JP2016140905A - Lubrication treatment method for plastic working workpiece, and plastic working workpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubrication treatment method giving high lubricity on the surface of a workpiece used for plastic working such as forging.SOLUTION: A lubrication treatment method for plastic working workpiece includes forming a lubrication film by spraying in a dry process, the carbide particulate such as silicon carbide SiC(α) on the surface of a plastic working workpiece to deposit the carbon element in the carbide particulate on the surface of the workpiece. Plastic working such as forging is performed using the workpiece as it is on which the lubrication film is formed, or after coating a lubricant such as a forging oil, or after forming on the lubrication film, a chemical conversion film such as a zinc phosphate film and after coating the lubricant such as the forging oil.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of lubricating a workpiece for plastic working and a workpiece for plastic working, and more particularly, for the purpose of imparting lubricity to the surface of the workpiece in plastic working such as cold forging. Further, the present invention relates to a lubrication method performed as a pre-processing for plastic working on a workpiece, and a workpiece subjected to the lubrication treatment.

  In the manufacture of automobiles and other machine parts, because of the demands for energy saving and cost reduction, or the demands for reducing the environmental load, there are fewer materials used compared to the manufacturing by cutting, and the merits of shortening the processing time, etc. Forging and other plastic processing that can be expected to be used, especially in the manufacture of automobile parts, in order to improve the efficiency of manufacturing, parts with complex shapes that were conventionally manufactured by cutting are also used. Attempts have been made to switch to cold forging.

  As an example of such plastic working, cold forging, which is becoming the mainstream manufacturing method for machine parts, will be described as an example. This cold forging is roughly classified as shown in FIG. ”,“ Heat treatment ”,“ lubrication treatment ”, and“ press (forging) ”.

  Of these, “material removal” is a process of cutting into a material for one product manufactured from a metal material provided in the form of a plate, bar, etc. by methods such as punching, parting off, shearing, sawing, The material cut out in this way is subjected to annealing, low-temperature annealing, spherical annealing, etc. in the “heat treatment” to modify it so that it is easily deformed, and then subjected to a “lubrication treatment” to form a mold. Applying lubrication to the surface, such as forming a lubricating film to prevent seizure and improving releasability and applying a lubricant, and then processing into a predetermined shape in “press (forging)” To do.

  “Lubrication treatment” in the above process is a treatment for imparting lubricity to the surface of the material to be treated as described above, and in cold forging, such a lubrication treatment is called the bonde-bonderube method. It is common to perform processing by a method.

  This lubrication treatment by the bonde-bonderube method includes a step of depositing zinc phosphate crystals on the surface of the workpiece by chemical conversion treatment and a step of applying a lubricant such as metal soap. As shown in FIG. 5, a zinc phosphate coating and a coating layer of a lubricant such as a metal soap formed thereon are formed on the surface.

  The zinc phosphate crystals deposited on the surface of the workpiece in this way have a cleaved surface with a weak bond between the crystal lattices, and cleave the shearing force at the friction interface during forging. It exerts the function to reduce friction. In addition, it has a function to repair and coat the surface of the work material. With these functions, the zinc phosphate coating is highly effective in preventing seizure with the mold and is applied as a lubricant on it. Metal soap reduces frictional resistance. Combined with this, the surface of the workpiece is given high lubricity that enables severe cold forging.

  In such a lubrication process using the bonde-bonderube method, in order to improve the adhesion of the zinc phosphate coating, dirt such as oil and fat, oxide coating, rust, etc. adhering to the surface of the material to be processed, For the purpose of forming fine irregularities on the surface of the material, blasting such as drive blasting and wet blasting, degreasing and pickling are performed before chemical conversion.

  An example of the overall flow of the lubrication treatment by the bonde-bonderube method including such blast treatment, degreasing, and pickling is as shown in FIG. 4 (FIG. 6, [0005] to [0005] in Patent Document 1). [0016] column).

  In the lubrication treatment shown in FIG. 4, the oxide film generated during the heat treatment, which is the previous process, is removed by “drive last”, and irregularities that improve the adhesion of the lubricant film are formed on the surface of the workpiece. ”To remove oil, dirt, and cutting powder generated by drive last on the surface of the workpiece, and then wash away the degreasing agent with“ washing ”and rust on the surface of the workpiece with“ pickling ”. After removal, the acid is washed away with "washing".

