Method of preventing moisture absorption of lubricating film formed of aqueous dry film type lubricant for use in plastic working of metal

Abstract

To provide a method of simply and effectively preventing moisture absorption of a lubricating film which is formed of an aqueous dry film type lubricant for use in the plastic working of metal and is formed on the surface of a material to be worked.SOLUTION: The method of preventing moisture absorption of a lubricating film which is formed of an aqueous dry film type lubricant for use in the plastic working of metal, includes the following steps of (1) applying the aqueous dry film type lubricant over the surface of a material to be worked and drying the lubricant to form a lubricating film, and (2) coating the entire surface of the lubricating film with an oily liquid or an oily solid before the lubricating film formed in the step (1) absorbs moisture.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for preventing moisture absorption of a lubricating film formed on the surface of a workpiece by an aqueous dry film type lubricant used in the plastic working of metals. [Background technology]

[0002] Aqueous dry film type lubricants are applied to the surface of a metal workpiece, such as a steel plate, and dried to form a lubricating film, which is then used for plastic working such as pressing and forging.

[0003] A lubricating film formed using an aqueous dry film-type lubricant can exhibit its inherent lubricating processing performance if it is dried and contains substantially no water, but if it is left for a long time after drying before being used for plastic processing, the lubricating film will absorb moisture from the air, reducing the strength and adhesion of the film and significantly reducing its lubricating performance, causing seizure and other problems, which can lead to processing defects and a shortened mold life.

[0004] Therefore, when a lubricating film formed using an aqueous dry film type lubricant must be left for a long time after drying before being subjected to plastic processing, measures to prevent moisture absorption have been required, such as storing the film in a humidity-controlled drying room until plastic processing, or adding a re-drying process using hot air or the like immediately before plastic processing.

[0005] However, since storage in a drying chamber and additional drying processes are required, the time and effort required for plastic processing increases, and additional energy is required for power sources and heat sources, which is undesirable from the standpoints of work efficiency and cost.

[0006] In view of the current situation as described above, the moisture absorption of lubricating films formed by aqueous dry film type lubricants has been a major issue for some time, but the problem has not yet been completely resolved.

[0007] Patent Document 1 relates to an aqueous lubricant for steel sheets, which contains water, a specific anti-rust additive, a specific lubricant, a specific lubrication aid, and a specific surfactant, and is characterized in that it is applied on an oil film such as anti-rust oil or press oil already applied to the steel sheet. It describes that applying this lubricant on the oil film provides excellent lubrication in press working and good anti-rust properties.

[0008] However, Patent Document 1 states that it is desirable to dry the film formed from the aqueous lubricant, but that sufficient lubricity is exhibited even when semi-dried or immediately after application (paragraph

[0019] ), but does not state or suggest at all how to prevent moisture absorption by the lubricating film formed by the aqueous dry film type lubricant. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-200287 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a simple and effective method for preventing moisture absorption by a lubricating film formed on the surface of a workpiece using an aqueous dry film type lubricant used in the plastic working of metals. [Means for solving the problem]

[0011] As a result of extensive research conducted by the inventors in order to achieve the above-mentioned object, it was discovered that moisture absorption by a lubricating film formed by an aqueous dry film type lubricant for plastic working of metals can be simply and effectively prevented by applying an oily liquid or oily solid to the entire surface of the lubricating film formed by applying and drying an aqueous dry film type lubricant for plastic working of metals to the surface of a workpiece before the lubricating film has absorbed moisture, thereby covering the lubricating film with an oil film, and the inventors have completed the present invention based on this finding.

[0012] That is, the present invention provides a method for preventing moisture absorption of a lubricating film formed by an aqueous dry film type lubricant for use in the plastic working of metals, as described below.

[0013] 1. A method for preventing moisture absorption of a lubricating film formed by an aqueous dry film type lubricant for metal plastic working, comprising the following steps: (1) applying the aqueous dry film type lubricant to the surface of a workpiece and drying it to form a lubricating film; (2) A step of applying an oily liquid or oily solid to the entire surface of the lubricating film formed in step (1) before the lubricating film absorbs moisture, thereby covering the lubricating film with an oil film.

[0014] 2. A method for preventing moisture absorption of a lubricating film according to item 1 above, wherein the lubricating film does not absorb moisture in step (2) until the amount of moisture absorbed by the lubricating film is 5% by weight or less.

[0015] 3. The method for preventing moisture absorption of a lubricating coating according to item 1 above, wherein the material of the workpiece is selected from the group consisting of iron, aluminum, copper, titanium, and alloys of each of these.

[0016] 4. The method for preventing moisture absorption of a lubricating film according to item 1 above, wherein the aqueous dry film type lubricant for plastic working is an aqueous lubricant for press working or an aqueous lubricant for forging.

[0017] 5. The method for preventing moisture absorption of a lubricating coating according to item 1, wherein the oily liquid is at least one selected from the group consisting of mineral oil, fatty acid ester, sulfurized oils and fats, sulfurized fatty acids, sulfurized fatty acid esters, sulfurized olefins, phosphate esters, fluorinated oils, chlorinated paraffins, silicone oils, cutting oils, grinding oils, former oils, press oils, sizing oils, and rust preventative oils.

