KR20100027676A - Metal forming dies and mold having deep nitriding hard layer and excellent lubricant, and a method of preparing the same - Google Patents

Abstract

PURPOSE: A metal forming die which has a nitrogen hardening layer with excellent lubricant, and a manufacturing method thereof are provided to form a hybrid multi layer through deep-nitriding and lubricant-coating. CONSTITUTION: A manufacturing method of a metal forming die which has a nitrogen hardening layer with excellent lubricant is as follows. The surface of a material is washed and dried(S100). A nitrogenous compound layer is formed on the surface(S200). A porous compound layer is formed on the nitrogenous compound layer(S300). A lubricant is sprayed on the porous compound layer, or the material in which the porous compound layer is formed is immersed in the lubricant(S400). The lubricating film layer is hardened in 150°C to 400°C.

Description

Metal molding having a nitrogen-hardened layer having excellent lubricity and a method for manufacturing the same {Metal forming dies and mold having deep nitriding hard layer and excellent lubricant, and a method of preparing the same}

The present invention relates to a metal molded body having a nitrogen-hardened layer having excellent lubricity and a method for manufacturing the same, and specifically, a metal molded body having a nitrogen-cured layer having excellent lubricity as a treatment for preventing surface damage of a steel sheet or a plate of nonferrous metal, and a method of manufacturing the same. It is about.

The plate constituting the vehicle body is composed of materials and specifications of various mechanical properties according to the part and function. Recently, in order to cope with the reduction of emissions and increase in the free warranty period by lightening the vehicle, a lot of changes are rapidly occurring in the automotive parts and materials industry.

First of all, in the case of automobile chassis parts, the adoption of high strength low alloy (HSLA), sandwich panels, and tail welded blank (TWB) steel sheets is rapidly increasing in order to supplement properties due to the thinning of steel sheets. In addition, the use of stainless steel plate, alloy plated steel plate, double plated steel plate, resin coated plated steel sheet, and other special surface treated steel sheet is also rapidly increasing in order to supplement corrosion resistance according to the increase of free warranty period.

Since these special materials and surface treatment plates have high strength and low elongation, the frictional resistance between the mold and the plate increases due to high surface pressure or load during molding, which causes scratches and wear on the mold surface. The speed will increase. Plated steel sheets, which are dropped during the molding operation, are pressed to the contact surface and act as abrasion, causing severe scratches on the mold surface, causing damage to the mold surface and scratches on the surface of the object. This causes serious quality problems.

In addition, there is an urgent situation in which the quality of molds must be drastically improved due to the increase in the production of molds (SPM, Strokes Per Minute), the increase in the number of strokes and the increase in the service life. In order to solve these problems, the strength of mold materials, the improvement of heat treatment technology, and the formation of hard surface coatings have been made, but the limit situation has already been reached, and the lubrication is required to fundamentally solve the wear, sticking and scratch occurrence. Surface hardening of the mold is required.

Commonly applied techniques for abrasion resistant coatings on molds include physical vapor deposition (PVD) coating, chemical vapor deposition (CVD), thermal diffusion layer (TD), and hard chromium plating. And the like have been applied.

In terms of each technology, in the case of physical vapor deposition, PVD technology and diffusion have been growing, and this technology is also widely used in mold coating. Although it is possible to apply a hard coating of various physical properties to the mold with low processing temperature, the installation cost of coating and washing apparatus is expensive, the processing cost is also expensive, and the coating process parameters are high and the control is difficult. In addition, the size of the treated product is limited, and before the coating treatment, an electrothermal treatment such as quenching treatment or plasma nitriding is required. In addition, cast iron mold has a high risk of outgassing and electrical arcing caused by the coating process because the flake or spherical graphite contained therein absorbs the cleaning solution during the cleaning process.

In addition, the thermal diffusion (TD) method is a technique for forming a hard film on the surface of the mold by heat permeation diffusion method using a molten salt of high temperature, the film is solid, and the processing process is simple, but was widely used in Korea until several years ago. In recent years, demand has been declining due to the following problems. The problem of thermal diffusion treatment is that the mold becomes vulnerable due to the severe deformation and coarsening of the tissue due to the long-term treatment for 10 to 12 hours at the processing temperature of about 1,000 ° C, and the waste sludge generation and the air pollution problem are involved. Processing is impossible. Also, It can be applied only to some high grade steel such as high speed steel or alloy mold steel, and can not be used for general purpose steel such as carbon tool steel, low carbon alloy steel, cast iron and so on. In addition, it is difficult to recycle due to aging of the mold due to long-term processing at high temperature. There is a disadvantage that it is difficult to keep the molten salt composition constant.