  After that, the workpiece is immersed in a phosphate solution by “chemical conversion treatment”, crystals of zinc phosphate are deposited on the surface of the workpiece to form a lubricating film, and the phosphate is then washed by “water washing”. After washing off the solution, neutralize the excess coating agent that could not be removed in the water washing step after the chemical conversion treatment step by "neutralization", and then wash away this neutralizing agent by "water washing". The material to be treated is immersed in a metal soap solution by “lubricant application”, and then dried by “drying” to be fixed on the surface of the material to be treated.

  As described above, in cold forging, the lubrication process performed before pressing (forging) is composed of an extremely large number of processes, so that a large-scale processing facility is required and chemical treatment is included in order to include chemical conversion treatment. Because the chemical reaction due to the process is slow, the processing speed is slow, the mass productivity is poor and the cost is high, and the treatment of waste liquid and other industrial waste is necessary. There is an urgent need for the development of means that can be carried out easily with less man-hours and without causing pollution.

  In particular, since heat treatment and lubrication are necessary steps each time pressing (forging), cold forging is applied to machine parts with complex shapes. If the work piece cannot be deformed to the final shape in this way and this is performed in multiple steps, heat treatment and lubrication treatment are required each time, so there is a greater demand for simplification of the lubrication treatment. It has become.

  In order to meet such demands, the reaction time is long because it requires a reaction, and a large initial investment is required for the processing equipment, and by eliminating the chemical conversion treatment having problems such as waste liquid treatment, It has been proposed to simplify the lubrication process.

  Therefore, in order to eliminate the chemical conversion treatment from the lubrication treatment, the required lubricity can be obtained simply by applying and drying directly on the surface of the workpiece without forming a film by chemical conversion treatment. Lubricants for cold forging called “one-component type (non-reactive type)” have also been developed.

  As an example of the one-component (non-reactive) lubricant, a lubricant in which a water-soluble inorganic salt and a solid lubricant, an oil component, and a surfactant are blended at a predetermined ratio has been proposed (Patent Document 2). Claim 1).

  In addition, a metal conversion process (formation of zinc phosphate crystal coating) is made unnecessary by increasing the adhesion of metal soap applied as a lubricant to the surface of the material to be processed. It has also been proposed to form irregularities on the surface of the workpiece to improve the adhesion of the lubricant by performing a blasting process that injects a slurry, which is a mixture of liquid and abrasive grains, before applying the soap. (Claim 1 of Patent Document 1).

  The inventor of the present invention uses a solid lubricant powder such as zinc, molybdenum disulfide, or tin as a method of forming a film having lubricity on the sliding surface of a metal or ceramic product without using chemical conversion treatment. Proposes a method of forming a lubricant film by spraying the body onto the surface of the sliding part at a predetermined spraying speed or pressure to diffuse and infiltrate the elements in the composition of the lubricant powder into the surface of the sliding part. (Patent Document 3).

  Although not an invention relating to imparting lubricity, the inventor of the present invention covers the carbon element in the carbide powder by injecting carbide powder such as SiC onto the surface of the processed product made of a metal material. It has been found that “carburization” can be performed by diffusing to the surface of the treated product to obtain an improvement in surface hardness, and this has been filed as a “room temperature carburizing method” (see Patent Document 4).

JP 2007-38309 A Japanese Patent Laid-Open No. 10-8085 Japanese Patent No. 3357586 Japanese Patent No. 3420060

  The invention introduced as Patent Document 1 and Patent Document 2 was developed for the purpose of eliminating the chemical conversion treatment that was essential in the lubrication treatment by the Bonde-Bondalube method in order to simplify the lubrication treatment. Processing means.

  However, as described in claim 1 of Patent Document 1, even if a slurry, which is a mixture of liquid and abrasive grains, is sprayed to form irregularities on the surface of the material to be treated, chemical conversion treatment is performed thereafter. If the metal soap was applied and dried without any problem, it was lubricated by the bonde-bonderube method, and the zinc phosphate coating was simply removed from the surface of the workpiece shown in FIG. Therefore, the lubricity should be much inferior to the lubrication process by the bonde-bonderube method, and it is unlikely that the lubricity can withstand severe cold forging.

