KR101714016B1 - Method of metal surface treatment for helical or spur gear of automatic transmission - Google Patents
Method of metal surface treatment for helical or spur gear of automatic transmission Download PDFInfo
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- KR101714016B1 KR101714016B1 KR1020150173876A KR20150173876A KR101714016B1 KR 101714016 B1 KR101714016 B1 KR 101714016B1 KR 1020150173876 A KR1020150173876 A KR 1020150173876A KR 20150173876 A KR20150173876 A KR 20150173876A KR 101714016 B1 KR101714016 B1 KR 101714016B1
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- C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
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- C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
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- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
- C23C28/347—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with layers adapted for cutting tools or wear applications
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- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/20—Carburising
- C23C8/22—Carburising of ferrous surfaces
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- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
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- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/24—Nitriding
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- C23C8/42—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions only one element being applied
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- C23C8/80—After-treatment
Abstract
Description
The present invention relates to a surface hardening treatment method of gears.
Power transmission gears for automobiles and machines are constructed with a complex load. Thus, in order to increase the rigidity, abrasion resistance and fatigue resistance, the carburizing hardening treatment is usually performed.
In order to improve the durability of the gears, the gears are usually subjected to surface hardening treatment in order to increase the rigidity, abrasion resistance, fatigue resistance and the like in the finished state. Carburizing hardening treatment is mainly used.
However, since the carburizing hardening treatment is carried out at a high temperature of 900 ° C or higher during the heat treatment, it causes dimensional changes due to thermal deformation, transformation stress, and the like, which necessitates the second and third additional processing steps.
In addition, due to the deformation at the high temperature, noise or the like occurs when the finished product is used, thereby causing noise pollution.
Therefore, various methods have been proposed to reduce the amount of heat treatment change, and a method of lowering the temperature or changing the cooling method is mainly used.
However, the effect is very low. The cooling method employs gas cooling or a method that differs in the temperature and properties of the cooling oil, but the desired effect can not be obtained due to the high carburizing temperature.
On the other hand, in Japan, there is a case where a technique of applying an antioxidant to the surface after the salt bathing and reheating and cooling has been used, but this technique has not been used as a mass production process because of the difficulty of applying antioxidant and stabilization of reheating process.
In Korean Patent No. 0435370, there has been proposed a method of surface hardening treatment which is a process of gas quenching or oil quenching immediately after reheating. However, due to a still high carburizing temperature, sufficient process stabilization Did not bring it.
SUMMARY OF THE INVENTION The present invention has been devised to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method of surface treatment of a gear flow in which a heat treatment variation amount is minimized through rapid heating using a double- It is for that purpose.
However, the technical problem to be solved by the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.
In order to solve the above-described problems, the present invention provides a method of manufacturing a semiconductor device, comprising: a preprocessing step (S1) of preparing a metal material and then subjecting it to hot forging to form a gear shape;
Machining the material pretreated in S1 in a gear shape (S2);
A step (S3) of charging nitride processed material into the nitriding atmosphere heat treatment furnace to cover the nitride;
(S4) covering the oxide film by performing a precipitation treatment in the heat treatment furnace after covering the nitride in S3;
(S5) heating the workpiece by applying a double frequency wave after coating the oxide film in S4;
And cooling the heated material with a coolant (S6).
As a feature of the present invention, the pre-treatment temperature is as low as 650 ° C or less, the secondary processing method is rapid heating and cooling, and the total process is reduced by half, and the energy consumption is reduced to 30% or more. It is possible. The low temperature and low-temperature deformation can be achieved by the rapid heating by the double frequency in the preliminary treatment, and the quality characteristic of the gear is increased by increasing the compressive stress on the surface. This means that gears used in automotive gearboxes can be dealt with by increasing the complexity of shape and weight, and by increasing the required characteristics. In addition, the surface portion remains a nitrogen compound layer having wear characteristics, and the lower portion thereof is made of a hard martensite structure, so that the durability characteristics of the gear are improved.
1 is a view showing a gear manufacturing process.
2 is a view showing the shape of gears manufactured in the present invention.
3 is a view showing a result of observing the depth of curing.
Fig. 4 is a view showing the result of observing the thickness of the under-nitrogenized layer after the contour hardening treatment.