In addition, the hard chromium plating method has the advantages of low processing cost, simple process, and large size limitation of the mold, but hexavalent chromium, which is fatal to the human body, is discharged into the plating waste liquid. Regulation is growing day by day. In addition, since the hardness and adhesion of the film is low, it is used only for forming thin plates, and the installation cost of plating line is expensive, and the quality is severely deteriorated depending on the material condition and processing company.

Due to the above disadvantages, excellent lubricity on the hard ceramic layer, CrN, TiN, TiAlN, CrTiN, TiAlCrN, or a combination of these layers is achieved through conventional methods of physical vapor deposition (PVD) or chemical vapor deposition (CVD). Although methods for depositing materials such as WC / C and molybdenum disulfide (MoS ₂ ) by sputtering have been introduced, the equipment and processing costs are high and the process is difficult, which leads to the early wear and layering of the lower and lower ceramic layers. The separation did not succeed in the expansion. In addition, by spraying molybdenum disulfide (MoS ₂ ), which is a liquid lubricating film, onto the hard ceramic layer and solidifying at 190 to 250 ° C., molybdenum disulfide penetrates into the ceramic coating layer to provide lubricity for longer periods of time. Although technology has been developed and widely used, this is mainly applied only to steel, but PVD is mostly made of cast iron containing flake or spherical graphite. Surface treatment techniques such as CVD, Thermal Diffusion (TD), etc. are not practically applicable to these materials.

At present, these cast iron molds rely on hard chromium treatment and partially apply high frequency or laser heat treatment. However, hard chromium plating causes deformation of heat treatment and laser heat treatment due to environmental pollution and lack of durability due to hexavalent chromium emission. , Risk of cracking, There are still problems of geometric limitations and expensive cost and lack of lubricity. In accordance with Korean Patent Invention No. 391307, the method of forming a solid lubricating film on a surface of a component having a predetermined shape, comprising: preparing a medium having a predetermined size and shape; A method of forming a solid lubricating film comprising the step of depositing lubricant powder on the medium; applying the lubricant powder to the surface of the part by physically contacting the medium on which the lubricant powder is deposited and the part has been proposed. However, the formed lubricating film has a limitation in applying to parts that must withstand high surface pressure and high load because the adhesion, abrasion resistance or frictional resistance of the parts are not completely improved.

In addition, in Japanese Patent Laid-Open No. 2005-2457, carbide powder is sprayed onto the surface of the base material of the portion where the carbon-based hard film is formed, and the carbon element in the carbide powder is moved from the outermost surface to the inner side in the vicinity of the workpiece. Accordingly, a composite surface modification method has been proposed in which base material pretreatment in which carbon amount is gradually reduced is performed. However, the complex surface modification method is difficult to set the conditions for injecting carbide powders because of the amount of carbon to be controlled, many process control parameters, and the lubricity is not remarkably improved, so that uniform surface modification is not achieved. There is concern. In order to solve this problem, it is basically applicable without cast iron or steel, and it has high lubricity to withstand high surface pressure and high load during molding, less sticking, minimize frictional heat generation, and reduce scratch and wear. This rich film development is required, the processing cost is low, the process is simple, and the development of the technology which is not affected by the mold size and material is urgently needed.

In order to solve the above problems, an object of the present invention is to form a lubrication property by forming a hybrid multi layer through deep nitriding and a lubricant coating in forming a steel sheet or a non-ferrous metal sheet. SUMMARY OF THE INVENTION An object of the present invention is to provide a metallic foam having a nitrogen cured layer (nitride layer) having excellent lubricity exhibiting excellent adhesion, release property and wear resistance.

In order to achieve the above object, the present invention comprises a substrate selected from a mold, a steel plate and a non-ferrous metal sheet in forming a nitrogen-hardened layer having excellent lubricity; A nitrogen compound layer induced on the substrate by a nitriding treatment; an oil hole is formed on the nitrogen compound layer to provide penetration of the lubricating film or improvement of adhesion; It provides a metal molded body having a nitrogen-cured layer excellent in lubricity, including; and a lubricating film layer for providing lubricity on top of the porous compound.

In addition, the present invention is a diffusion layer which is a layer in which nitrogen is diffused into the nitrogen compound layer; And a densified compound layer including a dense compound layer including a compound selected from the group consisting of Fe ₂ N, Fe ₃ N, Fe ₄ N, and a mixture thereof on top of the diffusion layer.

The present invention also provides a metal molded body having a nitrogen cured layer having excellent lubricity of 0.1 to 1 mm as the nitrogen compound layer.

In addition, the present invention provides a metal molded body having a nitrogen-hardened layer excellent in lubricity of the hardness of HV 500 to 1500 as the nitrogen compound layer.

