JP5192205B2 - Vacuum carburized parts and manufacturing method thereof - Google Patents

Description

The present invention relates to a vacuum carburizing component and manufacturing how, in particular, those related to the preferred vacuum carburizing components and manufacturing methods from component surface processing such as shot peening or grinding after vacuum carburizing is performed.

Conventionally, due to high strength and high reliability of gears and shafts, surface fatigue fatigue strength such as pitching life by strengthening by shot peening etc. after vacuum carburizing treatment where no grain boundary oxide layer is recognized In addition, there has been proposed a surface treatment method for carburized parts that enhances tooth fatigue strength and obtains a tough and highly reliable high surface pressure gear (see Patent Document 1).
Japanese Patent No. 2945714

  By the way, in the surface treatment method for carburized parts of the above-mentioned conventional example, since the carburizing process is performed under vacuum (1 [kPa] or less), almost no oxide film is formed on the surface of the part, and the glitter of the treated product is excellent. . For this reason, there is little change in the surface color even by surface processing such as shot peening performed thereafter, there is a concern that whether shot peening has been performed or not, and there is a concern that the shot peening process will not be performed and will be flowed to the subsequent process . In addition, for the same reason, there is a problem that it is impossible to determine from the appearance whether a part in a subsequent process is identified as being subjected to vacuum carburization or not.

The present invention has been made in view of the above problems, and an object thereof is to provide a suitable vacuum carburizing parts and manufacturing how to check the implementation of the vacuum carburization and subsequent processing.

The present invention relates to a method for manufacturing a vacuum carburized component in which a carburized surface is processed by vacuum carburizing, wherein a colored additive is blended with a workpiece subjected to vacuum carburizing treatment (however, the colored additive is (a) zinc thiophosphate). At least one metal compound selected from a compound, a molybdenum thiophosphate compound, a zinc thiocarbamate compound and a molybdenum thiocarbamate compound, (b) a dihydrocarbyl polysulfide compound, (c) any one of a phosphate ester compound, or At least a part of the colored film is formed by applying a quenching treatment with heat-treated oil ( mixed by selecting two or more) to form a colored film on the surface of the workpiece, and then processing the portion where the colored film is formed. Was to be removed.

Therefore, in the present invention, the workpiece subjected to vacuum carburizing treatment was blended with a coloring additive, and the workpiece subjected to vacuum carburizing treatment in which a coloring additive was blended (however, the coloring additive includes (a) a zinc thiophosphate compound, a molybdenum thiophosphate compound, At least one metal compound selected from a zinc thiocarbamate compound and a molybdenum thiocarbamate compound, (b) a dihydrocarbyl polysulfide compound, and (c) a phosphate ester compound, Since a colored film is formed on the work surface by quenching with a heat-treated oil ( mixed) , and then processing is performed on the portion where the colored film is formed, at least a part of the colored film is removed. Without increasing the number of processes, it is possible to form a colored film on the workpiece surface at the same time as quenching. , It can be easily confirmed by the presence or absence of a colored film on the workpiece surface the implementation of the processing of the workpiece. For this reason, it is possible to prevent the untreated product of vacuum carburization and the leaked product from being discharged to the subsequent process.

Hereinafter, an embodiment of a vacuum carburizing component and manufacturing how the present invention will be described with reference to FIG. FIG. 1A is a process diagram showing a vacuum carburized component and a manufacturing method thereof according to a first embodiment to which the present invention is applied. As a vacuum carburized component, from carburized quenching of a driven gear in a vehicle final drive device to a final drive device. It is process drawing to assembly / shipment process. FIG. 1B is a process diagram showing the type and method of surface treatment.

  In the driven gear in the final drive device, in a previous process (not shown), a workpiece is forged, and a workpiece processed as a gear by machining such as cutting is pre-cleaned and loaded. The surface color of the workpiece is silver white which is the surface color that the workpiece material originally has. First, a vacuum carburizing process (S1) and an oil quenching process (S2) are performed in a carburizing process furnace, and then the quenching oil adhering to the surface of the workpiece subjected to the vacuum carburizing and quenching process is washed (S3).

