JPWO2017018365A1 - Mold lubricant for producing high-density sintered body, spray application device for mold lubricant, green compact forming device equipped with spray applicator, green compact forming method using the same, and method thereof Sintered body obtained by - Google Patents

Abstract

The present invention has been made in view of the above circumstances, and is a mold lubricating oil and spray that are excellent in quick-drying, can form a uniform oil film with a small amount of coating, and a uniform amount of coating with a small amount of coating. An object of the present invention is to provide a coating apparatus and a green compact molding apparatus to realize high-speed compacting of compacts and compacts of arbitrary shapes. The present invention relates to a mold lubricating oil containing a hydrocarbon solvent having 7 to 18 carbon atoms and an oiliness improver or extreme pressure agent. The present invention is preferably a mold lubricating oil having a hydrocarbon solvent content of 50 to 98% by mass. [Selection figure] None

Description

  The present invention provides a sintered compact such as a sintered alloy obtained by sintering a green compact obtained by compressing a metal powder into a mold at a high temperature to achieve high density of the sintered compact. The present invention relates to a mold lubricating oil, a mold lubricating oil spray coating apparatus, and a green compact molding apparatus including the spray coating apparatus.

  As is well known, powder metallurgy is a metal processing method in which a metal powder poured into a metal mold made of a special steel material is pressed at high pressure to form a green compact, and the green compact is sintered. .

  For example, in iron-based powder metallurgy, iron powder is compressed and compacted at a high pressure of 500 to 1000 MPa, and the compacted compact is sintered at 600 to 1250 ° C.

  Powder metallurgy does not require cutting such as deburring after molding. Therefore, it is a metal processing method suitable for net shape. In addition, two or more parts produced by powder metallurgy can be used in combination, or can be used as new parts by combining with parts made by other metal processing methods. Therefore, parts produced by powder metallurgy are used for complex parts such as automobile parts, household appliances, etc., multi-functional parts such as gears, pulleys, or magnetic materials.

  In the step of compressing the metal powder in the mold, a mixed lubricant such as metal soap is mixed with the metal powder in advance in order to reduce galling between the metal powder and the mold. In some cases, a solid lubricant for the mold that is directly applied to the mold is used. These mixed lubricants and solid lubricants for molds have no significant difference in lubricating components. Generally, solid lubricants such as stearic acid or stearates (also referred to as metal soaps) or waxes are used. Is used.

  In the conventional powder metallurgy technology, from the viewpoint of ease of implementation and mass production, there is a method in which a green compact of metal powder is sintered by adding about 1% of a mixed lubricant to the metal powder. , Generally adopted.

  However, when the mixed lubricant is mixed excessively, there are problems that the fluidity of the metal powder is hindered and the formed green compact does not become dense. Further, when the green compact of the metal powder is sintered, there is a problem in that the density of the green compact becomes low because voids are generated by removing the mixed lubricant. Furthermore, since a large amount of gas containing carbon dioxide, zinc oxide, and the like is generated in the sintering process, there is a problem that the working environment is deteriorated.

  As a countermeasure to the above problems, the mold temperature is set to about 95 ° C., and a stearic acid powder having a melting point of 70 ° C. is electrostatically applied to the inner surface by a triboelectric charging method as a mold lubricant. A method has been proposed in which stearic acid powder is melted by heat to form a liquid lubricating coating (see, for example, Patent Document 1).

  However, a liquid lubricating coating formed by melting a solid lubricant has a high viscosity and is difficult to dry. For this reason, there is a drawback that dripping is likely to occur, non-uniform unevenness of the oil film is caused, and causes poor lubrication. Further, in such a method, a large amount of lubricant for the mold is applied, the lubricant for the mold sticks to the mold, the dimensional accuracy of the sintered body is impaired, and the sintered body There is also a drawback in that the coloration causes poor appearance. In addition, it is difficult to produce green compacts of any shape, such as compact green compacts or compact green compacts, in methods that require a large amount of lubricant for the mold. There is a drawback.

  As another countermeasure, there has been proposed a method in which a powder metallurgy powder containing a lubricant is filled in a mold in which a lubricant is applied to the inner wall surface, and compression molding is performed warmly or hotly (for example, , See Patent Document 2).

  However, the method in which the lubricant applied to the mold is melted by heating has the disadvantage that it takes extra time until the lubricant melts and until a uniform oil film is formed after melting. is there. As a result, the cycle time for forming the green compact becomes long, and the production efficiency of the sintered body is reduced. In addition, the method using such a solid or powder lubricant is also not suitable for applying a small amount of lubricant, so that it cannot produce small green compacts or compact green compacts. Has drawbacks.

  In addition, a method has also been proposed in which powdered lithium stearate is dispersed in water and applied to a mold (see, for example, Non-Patent Document 1). However, this method also has a drawback that since it takes time for water to evaporate, the cycle time for forming the green compact becomes long, and the production efficiency of the sintered body decreases. In addition, there is a drawback that the lubricant in powder form aggregates or unevenness in the oil film is caused, resulting in poor lubrication.

JP-A-11-140505 JP 2000-199022 A

"Powder and Powder Metallurgy Vol.62 No.3" by the Powder Powder Metallurgy Association, Meihosha, March 15, 2015, p. 95-100

  The present invention has been made in view of the above circumstances, and provides a mold lubricating oil, a spray coating apparatus, and a green compact molding apparatus that are excellent in quick drying and can form a uniform oil film with a small amount of coating. Thus, an object of the present invention is to realize high-speed molding of a green compact and molding of a green compact of an arbitrary shape.

  In addition, by using the above mold lubricant, spray coating device, and compacting device, even if the mixed lubricant such as metal soap mixed with the metal powder is reduced, sintering does not occur. It is another object of the present invention to provide a method capable of producing a body at high speed.

  Furthermore, by reducing the mixed lubricant such as metal soap mixed with the metal powder, the void generated after sintering is reduced, and molding is performed at a high pressure to realize high density of the sintered body. Objective. In addition, it aims at reducing the generation | occurrence | production of gas, such as a carbon dioxide and zinc oxide, and reducing the deterioration of a working environment.

  The present invention relates to a mold lubricating oil containing a hydrocarbon solvent having 7 to 18 carbon atoms and an oiliness improver and / or extreme pressure agent.

  Furthermore, the present invention is preferably a mold lubricating oil having a hydrocarbon solvent content of 50 to 98% by mass.

  The present invention is preferably a mold lubricating oil in which the content of the oiliness improver and / or extreme pressure agent is 20% by mass or less.

  In the present invention, further, the hydrocarbon solvent is one or more kinds of solvents selected from the group consisting of paraffinic hydrocarbon solvents, olefinic hydrocarbon solvents, naphthene hydrocarbon solvents, and aromatic hydrocarbon solvents. Preferably, it is a mold lubricant.

  In the present invention, it is preferable that the oiliness improver is a mold lubricating oil which is one or more compounds selected from the group consisting of silicones, animal and vegetable oils and fats, and higher fatty acid esters.

  In the present invention, it is further preferable that the extreme pressure agent is a mold lubricant which is one or more compounds selected from the group consisting of phosphate ester, TCP, sulfide sulfide oil, MoDTC, ZnDTP, and MoDTP.

  The present invention further includes a needle having a substantially frustoconical inclined portion and a needle receiving portion having a substantially frustoconical inclined portion, and the needle and the needle receiving portion are each substantially frustoconical. The present invention relates to a spray coating apparatus in which a mold lubricating oil can be fitted approximately at a slanted portion, and a mold lubricating oil passes between the substantially fitted needle and the needle receiving portion.

  The present invention further includes a needle tip formed on a narrowed side of a substantially truncated cone-shaped inclined portion of the needle and a narrowed side of a substantially truncated cone-shaped inclined portion of the needle receiving portion. The needle receiving hole is connected to an oil supply pipe for supplying the mold lubricating oil into the spray coating device on the side facing the needle receiving part. And the diameter of the needle receiving hole at the portion substantially mating with the needle tip is 0.6 to 1.8 mm, and the diameter of the needle tip is 0.5 to 1.7 mm. The spray coating apparatus preferably has a difference between the diameter of the needle receiving hole and the diameter of the needle tip of 0.05 to 0.4 mm.

  Furthermore, the present invention is preferably a spray coating apparatus capable of injecting a mold lubricating oil in an amount of 0.01 to 10 ml / time.

  The present invention further includes an injection nozzle having a plurality of air supply holes for supplying air and an oil supply hole for supplying mold lubricant to the mold, and a plurality of air supply holes are provided around the oil supply hole. When the angle between the air supply hole and the oil supply hole is measured from a direction perpendicular to a substantially plane including one air supply hole, the air supply hole and the oil supply hole are arranged in a twisted position. It is preferable that the spray coating apparatus has an angle formed by the supply hole and the oil supply hole of 20 to 40 degrees.