Fig. 5 is a photograph showing a tissue obtained by identifying the residual compound layer. Fig.
Fig. 6 is a diagram showing the post-thermal change of the gear.
An object of the present invention is to provide a surface hardening treatment method comprising a step of forming and diffusion-treating an oxidation-prevention film after coating with a nitrogen compound, followed by a dual-frequency heating and cooling step in a method of surface hardening treatment of gears.
That is, the main object of the present invention is to increase the desired curing properties and storage effect of the surface nitrogen compound layer by instantaneous rapid heating and cooling while maintaining the nitriding compound generated in the preliminary treatment after the oxide film is coated on the surface in the preliminary treatment will be.
The method of the present invention is characterized in that after machining, it is coated with nitride and includes a double-frequency heating and cooling step, wherein carbon steel, SCM, SCr alloyed steel is subjected to tempering before machining (a) (C) coating the oxide film (d), followed by a double-frequency heating and cooling step (e).
Alternatively, in the case of high alloy steels, the non-tempering treatment may be surface hardened by machining (a), after nitriding (b) diffusing (c), including dual frequency heating and cooling (d) .
That is, the present invention includes a pre-treatment step (S1) of preparing a metal material and then subjecting it to hot forging to form a gear shape;
Machining the material pretreated in S1 in a gear shape (S2);
A step (S3) of charging nitride processed material into the nitriding atmosphere heat treatment furnace to cover the nitride;
(S4) covering the oxide film by performing a precipitation treatment in the heat treatment furnace after covering the nitride in S3;
(S5) heating the workpiece by applying a double frequency wave after coating the oxide film in S4;
And cooling the heated material with a coolant (S6).
The metal material may be carbon steel, alloy steel, or high alloy steel, but is not limited thereto.
The method of the present invention has been described in detail below.
[Pretreatment: hot forging]
In the present invention, the metal material used for manufacturing the gear is cut to a size suitable for the production of the gears, and is subjected to the plastic working in a gear-like shape through hot forging. There is no restriction on the method of hot forging in the pre-treatment.
[Treating]
In the present invention, the tempering treatment is carried out by heating at a suitable temperature of about 840 to 880 DEG C, maintaining the steel in a stable Austenite zone, quenching it in an appropriate refrigerant oil or water, and subjecting it to tempering in accordance with its mechanical properties , The hot-forged metal material is heated and then quenched into a coolant and heat-treated. The steaming treatment in the present invention is not limited to the steaming treatment.
In the present invention, the tempering treatment is applied to a power transmission gear using carbon steel or a low alloy steel.
[Machining]
In the present invention, the machining is a step of machining a gear shape so that the shape of the gear is in conformity with the shape to be manufactured. It is a step of placing a tempered metal material on a die having a gear shape engraved therein, To form a gear shape. At this time, the method of machining is not limited to the above-mentioned method, and it can be performed by selecting an appropriate method according to the type of the gear flow to be manufactured.
[Pretreatment: nitride coating]
In the present invention, the step of coating the nitride, which is a preliminary treatment, is a step of charging a metal material of carbon steel, SCM, or SCr alloyed steel in a nitriding atmosphere heat treatment furnace and coating the nitride part on the surface part thereof and being treated through the gas nitriding heat treatment method.
[Oxide coating]
In the present invention, oxide coating is a step of depositing an oxide film on a metallic material such as the above material. In this method, steam or air is injected at a temperature of 550 to 650 ° C in a closed heat treatment furnace, . At this time, the coated thickness is about 3 to 10 μm.
[diffusion]
In the present invention, the diffusion is a step of maintaining the nitride diffusion layer under the nitride generated at the nitriding treatment at a nitriding treatment temperature of about 500 to 600 DEG C, and is performed through a method of adjusting the amount of the nitriding atmosphere gas in the heated heat treatment furnace will be.
The diffusion in the present invention is applied to a power transmission gear to be used by non-tempering treatment in the case of high alloy steel.
[Dual frequency heating]
In the present invention, the step of heating the metallic material using the double frequency is performed through a method of adjusting the frequency ratio and the time.
[Cooling]
In the present invention, the cooling is performed through a method of cooling with oil or water after the double-frequency heating. Cooling is performed by using cooling oil prepared by adding a water-soluble polymer to water, adjusting the concentration of the refrigerant to an appropriate ratio, and controlling the refrigerant temperature to be constant.