  Then, in the configuration described in Patent Document 1, if high lubricity that can withstand cold forging can be obtained even if the formation of the zinc phosphate coating by the chemical conversion treatment is omitted, Patent Document 2 can be applied as a lubricant to be applied. Patent Document 1 uses a one-pack type (non-reactive type) lubricant, except that it is premised on the use of a “one-pack type (non-reactive type)” lubricant as described in Even in this case, just as in the case of the Bonde-Bondalube method, it is merely shown that it is effective to perform blasting in advance.

  A so-called “one-component (reacted)” lubricant (Patent Document 2) has a structure in which a powdered solid lubricant is dispersed in a water-soluble inorganic salt, and this is used as a work material. When applied to the surface and dried, a powdered solid lubricant adheres to the surface of the work material using a water-soluble inorganic salt as a binder, thereby imparting lubricity.

  Therefore, if the solid lubricant dispersed in the water-soluble inorganic salt is mica, molybdenum disulfide, graphite, etc. (column [0010] in the same document), or a solid lubricant having a cleavage property, the bonde-bonderube method is used. It is considered that a film having the same function as the zinc phosphate film formed by the chemical conversion treatment can be formed.

  However, this method uses a water-soluble inorganic salt as a binder to attach a solid lubricant to the surface of the workpiece. Therefore, if the amount of the water-soluble inorganic salt is increased in order to improve adhesion, the lubricity decreases. If the amount of solid lubricant is increased (the amount of water-soluble inorganic salt is decreased) to improve lubricity, adhesion strength decreases and film breakage occurs (column [0016] in the same document). Therefore, the amount of solid lubricant that can be added is limited, and the amount of solid lubricant that can be deposited is less than that in the case of forming a film by depositing zinc phosphate crystals without interposing a binder. The lubrication performance is considered to be poor.

  On the other hand, in the method for forming a lubricating coating of Patent Document 3, a solid lubricant powder such as zinc, molybdenum disulfide, or tin is injected onto the surface of a workpiece at a predetermined injection speed or a predetermined injection pressure. As a result, it is possible to form a lubricant film by diffusing and infiltrating the components of the solid lubricant into the surface of the workpiece without interposing a binder. By using, for example, molybdenum disulfide, which has cleavage properties, it is possible to reduce frictional resistance and prevent seizure by cleaving directly on the surface of the workpiece without using chemical conversion treatment and without using a binder. , It is possible to form a lubricating film capable of exhibiting effects such as improvement of releasability.

  However, since the above-mentioned molybdenum disulfide is a relatively expensive substance, if it is used as a spray powder to form a lubricating coating, the processing cost increases, and if this processing cost is transferred to a product, the price competitiveness in the market will increase. descend.

  The present invention is based on the accumulation of many years of lubrication technology by the inventor and the knowledge obtained as a result of experiments. It is relatively simple and relatively inexpensive, and can be used for dust fires and explosions. A lubrication method capable of imparting a higher lubricity to a workpiece for plastic working than a conventional method by a safe method with less risk such as By providing workpieces, it is intended to reduce the defect rate during plastic working and extend the life of molds.

  In other words, the inventor of the present invention uses a relatively simple method of powder injection (Patent Document 3) to provide a solid lubricant film that exhibits excellent lubricity similarly to zinc phosphate and molybdenum disulfide. In order to form the film at a lower cost, research was conducted on a means for forming such a lubricating film from carbon (C), which is cheaper than molybdenum disulfide.

  However, when a solid lubricant film is formed by spraying a solid lubricant powder, carbon particles such as graphite are sprayed to form a carbon film. Carbon particles are extremely ignitable substances, and if they are sprayed using a blasting machine, there is a risk of dust fires and dust explosions, and they cannot be handled easily.

  In addition, when the inventor of the present invention injects carbide powder onto the surface of the processed product made of a metal material, the carbon element in the carbide powder is diffused and penetrated into the surface of the processed product. It has been found that “carburization” for improving the surface hardness can be performed, and this method has already been patented as “room temperature carburizing treatment method” (Patent Document 4).

  However, the invention described in this document is a proposal for “carburizing” to improve the surface hardness of the processed product, and is processed by the method described in Patent Document 4 as a pretreatment for cold forging formed by plastic deformation. If carburizing is performed on the material, it is predicted that the plastic deformation of the workpiece will decrease due to surface hardening and the defect rate will increase.

