CN113528793B - Camshaft strengthening treatment process - Google Patents
Camshaft strengthening treatment process Download PDFInfo
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- CN113528793B CN113528793B CN202110801450.0A CN202110801450A CN113528793B CN 113528793 B CN113528793 B CN 113528793B CN 202110801450 A CN202110801450 A CN 202110801450A CN 113528793 B CN113528793 B CN 113528793B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/30—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for crankshafts; for camshafts
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2251/00—Treating composite or clad material
- C21D2251/02—Clad material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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Abstract
The invention discloses a camshaft strengthening treatment process, which belongs to the field of machining and comprises the following steps: blanking, normalizing, mechanically rough machining, straightening, stress-relieving tempering, laser melting quenching strengthening, mechanically finish machining, warehousing of finished products, normalizing the whole camshaft, and strengthening the cam and the shaft diameter by laser melting quenching. By adopting the treatment process, the surface hardness, the wear resistance and the contact fatigue resistance of the camshaft are improved, and the working condition requirements of a high-power, high-detonation pressure and high-reliability heavy-load engine are met.
Description
Technical Field
The invention belongs to the field of machining, and relates to a camshaft strengthening treatment process.
Background
The camshaft is an important driving and controlling part of the engine, and the main body of the camshaft is a cylindrical rod body with the same length as the cylinder group, and is provided with a plurality of cams and shaft diameters. It has a great influence on the reliability, the use efficiency and the service life of the engine. When the camshaft works, the intake and exhaust valves are accurately opened and closed at regular time according to the gas distribution phase, relative sliding friction is generated between the cam and the ejector rod, the profile of the cam is in a boundary lubrication or mixed lubrication state, and the formed lubrication film is thin and uneven, so that the cam surface often has failure modes such as scratch, pitting corrosion, rapid wear and the like. With the increasing power of engines and the increasing emission requirements of the environment, increasing the intake pressure by turbocharging has been one of the main ways to improve the performance of engines. The improvement of the air inlet and exhaust pressure of the engine also leads to the great improvement of the contact stress between the camshaft cam and the valve ejector rod. In order to ensure that the engine service performance, the service life and the emission index meet the regulations, the camshaft is required to have sufficient toughness and rigidity, and also have good contact fatigue resistance, scratch resistance and wear resistance.
The engine camshaft generally adopts materials such as nodular cast iron, alloy cast iron, steel and the like, and adopts strengthening treatment technologies such as an induction quenching treatment technology, a gas nitriding (carburizing) technology, a surface vapor deposition technology and the like, and then is polished, but the processes have the problems of more process parameter influence factors, uneven quenching layer, large deformation, subsequent processing, complex process, low efficiency, serious pollution and the like.
The whole quenching after carburization produces uneven depth of an effective hardened layer, the carburization time is as long as nearly 30 hours, the nitriding technology is adopted for a longer time, the camshaft can be greatly deformed due to long-time heating and heat preservation, and the surface can be decarburized in the cooling process. In order to ensure the product performance, the subsequent processing amount after induction quenching, carburizing quenching and the like is within the range of 0.5-1mm, the subsequent processing efficiency is low due to higher surface hardness, and the hardened layer with the most wear-resistant and optimal contact fatigue performance is removed due to the deformation problem, so that the finished product on the surface of the camshaft has lower hardness and poorer contact fatigue resistance. Oil quenching is adopted for integral quenching, a large amount of oil smoke is easily generated, and ammonia gas is adopted as a carrier of N atoms in the nitriding process, so that severe environmental pollution can be caused. The surface structure of the camshaft formed by quenching into an acicular martensite structure has the advantages of high hardness, good wear resistance and the like, but the surface structure cannot play the greatest advantage because of subsequent grinding and polishing removal, and meanwhile, the core structure is not refined due to poor cooling conditions, so that a coarse ferrite structure generated by long-time carburization remains. Therefore, a processing technology for strengthening treatment of the camshaft is urgently needed at present, the surface hardness, the wear resistance and the contact fatigue resistance of the distribution camshaft can be improved, and the working condition requirements of a high-power, high-detonation pressure and high-reliability heavy-load engine are met.
Disclosure of Invention
The invention provides a camshaft processing technology with integral heat treatment and surface laser composite reinforcement, which improves the surface hardness, wear resistance and contact fatigue resistance of the camshaft and meets the working condition requirements of a heavy-load engine with high power, high detonation pressure and high reliability.
In order to achieve the purpose, the invention adopts the technical scheme that:
a camshaft strengthening treatment process comprises the following steps: blanking, normalizing, mechanically rough machining, aligning, stress relieving tempering, laser melting quenching strengthening, mechanically finish machining, warehousing of finished products, normalizing the whole camshaft, and strengthening the cam and the shaft diameter by laser melting quenching.