[After treatment]
In the present invention, the post-treatment is a process of washing after cooling and cooling the material to a predetermined temperature in a heating furnace when the material is at room temperature, thereby releasing stress generated during heating and cooling.
Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the following examples.
[Example]
Example 1: Production of gears through surface hardening treatment (tempered steel)
1.1. Material preparation
In this embodiment, a gear of 0.3 kg having the composition shown in the following Table 1 was prepared for gear production.
The material used for the treatment may be another kind of carbon steel or alloy steel. In this case, the bar having a diameter of 9 cm is cut to have a size of 3 cm.
The cut material was hot-forged at 900 ° C.
1.2. Tempering treatment
The material prepared in 1.1 was maintained at a temperature of about 840 to 880 ° C for 1 to 3 hours and then cooled using oil to homogenize the material.
1.3. Machining
The material subjected to the tempering treatment in the step 1.2 was subjected to roughing, finishing, and gearing to form a gear as shown in FIG.
1.4. Nitride coating
The material machined in 1.3 above was coated with nitride using gas nitridation.
1.5. Oxide coating
An oxidation film (oxidation-preventive film) was formed by using the oxidation treatment method of the material coated with nitride in 1.4. At this time, the oxidation preventing film may be composed of Fe 3 O 4 or may be composed of a falling film (FeS).
1.6. Double-frequency heating
In 1.5, the material coated with the oxide film was rapidly heated to a temperature of 800 ° C or more by applying a double frequency.
delete
1.7. Cooling
In 1.6, the material was cooled to a temperature of 100 ° C or lower through a method of spraying a coolant onto a metal-heated material.
1.8. After treatment
In the present invention, the post-treatment is a process in which cleaning is performed after cooling, and when the material is at room temperature, the material is heated to a predetermined temperature in a heating furnace to release stress generated during heating and cooling.
The finished gear was assembled and completed.
Example 2. Manufacturing of gears by surface hardening treatment High alloy steel Etc Nonconditioning treatment Steel case)
2.1. Material preparation
In this embodiment, gears were prepared by preparing 0.3 kg of material having the composition shown in Table 2 below for gear fabrication.
Composition scheme of material
The material used for the treatment may be of another type of high alloy steel, in which a bar having a diameter of 9 cm is cut to a size of 3 cm.
The cut material was hot-forged at 900 ° C.
2.2. Machining
The material prepared in 2.1 above was subjected to roughing, finishing, and gearing to form a gear as shown in Fig.
2.3. Nitride coating
The material machined in 2.2 above was coated with nitride using gas nitridation.
2.4. Oxide coating
An oxide film (oxidation preventing film) was formed by using the oxidation treatment method in the material coated with nitride in the above 2.3. At this time, the oxidation preventing film may be composed of Fe 3 O 4 or may be composed of a falling film (FeS).
2.5. diffusion
In the present invention, the diffusion is a step of maintaining at a nitriding treatment temperature so that the nitrogen diffusion layer under the nitride generated in the nitriding process becomes deeper, and the nitriding atmosphere gas amount is controlled in the heated heat treatment furnace.
When the metal material is a high alloy steel, the material coated with the oxide film is placed in a heat treatment furnace for nitriding atmosphere, and the nitrogen diffusion layer is diffused by heating at 500 to 600 ° C.
2.6. Double-frequency heating
In 2.5, the material coated with the oxide film was rapidly heated to a temperature of 800 ° C or higher in a time of less than a few seconds by applying a double-frequency.
2.7. Cooling
In 2.6, cooling was performed at a temperature of 100 ° C or lower through a method of spraying a coolant onto a metal-heated material.
2.8. After treatment
In the present invention, the post-treatment is a process in which cleaning is performed after cooling, and when the material is at room temperature, the material is heated to a predetermined temperature in a heating furnace to release stress generated during heating and cooling.
The finished gear was assembled and completed.
≪ Evaluation of physical properties &
① Check depth of hardening
The hardening depth was confirmed by Vickers hardness tester using KSD0274 method.
② Check surface hardness
As a method of confirming the surface hardness of the manufactured gear, it was confirmed by a Vickers hardness tester using the method of KSD0274.