  The green compact molding apparatus of the present invention includes a coating means for applying mold lubricant oil by a spray coating apparatus, a filling means for filling metal powder in a mold coated with the mold lubricant oil, and pressing the filled metal powder. And forming means for forming the green compact, extraction means for extracting the formed green compact to the upper part of the mold, and dispensing means for discharging the extracted green compact from the upper part of the mold. The dispensing means and the spray coating device move in conjunction with a dispensing direction that is a direction toward the upper part of the mold in a state before dispensing, and the dispensing means is more along the dispensing direction than the spray coating device. It is provided in the front, and the dispensing means and the spray coating device move in the dispensing direction, so that the dispensing means passes the upper part of the mold and dispenses the green compact, and the spray coating apparatus is placed on the upper part of the mold. When it arrives, apply mold lubricant to the mold. The present invention relates to a green compact molding apparatus as described above.

  In the green compact molding apparatus of the present invention, the dispensing means, the spray coating apparatus, and the filling means move in conjunction with a dispensing direction that is a direction toward the upper part of the mold in a state before dispensing. is there. The filling means is provided behind the spray application device along the dispensing direction, and the spray coating device and the filling means move in the dispensing direction in conjunction with each other, so that the filling means is connected to the mold by the spray coating device. Immediately after applying the mold lubricant, when the upper part of the mold is reached, the mold is filled with metal powder. The present invention is preferably a green compact molding apparatus as described above.

  The green compact molding apparatus of the present invention further includes a scraping means for scraping off the metal powder existing above the mold among the metal powder filled in the mold. The dispensing means and the spray coating device are configured to reciprocate alternately in the dispensing direction and the reverse direction of the dispensing direction to dispense the green compacts that are sequentially molded, and repeatedly apply the mold lubricant to the mold. The scraping means is provided behind the spray applicator along the dispensing direction, and the metal powder filled in the mold is moved in the reverse direction of the dispensing direction in conjunction with the spray applicator and the scraping means. Scrape off. The present invention is preferably a green compact molding apparatus as described above.

  The green compact molding method of the present invention includes a coating process in which a mold lubricant is applied by a spray coating device, a filling process in which a metal powder is filled in a mold coated with the mold lubricant, and the filled metal powder is pressed. A molding process for molding the green compact, an extraction process for extracting the molded green compact above the mold, and a dispensing process for dispensing the extracted green compact from the upper part of the mold by the dispensing means. Prepare. The dispensing means and the spray coating device move in conjunction with the dispensing direction, which is the direction toward the upper part of the mold in the state before dispensing, and the dispensing means is more forward in the dispensing direction than the spray coating device. As the dispensing means and spray application device move in the dispensing direction, the dispensing means passes the upper part of the mold and dispenses the green compact, and the spray coating apparatus reaches the upper part of the mold. When doing so, apply mold lubricant to the mold. The present invention relates to a green compact molding method as described above.

  The present invention relates to a sintered body obtained by sintering a green compact formed by the green compact forming method.

  According to the mold lubricant of the present invention, it is possible to provide a mold lubricant that is excellent in quick-drying and can form a uniform oil film with a small amount of coating. Powder molding can be realized. Further, by using the above-described mold lubricant oil, a sintered body can be produced at high speed without generating galling even if the mixed lubricant such as metal soap mixed with the metal powder is reduced.

  Furthermore, by reducing the mixed lubricant such as metal soap mixed with the metal powder, the voids generated after sintering can be reduced, and molding can be performed at a high pressure to achieve high density of the sintered body. it can. In addition, the generation of gases such as carbon dioxide and zinc oxide can be reduced, and the deterioration of the working environment can be reduced.

It is the schematic diagram (a) of the cross-sectional view of the spray coating device which injects the mold lubricant of the present invention, and the schematic diagram (b) of the cross-sectional view of the spray nozzle in the spray coating device. It is a schematic diagram of the perspective view of the spray nozzle in a spray coating device. It is the schematic diagram which showed the schematic diagram of sectional drawing of the compacting apparatus of this invention, and the application | coating mechanism, the filling mechanism, the abrasion mechanism, the shaping | molding mechanism, the extraction mechanism, and the discharge mechanism.

<Mold lubricant>
According to the mold lubricant of the present invention, an oil film that maintains high strength can be formed on the mold surface without heating the mold. Moreover, the mold lubricating oil of the present invention can suitably exhibit lubricating performance even under high pressure. Hereinafter, the composition of the mold lubricant of the present invention will be described in detail.

  The mold lubricating oil of the present invention is a composition containing a hydrocarbon solvent having 7 to 18 carbon atoms and an oiliness improver or extreme pressure agent. Since the mold lubricant has the above composition, quick drying is enhanced and a uniform and uniform oil film is formed, so that high-speed molding of compacts and compacts of arbitrary shapes can be realized. become. In addition, by using the above mold lubricant, the sintered body can be produced at high speed without generating galling even if the mixed lubricant mixed with the metal powder is reduced.

  Furthermore, if the above-mentioned mold lubricant that has good lubricity and can be applied in a small amount can be used, the mixed lubricant mixed with the metal powder can be reduced. Molding can achieve high density of the sintered body. In addition, the generation of gases such as carbon dioxide and zinc oxide can be reduced to reduce the deterioration of the working environment.

  Moreover, since the mold lubricating oil of the present invention is excellent in quick drying, an oil film is easily formed at room temperature, and it is not necessary to heat the mold. Therefore, the mold lubricating oil of the present invention can be used, for example, in a mold having a surface temperature of 40 ° C. or less. As described above, since the time for heating the mold and the time for melting the lubricant used in the mold are not required, the molding process of the green compact can be speeded up.

  Since the mold lubricant of the present invention can be applied in a small amount as will be described later, it is preferable to apply the mold lubricant to the mold using a spray coating apparatus among general coating methods. By applying the mold lubricating oil of the present invention to a mold with a spray coating apparatus, it becomes easy to realize compacting of an arbitrarily shaped green compact such as a compact green compact or a fine green compact.

In order to apply the mold lubricant with a spray coating apparatus, it is preferable to optimize the kinematic viscosity of the mold lubricant from the viewpoint of realizing stable injection. The kinematic viscosity of the mold lubricant at 40 ° C. is preferably less than ^{2 to} 100 mm ² / s. When the kinematic viscosity at 40 ° C. of the mold lubricant is less than 2 mm ² / s, the spray pump of the spray coating device tends to be easily worn. When the kinematic viscosity at 40 ° C. of the mold lubricant exceeds 100 mm ² / s, it tends to be difficult to inject the mold lubricant.

From the viewpoint of realizing a stable spray coating, the kinematic viscosity at 40 ° C. of the mold lubricant, more preferably from 2 to 50 mm ² / s, more preferably from 2 to 20 mm ² / s. In order to perform spray coating under the condition that the kinematic viscosity at 40 ° C. of the mold lubricant is 100 mm ² / s or less, the mold lubricant is injected in the air flow rate, the air pressure, the pressure feeding device such as a gear pump, or the spray coating device. It is preferable to appropriately adjust the diameter of the oil supply holes.

Moreover, when the kinematic viscosity at 40 ° C. of the mold lubricant exceeds 10 mm ² / s, the mold opening may be opened when the metal powder is filled into the mold even if the mold lubricant is applied to the mold. In the vicinity, the mold lubricating oil tends to come into contact with the metal powder, and agglomerates (so-called lumps) tend to be formed. If an agglomerate is formed in the vicinity of the opening of the mold, the metal powder cannot be filled to the back of the mold, and it tends to be difficult to mold the green compact into a desired shape. Therefore, from the above viewpoint, it is preferable that the kinematic viscosity at 40 ° C. of the mold lubricant is 10 mm ² / s or less.

  The kinematic viscosity of the mold lubricant can be measured by, for example, an Ubbelohde viscometer (ASTM D445).

  In addition to the hydrocarbon solvent, oiliness improver, and extreme pressure agent described later, in the mold lubricant oil, an antioxidant, a metal deactivator, a rust inhibitor, as long as it does not contradict the spirit of the present invention, Or additives, such as an antifoamer, may be contained.

(1) Hydrocarbon solvent The solvent in the mold lubricant must be evaporated quickly after the mold lubricant is applied to the mold. Since the solvent in the mold lubricating oil quickly evaporates, the lubricating component in the mold lubricating oil forms an oil film having a high strength, so that lubricity is suitably ensured.

  On the other hand, if the solvent in the mold lubricant is difficult to evaporate or if the solvent remains even after evaporating, the mold lubricant will drip without forming a strong oil film. As a result, the lubricity decreases.

  Therefore, it is preferable that the solvent in the mold lubricating oil is a solvent that easily evaporates and does not remain, that is, a highly dry solvent. Also, from the viewpoint of preventing the health hazard of workers, the solvent in the mold lubricating oil has a high content of saturated hydrocarbons and a refinement degree with extremely low sulfur and nitrogen contents. It is preferable that it is a high hydrocarbon solvent.