[0018] 6. A method for preventing moisture absorption of a lubricating coating according to item 1 above, wherein the melting point of the oily solid is 200°C or lower.

[0019] 7. The method for preventing moisture absorption of a lubricating coating according to item 1 above, wherein the oily solid is one or more selected from the group consisting of paraffin wax, beeswax, carnauba wax, polyethylene, polystyrene, polypropylene, acrylic resin, polyvinyl chloride, and acrylonitrile butadiene styrene resin.

[0020] 8. A method for preventing moisture absorption of a lubricating coating according to item 1 above, wherein the oily liquid is applied by brush coating, dip coating, spray coating, shower coating, electrostatic coating or mist coating.

[0021] 9. A method for preventing moisture absorption of a lubricating coating according to item 1 above, wherein the oily solid is applied by either brushing, immersion, spraying or showering the oily solid in a liquid state after being heated to above its melting point or by sprinkling the oily solid in a powder state onto a workpiece heated to above its melting point. [Effects of the Invention]

[0022] The method of the present invention for preventing moisture absorption of a lubricating film formed by an aqueous dry film type lubricant for use in the plastic working of metals provides the following significant effects.

[0023] (1) The method of the present invention for preventing moisture absorption in a lubricating film formed by an aqueous dry film type lubricant for use in the plastic working of metals makes it possible to simply and effectively prevent moisture absorption in a lubricating film formed by an aqueous dry film type lubricant used in the plastic working of metals. That is, the method of the present invention effectively prevents moisture absorption in a lubricating film by simply forming a lubricating film of an aqueous dry film type lubricant on the surface of a workpiece and then covering the lubricating film with an oil film, thereby preventing a decrease in lubricating performance due to moisture absorption in the lubricating film.

[0024] (2) According to the method of preventing moisture absorption of a lubricating film formed by an aqueous dry film type lubricant for plastic processing of metals of the present invention, the lubricating film does not absorb moisture from the atmosphere and its lubricating performance does not decrease, so there is no need to store the workpiece on which the lubricating film has been formed in a humidity-controlled drying room until plastic processing, or to add a re-drying step using hot air or the like immediately before plastic processing.

[0025] (3) Therefore, according to the method for preventing the formation of a lubricating film of the present invention, after a lubricating film of an aqueous dry film type lubricant is formed on a workpiece, the workpiece can be stored for a long period of time without using a drying room and without having to worry about location, and can be plastically processed without re-drying, thereby significantly reducing space, time, effort, cost, etc. DETAILED DESCRIPTION OF THE INVENTION

[0026] Method for preventing moisture absorption of lubricating film formed by aqueous dry film type lubricant for metal plastic working The method of the present invention for preventing moisture absorption by a lubricating film formed by an aqueous dry film type lubricant for use in the plastic working of metals comprises the steps of: (1) applying and drying the aqueous dry film type lubricant to the surface of a workpiece to form a lubricating film; and (2) applying an oily liquid or oily solid to the entire surface of the lubricating film formed in step (1) before the lubricating film has absorbed moisture, thereby coating the lubricating film with an oil film. This simple method effectively prevents moisture absorption by the lubricating film formed on the surface of the workpiece, and therefore does not cause a decrease in lubricating performance due to moisture absorption by the lubricating film.

[0027] (1) A step of applying the above-mentioned aqueous dry film type lubricant to the surface of the workpiece and drying it to form a lubricating film. This is a process in which an aqueous dry film type lubricant is applied to the surface of a metal material, such as a steel plate, which is the workpiece to be subjected to plastic working of the metal, and then dried to form a lubricating film. This process is the same as the process in which a lubricating film is formed on the surface of a workpiece when performing ordinary plastic working of metal materials.

[0028] The workpiece to be processed by the method of the present invention is a metal material to be plastically processed, and examples of such materials include iron, aluminum, copper, titanium, etc., and various alloys of these metals. Specific examples of metal materials include carbon steel, stainless steel, chromium steel, chromium-molybdenum steel, bearing steel, pure aluminum, duralumin, pure copper, brass, etc.

[0029] The aqueous dry film type lubricant used in the present invention is a type in which various components such as water-soluble or water-dispersible polymer compounds, lubricant additives, rust inhibitors, surfactants, etc. are dissolved and / or dispersed in water as a base solvent, and a film is formed by applying and drying.Specific examples of aqueous dry film type lubricants include lubricants for plastic working such as press working lubricants and forging working lubricants, and they are used as is or diluted with water to a desired concentration.

[0030] Aqueous dry film type lubricants are applied to the surface of a workpiece by, for example, tank dip coating or spray coating, and then the water is evaporated by hot air, air blowing, natural drying, etc. A dried lubricating film is formed by substantially completely evaporating the water.