In addition, the present invention (a) a pre-treatment step including a surface control step or a cleaning and drying step to facilitate the surface treatment of the substrate; (b) a nitriding treatment step of forming a nitrogen compound layer on the surface of the substrate; (c) A mapping step of forming a porous compound layer acting as an oil hole by applying an unevenness to the upper portion of the nitrogen compound layer; (d) forming a lubricating film layer for spraying a lubricant on the upper portion of the porous compound layer or immersing the substrate on which the porous compound layer is formed on the lubricant Lubricant treatment step; And (e) a solidifying step of curing the lubricating film layer at 150 to 400 ° C.

In addition, the present invention in the step (a), the nitriding treatment of the metal molded body having a nitrogen-hardened layer excellent in lubricity selected from gas nitriding, plasma nitriding, salt bath nitriding, low pressure nitriding and a method of mixing these methods It provides a manufacturing method.

In addition, the present invention provides a method for producing a metal molded body having a nitrogen-hardened layer excellent in lubricity further comprising the step of surface hardening heat treatment by high frequency curing or laser curing before step (b).

In addition, the present invention provides a method for producing a metal molded body having a nitrogen-hardened layer excellent in lubricity selected from sandpaper, sand blast, shot blast and a method of mixing them in the step (c), the method of imparting the unevenness. .

In addition, in the step (c), the present invention is a metal having a nitrogen-curable layer excellent in lubricity selected from the group consisting of molybdenum disulfide, tungsten disulfide, graphite, boron nitride, polytetrafluoroethylene and mixtures thereof as the lubricant. It provides a method for producing a molded article.

In addition, the present invention provides a method for producing a metal molded article having a nitrogen-cured layer excellent in lubricity, which is a solid lubricating film treatment using a lubricant of powder in the step (d).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, it should be noted that in the drawings, the same components or parts denote the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

As used herein, the terms "about", "substantially", and the like, are used at, or in close proximity to, numerical values when manufacturing and material tolerances inherent in the meanings indicated are intended to aid the understanding of the invention. Accurate or absolute figures are used to assist in the prevention of unfair use by unscrupulous infringers.

In the present specification, the nitrogen cured layer may be used in terms of a nitride hardened layer, a nitride layer, or a nitride treated film.

1 is a cross-sectional view of a metal molded body having a nitrogen cured layer excellent in lubricity according to an embodiment of the present invention. Referring to FIG. 1, the nitrided cured coating 100 having excellent lubricity of the present invention includes a nitrogen compound layer, a diffusion layer 110, a porous compound layer 130, and a lubricating coating layer 150 on a metal substrate 1 such as a metal mold, a steel sheet, and a nonferrous metal sheet. The compound layer 110 may include a diffusion layer 111 and a dense compound 113. In this case, the porous compound layer 130 is removed by the nitriding graphite in the substrate containing the graphite through sand finishing or sandblasting, such as irregularities are provided to the area by the oil hole 10 is formed to form the hole of the porous compound layer 130 The lubricating film layer 150 penetrates into the oil hole 10 formed on the upper portion, and thus durability can be improved in adhesion and lubricity due to an anchoring effect.

Accordingly, the present invention provides a metal molded body having a nitrogen-cured layer having excellent lubricity, comprising: a substrate selected from a metal mold, a steel sheet and a nonferrous metal sheet; A nitrogen compound layer derived from nitriding on the substrate; A porous compound layer having an intaglio formed on top of the nitrogen compound layer to provide an improvement in penetration or adhesion of the lubricating film; It provides a metal molded body having a nitrogen-cured layer excellent in lubricity, including; and a lubricating film layer for providing lubricity on top of the porous compound.

The metal substrate used in the present invention is in the form of a mold, a steel sheet or a non-ferrous metal sheet selected from the group consisting of stainless steel, aluminum, carbon steel, cast iron, and mixtures thereof. The cast iron is preferably a mold of spherical graphite cast iron.

The nitrogen compound layer may include a solidified diffusion layer obtained by nitriding treatment and a dense compound layer which is an outermost compound layer formed by mixing a white nitrogen compound on a surface thereof. The nitrogen compound layer is a diffusion layer which is a layer in which nitrogen is diffused and solidified; And a densified compound layer including a dense compound layer including a compound selected from the group consisting of Fe ₂ N, Fe ₃ N, Fe ₄ N, and a mixture thereof on top of the diffusion layer.