  The hydrocarbon solvent used as the solvent for the mold lubricant of the present invention is liquid at room temperature. Moreover, carbon number of a hydrocarbon solvent is 7-18, and it is preferable that it is 10-15. When the carbon number of the hydrocarbon solvent is less than 7, the drying property is too high, so that the adhesion to the mold may be deteriorated, and the risk of fire increases. When the hydrocarbon solvent has more than 18 carbon atoms, the solvent is difficult to evaporate and the drying property is lowered, and the viscosity of the oil film formed by the oiliness improver and extreme pressure agent described later is reduced to a low viscosity in the solvent. The undried portion is lowered, and the lubricity of the oil film is lowered or galling is caused.

  As described above, the hydrocarbon solvent used in the present invention needs to have suitable drying properties, but it can be said that any hydrocarbon solvent having suitable drying properties can be used in the present invention. The hydrocarbon solvent having 7 to 18 carbon atoms has particularly suitable drying properties and is particularly suitable as a solvent for the mold lubricating oil.

  The hydrocarbon solvent is preferably the component having the largest mass in the mold lubricant, that is, the main component. The content of the hydrocarbon solvent is preferably 50 to 98% by mass, more preferably 60 to 98% by mass, and further preferably 60 to 95% by mass with respect to the total amount of the mold lubricating oil. preferable.

  If the content of the hydrocarbon solvent is less than 50% by mass, the blending ratio of the oiliness improver or the extreme pressure agent described later increases, so that the oil film tends to be difficult to dry on the inner wall surface of the mold. When the content of the hydrocarbon solvent exceeds 98% by mass, the oil film of the mold lubricating oil becomes thin, so that the lubricity of the mold lubricating oil tends to decrease.

  Although the kind of hydrocarbon solvent is not specifically limited, For example, a paraffin hydrocarbon solvent, an olefin hydrocarbon solvent, a naphthene hydrocarbon solvent, an aromatic hydrocarbon solvent, etc. are mentioned.

  Paraffin hydrocarbon solvent is a solvent containing a chain-like saturated hydrocarbon compound that is not cyclic. Compared with other hydrocarbon solvents, it is less likely to cause health problems for workers and changes in viscosity due to temperature. Few. Therefore, by using a paraffinic hydrocarbon solvent as a solvent for the mold lubricant, the mold lubricant can be stably sprayed.

  Paraffin hydrocarbon solvents have low reactivity and high chemical stability compared to other hydrocarbon solvents. Therefore, by using a paraffinic hydrocarbon solvent as a solvent for the mold lubricating oil, it is difficult for the lubricating components and the like in the mold lubricating oil to be altered.

  From the above viewpoint, as the solvent used for the mold lubricating oil, paraffinic hydrocarbon solvents are particularly preferable among the hydrocarbon solvents.

  The type of the paraffinic hydrocarbon solvent is not particularly limited, and examples thereof include alkane solvents such as heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, and pentadecane.

  The olefinic hydrocarbon solvent is a solvent containing a hydrocarbon compound having a double bond. Although the kind of olefin type hydrocarbon solvent is not specifically limited, For example, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. are mentioned.

  A naphthenic hydrocarbon solvent is a solvent containing a compound having at least one saturated aliphatic ring in the molecule, and has a property of higher drying than an aromatic hydrocarbon solvent described later. Although the kind of naphthene type hydrocarbon solvent is not specifically limited, For example, a cyclopentane, a cyclohexane, or cyclooctane etc. are mentioned.

  The aromatic hydrocarbon solvent is a solvent containing a compound having at least one aromatic ring in the molecule. Although the kind of aromatic hydrocarbon solvent is not specifically limited, For example, toluene, xylene, etc. are mentioned.

  Various hydrocarbon solvents such as petroleum-based hydrocarbon solvents, hydrocarbon solvents derived from natural products, or chemically synthesized hydrocarbon solvents can be used.

  In addition, as a hydrocarbon solvent, the above solvents may be used independently, and multiple may be used. Further, the hydrocarbon solvent may contain additives, impurities and the like as long as they do not contradict the spirit of the present invention.

(2) Oiliness improver By adding an oiliness improver to the mold lubricant, the lubricity between the green compact and the mold can be ensured. The oiliness improver is a compound having polarity, and its polar part is physically adsorbed to the mold to form an oil film, so that it acts like a cushioning material between the green compact and the mold, It means a compound that can reduce friction. Moreover, it is preferable that an oiliness improver is a thing with high affinity with a solvent.

  The content of the oiliness improver is preferably 20% by mass or less, more preferably 2 to 18% by mass, and further preferably 2 to 15% by mass with respect to the total amount of the mold lubricating oil. preferable. When the content of the oiliness improver exceeds 20% by mass, the oil film becomes excessively thick, and voids generated after sintering tend to increase. In addition, the kinematic viscosity of the mold lubricating oil increases, and it tends to be difficult to perform stable spray coating. In addition, the oiliness improver tends to stick to the sintered body. When the content of the oiliness improver is less than 2% by mass, the oil film is not sufficient, which may cause seizure or the like.

  The type of oiliness improver is not particularly limited, and examples thereof include silicones, animal and vegetable oils and fats, and higher fatty acid esters.

  Although the kind of silicone is not specifically limited, For example, modified silicones, such as a phenol modified silicone, a methylstil modified silicone, an alkyl modified silicone, or an alkyl aralkyl modified silicone, or dimethyl silicone oil etc. are mentioned.

  Although the kind of animal and vegetable fats and oils is not specifically limited, For example, rapeseed oil, soybean oil, coconut oil, palm oil, cow oil, or pork fat is mentioned.

  The type of the higher fatty acid ester is not particularly limited, and examples thereof include monohydric alcohol ester or polyhydric alcohol ester of higher fatty acid such as coconut oil fatty acid, oleic acid, stearic acid, lauric acid, palmitic acid, or beef tallow fatty acid. Can be mentioned.

  In addition, as an oiliness improver, the above compounds may be used alone or in combination. In addition, the oiliness improver may contain additives, impurities, and the like within a range not departing from the spirit of the present invention.

(3) Extreme pressure agent Addition of an extreme pressure agent to the mold lubricating oil can reduce galling between the green compact and the mold when a high pressure load is applied. An extreme pressure agent forms a soft oil film by a chemical reaction between the green compact and the mold, and reduces direct contact between the green compact and the mold, thereby reducing the green compact. Means a compound capable of preventing galling and seizure between the mold and the mold. Moreover, it is preferable that an extreme pressure agent is a thing with high affinity with a solvent.

  The content of the extreme pressure agent is preferably 20% by mass or less, more preferably 0.5 to 18% by mass, and 0.5 to 15% by mass with respect to the total amount of the mold lubricating oil. More preferably it is.

  When the content of the extreme pressure agent exceeds 20% by mass, the kinematic viscosity of the mold lubricating oil increases, and it tends to be difficult to perform stable spray coating. In addition, the extreme pressure agent tends to stick to the sintered body. If the content of the extreme pressure agent is less than 2% by mass, the oil film may not be sufficient, which may cause seizure or the like.

  Although the kind of extreme pressure agent is not particularly limited, for example, sulfide sulfide oil such as dialkylpentasulfide, phosphate ester, TCP (tricresyl phosphate), MoDTC (molybdenum dithiocarbamate), ZnDTP (zinc dialkyldithiophosphate), Or MoDTP (molybdenum dithiophosphate) etc. are mentioned.

  In addition, as an extreme pressure agent, the above compounds may be used independently and multiple may be used. Further, the extreme pressure agent may contain additives, impurities, and the like within a range not departing from the spirit of the present invention.

  Further, by using an oiliness improver and an extreme pressure agent in combination, high lubricity and galling resistance can be expected. In the case where the oiliness improver and the extreme pressure agent are used in combination, the total amount of the oiliness improver and the extreme pressure agent is preferably 20% by mass or less, based on the total amount of the mold lubricating oil, and is 2 to 18% by mass. It is more preferable that it is 2-15 mass%.

<Mold lubricating oil spray coating device>
The method for applying the mold lubricant of the present invention is not particularly limited, and examples thereof include brush coating, roller coating, and spray coating using a spray coating apparatus. Brush coating or roller coating is suitable from the viewpoint of thickly applying the mold lubricant to the mold, but tends to cause unevenness in the thickness of the oil film formed by the mold lubricant. In addition, since the mold for forming the green compact is generally small in size, it tends to be difficult to apply by brush coating or roller coating. Therefore, when applying the mold lubricant to the mold, it is preferable to apply the spray by a spray application device.

  For example, a spray coating apparatus 10 as shown in FIG. 1 can be used as the spray coating apparatus for spraying the above-described mold lubricant.

  The spray application device 10 includes an oil amount adjusting knob 11, a spring chamber 12, a spring 13, a fixing ring 14, a needle 15, a needle receiver 16, a spray body 18, a spray nozzle 19, a spray nozzle cap 20, an air supply path 21, and an air branch. It has a passage 22, an air supply hole 23, an oil supply hose 31, an oil supply pipe 32, an oil supply hole 33, and the like.