  In the present embodiment, in the quenching treatment (S2), by using a quenching oil composed of a heat-treated oil composition to which an additive that exhibits a coloring function is added, the surface of the quenched workpiece is made the original surface of the material. A colored film having a color of silver white to dark gray to black of less than 100 [nm] and less than a micron order is formed and colored. This colored film is a range in which the colored surface film is peeled off by surface treatment processing such as shot peening performed in a later process or finishing by machining in order to make a tough and highly reliable high surface pressure gear. It is desirable that it is also applied to other surface portions including at least.

  As described above, by confirming the colored surface color of the workpiece, it is possible to easily determine from the appearance whether the component is subjected to vacuum carburizing or not subjected to vacuum carburizing in the subsequent process. The confirmation of the colored surface color is performed by visually checking the gloss of the surface of the workpiece immediately after the vacuum carburizing process or before or after the surface treatment process or finishing process, which is a subsequent process, or the surface light (colored This can be detected by a sensor or the like that detects the reflectance of reflected light having a specific wavelength from the surface. Before and after the surface treatment process or finishing process, which is a subsequent process, the difference in surface gloss between the processed surface part and the unprocessed surface part becomes clear, as will be described later. Can be discriminated (identified). For this reason, it can prevent that the workpiece | work which does not go through a vacuum carburizing process flows out into a post process, and is surface-treated and finished.

  Next, in the surface treatment step (S4), for example, shot peening is performed on the tooth surface of the gear of the workpiece using an iron-based shot having a particle size of 0.05 to 0.2 [mm], and the vicinity of the surface. Increase the residual stress value. By this surface treatment, the surface pressure fatigue strength such as the pitching life is increased and the tooth root fatigue strength is high, and a tough and highly reliable high surface pressure gear can be formed. At the same time, this surface treatment removes the colored film with a film thickness of micron order or less from the tooth surface and tooth bottom of the workpiece gear from the surface of the workpiece tooth surface (hereinafter, including “peeling”). The entire tooth surface is made silver-white, which is the surface color that the workpiece material originally has. In addition, although shot peening has been exemplified as the processing method performed in the surface treatment step (S4), as other processing methods, for example, as shown in FIG. FPP) may be employed, or a combination of these may be employed.

  Further, as described above, since the film thickness of the colored film formed on the workpiece surface is less than a micron order, it does not affect the strength of a single component, for example, a carburized layer. In addition, the formation of a colored film on the workpiece surface does not cause the carburized layer to corrode or form a starting point of destruction, and therefore does not affect the strength. Furthermore, the residual stress distribution after the surface treatment is equivalent to the case where there is no conventional colored film.

  On the other hand, the colored film adhering to a region deviating from the surface treatment range, for example, a portion deviating from the gear surface of the work remains black on the work surface. For this reason, it is possible to confirm that the surface treatment processing is reliably performed by comparing the workpiece surface colors between the surface treatment region and the outside of the surface treatment region. In addition, since the portion where the surface treatment is performed is clarified, it is easy to find a treatment abnormality in the surface treatment process such as a black skin residue. As described above, since it is possible to easily identify whether or not the surface treatment process is performed and whether or not the surface treatment process is normally performed, it is possible to prevent the leaked product of the surface treatment process from flowing into the subsequent process.

  In a subsequent finishing step (S5), for example, a grinding step and a lapping step, the tooth surfaces of the gears of the workpiece and the surface of the bearing portion are finish-ground and lapped. The colored film is removed (peeled) in the surface treatment step (S4) in the tooth surface portion of the workpiece, and therefore has no adverse effect on machining such as finish grinding and lapping, and its productivity. And does not affect others. In addition, the colored coating on the bearings of the gears of the workpiece is also removed by machining such as finish grinding and lapping in the finishing process, so the surface color of the workpiece between the machining area such as finishing and outside the machining area By comparing, it can be confirmed that machining has been performed reliably. Moreover, processing defects such as black skin residue in the machined part can be confirmed at the same time. As described above, since the presence / absence of machining and the normality / abnormality of machining can be easily identified, it is possible to prevent leakage of machined products to the subsequent process. Thereafter, it is assembled as a driven gear of the final drive device (S6) and shipped as a final drive device (S7).