In addition, the present invention provides a nitrogen cured layer coating having excellent lubricity of the nitrogen compound layer is 0.1 to 1 mm. The nitriding depth produced through the nitriding treatment is preferably 0.15 mm to 1 mm in the case of cast iron, and 0.1 mm to 0.5 mm in the case of steel. The nitrogenous compound layer maintains the surface hardness to a deep depth. When the thickness of the nitrogen compound layer is less than 0.1mm, durability cannot be provided because it does not provide a predetermined hardness required for the film of the present invention, and when it exceeds 1mm, the synergistic effect of the excess is not generated.

Accordingly, the present invention provides a metal molded body having a nitrogen cured layer having excellent lubricity, wherein the hardness of the nitrogen compound layer is HV 500 to HV 1300. In particular, in the case of cast iron is HV 600 to 1,000, in the case of steel is preferably HV 600 to 1,300. When the hardness of the nitrogen compound layer is less than HV 500, the wear resistance of the film is lowered, and it is difficult to obtain a hardness exceeding HV1300 by nitriding treatment.

Particularly, in the metal molded body having the nitrogen-curable layer having excellent lubricity, the porous compound layer is nitrided or soft-nitrided, and then sandpaper or sandblasted on the surface of the substrate of the graphite portion to be flaked on the mold surface of the cast iron mold. Unevenness occurs due to the graphite site formed by the escape of the spherical graphite, which can be utilized as an oil hole containing a lubricant, thereby improving the adhesion of the lubricating film layer to be processed and the penetration of the lubricant, thereby improving lubricity and adhesion resistance. , Releasability or wear resistance and the like can be excellently improved.

The metal molded body having such a nitrogen-curable layer having excellent lubricity may be formed by the following method, and may be made of a nitriding treatment process and a lubricating film treatment process, and may be specifically performed as follows.

2 is a manufacturing process diagram of a metal molded body having a nitrogen cured layer excellent in lubricity according to an embodiment of the present invention. Referring to Figure 2, the metal molded body having a nitrogen-hardened layer of excellent lubricity of the present invention can be prepared through a pretreatment step S100, nitriding step S200, finishing step S300, lubricant treatment step S400 and solidification step S500, the pretreatment Step S100 may proceed through a surface control step S11 and a cleaning and drying step S13. In addition, the surface hardening heat treatment step S110 may be further included before the nitriding treatment step according to the substrate.

The metal substrate used in the present invention is in the form of a mold, a steel sheet or a non-ferrous metal sheet selected from the group consisting of carbon iron, carbon steel, stainless steel, aluminum, and mixtures thereof. The metal substrate of the present invention preferably has a mold form as constituent graphite cast iron.

Process for producing a nitrogen-hardened layer excellent in lubricity of the present invention (a) can proceed to the pre-treatment step S100 including the artificial surface irregularities or cleaning and drying step, the pretreatment step S100 of the present invention is a nitriding treatment In the case of a nitriding method that is difficult to form the surface of the porous compound layer or a material that does not contain graphite therein, before the nitriding treatment, an artificial unevenness is applied to the surface by sand blast, shot blast, or a similar principle or method. By providing, the surface which acts as an oil hole can be provided, or the adhesion force can be increased.

The pre-treatment step S100 is a surface control step S11 for imparting artificial unevenness to the surface of the substrate to be easily nitrided; And a washing and drying step S13 of washing and drying the surface of the substrate, which has undergone the surface control step, with an alkali or an organic solvent, and drying the same.

In the surface control step S11, sandpaper, wire brush, grinding, wheel, etc., after finishing the treatment with a sand blast (Sand blast) to remove the rust or improve the nitriding effect or to improve the adhesion of the film at the same time Grant.

Since the blasted surface has a high occurrence of rust, the cleaning and drying step S13 may be performed after sandblasting. The washing is carried out by putting the activator in an alkali salt and boiled at a high temperature, the oil is removed by emulsification. If an alkaline solution remains on the surface, it is important to wash with water since it reduces the adhesion of the coating film. It is an aqueous solution made by adding organic solvent and emulsifier such as petroleum and naphtha to dissolved water, and degreased. After degreasing, it must be washed with hot water to remove lubricating oil or to remove grease, dirt and other foreign substances, and then to remove compressed air or vacuum without oil and water. The pretreatment step S100 may be performed by completely removing the dust through air blowing or hot air drying.

In addition, in the case of a mold that needs to withstand high surface pressure or high load, the surface hardening heat treatment step S110 is further performed by high frequency curing, laser curing, and mixing thereof to form a porous compound layer to be described later. 2.0mm or more in thickness and 50kg / mm ² or more in tensile strength) can be formed.

 (b) Nitriding treatment step S200 may be performed to form a nitrogen compound layer on the surface of the pretreated substrate.