  The needle 15 includes a needle small diameter portion 15S, a needle large diameter portion 15L, a needle inclined portion 15I, and a needle tip portion 15T. The needle narrow diameter portion 15S is connected to the needle large diameter portion 15L, and the needle inclined portion 15I is connected to the needle tip portion 15T, and each is arranged substantially linearly. In this embodiment, the diameter of the needle small diameter portion 15S is about 3.0 mm, the diameter of the needle large diameter portion 15L is about 10.0 mm, and the diameter of the needle tip portion 15T is about 0.65 mm. The needle receiver 16 has a needle receiver 16S and a needle receiving hole 16P.

  The oil amount adjustment knob 11 is a knob for controlling the oil amount to be constant. The oil amount adjusting knob 11 is provided with a spring chamber 12, and a spring 13 is incorporated in the spring chamber 12. In addition, the spring 13 is provided so as to be wound around the needle small diameter portion 15S, and is configured to compensate for the vertical movement of the needle 15. The load during use of the spring 13 is preferably 1.0 to 3.0N.

  After adjusting the oil amount to be injected by the oil amount adjusting knob 11, the oil amount adjusting knob 11 is fixed by the fixing ring 14. By fixing the oil amount adjustment knob 11 with the fixing ring 14, the oil amount for each injection can be made constant.

  The needle 15 has a needle inclined portion 15I configured by a substantially truncated cone-shaped inclined portion, and the needle receiving portion 16 has a needle receiving portion 16S configured by a substantially truncated cone-shaped inclined portion. Further, the needle 15 and the needle receiving portion 16 can be substantially fitted in the needle inclined portion 15I and the needle receiving portion 16S, and a mold lubricating oil is provided between the substantially fitted needle inclined portion 15I and the needle receiving portion 16S. Can pass through.

  The angle formed by the substantially frustoconical inclined portion in the needle inclined portion 15I is preferably 20 to 40 degrees. The angle formed by the substantially truncated cone-shaped inclined portion in the needle receiving portion 16S is preferably −5 to −1 degree with respect to the angle formed by the substantially truncated cone-shaped inclined portion in the needle inclined portion 15I. In the needle inclined portion 15I and the needle receiving portion 16S, each substantially truncated cone-shaped inclined portion has the above-described angle relationship, so that it becomes easy to finely adjust the amount of the mold lubricant to be injected.

  The spray coating apparatus 10 includes a needle tip portion 15T formed on the narrowed side of the substantially truncated cone-shaped inclined portion in the needle inclined portion 15I, and a narrowed side of the substantially truncated cone-shaped inclined portion in the needle receiving portion 16S. And a needle receiving hole 16P connected thereto. Further, the needle receiving hole 16P is connected to an oil supply pipe 32 that supplies mold lubricating oil into the spray coating device 10 on the side facing the needle receiving portion 16S, and the needle receiving hole 16P and the needle tip portion 15T are connected to each other. Is substantially matable.

  In the fitting portion between the needle receiving hole 16P and the needle tip 15T, the diameter of the needle receiving hole 16P is preferably 0.6 to 1.8 mm, and the diameter of the needle tip 15T is 0.5 to 1.7 mm. It is preferable that Further, the difference between the diameter of the needle receiving hole 16P and the diameter of the needle tip 15T is preferably 0.05 to 0.4 mm. When the needle receiving hole 16P and the needle tip portion 15T satisfy the above conditions, a small amount of mold lubricating oil tends to be easily applied.

  The needle receiving hole 16P is connected to the oil supply pipe 32 as described above, and forms a part of the oil supply pipe 32. An oil supply hose 31 for supplying mold lubricant is connected to an oil supply pipe 32. A needle receiving hole 16 </ b> P that forms part of the oil supply pipe 32 is connected to an oil supply hole 33 provided in the injection nozzle 19. An air supply path 21 for supplying air is connected to an air branch path 22 and an air supply hole 23.

  The air supply hole 23 is preferably provided so as to be inclined at 20 to 40 degrees with respect to the central axis of the injection nozzle 19. By providing the air supply hole 23 in the above-described manner, the mold lubricant tends to be easily sprayed over a wide range.

<Method of spraying mold lubricant>
By turning the oil amount adjusting knob 11 counterclockwise, the spring chamber 12 moves counterclockwise and moves to the opposite side of the needle large diameter portion 15L. As the spring chamber 12 moves to the side opposite to the needle large diameter portion 15L, the spring 12 incorporated in the spring chamber 12 is loosened. When the spring 12 is loosened and the elastic force of the spring 12 is reduced, the needle large-diameter portion 15L moves to the side opposite to the needle receiver 16 side.

  As the needle large-diameter portion 15L moves to the side opposite to the needle receiver 16 side, the fitting state between the needle 15 and the needle receiver 16 changes. As a result, the amount of mold lubricating oil supplied per unit time supplied from the needle receiving hole 16P (oil supply pipe 32) to the oil supply hole 33 increases. As described above, the amount of mold lubricating oil supplied from the oil supply hole 33 can be slightly increased.

  By rotating the oil amount adjustment knob 11 counterclockwise, the spring chamber 12 moves to the needle large diameter portion 15L side while rotating counterclockwise. As the spring chamber 12 moves toward the needle large diameter portion 15L, the spring 12 incorporated in the spring chamber 12 contracts. When the spring 12 contracts and the elastic force of the spring 12 increases, the needle large diameter portion 15L moves to the needle receiver 16 side.

  As the needle diameter portion 15L moves to the needle receiver 16 side, the fitting state between the needle 15 and the needle receiver 16 changes. As a result, the supply amount of the mold lubricating oil per unit time supplied from the needle receiving hole 16P (oil supply pipe 32) to the oil supply hole 33 decreases. As described above, the amount of mold lubricant supplied from the oil supply hole 33 can be slightly reduced.

  Air is introduced into the spray body 18 from the air supply path 21. A solenoid valve is used for the air introduction operation. The air pressure of the supplied air is preferably 3 MPa or more. In order to prevent the air pressure from becoming too high, it is preferable to adjust to an appropriate air pressure using a regulator or the like. When air flows into the air supply path 21 and the air branch path 22, the needle 15 is pushed up, a gap is formed in the needle receiver 16, and the mold lubricating oil can be supplied to the mold. The hydraulic pressure of the mold lubricant is preferably 0.1 to 1.0N.

  The air supplied from the air supply path 21 passes through the air branch path 22 and is also supplied to the needle large diameter portion 15L side. Due to the pressure of the air supplied from the air branch path 22, the needle large diameter portion 15 </ b> L moves to the side opposite to the needle receiver 16 side. This mechanism also finely adjusts the amount of mold lubricant supplied.

  The air supplied from the air supply path 21 is jetted toward the outside of the spray body 18 through the air supply hole 23 and the air jet groove 24.

  In the injection nozzle 19 provided with the air supply hole 23 and the oil supply hole 33, six air supply holes 23 are provided around the oil supply hole 33 (in FIG. 2, 23a, 23b, 23c, 23d, 23e, And 23f). The air supply hole 23 and the oil supply hole 33 are arranged at a twisted position, and the angle formed by the air supply hole 23 and the oil supply hole 33 is measured from a direction perpendicular to a substantially plane including one air supply hole 23. In this case, the angle formed by the air supply hole 23 and the oil supply hole 33 is preferably 20 to 40 degrees. That is, when the air supply hole 23 and the oil supply hole 33 are viewed from the position where the end of one air supply hole 23 on the air supply path 21 side seems to overlap the oil supply hole 33, It is preferable that the angle formed with the oil supply hole 33 is 20 to 40 degrees. When the angle formed by the air supply hole 23 and the oil supply hole 33 satisfies the above range, the air is swirled when the air is ejected from the air ejection groove 24.

  The air supplied from the air supply path 21 passes through the air supply hole 23 provided in the injection nozzle 19 and then flows through the gap (0.3 to 1.5 mm) between the injection nozzle 19 and the injection nozzle cap 20. It is ejected from the ejection groove 24 while swirling. When air is injected, the vicinity of the oil supply hole 33 is in a vacuum state, so that the air draws the mold lubricating oil from the oil supply hole 33. Therefore, the air and the mold lubricant are mixed to form a mist and sprayed onto the mold 70.

  The injection amount of the mold lubricating oil is preferably a very small amount from the viewpoint of easily drying the solvent of the mold lubricating oil. The injection amount of the mold lubricant is preferably 0.01 to 10 ml / time, and more preferably 0.05 to 5 ml / time. If the injection amount of the mold lubricating oil is less than 0.01 ml / time, the formation of an oil film becomes insufficient, which tends to cause galling. When the injection amount of the mold lubricant exceeds 10 ml / time, the solvent of the mold lubricant tends to be difficult to evaporate.