  Further, in the invention described in the same document, the carbon element in the carbide as the injection powder diffuses and permeates the surface of the processed product, that is, based on the knowledge that it enters the inside and generates “carburization”. Thus, it is impossible to predict that carbon diffused and penetrated into the surface in this way will give lubricity to the surface of the processed product.

  Thus, combining the “lubricating process” performed as a pre-treatment in plastic working with “carburizing” for predicting that the plastic deformability is lowered is a means for those skilled in the art to avoid the application. However, the inventor of the present invention tried to experiment and examine the “room temperature carburizing treatment method” described in Patent Document 4 instead of the chemical conversion treatment in the lubrication treatment by the bonde-bonderube method.

  As a result, contrary to the above-mentioned prediction, the workpiece that has been processed in this way has reduced molding defects during plastic processing, reduced seizure, and improved mold life due to improved mold release. Experimental results confirming that the surface lubricity of the material has been improved.

  Further, in place of the drive last performed in the conventional lubrication treatment described with reference to FIG. 4, the “room temperature carburizing treatment method” described in Patent Document 4 is performed, and thereafter the pickling treatment and the like are omitted. A plastic working experiment was performed using a lubricated workpiece that performs the treatment after the chemical conversion treatment. In this case as well, a workpiece that was lubricated according to the process shown in FIG. 4 was used. Compared to the case of plastic working, the results confirming the improvement in lubricity, such as a reduction in the defect rate and an extension of the die life, were confirmed.

As a result of the above experiments and research, the lubrication method for the plastic working material of the present invention is as follows.
In the lubrication treatment for imparting lubricity to the surface of the workpiece, which is performed as a pretreatment for the workpiece before plastic deformation,
Including a process of forming a lubricating film formed by adhering carbon elements in the carbide powder to the surface of the workpiece by spraying the carbide powder onto the surface of the workpiece in a dry manner. (Claim 1).

  In the above lubricating treatment method, the carbide powder is preferably a carbide powder having a hexagonal crystal structure such as SiC (α).

  Furthermore, in the lubricating treatment method, it is preferable that the surface of the workpiece on which the lubricating coating is formed is formed with irregularities of 0.2 μm or more in arithmetic mean roughness (Ra).

  The carbide powder is injected by spraying the carbide powder having a particle size of # 220 to # 1000 at an injection speed of 80 to 250 m / sec or an injection pressure of 0.2 to 0.6 MPa. (Claim 4).

  The lubricating treatment method of the present invention may further include a step of applying a lubricant to the surface of the workpiece on which the lubricating coating is formed (Claim 5).

  Further, the lubrication treatment method of the present invention comprises a step of forming a chemical conversion film having lubricity by a chemical conversion treatment on the surface of the workpiece on which the lubricating film is formed, and a lubricant on the chemical conversion film. A step of applying may be included (claim 6).

  Furthermore, the work material for plastic working of the present invention is a work material that has been lubricated by any of the methods described above.

According to the configuration of the present invention described above, the following remarkable effects can be obtained by performing plastic working using a workpiece that has been lubricated by the method of the present invention.
By forming a lubricant film on the surface of the workpiece by spraying carbide powder, it was possible to impart lubricity to the surface of the workpiece.

  Such a lubricating coating can be formed by a relatively simple method of spraying carbide powder in a dry manner, and by using an equivalent carbide powder such as SiC, a carbon powder such as graphite. There was no risk of dust fire or dust explosion as in the case of spraying, and it was possible to form safely.

  Moreover, by spraying carbide powder, it is possible to remove the oxide film formed on the surface by the heat treatment process and remove dirt such as rust at the same time. There is no need to perform the process, and the process can be omitted.

  The lubricating coating formed as described above can be used as a layer in place of the zinc phosphate coating by the Bonde-Bonderube method described as the prior art or as an underlayer together with the zinc phosphate coating. It can be used for any purpose, and the defect rate can be reduced and the die life can be extended with improved lubricity compared to the conventional lubrication process using the bonde-bonderube method. I was able to.

  In addition, when the above-described lubricating coating is used in place of the conventional zinc phosphate coating, during the lubricating treatment described with reference to FIG. As a result, the number of steps in the lubrication process can be greatly reduced.