[0031] (2) A step of applying an oily liquid or oily solid to the entire surface of the lubricating film formed in step (1) before the lubricating film absorbs moisture, thereby covering the lubricating film with an oil film. This is a step of applying an oily liquid or oily solid to the entire surface of the lubricating film formed on the surface of the metal material, such as a steel plate, as the workpiece in step (1) before the lubricating film absorbs moisture, thereby covering the lubricating film with an oil film. The lubricating film formed in step (1) can exhibit its original lubricating performance if it is substantially free of moisture immediately after drying, but if it is left as is after drying, it will gradually absorb moisture from the atmosphere and its lubricating performance will deteriorate. Therefore, in step (2) of the present invention, an oily liquid or oily solid is applied to the entire surface of the lubricating film formed in step (1) before the lubricating film absorbs moisture, forming an oil film and completely covering the lubricating film, thereby blocking contact between the lubricating film and moisture in the surrounding atmosphere and preventing the lubricating film from absorbing moisture.

[0032] Here, "before the lubricating film absorbs moisture" means before the lubricating film has substantially absorbed moisture. Specifically, as shown in the evaluation criteria and examples described below, as long as the amount of moisture absorbed by the lubricating film is about 5% by weight or less, the lubricating performance of the lubricating film will not be reduced.

[0033] The oily liquid used in step (2) is an oil-soluble substance that is liquid at room temperature and atmospheric pressure (25°C and 1013 hPa). Various oily liquids can be used as long as they form an oil film on the lubricating coating and function as a barrier against surrounding moisture until the workpiece is subjected to plastic working. For example, one or more of the following can be used: mineral oils such as paraffinic mineral oil and naphthenic mineral oil; fatty acid esters such as oleic acid esters and glycerin fatty acid esters; sulfurized oils and fats such as sulfurized lard; sulfurized fatty acids such as sulfurized oleic acid; sulfurized fatty acid esters such as sulfurized methyl oleate; sulfurized olefins such as sulfurized isobutene; phosphate esters such as trimethyl phosphate; cutting oil; grinding oil; former oil; press oil; sizing oil; and rust-preventive oil. Depending on the type of oily liquid selected, advantageous effects such as improved lubricity and rust prevention can also be obtained.

[0034] The viscosity of the oily liquid is not particularly limited, but from the viewpoint of forming a continuous oil film without a break on the lubricating film and blocking the outside air, the kinematic viscosity at 40°C is 1 to 1000 mm 2 / s, and 2 to 600 mm 2 It is more preferable that the density is about / s.

[0035] The oily solid used in step (2) is an oil-soluble substance that is solid at room temperature and atmospheric pressure (25°C and 1013 hPa). The oily solid is applied in a liquid state by heating above its melting point, and solidifies when the temperature drops below its melting point after application, forming an oil film on the lubricating coating. Various oily solids can be used as long as they can achieve the function of blocking surrounding moisture until the workpiece is subjected to plastic processing. Furthermore, the solidified oil film also prevents stickiness and adhesion between workpieces. The melting point of such an oily solid is preferably 200°C or less, more preferably 150°C or less, and even more preferably 100°C or less, from the viewpoint of being able to be heated, melted, and applied.

[0036] As the oily solid, for example, one or more selected from paraffin wax, beeswax, carnauba wax, polyethylene, polystyrene, polypropylene, acrylic resin, polyvinyl chloride, acrylonitrile butadiene styrene resin, etc. can be used.

[0037] The viscosity of the heat-melted liquid of the oily solid is not particularly limited, but from the viewpoint of forming a continuous, seamless oil film on the lubricating coating and blocking out external air, it is preferably 10,000 mPa·s or less, more preferably 1,000 mPa·s or less, and even more preferably 100 mPa·s or less.

[0038] In step (2), after the formation of a lubricating film of the aqueous dry film type lubricant on the surface of the workpiece, an oily liquid or oily solid is applied so as to cover the entire surface of the formed lubricating film before the lubricating film has substantially absorbed moisture. coating It is desirable to apply an oily liquid or oily solid to cover the entire surface of the lubricating coating within 10 minutes, or even within 5 minutes, after the lubricating coating is formed. By applying an oily liquid or oily solid promptly after the lubricating coating is formed, it becomes easy to keep the moisture absorption of the lubricating coating to about 5% by weight or less.

[0039] The oily liquid can be applied by, for example, dip coating, brush coating, spray coating, shower coating, electrostatic coating, mist coating, etc. By applying the oily liquid, a continuous oil film is formed that covers the entire surface of the lubricating coating, thereby blocking contact between the lubricating coating and moisture in the outside air. The amount of oily liquid to be applied is not particularly limited, as long as a continuous oil film is formed. Furthermore, after application of the oily liquid, as long as a continuous oil film is formed, there is no particular need to dry it, and after application of the oily liquid, it can be left to stand, or, if necessary, the liquid can be drained using an air blower, barrel, centrifuge, etc.

[0040] Furthermore, multiple types of oily liquids may be applied in layers. For example, by applying a rust-preventive oil for improving rust prevention and a press oil for improving lubricity in layers, a composite effect can be obtained.