The surface of the substrate surface nitrided through deep nitriding is composed of a nitrogen compound layer on the outermost surface and a diffusion layer in which a solid nitride of supersaturated solid solution or alloy element in which only N is dissolved in Fe is deposited. . According to the treatment conditions and treatment methods, the compound layer has different densities of the tissues, hardness of the produced nitride, the type of phase, and the amount of carbon employed, and its properties affect wear resistance and corrosion resistance. Since the diffusion layer has a low nitriding temperature, only nitrogen penetrates regardless of the nitriding method, and the depth to which nitrogen is penetrated is called the diffusion layer length, that is, the depth of the nitride layer, and depends on the type of steel and the treatment time. Usually, the same time-treated plasma nitridation (or ionization) and salt bath nitriding methods are formed deeper than gas nitridation.

The nitriding treatment provides a method for producing a nitrogen cured layer having excellent lubricity selected from gas nitriding, plasma nitriding, salt bath nitriding, low pressure nitriding and a method of mixing these methods.

For example, in the case of plasma nitriding (also referred to as ion nitriding) after gas nitriding, deeper nitriding depth and high surface hardness can be secured simultaneously. Therefore, the nitriding treatment method can further increase the nitriding effect by using alone or in combination of two or more to suit the intended use.

The gas nitriding or gas soft nitriding treatment is a method of hardening a surface by infiltrating nitrogen into a metal surface, and does not require a separate quenching process to obtain a hard surface, and is a transformation point of metal as a surface hardening heat treatment method. Treatment with ammonia gas (40-90% NH ₃ , 5-10% CO ₂ and the remaining N ₂ ) at a temperature below 723 ° C. at 500-600 ° C. In order to form a porous compound layer, the higher the treatment temperature and the ammonia gas ratio, the better.

The salt bath nitriding is also referred to as salt bath nitriding, and the salt composition is formed of NaCO ₃ , NaCN, KCN, O _2, etc. at a treatment temperature of 530 to 580 ° C., and when nitriding the salt bath, tempering is optionally performed after nitriding. Is needed. The alkali metal cyanate (MCNO), which is the main component of the nitriding agent, is decomposed at this temperature to provide nitrogen and carbon atoms of the generator.

The plasma nitriding is performed by using a nitrogen gas by using a glow discharge in a low pressure atmosphere by using N ₂ , H ₂ , Ar, CH ₄ , C ₂ H ₂ , or the like as an auxiliary gas at a treatment temperature of 450 to 600 ° C. It is a method of ionizing a gas and making it nitrate by making it collide with the surface of the to-be-processed object.

The hardness of the nitrogen compound layer provided by the nitriding treatment of the present invention may vary depending on the general requirements of the HV 500 to 1300 or mold material, whether or not heat transfer treatment, type of molding, and the like. In particular, cast iron is preferably HV 700 to 1,300, and carbon steel is preferably HV 600 to 1,000. If the hardness of the nitrogen compound layer is less than HV 500, the wear resistance of the film is reduced, it is difficult to obtain a hardness exceeding HV1300 by nitriding treatment. In particular, since the thickness of the compound layer is a micron unit (10 to 20 μm), the compound layer hardness cannot be measured using a general microhardness meter. The compound layer hardness of carbon steel measured by a special method is about HV600-800, and the alloy steel is about HV 1000 to 1300. to be.

(c) The finishing step S300 may be performed to impart unevenness to the upper portion of the nitrogen compound layer formed by the nitriding treatment to form a porous compound layer serving as an oil hole.

The method for imparting irregularities provides a method for producing a nitrogen cured layer having excellent lubricity selected from sandpaper, sandblasted, shotblasted, and a method of mixing them. In the finishing step S300, the surface finish is more preferably sandblasting of the particle size # 200 ~ 600, after sandpaper treatment of the particle size # 200 ~ 600.

By making part or most of the outermost part of the nitrogen compound layer into the porous nitride layer, the liquid lubricating film is more absorbed and penetrated into the nitriding layer into the porous compound layer due to the formation of the oil hole, thereby increasing the lubricity, and the anchoring effect. It is characterized in that the adhesion of the lubricating film is improved to be maintained on the mold surface for a long time.

Particularly in the case of cast iron, graphite phases in the form of flakes, spheres or a mixture are contained therein, and these graphites are generally porous. Here, the graphite exposed on the surface may serve as an oil hole by absorbing the lubricating film during the solid lubrication coating.

On the other hand, when a carbon steel material is used as a mold, unlike cast iron, since graphite does not contain graphite in the tissue, the formation of a porous compound layer is further increased due to the lack of oil hole sites.

Therefore, in the case of a mold that needs to withstand high surface pressure or high load as described above, the surface hardening heat treatment step S110 is performed by a method of hardening, laser hardening, and mixing them to form a high strength steel plate for forming a porous compound layer ( 2.0mm or more in thickness and 50kg / mm ² or more in tensile strength) can be formed.