  Further, even when the above-described lubricating coating is used as a base layer of a chemical conversion coating such as a zinc phosphate coating, as described above, the pickling treatment after blasting is not performed in the present application. Compared to the conventional lubrication process described above, the processing steps can be greatly reduced.

  Furthermore, by the injection of the carbide powder, irregularities are formed on the surface of the work material to have a predetermined surface roughness, so that a water-soluble or oil-based lubricant is further formed on the formed lubricating coating. When applying a metal soap or other known lubricant, the applied lubricant is likely to adhere to the surface of the workpiece, and once adhered, the lubricant is held on the surface irregularities by capillarity or the like. Since the film breakage is less likely to occur, the lubricity can be further improved and the adhesion of the chemical conversion film can be improved even when a chemical conversion film such as zinc phosphate is further formed on the lubricating film. Was able to improve.

  As described above, the lubrication treatment by the method of the present invention can improve the lubricity of the workpiece as compared with the conventional method. It was possible to obtain the possibility of forming by cold forging, or the possibility of forming by warm forging of products that could only be formed by hot forging.

  As described above, the carbon element in the carbide powder adheres to the surface of the workpiece, so that when the workpiece is subjected to a heat treatment such as quenching after plastic working, the carbon adhering to the surface is not. Demonstrates the effect of improving hardenability.

It is a surface micrograph of a workpiece after spraying SiC (α) # 400 by the method of the present invention to form a lubricant film, (A) is 50 times, (B) is 100 times, (C) is 1000 times, (D) is 500 times. The graph which shows the Raman spectroscopic analysis result of the workpiece (Example 1) after injecting carbide powder. It is an element mapping of the electron beam microanalyzer (EPMA) of the workpiece (Example 1) after spraying the carbonized part powder, (A) is the element mapping of carbon, and (B) is the element mapping of silicon. Explanatory drawing which showed the process of cold forging (conventional). Sectional schematic diagram of the surface portion of the workpiece after lubrication by the bonde-bonderube method (conventional).

  Next, embodiments of the present invention will be described below with reference to the accompanying drawings.

  In the following description, forging, particularly cold forging, will be described as an example of plastic working. However, lubricity may be imparted to the surface of a workpiece that comes into contact with the surface of a mold or the like. What is important is not only forging but also a common problem in other plastic working such as rolling and drawing, and the scope of the present invention is limited to cold forging and forging typified by cold forging. It can also be applied to other workpieces for plastic working.

  When plastic working is cold forging as an example, as shown in FIG. 4, it is roughly divided into “material removal”, “heat treatment”, “lubrication”, and “press (forging)” processes. The point is as described above, and when the present invention is applied to such a material for cold forging, the present invention relates to the “lubricating treatment” of FIG. This is the same as the lubrication treatment by the Bonde-Bondalube method described above.

  However, in the lubrication treatment method of the present invention, instead of forming the chemical conversion film in the Bonde-Bondalube method described as the prior art, or by applying a dry powder of carbide powder as a base treatment for forming this chemical conversion film, It differs from conventional lubrication treatment in that it forms a coating.

  As described above, when the target plastic working is cold forging as an example, the workpiece to be processed according to the present invention is cut into a size of one product manufactured by material removal, In addition, the workpiece is subjected to a predetermined heat treatment for improving plastic deformability.

  In the lubrication treatment of the present invention, the oxide film formed on the surface of the work material by the heat treatment that is the previous step, and dirt such as rust generated on the surface of the work material are caused by the carbide powder described later. Since it is removed by jetting / collision, it is not necessary to subject the workpiece after heat treatment to pickling before the carbide powder is jetted (although it can be done).

  The material of the material to be processed is not particularly limited as long as it is a metal material that is the object of plastic working, in this embodiment, cold forging, and various metal materials can be processed, such as steel. However, the present invention is not limited to ferrous metals, and nonferrous metals such as aluminum alloys can also be targeted.

  In the surface treatment method of the present invention, the carbide powder can be sprayed by various types of blasting apparatus applied to a known sandblasting process or shot peening process as long as this is performed in a dry manner.

  As such a blasting device, it is possible to use a centrifugal type that projects powder by centrifugal force, but it is relatively easy to control the injection speed, injection pressure, etc. The apparatus can be preferably used.