  The spray coating apparatus 10 can spray not only oil-based mold lubricants but also general mold lubricants including water-based ones.

  The green compact forming apparatus shown in FIG. 3 will be described below.

  The type of metal powder 50 that can be applied to the green compact molding apparatus of the present invention is not particularly limited. For example, iron, copper, nickel, chromium, tungsten, molybdenum, or stainless steel in which iron contains chromium or nickel. And metals such as alloy steels. In addition, a mixture of the above metals or a mixture of the above metals containing carbon for enhancing the sintering strength or surface hardening can be used.

<Green compacting device>
The green compact molding apparatus for molding the metal powder 50 filled in the mold 70 into the green compact 51 includes an application means for applying the mold lubricating oil by the spray coating apparatus 10 and a mold having the mold lubricating oil applied thereto. Filling means for filling the mold 70 with the metal powder 50, scraping means for scraping the metal powder 50 existing above the mold 70 out of the metal powder 50 filled in the mold 70, and the filled metal powder 50 Forming means for pressing to form the green compact 51, extracting means for extracting the formed green compact 51 above the mold 70, and paying out the extracted green compact 51 from the top of the mold 70 Means.

  The filling means is provided behind the application means, and the dispensing means is provided in front of the application means. The scraping means is provided behind the applying means and ahead of the filling means.

  That is, in the green compact molding apparatus of the present invention, the dispensing means, the application means, the scraping means, and the filling means are arranged in this order, and the feeder 40 extends back and forth above the die plate 60 along the arrangement direction. It is a slidable aspect.

  In the present embodiment, the spray application device 10 constitutes the application means, the feeder 40 constitutes a part of the feeder 40, the abrasion means 42 constitutes the abrasion means, and the molding means serves as the mold 70 and the upper punch 91 and The lower punch 92 is configured, the lowering punch 92 is configured as the extracting means, and the discharging unit 43 is configured as the discharging means.

  The feeder 40 has an opening on the grounding surface side to the die plate 60, and the entire surface on the grounding surface side forms a falling portion of the metal powder 50, thereby constituting a filling means.

  The falling part of the metal powder 50 may be an aspect in which the entire ground surface side to the die plate 60 is opened as in this embodiment, or a part of the ground surface side forms an opening. It may be a mode.

  The upper part of the outer wall 41 constituting the feeder 40 may be partially configured with a transparent member so that the remaining amount of the metal powder 50 inside the feeder 40 can be confirmed, or opened without providing any member. Also good.

  A part of the outer wall 41 on the grounding surface side to the die plate 60 forms a shape like a frame portion, and the metal powder 50 is held in the frame portion, and the metal powder 50 moves on the die plate 60 together with the feeder 40. It is a mode that can slide back and forth.

  By using the green compact molding apparatus as described above, the spray application of the mold lubricating oil and the filling of the metal powder 50 into the mold 70 can be performed almost simultaneously. Further, the green compact 51 can be formed and the green compact 51 can be discharged almost simultaneously. Therefore, it is possible to speed up the molding of the green compact 51 to be described later, and to mass-produce a sintered body obtained by sintering the green compact 51 at a high speed.

  Hereinafter, the coating mechanism, the filling mechanism, the scuffing mechanism, the forming mechanism, the extracting mechanism, and the dispensing mechanism shown in FIG.

[Step A]
(Coating mechanism)

  The feeder 40 having the dispensing means, the spray coating device 10, and the filling means is a dispensing direction that is a direction toward the upper portion of the mold 70 in a state before the dispensing on the substantially flat die plate 60, that is, an arrow 40a. Slides in conjunction with the direction. Note that the state before dispensing means a state from when the green compact is formed to before the green compact is dispensed.

  When the spray nozzle 19 of the spray coating device 10 provided in front of the feeder 40 is positioned above the mold 70, the spray coating device 10 sends a signal for opening the electromagnetic valve of the air supply path 21. Received from the compacting device. When the solenoid valve of the air supply path 21 is opened, air flows into the air supply path 21 and the air branch path 22 shown in FIG. 1, the needle 15 is pushed up, and a gap is formed in the needle receiving portion 16. As a result, the spray coating apparatus 10 can inject the mold lubricating oil onto the mold 70. By this step, an oil film 80 of mold lubricating oil is formed on the inner wall surface of the mold 70.

  When the spray nozzle 19 of the spray coating device 10 is no longer positioned above the mold 70, a signal for closing the electromagnetic valve of the air supply path 21 is received from the green compact molding device. When the solenoid valve of the air supply path 21 is closed, the needle 15 and the needle receiving portion 16 come into contact with each other by the elastic force of the spring 13 shown in FIG. As a result, injection of the mold lubricating oil by the spray application device 10 stops.

  As described above, the timing control method for injecting the mold lubricant from the spray coating apparatus 10 is to be injected at a predetermined timing by a sensor that senses that a predetermined portion such as the feeder 40 exists at a predetermined position. A method is mentioned. In addition to the above method, there is a method of injecting at predetermined intervals based on the reciprocation time when the feeder 40 slides back and forth.

[Step B]
(Filling mechanism)

  The metal powder 50 is carried to the upper part of the mold 70 by the frame portion formed by the outer wall 41 of the feeder 40. Since the grounding surface side of the feeder 40 is opened to form a falling portion of the metal powder 50, a part of the metal powder 50 inside the feeder 40 falls in the direction of the arrow 50b, and the mold 70 Filled in.

[Step C]
(Scraping mechanism)
The feeder 40 slides on the substantially flat die plate 60 in the direction of the arrow 40c. At this time, the scraping portion 42 formed in front of the frame portion of the outer wall 41 scrapes the upper portion of the metal powder 50 filled in the mold 70 along the upper surface of the substantially flat die plate 60.

[Step D]
(Molding mechanism)
The metal powder 50 filled in the mold 70 is moved by the upper punch 91 that moves in the direction of the arrow 91d from the upper direction of the mold 70 and the lower punch 92 that moves in the direction of the arrow 92d from the lower direction of the mold 70. By being pressed, the green compact 51 is formed.

[Step E]
(Extraction mechanism)
After molding the green compact 51, the upper punch 91 moves in the direction of the arrow 91e. The lower punch 92 moves in the direction of the arrow 92e until the upper surface of the lower punch 92 is positioned on the upper surface of the die plate 60, and moves the green compact 51 to the upper surface of the die plate 60.

(Payment mechanism)
The feeder 40 slides again in the direction of the arrow 40e. The green compact 51 is paid out in the direction of the arrow 51e by the pay-out portion 43 provided in front of the sliding feeder 40.

  After the step E, the step A is performed again, and the mold lubricant is again sprayed from the spray coating apparatus 10 to the mold 70.

  As described above, the feeder 40 reciprocates alternately in Step A to Step E, so that the mold lubricant can be repeatedly applied to the mold, and the green compacts that are sequentially formed can be dispensed.

The cycle of step A to step E can be performed in about 6 seconds per cycle. Therefore, by using the mold lubricating oil, spray coating apparatus, and green compact molding apparatus of the present invention, spray coating of mold lubricating oil, filling metal powder into the mold, compacting of green compact, compacting The body can be dispensed at high speed.
<Production of sintered body>

  The green compacts produced as described above can be made into a sintered body by sintering a large number of them in a furnace. In the production of the sintered body, the process A to the process E cycle, that is, the steps of spray application of the mold lubricant, filling of the metal powder into the mold, molding of the green compact, and discharging of the green compact are performed. It becomes a rate-limiting process. Therefore, by speeding up the above process, the production of the sintered body can be speeded up.

  In addition, although the cycle of the process A to the process E can be performed in about 6 seconds per cycle, the cycle time is increased by 16 to 50% just by delaying the cycle by about 1 to 3 seconds. . In addition, if troubles such as galling occur in the cycle of the process A to the process E, the production of the green compact cannot be continued, which causes a serious hindrance to the production of the sintered body.

  Therefore, it is preferable to perform the cycle of process A-process E in the aspect which does not produce the delay of several seconds, and can suppress generation | occurrence | production of a trouble as much as possible.

  In the cycle of Step A to Step E, for example, powder mold lubricant oil is used, mold lubricant oil that cannot form a uniform and uniform oil film is used, or a solvent that does not easily evaporate is used as mold lubricant oil. Then, the cycle time becomes long or troubles such as galling occur, and the production efficiency of the sintered body tends to be greatly reduced.

  Also, time lag between spray application of mold lubricant and filling metal powder into mold, time lag between filling metal powder into mold and compacting, or compacting When the time lag between the powder and the green compact is increased, the cycle time becomes longer, and the production efficiency of the sintered body tends to be greatly reduced.