(d) A lubricant treatment step S400 may be performed to spray a lubricant on top of the porous compound layer or to form a lubricating film layer immersing a substrate on which the porous compound layer is formed on the lubricant.

The lubricant may be a nitrile having excellent lubricity selected from the group consisting of molybdenum disulfide (MoS ₂ ), tungsten disulfide (WS ₂ ), graphite, boron nitride (BN), polytetrafluoroethylene (PTFE), and mixtures thereof. Provided are methods for producing a cured coating film. The lubricant is preferably used in the form of a solid film lubricating coating.

(e) a solidification step S500 of curing the lubricating film layer at 150 to 400 ° C .; provides a method for producing a nitrogen cured layer having excellent lubricity including. The curing is carried out in the atmosphere and can vary depending on the lubricant.

If the temperature of curing the lubricating film layer in the solidification step is less than 150 ℃, the lubricating film layer is not sufficiently solidified there is a risk of leakage of the lubricant, if it exceeds 400 ℃, due to too high temperature of the waste of lubricant May cause aging.

As described above, the metal molded body having the nitrogen-curing layer having excellent lubricity of the present invention has a low friction, lubrication, and sticking resistance due to an increase in the permeability of the lubricant due to the oil hole formed in the film. ), Demolding properties and wear resistance are exerted, and the surface state of the molded article is improved.

In addition, the method of manufacturing a metal molded body having a nitrogen-hardened layer having excellent lubricity of the present invention is simpler than the conventional physical vapor deposition, chemical vapor deposition, and thermal diffusion coating. As a result, the cost of the film treatment is low.

In addition, the metal molded body having a nitrogen-hardened layer having excellent lubricity prepared by the method of the present invention is excellent in lubricity and durability even when applied to a large mold that was limited in size, as well as a cast iron-based mold, which was only dependent on conventional chromium plating. It is effective.

In addition, the metal molded body having a nitrogen-hardened layer having excellent lubricity prepared by the method of the present invention is applied to various molding tools such as metal molds such as automobile bodies, outer plates, frames, chassis, and the like, punches or dies, which are metal sheet press molds. There is a possible effect.

Hereinafter, the method for producing a nitrogen-cured layer excellent in lubricity of the present invention will be described in more detail, but the present invention is not limited to the following examples.

Example  One

Spheroidal graphite cast iron (FCD 550) was used as the base material for forming the door rail road for automobile parts with 1.6t thickness and 44kg / mm2 tensile strength, and sandblasting of # 200 for nitriding pretreatment. After removing rust and foreign substances on the surface, sand polishing with particle size # 220, # 320, # 400, followed by finishing polishing, washed with alcohol and acetone, dried by air blowing, and gas soft nitriding method for surface hardening. After preheating at 400 ° C. for 1 hour, at 575 ° C. for about 4.5 hours in an atmosphere containing at least 50% NH ₃ (gas ratio 50:50) and other RX gases (80% N ₂ and 20% CO) Nitriding. Thereafter, after finishing polishing again with sandpaper having a particle size of about # 600, mirror polishing was performed using a wool wheel. At this time, in order to increase the polishing efficiency, an abrasive containing a small amount of artificial diamond having a particle size of 1 ~ 4μm in olive oil was used together. After cleaning the surface with alcohol and acetone and drying by air blowing, spray and naturally dry the solid lubricating film (SANDSTROM, product # 103), which is mainly composed of MoS ₂ , using a pneumatic spray gun to lubricate the nitride surface. Then, the temperature was slowly elevated to 200 ° C. in a BATCH baking furnace, and solidified for about 3 hours.

The lubricating nitrogen hardening layer prepared by the above method had a lubricating film thickness of 15 μm, a total nitriding depth of 420 μm, a compound layer thickness of about 12 μm on the outermost surface of the nitrogen hardening layer, and a surface hardness of the nitrogen hardening layer of HV 720. .

Example  2

Sandblasting of # 200 in the pretreatment process using gray cast iron (FC 300) as a base material for the purpose of forming door parts for automotive parts with a high tensile strength steel plate of 1.2t and tensile strength of 44kg / mm2. After removing foreign matters, sandpaper with particle size # 220, # 320, # 400, followed by finishing polishing, washed with alcohol and acetone, dried by air blowing, and proceeded by gas softening method for surface hardening. after pre-heating for one hour at ℃, nitriding treatment was for approximately 4.5 hours at 575 in a ℃ least 50% NH ₃ (gas ratio 50: 50) and other RX gas (80% N ₂ and 20% CO) is the main component atmosphere. Thereafter, after finishing polishing again with sandpaper having a particle size of about # 600, mirror polishing was performed using a wool wheel. At this time, in order to increase the polishing efficiency, an abrasive containing a small amount of artificial diamond having a particle size of 1 ~ 4μm in olive oil was used together. After cleaning the surface with alcohol and acetone and drying by air blowing, spray and naturally dry the solid lubricating film (SANDSTROM, product # 103), which is mainly composed of MoS ₂ , using a pneumatic spray gun to lubricate the nitride surface. Then, the temperature was slowly elevated to 200 ° C. in a BATCH baking furnace, and solidified for about 3 hours.