In the heat-treated oil composition used in the present embodiment, a heat-treated oil composed of mineral oil and / or synthetic oil can be used as a lubricating base oil. In particular, it is desirable to use bright quenching oil (for example, Bright Quench, Bright Quench S Idemitsu Kosan Co., Ltd., Bright Heat Treatment Oil, trade name). That is, it is not particularly limited as long as it is generally used as a base oil for heat-treated oil, but a kinematic viscosity at 100 ° C. of 1.5 [mm ² / s] or more is preferable, and 2 to 50 [ Those in the range of [mm ² / s] are more preferable. If the viscosity of the base oil is too low, the vapor film stage becomes long and the cooling performance is insufficient. At the same time, the occurrence of mist may cause deterioration of workability and increase the risk of fire, which is not preferable. The pour point, which is an index of low temperature fluidity of the base oil, is not particularly limited, but is preferably −10 [° C.] or less.

  The additive blended in the bright heat treatment oil includes (a) at least one metal compound selected from a zinc thiophosphate compound, a molybdenum thiophosphate compound, a zinc thiocarbamate compound and a molybdenum thiocarbamate compound, and (b) di At least any one of hydrocarbyl polysulfide compound, (c) phosphate ester compound, or a combination of two or more thereof can be used.

  As the at least one metal compound selected from the zinc thiophosphate compound, the molybdenum thiophosphate compound, the zinc thiocarbamate compound and the molybdenum thiocarbamate compound of (a), specifically, zinc dithiophosphate (Zn-DTP) , Molybdenum dithiophosphate (Mo-DTP), zinc thiocarbamate (Zn-DTC), and molybdenum thiocarbamate (Mo-DTC). Of these, Zn-DTP is preferable. The component (a) may be used alone or in combination of two or more.

  As the dihydrocarbyl polysulfide compound (b), the general formula (R1-Sx-R2, R1 and R2 are each an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, carbon An alkylaryl group having 7 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms, which may be the same as or different from each other, and x represents an integer of 2 to 8. . Here, when R1 and R2 are alkyl groups, they are referred to as alkyl sulfides.

  Specific examples of R1 and R2 in the above general formula include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various pentyl groups, various types. Hexyl group, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, cyclohexyl group, cyclooctyl group, phenyl group, naphthyl group, tolyl group, xylyl group, benzyl group, phenethyl group, etc. be able to.

  Preferred examples of the dihydrocarbyl polysulfide compound include dibenzyl polysulfide, di-tert-nonyl polysulfide, didodecyl polysulfide, di-tert-butyl polysulfide, dioctyl polysulfide, diphenyl polysulfide, and dicyclohexyl polysulfide. One type of component (b) may be used, or two or more types may be used.

  As the phosphoric acid ester compound (c), the phosphoric acid ester compound includes a phosphoric acid ester, an acidic phosphoric acid ester, a phosphorous acid ester, and an acidic phosphorous acid ester. Examples of phosphate esters include triaryl phosphates, trialkyl phosphates, dialkyl aryl phosphates, diaryl alkyl phosphates, and trialkenyl phosphates. Specific examples include triphenyl phosphate, tricresyl phosphate, benzyl diphenyl phosphate, and ethyl diphenyl. Phosphate, tributyl phosphate, ethyl dibutyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, (ethylphenyl) diphenyl phosphate, di (ethylphenyl) phenyl phosphate, (propylphenyl) diphenyl phosphate, di (propylphenyl) phenyl phosphate, tri (Ethylphenyl) phosphate, tri (propylphenyl) phosphate, (butylphenyl) Nyl) diphenyl phosphate, di (butylphenyl) phenyl phosphate, tri (butylphenyl) phosphate, trihexyl phosphate, tri (2-ethylhexyl) phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tri Examples include stearyl phosphate and trioleyl phosphate.

  Specific examples of the acidic phosphate ester include 2-ethylhexyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, tridecyl. Acid phosphate, stearyl acid phosphate, isostearyl acid phosphate and the like can be mentioned.

  Specific examples of the phosphite ester include triethyl phosphite, tributyl phosphite, triphenyl phosphite, tricresyl phosphite, tri (nonylphenyl) phosphite, and tri (2-ethylhexyl) phosphite. , Tridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenylisodecyl phosphite, tristearyl phosphite, trioleyl phosphite and the like.

  Specific examples of the acidic phosphite ester include dibutyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, distearyl hydrogen phosphite, diphenyl hydrogen phosphite and the like. .

  Among the above phosphoric acid ester compounds, acidic phosphoric acid esters such as 2-ethylhexyl acid phosphate, oleyl acid phosphate, lauryl acid phosphate, stearyl acid phosphate are preferable. One type of component (c) may be used, or two or more types may be used.