[0041] The oily solid can be applied by heating above its melting point to melt it into a liquid state, and then by, for example, immersion coating, brush coating, spray coating, shower coating, etc. By applying the oily solid, a continuous oil film is formed that covers the entire surface of the lubricating coating, thereby blocking contact between the lubricating coating and moisture in the outside air. Furthermore, since it solidifies below its melting point, it is effective in preventing stickiness and adhesion between workpieces. The amount of oily solid to be applied is not particularly limited, as long as a continuous oil film is formed. Furthermore, after application of the oily solid, there is no particular need to dry it, as long as a continuous oil film is formed, and if necessary, the liquid may be removed using an air blower or the like immediately after application.

[0042] The oily solid can also be sprinkled in powder form onto a workpiece heated to above its melting point to form a film.

[0043] A plurality of types of oily solids may be applied in layers. Alternatively, an oily solid may be used in combination with an oily liquid, but from the viewpoint of film adhesion, it is preferable to apply the oily liquid in layers on top of the oily solid.

[0044] After the formation of the lubricating film, while the lubricating film has not yet substantially absorbed moisture, the entire surface of the lubricating film is covered with an oil film, which is a hydrophobic film, thereby completely blocking direct contact between the lubricating film and moisture in the atmosphere, and therefore the lubricating film will not absorb moisture and lose its lubricating performance even if stored for a long period of time in an environment where water does not adhere due to rain, etc. Furthermore, because the formed lubricating film is water-based, it will not dissolve even if an oily liquid or oily solid is applied, and even if it is kept in contact with the oil film for a long period of time, the strength and adhesion of the lubricating film will not be affected, and lubricating performance will be maintained. [Example]

[0045] EXAMPLES The present invention will be explained in more detail below with reference to Examples, Comparative Examples and Reference Examples, but the present invention is not limited to these examples in any way.

[0046] In each example, the workpiece, aqueous dry-type lubricant, and oily liquid or oily solid used are as follows:

[0047] Work material The workpieces used for the moisture absorption test were cylindrical specimens made of S10C (low carbon steel, spheroidized annealed) with a diameter of 20 mm and a total length of 35 mm. For the back-piercing test, specimens made of the same material but with five different shapes (Levels 1 to 5) were used.

[0048] Water-based dry lubricant The water-based dry lubricant used is Daido Chemical Co., Ltd.'s cold forming lubricant "Aqualve CFW-87J" or "Aqualve CFW-57M." "Aqualve CFW-87J" is primarily composed of water-soluble polymer compounds, lubricant additives, and surfactants, and is characterized by extremely high adhesion between the lubricant film and the workpiece. "Aqualve CFW-57M," meanwhile, is primarily composed of water-soluble polymer compounds, lubricant additives, and surfactants, and contains a lower proportion of water-soluble polymer compounds than "Aqualve CFW-87J." This means that the lubricant film has slightly lower adhesion, but is characterized by extremely high heat resistance.

[0049] The two types of lubricants mentioned above are usually diluted with water to a desired concentration and applied to the surface of a workpiece at room temperature to 200°C by dip coating, spray coating, etc., and then the water is evaporated by hot air, air blowing, etc. to form a dry film, which is then used for cold plastic working such as cold forging. There are no particular restrictions on the water used for dilution as long as it does not contain foreign matter or dirt, and industrial water, tap water, etc. can be used.

[0050] In the following Examples, Comparative Examples, and Reference Examples, each aqueous dry film type lubricant was diluted with distilled water to a film deposition amount of 4.5 g / m to eliminate variations in results due to differences in the amount of lubricating film deposition. 2 ~5.5g / m 2 In each example, the oily liquid was drained by leaving it to stand, and the molten oily solid was drained by air blowing.

[0051] oily liquid The oily liquids used were as follows: Mineral oil: Eneos Corporation's "Super Oil K46", paraffinic mineral oil, kinematic viscosity at 40°C approximately 50 mm 2 / s Fatty acid ester: NOF Corporation's "Unistar H-381R", oleic acid ester, kinematic viscosity at 40°C approximately 50 mm 2 / s Sulfurized olefin: DIC Corporation's "Dailube GS-440L," kinematic viscosity at 40°C approximately 50 mm 2 / s Sulfurized oil: DIC Corporation's "Dailube FS-200," kinematic viscosity at 40°C approximately 600mm 2 / s Cutting oil: Daido Chemical Co., Ltd.'s "Daikatol FP-1," kinematic viscosity at 40°C approximately 10 mm 2 / s Press oil: Daido Chemical Co., Ltd.'s "Daipress PR-200," whose main components are mineral oil and sulfurized oil, and whose kinematic viscosity at 40°C is approximately 200 mm 2 / s Rust preventive oil: "Daist D-381H" manufactured by Daido Chemical Co., Ltd., the main component is mineral oil, the kinematic viscosity at 40°C is approximately 2 mm 2 / s

[0052] oily solid The following oily solids were used: Paraffin wax: "Paraffin Wax 125" manufactured by Nippon Seiro Co., Ltd., melting point 53°C, viscosity of the heated molten liquid at 80°C approximately 5 mPa·s Carnauba wax: "Carnauba Wax No. 2" manufactured by Cerarica NODA Co., Ltd., melting point 80-86°C, viscosity of molten liquid at 100°C approximately 20 mPa·s

[0053] Example 1 In step (1), the workpiece (test piece) was immersed in "Aqualve CFW-87J," an aqueous dry film type lubricant at room temperature (25°C) diluted with distilled water to a specified concentration, and then dried with a heat gun after being pulled out to form a lubricating film. Next, in step (2), mineral oil, an oily liquid, was immersed in the workpiece immediately after the lubricating film was formed in step (1), and the liquid was drained off to cover the entire surface of the lubricating film with an oil film.

