in the lubricating liquid application step, when the minimum number density N / mL defined by formula (1) is calculated for each of the cold plastic workings with each of the plastic working tools, the number density of the fine bubbles in the lubricating liquid is set to be equal to or greater than the maximum value of the minimum number density N / mL. N = 50 x (P / 100) x V (1) Here, P in formula (1) is substituted with the area reduction rate (%) of the plastic processing tool defined by formula (2), and V is substituted with the moving speed V (mpm) of the metal material at the outlet side of the plastic processing tool. P = {(A0 - A1) / A0} x 100 (2) Here, A0 in formula (2) is substituted with the cross-sectional area (mm ２ ) is substituted into A1, and the cross-sectional area (mm ２ ) is substituted.

12. A method for producing a metallic material according to any one of claims 1 to 4, wherein in the cold plastic working step, the cold plastic working is carried out using one of the plastic working tools, and when the plastic working tool is a die and the cold plastic working is cold extrusion, the area reduction rate of the metallic material at the plastic working tool is set to be 50.0% or more and 95.0% or less, and in the lubricating liquid application step, when the minimum number density N / mL defined by formula (1) is determined in the cold plastic working with the plastic working tool, the number density of the fine bubbles in the lubricating liquid is set to be equal to or greater than the maximum value of the minimum number density N / mL: N = 50 × (P / 100) × V (1) where, in formula (1), the area reduction rate (%) at the plastic working tool defined by formula (2) is substituted for P, and the moving speed V (mpm) of the metallic material at the outlet side of the plastic working tool is substituted for V. P = {(A0 - A1) / A0} × 100 (2) where A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted into A1, and the cross-sectional area (mm ２ ) is substituted.

13. A method for producing a metallic material according to any one of claims 1 to 4, wherein in the cold plastic working step, the cold plastic working is carried out using one or more of the plastic working tools, and when the plastic working tools are work rolls and the cold plastic working is cold rolling, the total area reduction rate of the metallic material by all of the plastic working tools is set to 50.0% or more and 95.0% or less, and in the lubricating liquid application step, when the minimum number density N / mL defined by formula (1) is calculated for each of the cold plastic workings with each of the plastic working tools, the number density of the fine bubbles in the lubricating liquid is set to be equal to or greater than the maximum value of the minimum number density N / mL. N=50×(P / 100)×V (1) Here, P in formula (1) is substituted with the area reduction rate (%) of the plastic processing tool defined by formula (2), and V is substituted with the moving speed V (mpm) of the metal material at the outlet side of the plastic processing tool. P={(A0-A1) / A0}×100 (2) Here, A0 in formula (2) is the cross-sectional area (mm ２ ) is substituted into A1, and the cross-sectional area (mm ２ ) is substituted.

14. A cold plastic processing apparatus capable of performing cold plastic processing on a metal material, comprising: a plastic processing tool; a fine bubble generating device that generates a lubricating liquid containing fine bubbles; and a lubricating liquid applying device that applies the lubricating liquid containing fine bubbles to at least one of the surface of the plastic processing tool and the surface of the metal material before or during the cold plastic processing.

15. A cold plastic processing apparatus according to claim 14, wherein the lubricating liquid application device includes: a nozzle that discharges the lubricating liquid containing the fine bubbles onto at least one of the surface of the plastic processing tool and the surface of the metal material; and a supply device that supplies the lubricating liquid containing the fine bubbles to the nozzle.

16. A cold plastic processing device according to claim 15, wherein the nozzle is disposed on the inlet side of the plastic processing tool, and discharges the lubricating liquid containing the fine bubbles from the inlet side of the plastic processing tool onto at least one of the surface of the plastic processing tool and the surface of the metallic material.

17. A cold plastic processing apparatus according to any one of claims 14 to 16, wherein the plastic processing tool is a die capable of performing wire drawing or cold drawing on the metal material, and the cold plastic processing apparatus further comprises a drawing device that draws the metal material from the plastic processing tool.

18. A cold plastic processing apparatus as defined in claim 17, wherein the cold plastic processing apparatus is capable of performing the wire drawing process on the metal material, the lubricating liquid application device includes a storage tank capable of storing the lubricating liquid containing the fine bubbles, and an immersion mechanism that immerses the metal material in the lubricating liquid in the storage tank at the entry side of the die before it passes through the die, and the die is positioned at a position where it is immersed in the lubricating liquid in the storage tank.

19. A cold plastic working apparatus according to claim 18, further comprising a withdrawal mechanism for withdrawing the metal material from the lubricating liquid in the reservoir at the exit side of the die after it has passed through the die.

20. A cold plastic working apparatus according to claim 14, wherein the plastic working tool is a die capable of cold extrusion working the metal material, and the cold plastic working apparatus further comprises: a container for storing the metal material; and a stem for extruding the metal material stored in the container from the die.

21. A cold plastic working apparatus according to any one of claims 14 to 16, wherein the plastic working tool is a work roll capable of cold rolling the metal material.

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