③ Confirm residual compressive stress
The method to confirm the residual compressive stress of the manufactured gear was confirmed using KS B0951 method.
(4) Residual compound layer
The method of identifying the residual compound layer of the manufactured gear was confirmed by optical microscope using the method of KSD0274.
⑤ Gear tooth type change amount result
The profile and lead of the manufactured gear were measured.
≪ Property evaluation result >
① Curing Depth Result
As a result of checking the hardening depth, the hardening depth of the gear manufactured using the method of Example 1 was measured by a Vickers hardness tester, and an effective hardening depth of 0.7 to 1.20 mm when Hv 550 was measured. And have the characteristics that are generated. Table 3 and FIG. 3 show the characteristic graph results. This improves the gear quality characteristics by eliminating excessive curing of the tooth tip in the existing high frequency processing.
(Hv 550)
Example of pcd part and tooth bottom curing depth
② Check surface hardness
Table 4 shows the results of confirming the surface hardness. Example 1 The surface hardness of the gears was about Hv (0.3) of about 650 to 800, and the hardness of the surface portion was Hv 80 to 1000, which is the hardness of the nitrogen compound, while the lower portion thereof was a hardened structure transformed into martensite Hv700 ~ 800 and it was confirmed that it has excellent properties with strong abrasion and rigidity.
Example of pcd part and tooth bottom surface hardness measurement
③ Result of residual compressive stress confirmation
The residual compressive stress of the manufactured gear was confirmed and the results are shown in FIG. Compared with the conventional carburizing method, the stress distribution increases by more than 50%. This is because the compressive residual stress is increased due to the hardening due to the transformation on the surface and the hardening on the inside. This is a method that can eliminate this process, which usually requires a sub-step of increasing the compressive residual stress by adding a shot peening method to the carburized material.
(4) Residual compound layer
The residual compound layer of the gear was found to have a thickness of 1 to 3 μm less than the initial generated thickness, which is the thickness of the residual nitrogenized layer after the outline hardening process (FIG. 4). (Fig. 5).
⑤ Gear tooth type change amount result
It can be seen that the post-heating change of the gear manufactured by this method is located between the carburizing heat treatment and the contour hardening heat treatment as shown in the example chart (Fig. 6), and is reduced by 30% or more as compared with the carburizing.
It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.
Claims (6)
Machining the material pretreated in S1 in a gear shape (S2);
A step (S3) of charging the material processed in S2 into a nitriding heat treatment furnace and covering the nitride with a gas nitriding heat treatment process;
(S4) coating the Fe 3 O 4 oxide film by treating the nitride in S 3 and then performing a precipitation treatment in the heat treatment furnace;
(S5) heating the workpiece by applying a double frequency wave after coating the oxide film in S4; And
(S6) a step of cooling the heated material by a method of spraying a coolant;
Said metallic material is carbon steel, alloy steel, or high alloy steel;
When the metal material is carbon steel or alloy steel, the material pretreated in S1
Heating to 840 to 880 캜, followed by quenching with a refrigerant, followed by tempering by tempering;
If the metal material is a high alloy steel, the method further comprises the steps of: heating the material coated with the oxide film in a nitriding atmosphere heat treatment furnace at 500 to 600 ° C to diffuse the nitrogen diffusion layer;
Wherein the refrigerant is a cooling oil prepared by adding a water-soluble polymer to water;
The heat treatment furnace in the step S4 is maintained at 500 to 600 deg.
The step of cooling the material heated in S6 and washing the material, and cooling the heated material in a heating furnace after cooling the material to room temperature, thereby releasing the stress.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20100073602A (en) * | 2008-12-23 | 2010-07-01 | 안전공업주식회사 | Surface treating method of engine valve |
| KR20110000758A (en) * | 2008-05-19 | 2011-01-05 | 고오슈우하네쓰렌 가부시기가이샤 | Iron and steel material having quenched surface layer part, process for producing the iron and steel material, and quenched component |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20110000758A (en) * | 2008-05-19 | 2011-01-05 | 고오슈우하네쓰렌 가부시기가이샤 | Iron and steel material having quenched surface layer part, process for producing the iron and steel material, and quenched component |
| KR20100073602A (en) * | 2008-12-23 | 2010-07-01 | 안전공업주식회사 | Surface treating method of engine valve |
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