[0054] When draining the oily liquid, the test piece was left standing for about 5 minutes with the long side tilted at an angle of 45° (the same applies below).

[0055] Example 2 In Example 1, a lubricating film was formed on the workpiece in the same manner as in Example 1, except that a fatty acid ester was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0056] Example 3 In Example 1, a lubricating film was formed on the workpiece in the same manner as in Example 1, except that a sulfurized olefin was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0057] Example 4 In Example 1, a lubricating film was formed on the workpiece in the same manner as in Example 1, except that a sulfurized oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0058] Example 5 In Example 1, a lubricating film was formed on the workpiece in the same manner as in Example 1, except that cutting oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0059] Example 6 In Example 1, a lubricating film was formed on the workpiece in the same manner as in Example 1, except that press oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0060] Example 7 In Example 1, a lubricating film was formed on the workpiece in the same manner as in Example 1, except that a rust-preventive oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0061] Example 8 In step (1), the workpiece was dip-coated with "Aqualve CFW-87J," an aqueous dry-film type lubricant at room temperature (25°C) diluted to a specified concentration with distilled water, and then dried with a heat gun after being pulled out, forming a lubricating film. Next, in step (2), mineral oil, an oily liquid, was dip-coated to the workpiece immediately after the lubricating film was formed in step (1), and after the liquid was drained, fatty acid ester, another oily liquid, was dip-coated and the liquid was drained, so that the entire surface of the lubricating film was covered with a composite oil film of mineral oil and fatty acid ester.

[0062] Example 9 In step (1), the workpiece was dip-coated with "Aqualve CFW-87J," an aqueous dry-film type lubricant at room temperature (25°C) diluted to a specified concentration with distilled water, and then pulled out and dried with a heat gun to form a lubricating film. Next, in step (2), mineral oil, an oily liquid, was dip-coated to the workpiece immediately after the lubricating film was formed in step (1), and after the liquid was drained, sulfurized olefin, another oily liquid, was dip-coated and drained, so that the entire surface of the lubricating film was covered with a composite oil film of mineral oil and sulfurized olefin.

[0063] Example 10 In step (1), the workpiece was dip-applied with "Aqualve CFW-87J," an aqueous dry-film type lubricant at room temperature (25°C) diluted to a specified concentration with distilled water, and then pulled out and dried with a heat gun to form a lubricating film. Next, in step (2), mineral oil, an oily liquid, was dip-applied to the workpiece immediately after the lubricating film was formed in step (1), and after the liquid was drained, cutting oil, another oily liquid, was dip-applied and the liquid was drained, so that the entire surface of the lubricating film was covered with a composite oil film of mineral oil and cutting oil.

[0064] Example 11 In step (1), the workpiece was immersed in "Aqualve CFW-57M," an aqueous dry film type lubricant at room temperature (25°C) diluted with distilled water to a specified concentration, and then dried with a heat gun after being pulled out to form a lubricating film. Next, in step (2), mineral oil, an oily liquid, was immersed in the workpiece immediately after the lubricating film was formed in step (1), and the liquid was drained off to cover the entire surface of the lubricating film with an oil film.

[0065] Example 12 In Example 11, a lubricating film was formed on the workpiece in the same manner as in Example 11, except that a fatty acid ester was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0066] Example 13 In Example 11, a lubricating film was formed on the workpiece in the same manner as in Example 11, except that a sulfurized olefin was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0067] Example 14 In Example 11, a lubricating film was formed on the workpiece in the same manner as in Example 11, except that a sulfurized oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0068] Example 15 In Example 11, a lubricating film was formed on the workpiece in the same manner as in Example 11, except that cutting oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0069] Example 16 In Example 11, a lubricating film was formed on the workpiece in the same manner as in Example 11, except that press oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0070] Example 17 In Example 11, a lubricating film was formed on the workpiece in the same manner as in Example 11, except that a rust preventive oil was used instead of mineral oil as the oily liquid used in step (2), and then the entire surface of the lubricating film was covered with an oil film.

[0071] Example 18 In step (1), the workpiece was dip-applied with "Aqualve CFW-57M," an aqueous dry-film type lubricant at room temperature (25°C) diluted to a specified concentration with distilled water, and then pulled out and dried with a heat gun to form a lubricating film. Next, in step (2), mineral oil, an oily liquid, was dip-applied to the workpiece immediately after the lubricating film was formed in step (1), and after the liquid was drained, cutting oil, another oily liquid, was dip-applied and the liquid was drained, so that the entire surface of the lubricating film was covered with a composite oil film of mineral oil and cutting oil.