  And (a) at least one metal compound selected from (a) zinc thiophosphate compound, molybdenum thiophosphate compound, zinc thiocarbamate compound and molybdenum thiocarbamate compound, (b) dihydrocarbyl polysulfide compound, (c) phosphoric acid In the case of using at least one of the ester compounds or a combination of two or more thereof, the blending amount is preferably in the range of 0.05 to 7 [mass%] based on the total amount of the composition, The range of 0.05-5 [mass%] is more preferable. If the amount is less than 0.05 [% by mass], coloring may be insufficient, and color unevenness may occur when serving as a black dyeing process. If the amount exceeds 7 [% by mass], the colored portion may be partially peeled off. There is a case. Even when all the additives (a) to (c) are used in combination for coloring, the total amount of each additive is 0.05 to 7 [mass based on the total amount of the composition] %] Is preferable, and a range of 0.05 to 5 [% by mass] is more preferable.

  In addition, although the thing using a bright quenching oil was demonstrated as a lubricating base oil of heat processing oil composition, a quenching oil with low luster can also be used as a lubricating base oil. The degree of glitter on the surface of the workpiece is varied, but by adding one or more of the additives (a), (b) and (c) described above, a certain coloration can be obtained. It can be surely secured. Of course, the combination of the bright quenching oil and the additive can maximize the coloring effect.

  In addition, one or two or more additives (a), (b) and (c), which are black dye additives, are blended with the lubricating base oil of the heat-treated oil composition. However, if an attempt is made to color other than the above-described black dye additive, a considerable amount of addition is necessary, and the cooling performance during quenching of the vacuum carburized parts changes, which is not desirable.

(Example)
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

  A luster quenching oil (Idemitsu Kosan Co., Ltd., product name: Daphne Bright Quench S) with the properties shown in FIG. 2 (Table 1) is used as the base oil, and the components (a), (b), and (c) are used as the base oil. Were added to prepare outlets (added mixed oil) 1-4.

  Next, the prepared outlets (added mixed oils) 1 to 4 were blended with the base oil at the ratio shown in FIG. 3 (Table 2) to prepare the quenching oils of Examples 1 to 10 and Comparative Examples 1 and 2. About these quenching oil, the quenching test was done by the following method and the physical property of the to-be-processed object was evaluated.

[Hardening Test] A test piece (SCM420H, diameter 10 [mm] × length 30 [mm]) was quenched under the following conditions:
Atmosphere: N ₂ + H ₂
Processing temperature: 850 [° C]
Heating time: 30 [minutes]
Cooling time: 5 [minutes]
Oil temperature: 100 [° C]
After the object to be treated was degreased with acetone, the appearance of the object to be treated was evaluated.

  Specifically, the colored state and the bright state were determined visually. The criteria for determining the glitter were three levels: good, slightly good, and poor, and the criteria for determining the colorability were three levels: good, slightly thin, and thin.

  From FIG. 3 (Table 2), the compositions of Examples 1 to 10 have “slightly inferior” luster in Examples 1, 4, 5, 7, 8, and 9, and coloring properties in Examples 3 and 6; 10 shows that although it is “slightly thin”, a substantially good result can be obtained.

  In the present embodiment, the following effects can be achieved.

  (A) In a vacuum carburized part manufacturing method in which a carburized surface is processed by vacuum carburizing, the vacuum carburized workpiece is quenched with heat treatment oil containing a coloring additive to form a colored film on the workpiece surface. Then, at least a part of the colored film was removed by processing the portion where the colored film was formed. For this reason, without increasing the number of steps, a colored film can be formed on the workpiece surface simultaneously with quenching, and the processing of the workpiece can be easily confirmed by the presence or absence of the colored film on the workpiece surface. Therefore, it is possible to prevent the untreated product of vacuum carburization and the leaked product from being discharged to the subsequent process.

  Examples of the processing on the workpiece surface include surface processing processing such as shot peening, shot blasting, and micro shot (FPP) and / or finishing processing by mechanical processing such as cutting and grinding. Implementation can be easily confirmed by the presence or absence of a colored coating on the workpiece surface. For this reason, it is possible to prevent leakage of the processed leaked product to the subsequent process.