The lubricating nitrogen hardening layer prepared by the above method had a lubricating film thickness of about 15 μm, a total nitride depth of 380 μm, a double surface compound layer having a thickness of 13 μm, and the surface hardness of the nitrogen cured layer was about HV 715.

Example  3

To form aluminum plated steel sheet (S45C) with a thickness of 1.4t, using ordinary carbon steel (non-heat treated steel, S45C) molding materials, the surface rust and debris are removed by sandblasting at # 200 in the nitriding pretreatment process. After finishing polishing with sandpaper of particle size # 220, # 320, # 400, ultrasonic cleaning and steam degreasing in a washing line composed of methylene chloride and trichloroethane, drying by air blowing, and plasma nitridation for surface hardening. Proceed with 70% N ₂ and 30% H ₂ Nitriding was carried out at 540 ° C. for 5 hours under atmosphere.

Then, after finishing with sandpaper of particle size # 400, mirror polishing was performed using a wool wheel. At this time, in order to increase the polishing efficiency, an abrasive containing a small amount of artificial diamond having a particle size of 1 ~ 4μm in olive oil was used together. After washing through the above washing line and drying by air blowing, in order to give lubrication to the nitride surface, spray and naturally dry the solid lubricating film (product of SANDSTROM company, # 103) whose main component is MoS ₂ using a pneumatic spray gun. Then, the temperature was slowly elevated to 200 ° C. in a BATCH baking furnace and solidified for about 2 hours. The lubricating layer thickness of the prepared lubricating nitrogen cured layer was about 12 μm, the surface hardness was HV 660, the total curing depth of the nitrogen cured layer was 150 μm, and the thickness of the double compound layer was about 12 μm.

Comparative example  One

Spherical graphite cast iron (FCD550) was subjected to only the same nitriding treatment as in Example 1.

Comparative Example 2

Only the same nitriding treatment as in Example 2 was performed on gray cast iron (FC300).

Figure 3a is a photograph observing the cross section in which the lubricating nitrogen cured layer formed on the spherical graphite cast iron according to Example 1 of the present invention with an optical microscope. Referring to FIG. 3A, it can be seen that spheroidal graphite 11 penetrates the cast iron, a dense compound layer 113 and a porous compound layer 130 are formed, and an oil hole 10 is formed in the spheroidal graphite site in the porous compound layer.

3B is a cross-sectional optical micrograph in which a lubricating nitrogen cured layer is formed on carbon steel according to Example 3 of the present invention. Referring to FIG. 3B, it can be seen that the dense nitride layer 113 and the finely porous nitride layer 130 are formed.

Figure 4a is a friction wear test graph of the spherical graphite cast iron according to Example 1 of the present invention. At this time, the test condition is 950g load and 100rpm speed. Referring to FIG. 4A, the spherical graphite cast iron coated by Example 1 may have a significantly lower coefficient of friction than Comparative Example 1. FIG.

Figure 4b is a graph of the friction wear test results of gray cast iron according to Example 2 of the present invention. Referring to FIG. 4B, the gray cast iron coated by Example 2 may have a significantly lower coefficient of friction than Comparative Example 2. FIG.

5A is an optical micrograph (100 times) of the nitrogen cured layer according to Comparative Example 1, and FIG. 5B is an optical micrograph (500 times) of the surface of the nitrogen cured layer according to Comparative Example 1. Referring to FIGS. 5A and 5B In addition, severe scratches and damaged graphite can be identified.

6A is an optical micrograph (100 times) of the surface of the lubricious nitrogen cured layer according to Example 1 of the present invention, and FIG. 6B is an optical micrograph (500 times) of the surface of the lubricious nitrogen cured layer according to Example 1 of the present invention. to be. 6A and 6B, it can be seen that the graphite has little scratches and damages and maintains its initial shape.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

1 is a cross-sectional view of a metal molded body having a nitrogen cured layer excellent in lubricity according to an embodiment of the present invention.

2 is a manufacturing process diagram of a metal molded body having a nitrogen cured layer excellent in lubricity according to an embodiment of the present invention.