  As such an air type blasting apparatus, various types of blasting apparatuses such as a gravity type (suction type), a direct pressure type, etc. are provided. Any type of blasting apparatus may be used as long as it can be injected at an injection speed or an injection pressure, and the injection type is not particularly limited.

  The formation of the lubricating film on the surface of the workpiece is performed by spraying carbide powder and attaching the carbon element in the carbide powder to the surface of the workpiece.

  As the carbide powder to be sprayed, various known carbide powders can be used. Preferably, a carbide powder whose crystal structure has a hexagonal crystal structure is used.

Examples of the carbide having such a hexagonal crystal structure include silicon carbide [SiC (α)], tungsten carbide (WC), and molybdenum carbide (Mo ₂ C).

  The particle size, the injection speed, or the injection pressure of the injection powder to be used can be set as appropriate according to the material of the workpiece, the dimensional accuracy, etc., but the preferred particle size range of the carbide powder is from # 220 to In the range of # 1000, the injection speed is in the range of 80 to 250 m / sec, and the injection pressure is in the range of 0.2 to 0.6 MPa.

  When carbide powder is sprayed dry onto the surface of the workpiece in this way, the carbide powder that collides with the surface of the workpiece at a high speed is instantaneously transformed on the surface of the workpiece due to heat generated during the collision. [As an example, the temperature rises to 2100 ° C for SiC (α)] or higher, and part of it decomposes into carbon (C) and other components [Si when the carbide powder is SiC (α)] And adheres to the surface of the processed product as a single component.

  Although carbon (C) adhering to the surface of the workpiece in this way partially diffuses and penetrates to the inside of the workpiece, it is distributed at the highest concentration on the surface of the workpiece. In addition, a carbon layer (lubricating film) is formed on the surface portion of the work piece evenly distributed without being biased toward the surface of the work piece.

  Further, fine bumps are formed on the surface of the workpiece due to the collision with the carbide powder, so that it changes into a satin finish as shown in FIG. Preferably, the carbide powder is sprayed so that the surface of the workpiece has a satin finish having an arithmetic average roughness (Ra) of 0.2 μm or more.

  By making the surface rough as described above, as will be described later, when a lubricant (lubricating oil) is further applied to the surface of the workpiece or when a chemical conversion film is formed, the lubricant or chemical conversion film is used. It is possible to improve the adhesion of the resin and obtain good lubricity.

  As described above, the surface of the work material on which a lubricant film has been formed by spraying carbide powder is subjected to air blowing, dust removal, degreasing, etc., as necessary. May be.

  However, in the lubrication process of the present application, unlike the conventional lubrication process described with reference to FIG. 4, the pickling process is not performed on the workpiece after the blasting process.

  That is, in the method of the present invention, carbide ceramics, which are hard materials such as SiC, are sprayed as the spray powder, so that dirt such as oxide film and rust adhering to the surface of the workpiece during heat treatment is carbide. Since it can be removed by spraying powder, there is no need to perform pickling separately. On the other hand, if pickling is performed, the lubricant film formed on the surface of the workpiece may be removed by collision of carbide powder. Pickling after injection of carbide powder is rather undesirable.

  As described above, the lubricating coating formed by the injection of carbide powder may be used as an alternative to the zinc phosphate coating formed by chemical conversion treatment in the Bonde-Bondalube method described as the prior art. Alternatively, this lubricating coating may be used as a base layer, and a chemical conversion coating such as a zinc phosphate coating may be further formed thereon.

  When a lubricating coating formed by injection of carbide powder is used in place of the chemical conversion coating described as the prior art, the workpiece on which this lubricating coating is formed may be directly subjected to the pressing (forging) process. Preferably, a lubricant is further applied on the lubricating coating.

  Lubricants to be applied on the lubricant film include metal soaps, one-component (reacted) lubricants, solid lubricant powders, etc. in water, mineral oil, oils and fats, carboxylates, etc. Various known lubricants such as water-soluble or oil-based lubricants dispersed can be used, and depending on the type of lubricant to be applied, it may be dried after application. The lubrication process for the workpiece is completed.