  (A) In a vacuum carburized part manufacturing method in which at least one of surface treatment or machining is applied to the surface carburized by vacuum carburizing, heat treatment in which a colored additive is blended with the workpiece subjected to vacuum carburizing A colored film is formed on the work surface by quenching with oil, and then the gloss of the work surface is visually detected or the reflectance of reflected light having a specific wavelength from the surface is detected by the colored film on the surface. By doing so, it is possible to discriminate (identify) the processed and unprocessed vacuum carburization by identifying the processing and unprocessed vacuum carburizing. For this reason, it can prevent that the workpiece | work which does not go through a vacuum carburizing process flows out into a post process, and is surface-treated or finished.

  (C) The heat-treated oil blended with the color additive is a heat-treated base oil and (a) at least one metal compound selected from a zinc thiophosphate compound, a molybdenum thiophosphate compound, a zinc thiocarbamate compound, and a molybdenum thiocarbamate compound , (B) dihydrocarbyl polysulfide compound, (c) a heat-treated oil composition selected from one or more of the phosphoric acid ester compounds, and the mixing ratio is 0.05 to 7 The hardened workpiece surface can be colored black without changing the cooling property during quenching of the workpiece as small as [mass%]. In addition, since the thickness of the colored film formed on the workpiece surface is on the order of microns or less, there is no formation of corrosion and fracture starting points of the carburized layer, and there is no influence on the strength of the workpiece. It can be surely removed by at least one of finishing by machining, and the residual stress distribution after finishing at least one of surface treatment or machining is equivalent to the case where there is no conventional film Without affecting productivity and others.

  (D) Since the base oil of the heat-treated oil is a bright heat-treated oil with good glitter, a colored film having a high degree of glitter can be obtained on the workpiece surface.

  (E) In the case of vacuum carburized parts where the surface carburized by vacuum carburizing is subjected to at least one of surface treatment or finishing by machining, and then quenching with heat-treated oil containing coloring additives after vacuum carburizing. By forming a colored film on the surface, finishing the surface part by surface treatment or machining, forming a vacuum on the workpiece surface by forming at least a part of the colored film Since the colored film by carburization and the colored film are removed by the finishing process by surface treatment or machining, the machining history of the workpiece can be confirmed with certainty.

  Although the drive gear in the final drive device of the vehicle has been described as the vacuum carburized component, it can also be applied to a crown gear that meshes with the drive gear, and can also be applied to other gear components and shaft components.

Process drawing which shows the vacuum carburized component of 1st Embodiment to which this invention is applied, and its manufacturing method. Process drawing which shows the kind and method of surface treatment processing. Table 1 showing the properties of the outlet (added mixed oil). The 2nd table | surface which shows each Example and comparative example which changed the mixture ratio with respect to the base oil of an addition mixed oil.

Claims (5)

In the method of manufacturing a vacuum carburized component in which processing is performed on the surface carburized by vacuum carburization,
Workpiece subjected to vacuum carburizing treatment was blended with a coloring additive (however, the coloring additive is (a) at least one metal selected from zinc thiophosphate compound, molybdenum thiophosphate compound, zinc thiocarbamate compound and molybdenum thiocarbamate compound) (B) Dihydrocarbyl polysulfide compound, (c) Phosphoric acid ester compound selected from one or more, and heat-treated oil is used for quenching to form a colored film on the workpiece surface And
Next, at least a part of the colored film is removed by processing the portion where the colored film is formed. 2. The method of manufacturing a vacuum carburized component according to claim 1 , wherein the heat-treated base oil is a bright heat-treated oil having good glitter . The method for manufacturing a vacuum carburized part according to claim 1 or 2, wherein at least a part of the colored film is removed by performing a surface treatment to improve surface fatigue strength . The method for manufacturing a vacuum carburized part according to claim 1 or 2, wherein at least a part of the colored film is removed by finishing by machining . In vacuum carburized parts in which at least one of surface treatment or finishing by machining is applied to the surface carburized by vacuum carburization,
A coloring additive was blended after vacuum carburizing treatment (however, the coloring additive is at least one metal compound selected from (a) a zinc thiophosphate compound, a molybdenum thiophosphate compound, a zinc thiocarbamate compound and a molybdenum thiocarbamate compound) And (b) a dihydrocarbyl polysulfide compound and (c) a phosphoric acid ester compound selected from one or two or more) and subjected to a quenching treatment to form a colored film on the surface. ,
The finishing by surface treatment or machining, giving the process the surface sites, vacuum carburizing parts you and forming by removing at least a portion of the colored coating.

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