  The mold lubricant can reduce friction between the mold and the metal powder. Therefore, the blending amount of the mixed lubricant can be reduced, and the compressibility of the green compact can be improved. From the viewpoint of lubricity between the metal powders, the blending amount of the mixed lubricant with respect to the metal powder is preferably 0.05% by mass or more, and more preferably 0.1 or more. Further, the blending amount of the mixed lubricant with respect to the metal powder is preferably 0.6% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.4% by mass or less. The content is particularly preferably 0.3% by mass or less. When the mixed lubricant blended in the metal powder is less than 0.05% by mass, the apparent density of the metal powder blended with the mixed lubricant tends to be low. In addition, since the metal powder is preferably difficult to rearrange from filling to the initial stage of compression, the density of the green compact tends to not increase. That is, the friction between the particles of the metal powder is increased, the fluidity of the metal powder is deteriorated, and the compressibility of the green compact tends to be lowered. Moreover, when the mixed lubricant mix | blended with a metal powder exceeds 0.6 mass%, it exists in the tendency for a mixed lubricant to inhibit compression and to raise the density of a green compact. That is, the mixed lubricant remains in the metal powder, and the compressibility of the green compact tends to be difficult to improve.

  The type of the mixed lubricant is not particularly limited, and examples thereof include metal soaps such as zinc stearate and lithium stearate, and amide lubricants such as stearamide, stearic acid bisamide, and ethylene bisstearamide.

  Like the mold lubricant of the present invention, the lubricity between the mold and the metal powder can be improved by using a mold lubricant that is easy to dry and can form a uniform and uniform oil film with a small amount of coating. It can be maintained, and the effect of preventing galling is also enhanced. Therefore, the amount of the mixed lubricant mixed with the metal powder can be reduced by about 75%. As a result, the fluidity of the metal powder can be maintained when the metal powder is filled into the mold in the green compact molding step. Further, since the green compact becomes dense, the density of the green compact tends to be improved. Furthermore, since voids generated by removing the mixed lubricant during sintering can be minimized, the density of the final sintered body can be increased.

  A sintered body having a high density has excellent physical properties in terms of rotational bending fatigue strength, crushing strength, dimensional accuracy, tensile strength, hardness, or wear resistance.

  Therefore, a sintered body having a high density can be suitably used for, for example, gears and clutch parts of a reduction mechanism used for electric tools, electromagnetic materials that are widely used in the field of automobiles and home appliances, and the like.

  Hereinafter, the mold lubricating oil of the present invention will be described in detail using Examples and Comparative Examples. The present invention is not limited to the following embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. Some components may be deleted from all the components shown in the embodiments. Furthermore, the constituent elements may be appropriately combined so as to be different embodiments.

Example 1
<Production of mold lubricant>
Solvent G as hydrocarbon solvent (ExxonMobil, Isoper-G; isoalkane mixture having 9 to 12 carbon atoms) 90% by mass, and oiliness improver A (Shin-Etsu Chemical Co., Ltd., X22-1877; modified silicone) A mold lubricating oil was obtained by mixing 10% by mass.

(Examples 2 to 4 and Comparative Examples 1 to 5)
A mold lubricating oil was prepared in the same manner as in Example 1 except that a hydrocarbon solvent and an oiliness improver or extreme pressure agent were blended with the composition shown in Table 3. The hydrocarbon solvent, oiliness improver, and extreme pressure agent used are as shown in Table 1 or 2.

<Measurement of kinematic viscosity of mold lubricant>
The mold lubricant obtained in the examples or comparative examples was poured into a Ubbelohde viscometer (U-1B-255, manufactured by Yoshida Scientific Instruments Co., Ltd.) and vertically placed in a constant temperature bath maintained at 40 ° C. for 10 minutes. Left to stand. Measure the time (seconds) that the lubricant meniscus (bending of the liquid level) passes from the time mark E to F with a stopwatch, and the measured value (seconds) and the viscometer constant of the Ubbelohde viscometer used The kinematic viscosity of the mold lubricant was measured by multiplying (inherent value). Table 3 shows the measurement results of the kinematic viscosity of the mold lubricant.

<Measurement of fracture time of mold lubricant>
0.03 g of the mold lubricant obtained in the examples or comparative examples was applied to a test piece (SPCC), and the test was performed using a friction and wear tester. FPR-2100 manufactured by Co., Ltd. was used as a friction player as a friction and wear tester. In addition, in order to measure the coefficient of friction against the test piece, the reciprocating speed is 42.9 cpm, the reciprocating width is 35 mm, the temperature is 50 ° C., the load is 3000 g, and the friction coefficient exceeds 0.8 on a SUJ-2 indenter. The required time was taken as the breaking time, and the breaking time of the mold lubricant was measured. Table 3 shows the measurement results of the breaking time.

<Measurement of average dynamic friction coefficient of mold lubricant>
0.03 g of the mold lubricant obtained in the examples or comparative examples was applied to a test piece (SPCC), and the test was performed using a friction and wear tester. As a friction player which is a friction and wear tester, FPR-2100 manufactured by Resuka Co., Ltd. was used. In order to measure the friction against the test piece, a SUJ-2 indenter was subjected to a linear reciprocating motion with a reciprocating width of 35 mm and a reciprocating speed of 42.9 cpm under the conditions of a temperature of 100 ° C. and a load of 3000 g. The average value of the dynamic friction coefficient when the indenter was reciprocated 20 times was defined as the average dynamic friction coefficient. The stop condition was such that the time required to reciprocate the indenter 20 times was 20 seconds. Table 3 shows the measurement results of the average dynamic friction coefficient.

<Evaluation of lubricity of mold lubricant>
The lubricity of the mold lubricant was evaluated in three stages in the order of “excellent”, “good”, and “impossible” according to the following criteria. Table 3 shows the evaluation results of the lubricity of the mold lubricant.
Excellent: Break time is 150 seconds or more Good: Break time is 50 seconds or more and less than 150 seconds Impossible: Break time is less than 50 seconds or cannot be measured

<Evaluation of safety of mold lubricant>
In consideration of the flammability of the solvent, the safety of the mold lubricant was evaluated in three stages in the order of “excellent”, “good”, and “impossible”. Table 3 shows the safety evaluation results of the mold lubricant. In addition, a main component means what has the largest content rate among composition components.
Excellent: The flash point of the main component is 95 ° C. or higher. Good: The flash point of the main component is higher than 30 ° C. and lower than 95 ° C. No: The flash point of the main component is 30 ° C. or lower.

  The mold lubricants obtained in Examples 1 to 4 all had a long fracture time, a low average dynamic friction coefficient, and good lubrication performance. Moreover, kinematic viscosity was also suitable, and it was a mold lubricating oil suitable for a small amount of application by spraying.

  The mold lubricating oil obtained in Comparative Example 1 was evaluated as “excellent” because the solvent E dried quickly and formed a lubricating film. However, since the flash point of the solvent E is −24 ° C., the mold lubricant is flammable and dangerous, and thus the safety evaluation is “impossible”.

  The mold lubricant obtained in Comparative Example 2 had a short fracture time, a high average dynamic friction coefficient, and poor lubrication performance. The mold lubricant obtained in Comparative Example 4 had a low drying property and could not form a uniform oil film. The mold lubricant obtained in Comparative Example 3 or 5 had a high kinematic viscosity and could not be applied in a small amount by spraying.

(Production Examples 1-4)
<Mixing of metal powder and mixed lubricant>
To a metal powder obtained by adding about 1 part of carbon powder to about 99 parts of Fe-Ni-Cu-Mo based partial diffusion alloy powder, commercially available zinc stearate as a mixed lubricant was mixed so as to have a ratio shown in Table 4. Thus, a metal powder containing a mixed lubricant was prepared. The Fe—Ni—Cu—Mo based partial diffusion alloy powder used in this production example is a powdery mixture containing iron as a main component. In the mixture, 1 to 5% by weight of nickel, copper 1 to 3% by weight, molybdenum 0.1 to 1.0% by weight, and carbon 0.2 to 1.5% by weight.

<Measurement of fluidity of metal powder>
The fluidity of the metal powder obtained in Production Examples 1 to 4 was measured based on JIS Z2502. Table 5 shows the measurement results of the fluidity.

<Measurement of apparent density of metal powder>
The apparent density of the metal powder obtained in Production Examples 1 to 4 was measured based on JIS Z2504. Table 5 shows the apparent density measurement results.

  When the fluidity and the apparent density are comprehensively determined, the blending amount of the mixed lubricant is preferably 0.6% by mass or less. However, if the blending amount of the mixed lubricant is 0% by mass, the apparent density is lowered, and the density of the green compact may be difficult to increase. Therefore, it can be said that it is preferable to add 0.05 to 0.6% by mass of the mixed lubricant to the metal powder. Moreover, it is more preferable to mix | blend 0.1-0.6 mass% of mixed lubricants with a metal powder, and it is still more preferable to mix | blend 0.1-0.4 mass% of mixed lubricants.

<Green compact molding>
The mold lubricant obtained in Example 1 was applied by spraying 0.1 ml onto a mold having a diameter of 16 cm and a depth of 30 cm using the spray coating apparatus shown in FIG. The gun distance from the nozzle tip of the spray coating device to the mold was 3 mm.