  When the lubricating coating formed by spraying carbide powder is used as the underlayer of the chemical conversion coating described as the prior art, further chemical conversion treatment is performed on the workpiece on which this lubricating coating is formed, A chemical conversion film typified by a zinc acid film is formed, and a lubricant is further applied onto the lubricating film, and if necessary, a lubricating process is completed through a drying process.

  As described above, in the plastic working performed using the workpiece subjected to the lubricating treatment of the present invention including the formation of the lubricating coating by the injection of carbide powder in the process, the lubricating coating is used instead of the conventional chemical coating. In both cases, when used as an undercoat and as an underlayer of a conventional chemical conversion coating, the occurrence of defect rates could be greatly reduced and the life of the mold could be extended. .

  Here, defects that occur in the product, for example, rough skin, wrinkles, galling, misalignment, etc., indicate that the workpiece does not exhibit good plastic fluidity at the contact part with the mold, that is, lubrication. Since the failure is considered to be one of the causes, the occurrence of such defects is reduced, and the lubrication treatment of the present invention in which the failure rate is reduced is compared with the conventional treatment. It can be seen that higher lubricity can be imparted to the surface.

  In addition, it can be predicted that the frictional resistance between the workpiece surface and the mold is reduced, the seizure is prevented, and the mold release is improved. Therefore, it can be seen that the lubrication treatment of the present invention can impart higher lubricity to the surface of the workpiece as compared with the conventional lubrication treatment.

  This improvement in lubricity is due to the fact that a lubricating film is formed by carbon adhering to the surface of the workpiece, and that the fine irregularities formed on the surface of the workpiece are not coated with the applied lubricant or The adhesion of the chemical conversion coating was improved to prevent film breakage. Furthermore, the surface of the workpiece was formed with the above-mentioned surface roughness irregularities and formed into a satin finish, so that small scratches on the surface could be obtained. It is the starting point of deformation, and it is easy to cause uniform deformation, and since the force does not concentrate on a single point but spreads uniformly, cracks and the like are less likely to occur. It is thought that it was obtained by the effect.

  However, as described with reference to FIG. 4, in view of the fact that surface ruggedness was formed by drive last prior to chemical conversion treatment in the conventional lubrication treatment, the improvement in lubricity is mainly as follows. It is considered that the improvement in lubricity due to the provision of the above-described lubricating coating, which is formed by adhering the carbon element in the carbide powder by the injection of the carbide powder, greatly contributes.

[Formation of lubricating film]
Carbide powder is injected to the workpiece made of SUS304 having a cylindrical shape with a diameter of 20 mm and a length of 40 mm under the conditions shown in Table 1 below, and the carbon element in the carbide powder is applied to the surface of the workpiece. And carbon layer (lubricant film) was formed.

  FIG. 2 shows the results of Raman spectroscopic analysis of the workpiece after the carbide powder is injected under the conditions shown in Table 1.

  From the analysis result of FIG. 2 (see the arrow in the figure), silicon (Si) and carbon (C) in SiC, which is the spray powder, each adhere to the surface of the workpiece as a single component. That is, it can be seen that the injected SiC powder is decomposed into Si and C and adhered to the surface of the workpiece.

  In addition, from the EPMA mapping diagram [FIGS. 3A, 3B] of the workpiece after the surface treatment, the silicon (Si) component is partially unevenly distributed among the decomposed components. However, it was confirmed that carbon (C) was uniformly distributed on the surface of the workpiece (see FIG. 3A).

Although a part of the carbon C diffuses and penetrates to the inside of the workpiece, the carbon C is distributed at the highest concentration in the surface portion of the workpiece, and the carbon C in the injected SiC It can be seen that the portion (Si or SiO ₂ ) adheres to the surface of the workpiece and forms a layer (lubricating film).

[Warm forging test]
The workpiece after spraying carbide powder as described above is transported to the coating device one by one with a parts feeder, and the surface is warm forged oil (containing graphite as a solid lubricant) as a lubricant. ) Was applied to finish the lubrication process.

  The workpiece after the above lubrication treatment was introduced into a heating furnace and heated to perform warm forging.

In a workpiece processed with alundum (Al ₂ O ₃ ) under the same processing conditions as in Example 1, a failure rate of around 5% occurred due to poor lubrication. For the workpieces that were lubricated, the defect rate decreased to 1% or less.