[0072] Example 19 In step (1), the workpiece was dip-coated with "Aqualve CFW-57M," an aqueous dry-film type lubricant at room temperature (25°C) diluted with distilled water to a specified concentration, and then pulled out and dried with a heat gun to form a lubricating film. Next, in step (2), the workpiece immediately after the lubricating film formation in step (1) was dip-coated with sulfurized olefin, an oily liquid, and after draining, dip-coated with rust-preventive oil, another oily liquid, and after draining, the entire surface of the lubricating film was covered with a composite oil film of sulfurized olefin and rust-preventive oil.

[0073] Example 20 In step (1), the workpiece was immersed in "Aqualve CFW-57M," an aqueous dry-film type lubricant at room temperature (25°C) diluted with distilled water to a specified concentration, and then removed and dried with a heat gun to form a lubricating film. Next, in step (2), the workpiece immediately after the lubricating film formation in step (1) was immersed in mineral oil, an oily liquid, and after draining, immersed in press oil, an oily liquid, and after draining, immersed in rust-preventive oil, another oily liquid, and after draining, the entire surface of the lubricating film was covered with a composite oil film of mineral oil, press oil, and rust-preventive oil.

[0074] Example 21 In step (1), the workpiece was immersed in "Aqualve CFW-57M," an aqueous dry-film type lubricant at room temperature (25°C) diluted with distilled water to a specified concentration, and then pulled out and dried with a heat gun to form a lubricating film. Next, in step (2), the workpiece immediately after the lubricating film formation in step (1) was immersed for approximately 10 seconds in paraffin wax, an oily solid that had been previously heated and melted in a thermostatic bath at 70°C, and the entire surface was then blown off with an air blower to coat the entire lubricating film with paraffin wax.

[0075] Example 22 In step (1), the workpiece was dip-coated with "Aqualve CFW-57M," an aqueous dry-film type lubricant at room temperature (25°C) diluted with distilled water to a predetermined concentration, and then dried with a heat gun to form a lubricating film. Then, in step (2), the workpiece immediately after the lubricating film formation in step (1) was dip-coated for approximately 10 seconds with carnauba wax, an oily solid, which had been previously heated and melted in a thermostatic bath at 100°C. The entire surface was then drained with an air blower, and the above-mentioned press oil, an oily liquid, was dip-coated and drained, resulting in a composite oil film of carnauba wax and press oil covering the entire surface of the lubricating film.

[0076] Comparative Example 1 In step (1), the workpiece was immersed in "Aqualve CFW-87J," an aqueous dry film type lubricant at room temperature (25°C) diluted with distilled water to a predetermined concentration, and then dried with a heat gun after being removed to form a lubricating film. Step (2) was not performed.

[0077] Comparative Example 2 In step (1), the workpiece was immersed in "Aqualve CFW-87J," an aqueous dry-film type lubricant at room temperature (25°C) diluted with distilled water to a predetermined concentration, and then dried with a heat gun after removal to form a lubricating film. The workpiece was then left to stand for one hour in a thermo-hygrostat at 40°C and 90% humidity to allow the lubricating film to absorb moisture. Next, in step (2), mineral oil, an oily liquid, was immersed in the workpiece that had absorbed moisture after the lubricating film was formed in step (1), and the liquid was drained off, coating the entire surface of the lubricating film with an oil film.

[0078] Comparative Example 3 In step (1), the workpiece was immersed in "Aqualve CFW-87J," an aqueous dry-film type lubricant diluted to a predetermined concentration with distilled water at room temperature (25°C), and then removed and dried with a heat gun to form a lubricating film. The workpiece was then left to stand for one hour in a constant temperature and humidity chamber at a temperature of 40°C and a humidity of 90%, allowing the lubricating film to absorb moisture. Next, in step (2), the workpiece that had absorbed moisture after the lubricating film formation in step (1) was immersed in press oil, an oil-based liquid, and then drained to coat the entire surface of the lubricating film with an oil film.

[0079] Comparative Example 4 In step (1), the workpiece was immersed in "Aqualve CFW-57M," an aqueous dry film type lubricant at room temperature (25°C) diluted with distilled water to a predetermined concentration, and then dried with a heat gun after being removed, forming a lubricating film. Step (2) was not performed.

[0080] Comparative Example 5 In step (1), the workpiece was immersed in "Aqualve CFW-87J," an aqueous dry-film type lubricant diluted with distilled water to a predetermined concentration at room temperature (25°C). After removal, the workpiece was dried with a heat gun to form a lubricating film. The workpiece was then placed in a constant temperature and humidity chamber at 40°C and 90% humidity for one hour to allow the lubricating film to absorb moisture. Next, in step (2), the workpiece that had absorbed moisture after the lubricating film formation in step (1) was immersed in cutting oil, an oil-based liquid, and then drained. Then, a rust-preventive oil, another oil-based liquid, was immersed in cutting oil, and the liquid was drained. The entire lubricating film was coated with a composite oil film of cutting oil and rust-preventive oil.