  In the spray coating apparatus, six air supply holes are provided around the oil supply hole. The air supply hole and the oil supply hole are arranged at twisted positions, and the angle formed by the air supply hole and the oil supply hole measured from a direction perpendicular to a substantially plane including one air supply hole is 30 degrees. Yes. That is, when the air supply hole and the oil supply hole are viewed from the position where the end on the air supply path side of one air supply hole appears to overlap the oil supply hole, the angle formed by the air supply hole and the oil supply hole is It is 30 degrees. Further, in the fitting portion between the needle receiving hole and the needle tip, the diameter of the needle receiving hole is 0.65 mm, the diameter of the needle tip is 0.8 mm, the diameter of the needle receiving hole and the diameter of the needle tip The difference is 0.075 mm. The angle formed by the substantially truncated cone-shaped inclined portion in the needle inclined portion is 25 degrees, and the angle formed by the substantially truncated cone-shaped inclined portion in the needle receiving portion is the angle of the substantially truncated cone-shaped inclined portion in the needle inclined portion. It is -2 degrees with respect to the formed angle.

  Using the green compact forming apparatus shown in FIG. 3, the metal powder obtained in Production Example 1 was filled in a mold, and the green compact was molded at 40 ° C. The load pressure at the time of compacting the green compact was 1000 MPa.

  The time required from the injection of the mold lubricating oil to the discharge of the green compact, that is, the cycle time was 6 seconds on average.

<Measurement of compressibility of green compact>
The compressibility of the green compact was measured based on JPMA P09 (Japan Powder Metallurgy Industry Association Standard). Table 6 shows the measurement results of the compressibility of the green compact.

<Measurement of press load at the start of extrusion>
The press load at the start of extrusion was measured by measuring the pressure when the lower punch of the green compact molding apparatus shown in FIG. 3 pushes up the green compact. Table 6 shows the measurement results of the press load at the start of extrusion.

<Measurement of compaction pressure>
The punching pressure of the green compact was measured based on JPMA P13 (Japan Powder Metallurgy Industry Association Standard). Table 6 shows the measurement results of the punching pressure of the green compact.

(Examples 5 to 8)
A mold lubricating oil was produced in the same manner as in Example 1 except that a hydrocarbon solvent and an oiliness improver or extreme pressure agent were blended with the composition shown in Table 6. The hydrocarbon solvent, oiliness improver, and extreme pressure agent used in the production of the mold lubricant are as shown in Table 1 or 2. In addition, a green compact was molded by the same method as in Example 1, and various physical properties were evaluated. Table 6 shows the compositions of the mold lubricants obtained in Examples 5 to 8 and the evaluation results of various physical properties.

  Compared with Example 1 in which the extreme pressure agent A was not blended, in Example 5 in which the extreme pressure agent A was blended in an amount of 0.1% by mass, the compressibility and punching pressure of the green compact were about the same as in Example 1. However, in Example 6 in which 0.5% by mass of the extreme pressure agent A was blended, the punching pressure was lower than in Example 1 and Example 5.

  Compared with Example 5 using only solvent G as a solvent, in Example 7 using equal amounts of solvent G and solvent I as solvents, the release pressure was higher. Compared with Example 5 using only the solvent G as a solvent, also in Example 8 using only the solvent I as a solvent, the extraction pressure became high.

  Below, the reference example at the time of shape | molding a green compact on various conditions with or without using the metal mold | die lubricating oil obtained in Example 1 is shown.

(Reference Example 1)
The green compact was molded in the same manner as in Example 1 except that the load pressure at the time of molding the green compact was 400 MPa and the mold lubricant was not applied.

(Reference Example 2)
A green compact was molded in the same manner as in Reference Example 1 except that 0.1 ml of the mold lubricant obtained in Example 1 was applied to the mold in the same manner as in Example 1.

(Reference Example 3)
A green compact was formed in the same manner as in Reference Example 1 except that the metal powder obtained in Production Example 2 was used instead of the metal powder obtained in Production Example 1.

(Reference Example 4)
A green compact was formed in the same manner as in Reference Example 2 except that the metal powder obtained in Production Example 2 was used instead of the metal powder obtained in Production Example 1.

(Reference Example 5)
The green compact was molded by the same method as in Reference Example 3 except that the load pressure at the time of compacting the green compact was 600 MPa.

(Reference Example 6)
The green compact was molded by the same method as in Reference Example 4 except that the load pressure at the time of compacting the green compact was 600 MPa.

  The compressibility of the green compacts obtained in Reference Examples 1 to 6 and the punching pressure when molding the green compacts were measured in the same manner as in Example 1. Table 7 shows the measurement results of compressibility and punching pressure.

In Reference Example 1 and Reference Example 2, in the case where the blending amount of the mixed lubricant is 0 mass% and the load pressure is 400 MPa, the compressibility and the unloading when the mold lubricant is applied and when it is not applied are as follows. The pressure is being compared. Compared to the compressibility (6.26 g / cm ³ ) of Reference Example 1 in which the mold lubricant was not applied, the compressibility (6.42 g / cm ³ ) of Reference Example 2 to which the mold lubricant was applied was It became high. Further, the extraction pressure (16.46 MPa) of Reference Example 2 in which the mold lubricant was applied was significantly lower than the extraction pressure (31.56 MPa) of Reference Example 1 in which the mold lubricant was not applied. It was.

In Reference Example 3 and Reference Example 4, in the case where the blending amount of the mixed lubricant is 0.2% by mass and the load pressure is 400 MPa, compressibility when the mold lubricant is applied and when it is not applied And the extraction pressure are compared. Compared compressibility of Reference Example 3 to the mold lubricant was not applied with (6.49g / cm ^3), the compressibility of the Reference Example 4 was applied to the mold lubricant (6.54 g / cm ³⁾ is It became high. Moreover, the extraction pressure (14.16 MPa) of Reference Example 4 in which the mold lubricant was applied was lower than the extraction pressure (16.39 MPa) in Reference Example 3 in which the mold lubricant was not applied.

Reference Example 5 and Reference Example 6 have compressibility when the mold lubricant is applied and when it is not applied when the blending amount of the mixed lubricant is 0.2 mass% and the load pressure is 600 MPa. And the extraction pressure are compared. Compared with the compressibility (6.93 g / cm ³ ) of Reference Example 5 in which the mold lubricant was not applied, the compressibility (7.0 g / cm ³ ) of Reference Example 6 in which the mold lubricant was applied was It became high. Moreover, the extraction pressure (27.17 MPa) of Reference Example 6 to which the mold lubricant was applied was lower than the extraction pressure (32.08 MPa) of Reference Example 5 to which the mold lubricant was not applied.

  As described above, when the mold lubricant was applied, the compressibility became high and the punching pressure was reduced, and good results were obtained.

(Reference Example 7)
The green compact was molded in the same manner as in Reference Example 5 except that the load pressure at the time of molding the green compact was set to 800 MPa. However, since the mold lubricant was not applied, galling was caused. The green compact could not be densified.

(Reference Example 8)
The green compact was molded by the same method as in Reference Example 6 except that the load pressure at the time of compacting the green compact was 800 MPa.

(Reference Example 9)
The green compact was molded by the same method as in Reference Example 6 except that the load pressure at the time of compacting the green compact was 1000 MPa.

(Reference Example 10)
The green compact was molded in the same manner as in Reference Example 6 except that the load pressure at the time of compacting the green compact was 1200 MPa.

  The compressibility of the green compacts obtained in Reference Examples 7 to 10 and the punching pressure when molding the green compacts were measured in the same manner as in Reference Example 1. Table 8 shows the measurement results of compressibility and extraction pressure.

  As in Reference Example 7 in which the mold lubricant was not applied, galling occurred when the load pressure reached 800 MPa. On the other hand, in Reference Examples 8 to 10 in which the mold lubricant was applied, the compressibility increased as the load pressure was increased, and the green compact could be formed without causing galling or the like.

In particular, in Reference Example 10 with a load pressure of 1200 MPa, compressibility could be increased to 7.5 g / cm ³ without causing galling even if molding was performed 200 times continuously.

(Reference Example 11)
The green compact was prepared in the same manner as in Reference Example 7 except that the amount of the mixed lubricant blended in the metal powder was 0.5% by mass, and a load pressure at which the compressibility was 7.2 g / cm ³ or more was applied. Molding was performed.

(Reference Example 12)
The green compact was prepared in the same manner as in Reference Example 8 except that the amount of the mixed lubricant blended in the metal powder was 0.5 mass% and a load pressure at which the compressibility was 7.2 g / cm ³ or more was applied. Molding was performed.

  The compressibility of the green compacts obtained in Reference Examples 11 and 12 and the punching pressure when molding the green compacts were measured in the same manner as in Reference Example 1. Table 9 shows the measurement results of compressibility and extraction pressure.