  Further, it was confirmed that the warm forging using the work material subjected to the lubrication treatment of this example can extend the life of the mold by 30% or more as compared with the prior art.

  Furthermore, the surface roughness of the product obtained by warm forging was improved, and post-processing could be simplified.

  From the above results, it was confirmed that the lubricating coating formed by the injection of carbide powder greatly contributed to the improvement of the lubricity on the surface of the workpiece.

  A SCM415 work piece (peeling finish) having a cylindrical shape with a diameter of 40 mm and a length of 60 mm was subjected to a spherical annealing treatment as a heat treatment and then a lubrication treatment.

In this embodiment, the lubricating treatment is performed by injecting carbide powder under the conditions shown in Table 2 below to form a lubricating coating, and then forming a zinc phosphate conversion coating by a known method, and forming a lubricant coating on the conversion coating. Further, a cold forging lubricating oil (containing molybdenum disulfide (MoS ₂ ) as a solid lubricant) was applied as a lubricant.

  The workpiece after the above-mentioned lubrication treatment is cold-rolled and formed into a pinion gear, and the defect rate and gold in the case of cold forging for the workpiece subjected to the conventional lubrication treatment (Bonde Bonderube method) Compared with mold life.

  In cold forging using the material to be treated in this embodiment, the defect rate is reduced and the die life is the same as in the case of Embodiment 1 compared to the conventional lubrication. It was confirmed that an extension of

  Therefore, the lubrication film formed by adhering carbon element to the surface of the work material by spraying carbide powder, even if it is formed as an underlayer of the conversion film, is lubricated on the surface of the work material. It was confirmed that it contributes to the improvement of sex.

  In addition, since the pickling process after blasting is not performed in the lubrication process performed in this embodiment, the pickling process and the pickling process are associated with the conventional lubrication process described with reference to FIG. Therefore, the number of processing steps can be reduced, and the processing equipment can be reduced, and waste liquid processing associated with pickling can be reduced.

  In addition, after performing the lubrication treatment of this example, carburizing treatment was performed on the molded product obtained by performing cold forging, and the molding produced using the work material subjected to the conventional lubrication treatment. Compared to products, carburizing time could be shortened by 30% and carburizing distortion could be reduced.

  From this, carbon elements adhering to the surface of the material to be treated by spraying carbide powder in the lubrication treatment not only contribute to imparting lubricity during plastic deformation, but also in the heat treatment performed after plastic deformation. It was confirmed that it also contributes to improvement of insertability.

Furthermore, the workpiece for plastic working according to the present invention has a lubricating coating on which carbon elements in carbide powder having a hexagonal crystal structure are attached to the surface of the workpiece before plastic deformation, and the surface of the lubricating coating. Are irregularities with an arithmetic mean roughness (Ra) of 0.2 μm or more (claim 7).

Claims (7)

In the lubrication treatment for imparting lubricity to the surface of the workpiece, which is performed as a pretreatment for the workpiece before plastic deformation,
Including a process of forming a lubricating film formed by adhering carbon elements in the carbide powder to the surface of the workpiece by spraying the carbide powder onto the surface of the workpiece in a dry manner. Lubricating method for workpieces for plastic working.   2. The method for lubricating a workpiece for plastic working according to claim 1, wherein the carbide powder is a carbide powder having a hexagonal crystal structure.   The workpiece for plastic working according to claim 1 or 2, wherein the surface of the workpiece on which the lubricating coating is formed is formed with irregularities of 0.2 µm or more in arithmetic mean roughness (Ra). Lubrication treatment method.   3. The plastic according to claim 1, wherein the carbide powder having a particle size of # 220 to # 1000 is injected at an injection speed of 80 to 250 m / sec or an injection pressure of 0.2 to 0.6 MPa. Lubrication method for workpieces for processing.   5. The method for lubricating treatment of a workpiece for plastic working according to claim 1, further comprising a step of applying a lubricant to the surface of the workpiece on which the lubricating coating is formed. .   The method further comprises a step of forming a chemical conversion film having lubricity by chemical conversion treatment on the surface of the workpiece on which the lubricating film is formed, and a step of further applying a lubricant on the chemical conversion film. The lubrication processing method of the workpiece for plastic working of any one of Claims 1-4.   A workpiece for plastic working that has been lubricated by the method according to claim 1.