3A is a cross-sectional optical micrograph of a metal molded body having a lubricated nitrogen hardened layer formed on a spheroidal graphite cast iron according to Example 1 of the present invention .

3B is a cross-sectional optical micrograph of a metal molded body having a lubricating nitrogen cured layer formed on carbon steel according to Example 3 of the present invention.

Figure 4a is a friction wear test results graph of the nodular graphite cast iron according to Example 1 of the present invention.

Figure 4b is a friction wear test results graph of the nodular graphite cast iron according to Example 1 of the present invention.

Figure 5a is an optical micrograph (100 times) of the surface of the nitrogen cured layer according to Comparative Example 1.

Figure 5b is an optical micrograph (500 times) of the surface of the nitrogen cured layer according to Comparative Example 1.

Figure 6a is an optical micrograph (100 times) of the surface of the lubricious nitrogen cured layer according to Example 1 of the present invention.

Figure 6b is an optical micrograph (500 times) of the surface of the lubricating nitrogen cured layer according to Example 1 of the present invention.

<Description of Major Symbols in Drawing>

1: description

10: oil hole, 11: nodular graphite

100: nitrogen-hardened layer excellent in lubricity

110: nitrogen compound layer

111: diffusion layer, 113: dense compound layer

130: porous compound layer, 150: lubricating film layer

Claims (13)

In a metal molded body having a nitrogen cured layer excellent in lubricity, Metal base; A nitrogen compound layer derived from nitriding on the metal substrate; An oil hole formed on top of the nitrogen compound layer to provide an improvement in penetration or adhesion of the lubricating film; And A lubricating film layer for imparting lubricity to the upper portion of the porous compound; Metal molding having a nitrogen-cured layer excellent in lubricity comprising a. The method of claim 1, The nitrogen compound layer, A diffusion layer which is a layer into which nitrogen is diffused; And Metal molded body having a nitrogen-hardened layer excellent in lubricity including a dense compound layer containing a compound selected from the group consisting of Fe ₂ N, Fe ₃ N, Fe ₄ N and mixtures thereof on top of the diffusion layer. The method of claim 1, The nitrogen compound layer is a metal molded body having a nitrogen cured layer excellent in lubricity of 0.1 to 1 mm. The method of claim 1, The nitrogen compound layer has a hardness of HV 500 to 1300 people A metal molded body having a nitrogen cured layer excellent in lubricity. The method according to any one of claims 1 to 4, The metal substrate is a metal molded body having a nitrogen-hardened layer having excellent lubricity selected from the group consisting of stainless steel, aluminum, aluminum, carbon steel, cast iron, and mixtures thereof. The method of claim 5, The cast iron Metal molding having a nitrogen-hardened layer excellent in lubricity, characterized in that it is gray cast iron or nodular graphite iron. The method of claim 6, The metal molded body having a nitrogen cured layer having excellent lubricity, characterized in that the metal molded body is a mold. (a) a pretreatment step comprising a surface control step or a cleaning and drying step to facilitate surface treatment of the substrate; (b) a nitriding treatment step of forming a nitrogen compound layer on the surface of the substrate; (c) a finishing step of forming a porous compound layer acting as an oil hole by applying unevenness to an upper portion of the nitrogen compound layer; (d) a lubricant treatment step of spraying a lubricant on top of the porous compound layer or forming a lubricating film layer for immersing the substrate on which the porous compound layer is formed; And (e) a solidifying step of curing the lubricating film layer at 150 to 400 ° C; Method for producing a metal molded article having a nitrogen cured layer having excellent lubricity including. The method of claim 8, In the step (a), the nitriding treatment is to produce a metal molded body having a nitrogen-hardened layer excellent in lubricity selected from gas nitriding, gas soft nitriding , plasma nitriding, salt bath nitriding, low pressure nitriding and a method of mixing these methods. Way. The method of claim 8, Before the step (b), the method of producing a metal molded body having a nitrogen-hardened layer excellent in lubricity further comprising a surface hardening heat treatment step by high-frequency curing or laser curing. The method of claim 8, In the step (c), the method of imparting irregularities is a method of producing a metal molded body having a nitrogen-hardened layer excellent in lubricity selected from sand paper, sand blast, shot blast and a method of mixing them. The method of claim 8, In the step (c), the lubricant is molybdenum disulfide, tungsten disulfide, graphite, boron nitride, polytetrafluoroethylene and a method for producing a metal molded body having a nitrogen-curable layer excellent in lubricity selected from the group consisting thereof. The method of claim 8, In the step (d), the lubricant treatment is a method for producing a metal molded body having a nitrogen-cured layer excellent in lubricity which is a solid lubricating film treatment using a powdered lubricant.

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