[0081] Comparative Example 6 In step (1), the workpiece was immersed in "Aqualve CFW-87J," an aqueous dry-film type lubricant diluted with distilled water to a predetermined concentration at room temperature (25°C). After removal, the workpiece was dried with a heat gun to form a lubricating film. The workpiece was then placed in a thermo-hygrostat at 40°C and 90% humidity for one hour to allow the lubricating film to absorb moisture. Next, in step (2), the workpiece that had absorbed moisture after the lubricating film formation in step (1) was immersed for approximately 10 seconds in paraffin wax, an oil-based solid that had been previously heated and melted in a thermo-hygrostat at 70°C. The entire workpiece was then blown off with an air blower, and the entire lubricating film was coated with paraffin wax.

[0082] Reference example 1 In step (1), the workpiece was immersed in "Aqualve CFW-87J," an aqueous dry film type lubricant at room temperature (25°C) diluted with distilled water to a specified concentration, and then dried with a heat gun after being removed to form a lubricating film.Then, without carrying out step (2), the workpiece was stored in a dry room with 0% humidity.

[0083] Reference example 2 In step (1), the workpiece was immersed in "Aqualve CFW-57M," an aqueous dry film type lubricant at room temperature (25°C) diluted with distilled water to a specified concentration, and then dried with a heat gun after removal to form a lubricating film. The workpiece was then stored in a dry room with 0% humidity without undergoing step (2).

[0084] For Examples 1 to 22, Comparative Examples 1 to 6, and Reference Examples 1 and 2, test pieces in which a lubricating film and an oil film, or only a lubricating film, was formed on the workpiece were subjected to a moisture absorption test and a back drilling test to examine lubrication performance.

[0085] 1. Moisture absorption test The moisture absorption amount was calculated by dip-coating a 20 mm outer diameter, 35 mm high S10C (low-carbon steel, spheroidized annealed) test piece at room temperature (25°C) with a dry-film-type lubricant diluted to a predetermined concentration at room temperature (25°C), removing it, and drying it with a heat gun to form a lubricating film. The oily liquid or oily solid was then dip-coated under the conditions of each Example and Comparative Example. The test piece was then drained in a 40°C thermostatic chamber for 24 hours or drained with an air blower. The test piece was then weighed while still in a Petri dish, and placed upright in a thermo-hygrostatic chamber at 40°C and 90% humidity for 6 hours. The weight was then measured again, and the difference between the weights was calculated according to the following formula: In the formula, W1 represents the weight before moisture absorption, and W2 represents the weight after moisture absorption. Moisture absorption amount (weight%) = [(W2-W1) / W1]×100

[0086] Next, the following test was carried out to evaluate the relationship between the moisture absorption (wt %) of a lubricating film formed from an aqueous dry film type lubricant and the lubricating performance.

[0087] As a water-based dry film type lubricant, "Aqualve CFW-3" (main components of water-soluble polymer compounds, lubricant additives, and surfactants) manufactured by Daido Chemical Co., Ltd., which is commonly used in cold forging, was diluted with distilled water to a film deposition amount of 6.5 g / m 2 ~7.5g / m 2After adjusting the material to be lubricating, a cylindrical piece of material S10C, 20 mm in diameter and 35 mm in length, was dip-coated, and after it was pulled out, it was dried with a heat gun to form a lubricating film. This was then left to stand in an atmosphere with a temperature of 27°C and a humidity of 56%, and the amount of moisture absorption was calculated from the change in weight over time, and the lubricating performance at that time was confirmed in a backward drilling test conducted under the conditions described below.

[0088] Table 1 shows the moisture absorption amount and the results of the rear perforation test.

[0089] [Table 1]

[0090] Based on the results in Table 1 above, it can be determined that the lubrication performance of a lubricating film formed from an aqueous dry film-type lubricant can be evaluated based on the moisture absorption of the film, with a moisture absorption of 5% by weight being the standard. Films that show good results at a moisture absorption of 5% by weight or less can be evaluated as ○, and films that show poor results at a moisture absorption of more than 5% by weight can be evaluated as ×.

[0091] 2. Posterior perforation test Test pieces (five levels) at room temperature (25°C) were immersed in an aqueous dry film type lubricant diluted to a predetermined concentration at room temperature (25°C), and then pulled out and dried with a heat gun to form a lubricating film. For each test piece in Examples 1 to 22, Comparative Examples 1 to 6, and Reference Examples 1 and 2, on which a lubricating film and oil film, or only a lubricating film, had been formed on the processed material, the liquid was drained off in a constant temperature bath at 40°C for 24 hours, and then the test piece was left to stand in a constant temperature and humidity bath at a temperature of 30°C and a humidity of 90% for 6 hours, after which a rear puncture test was performed according to the following items.