  The load pressure at which the density of Reference Example 11 and Reference Example 12 was 7.2 or higher was not significantly different between Reference Example 11 where the mold was not applied and Reference Example 12 where the mold was applied. On the other hand, the extraction pressure (17 MPa) of Reference Example 12 in which the mold lubricant was applied was reduced compared to the extraction pressure (27 MPa) of Reference Example 11 in which the mold was not applied. From this, it was confirmed that the punching pressure can be reduced by applying the mold lubricant.

<Production of sintered body>
(Reference Example 13)
The green compact obtained in Reference Example 4 was sintered at 1100 ° C. for 30 minutes in a reducing atmosphere to obtain a sintered body.

<Measurement of density of sintered body>
The density of the obtained sintered body was measured based on JIS Z 2501. Table 10 shows the measurement results of the density.

<Measurement of crushing strength of sintered body>
The crushing strength of the obtained sintered body was measured based on JIS Z 2507. Table 10 shows the measurement results of the crushing strength.

<Measurement of gas amount during sintering>
The amount of gas generated during sintering was measured by a build-up method using vocal mass manufactured by Nippon Metal Chemical Co., Ltd. Table 10 shows the estimated gas amount.

(Reference Example 14)
The green compact was molded in the same manner as in Reference Example 13 except that the green compact obtained in Reference Example 6 was used. The obtained green compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference Example 15)
The green compact was molded in the same manner as in Reference Example 13 except that the green compact obtained in Reference Example 8 was used. The obtained green compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference Example 16)
The green compact was molded in the same manner as in Reference Example 13 except that the green compact obtained in Reference Example 9 was used. The obtained green compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference Example 17)
A green compact was formed in the same manner as in Reference Example 13 except that the metal powder obtained in Production Example 4 was used in place of the metal powder obtained in Production Example 1. The obtained green compact was sintered by the same method as in Reference Example 13 to obtain a sintered body.

(Reference Example 18)
A green compact was molded in the same manner as in Reference Example 14 except that the metal powder obtained in Production Example 4 was used in place of the metal powder obtained in Production Example 1. The obtained green compact was sintered by the same method as in Reference Example 14 to obtain a sintered body.

(Reference Example 19)
A green compact was formed in the same manner as in Reference Example 15 except that the metal powder obtained in Production Example 4 was used instead of the metal powder obtained in Production Example 1. The obtained green compact was sintered by the same method as in Reference Example 15 to obtain a sintered body.

(Reference Example 20)
A green compact was formed in the same manner as in Reference Example 16 except that the metal powder obtained in Production Example 4 was used instead of the metal powder obtained in Production Example 1. The obtained green compact was sintered by the same method as in Reference Example 16 to obtain a sintered body.

  The density, crushing strength, and estimated gas amount of the sintered bodies obtained in Reference Examples 14 to 20 were measured in the same manner as in Reference Example 13. Table 10 shows the measurement results of the density, the crushing strength, and the estimated gas amount of the sintered bodies obtained in Reference Examples 14 to 20.

DESCRIPTION OF SYMBOLS 10 Spray application apparatus 11 Oil quantity adjustment knob 12 Spring chamber 13 Spring 14 Fixing ring 15 Needle 15S Needle thin diameter part 15L Needle large diameter part 15T Needle tip part 15I Needle inclination part 16 Needle receiving part 16S Needle receiving part 16P Needle receiving hole 18 Spray Main body 19 Injection nozzle 20 Injection nozzle cap 21 Air supply path 22 Air branch path 23 Air supply hole 24 Air injection groove 31 Oil supply hose 32 Oil supply pipe 33 Oil supply hole 40 Feeder 41 Outer wall 42 Scraping part 43 Discharge part 50 Metal powder 51 Pressure Powder 60 Die plate 70 Mold 80 Oil film 91 Upper punch 92 Lower punch

Claims (15)

A mold lubricant containing a hydrocarbon solvent having 7 to 18 carbon atoms and an oiliness improver or extreme pressure agent. The mold lubricant according to claim 1, wherein the content of the hydrocarbon solvent is 50 to 98% by mass. The mold lubricant according to claim 1 or 2, wherein the content of the oiliness improver and / or the extreme pressure agent is 20% by mass or less. The hydrocarbon solvent is at least one solvent selected from the group consisting of paraffinic hydrocarbon solvents, olefinic hydrocarbon solvents, naphthenic hydrocarbon solvents, and aromatic hydrocarbon solvents. The mold lubricant according to any one of the above. The mold lubricant according to any one of claims 1 to 4, wherein the oiliness improver is one or more compounds selected from the group consisting of silicones, animal and vegetable oils and fats, and higher fatty acid esters. The mold lubricant according to any one of claims 1 to 5, wherein the extreme pressure agent is one or more compounds selected from the group consisting of phosphate ester, TCP, sulfide sulfide oil, MoDTC, ZnDTP, and MoDTP. . A needle having a substantially frustoconical inclined portion and a needle receiving portion having a substantially frustoconical inclined portion, wherein the needle and the needle receiving portion are substantially in each substantially frustoconical inclined portion. A spray coating apparatus that is moldable and allows mold lubricant to pass between the needle and the needle receiving portion that are substantially fitted. A needle tip formed on the narrowed side of the substantially frustoconical inclined portion of the needle; and a needle receiving hole connected to the narrowed side of the substantially frustoconical inclined portion of the needle receiving portion. The needle receiving hole is connected to the oil supply pipe for supplying the mold lubricant into the spray coating device on the side facing the needle receiving part, and the needle receiving hole and the needle tip part can be substantially fitted together. The diameter of the needle receiving hole at the portion approximately fitted to the needle tip is 0.6 to 1.8 mm, the diameter of the needle tip is 0.5 to 1.7 mm, The spray coating apparatus according to claim 7, wherein a difference between the diameter and the diameter of the needle tip is 0.05 to 0.4 mm. The spray coating apparatus according to claim 8, wherein the mold lubricating oil can be sprayed in an amount of 0.01 to 10 ml / time. It has an injection nozzle that has a plurality of air supply holes for supplying air and an oil supply hole for supplying mold lubricant to the mold, and a plurality of air supply holes are provided around the oil supply hole. When the angle between the air supply hole and the oil supply hole is measured from a direction perpendicular to a substantially plane including one air supply hole, the air supply hole and the oil supply hole The spray coating apparatus according to any one of claims 7 to 9, wherein an angle formed by the above becomes 20 to 40 degrees. Application means for applying mold lubricant oil by a spray application device;
Filling means for filling metal powder into a mold coated with mold lubricating oil;
Forming means for pressing the filled metal powder to form a green compact;
Extraction means for extracting the green compact formed above the mold;
A dispensing means for dispensing the extracted green compact from the upper part of the mold,
The dispensing means and the spray coating device move in conjunction with the dispensing direction, which is the direction toward the top of the mold in the state before dispensing,
Dispensing means is provided in front of the spray application device along the dispensing direction,
When the dispensing means and the spray application device move in the dispensing direction, the dispensing means passes the upper part of the mold and dispenses the green compact. When the spray application apparatus reaches the upper part of the mold, A compact molding machine that applies mold lubricant. The dispensing means, the spray coating device, and the filling means move in conjunction with a dispensing direction that is a direction toward the upper part of the mold in a state before dispensing.
The filling means is provided behind the spray application device along the dispensing direction,
When the spray application device and the filling means move in the dispensing direction in conjunction with each other, the filling means reaches the top of the mold immediately after the spray application device applies the mold lubricant to the mold. The green compact forming apparatus according to claim 11, wherein the mold is filled with metal powder. Among the metal powder filled in the mold, comprising a scraping means for scraping off the metal powder existing above the mold,
The dispensing means and the spray coating device are configured to reciprocate alternately in the dispensing direction and the reverse direction of the dispensing direction to dispense the green compacts that are sequentially molded, and repeatedly apply the mold lubricant to the mold.
The scraping means is provided rearward along the dispensing direction from the spray application device,
The green compact molding apparatus according to claim 12 or 13, wherein the spray coating device and the scraping means move in the reverse direction of the dispensing direction in conjunction with each other to scrape off the metal powder filled in the mold. An application process of applying a mold lubricant with a spray application device;
A filling process of filling metal powder into a mold coated with mold lubricant,
A molding step of pressing the filled metal powder to form a green compact;
An extraction process for extracting the formed green compact above the mold,
A dispensing step of dispensing the extracted green compact from the upper part of the mold by a dispensing means;
The dispensing means and the spray coating device move in conjunction with the dispensing direction, which is the direction toward the top of the mold in the state before dispensing,
Dispensing means is provided in front of the spray application device along the dispensing direction,
When the dispensing means and the spray application device move in the dispensing direction, the dispensing means passes the upper part of the mold and dispenses the green compact. When the spray application apparatus reaches the upper part of the mold, A green compact molding method in which a mold lubricant is applied. A sintered body obtained by sintering a green compact formed by the green compact forming method according to claim 14.

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