[0092] Test piece material: S10C (low carbon steel, spheroidized annealed), Testing machine: 110 ton crank press, Test speed: 35 spm, Test piece shape: Total length (1st level) 17.0 mm, (2nd level) 21.5 mm, (3rd level) 26.0 mm, (4th level) 30.5 mm, (5th level) 35.0 mm, Outer diameter 20 mm φ, Punch outer diameter: 16.7 mm φ, Set area expansion ratio: Approximately 650%, approximately 1000%, approximately 1350%, approximately 1700 %, approximately 2050%, punch material: HAP72 (alloy tool steel), test temperature: 26°C, evaluation: Five levels of test pieces that had been coated with a dry film and oily liquid or oily solid according to each condition were placed in a mold with the sides and bottom restrained in order from the smallest overall length, and a punch was driven from the top to the center to form a cup shape so that the set area expansion rate was achieved, and the highest level at which no seizure occurred on the inner surface of the test piece after the test was confirmed.

[0093] The evaluation of the rear puncture test was based on the conditions of Reference Example 1 and Reference Example 2, and if the level of no seizure occurrence was equal to or higher, it was marked as ○, and if the level of no seizure occurrence was lower, it was marked as ×.

[0094] 3. Overall evaluation If both the moisture absorption test and the rear perforation test were judged to have a good result, the overall evaluation was judged to be good. If either the moisture absorption test or the rear perforation test was judged to have a bad result, the overall evaluation was judged to be bad.

[0095] The results of each test and the overall evaluation are shown in Tables 2 to 4.

[0096] [Table 2]

[0097] [Table 3]

[0098] [Table 4]

[0099] In addition, when the aqueous dry film type lubricant is completely dry and the film moisture absorption is zero, processing can be performed without seizure up to level 4 in the backward drilling test, as shown in Reference Examples 1 and 2.

[0100] Examples 1 to 22 had very little moisture absorption, and exhibited performance equal to or better than that of Reference Examples 1 and 2 in the back puncture test.

[0101] In contrast, Comparative Examples 1 and 4 absorbed a large amount of moisture, resulting in a significant decrease in performance in the back puncture test, indicating that lubrication performance decreases when the lubricating film of an aqueous dry film type lubricant absorbs moisture.Furthermore, Comparative Examples 2, 3, 5, and 6 also showed a significant decrease in performance in the back puncture test, indicating that when the lubricating film of an aqueous dry film type lubricant absorbs moisture, lubrication performance cannot be ensured even if an oily liquid or oily solid is applied. [Industrial Applicability]

[0102] The method of preventing moisture absorption of a lubricating film formed by an aqueous dry film-type lubricant for plastic processing of metals of the present invention makes it possible to simply and effectively prevent moisture absorption of a lubricating film formed on the surface of a workpiece, and is therefore suitable for use in the plastic processing of various metals.

Claims

1. A method for preventing moisture absorption of a lubricating film formed by an aqueous dry film type lubricant for metal plastic working, comprising the following steps: (1) applying the aqueous dry film type lubricant to the surface of a workpiece and drying it to form a lubricating film; (2) A step of applying an oily liquid or oily solid to the entire surface of the lubricating film formed in step (1) before the lubricating film absorbs moisture, thereby covering the lubricating film with an oil film.

2. 2. The method for preventing moisture absorption of a lubricating coating according to claim 1, wherein the lubricating coating does not absorb moisture in step (2) until the moisture absorption amount of the lubricating coating is 5% by weight or less.

3. 2. The method for preventing moisture absorption of a lubricating coating according to claim 1, wherein the material of the workpiece is selected from the group consisting of iron, aluminum, copper, titanium, and alloys thereof.

4. 2. The method for preventing moisture absorption of a lubricating film according to claim 1, wherein the aqueous dry film type lubricant for plastic working is an aqueous lubricant for press working or an aqueous lubricant for forging.

5. 2. The method for preventing moisture absorption of a lubricating coating according to claim 1, wherein the oily liquid is at least one selected from the group consisting of mineral oil, fatty acid ester, sulfurized oils and fats, sulfurized fatty acids, sulfurized fatty acid esters, sulfurized olefins, phosphate esters, fluorinated oils, chlorinated paraffins, silicone oils, cutting oils, grinding oils, former oils, press oils, sizing oils, and rust-preventive oils.

6. 2. The method for preventing moisture absorption of a lubricating coating according to claim 1, wherein the melting point of the oily solid is 200°C or lower.

7. 2. The method for preventing moisture absorption of a lubricating coating according to claim 1, wherein the oily solid is at least one selected from the group consisting of paraffin wax, beeswax, carnauba wax, polyethylene, polystyrene, polypropylene, acrylic resin, polyvinyl chloride, and acrylonitrile butadiene styrene resin.

8. 2. The method for preventing moisture absorption of a lubricating coating according to claim 1, wherein the oily liquid is applied by brush coating, dip coating, spray coating, shower coating, electrostatic coating or mist coating.

9. 2. The method for preventing moisture absorption of a lubricating coating according to claim 1, wherein the method for applying the oily solid is a method of heating the oily solid to above its melting point to form a liquid and then applying it by brushing, dipping, spraying or showering, or a method of sprinkling the oily solid in a powdered state onto a workpiece that has been heated to above its melting point.

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