The technical scheme of the invention is further improved as follows: the laser melting and quenching process comprises the following steps:
s1: cleaning the surface of the camshaft;
s2: uniformly brushing a light absorption coating on the surface of the camshaft;
s3: fixing the processed camshaft on laser fusing equipment, rapidly scanning by laser beams, and heating the surface of the camshaft to be higher than the melting temperature;
s4: after the laser beam scans, the melting layer of the camshaft is subjected to self-condensation solid crystallization.
The technical scheme of the invention is further improved as follows: the quenching numerical control system of the laser fusing equipment controls the camshaft to rotate and move, and the laser processing system adopts a helium-neon laser to perform accurate positioning and is matched with a light guide system to perform laser strengthening processing.
The technical scheme of the invention is further improved as follows: the laser fusing process parameters in the step S3 are as follows: the laser output power is 3kW, the defocusing amount is 220mm, and the scanning speed is 1.4-1.8m/min.
The technical scheme of the invention is further improved as follows: and step S3, a servo motor of the quenching numerical control system accurately controls the light guide system to follow up and down, and defocusing amount is kept consistent.
The technical scheme of the invention is further improved as follows: the light absorption coating in step S2 is a white silica light absorption coating, and is diluted with alcohol (dilution ratio 1.
The technical scheme of the invention is further improved as follows: and (3) heating the mixture by adopting a trolley furnace for normalizing at 850-890 ℃, keeping the temperature for 3 hours, then discharging the mixture out of the furnace, adopting a spray and fan to perform forced air cooling double cooling, and detecting the hardness.
The technical scheme of the invention is further improved as follows: the diameter of the light spot in the laser fusing and quenching process in the step S3 is 5mm.
The technical scheme of the invention is further improved as follows: the allowance of mechanical finishing is 0.05-0.1mm.
The technical scheme of the invention is further improved as follows: the cam and the shaft diameter of the finished camshaft are provided with 2-3 laser fusing scanning belts.
Due to the adoption of the technical scheme, the invention has the following technical effects:
the camshaft integral heat treatment and surface laser melting quenching composite strengthening process method replaces carburizing quenching and medium frequency induction quenching, and the metallographic structure of the surface layer of the camshaft treated by the process obtains superfine hidden needle martensite, so that the surface of the finished camshaft obtains high hardness and uniform depth of a hardened layer, the high wear resistance and high fatigue resistance of the product are ensured, meanwhile, the oil smoke environmental pollution caused by integral quenching is eliminated, and the risk factor of early failure of the engine caused by abnormal wear of the gas distribution camshaft in the prior art is completely eliminated.
The cam of the finished camshaft is provided with 3 laser melting scanning belts, the friction surface of the whole cam is hard and soft, the hardening belt can play a role of a hard framework and is wear-resistant, and the soft belt can store oil to play a role of lubrication and reduce the wear loss. Because the friction surface of the cam is in surface contact, the soft belt existing between the laser scanning belts is favorable for oil storage, cooling and lubrication.
Drawings
FIG. 1 is a metallographic structure drawing of a laser-hardened layer of the camshaft diameter after being treated by the strengthening process of the present invention;
FIG. 2 is a metallographic structure drawing of a laser-hardened layer of a camshaft cam after being subjected to a strengthening process according to the present invention.
Detailed Description
The technical solution of the present invention will be described in detail with reference to specific examples.
A camshaft strengthening treatment process comprises the following steps: blanking, normalizing, mechanically rough machining, straightening, stress-relieving tempering, laser melting quenching strengthening, mechanically finish machining, warehousing of finished products, normalizing the whole camshaft, and strengthening the cam and the shaft diameter by laser melting quenching.
The laser melting quenching process comprises the following steps:
s1: cleaning the surface of the camshaft;
s2: uniformly brushing a light absorption coating on the surface of the camshaft;
s3: the quenching numerical control system is used for controlling the camshaft to rotate and move, the laser processing system adopts a helium-neon laser for accurate positioning and is matched with the light guide system for laser strengthening processing.
The quenching numerical control system of the laser melting equipment controls the camshaft to rotate and move through the turntable and the supporting frame, and the laser processing system adopts a helium-neon laser to perform accurate positioning and is matched with a light guide system to perform laser strengthening processing. And step S3, a servo motor of the quenching numerical control system accurately controls the light guide system to follow up and down, and defocusing amount is kept consistent.
The laser fusing process parameters are as follows: the laser output power is 3kW, the defocusing amount is 220mm, and the scanning speed is 1.4-1.8m/min.
In the step S2, the light absorption coating is white silicon dioxide light absorption coating, and alcohol is used according to a dilution ratio of 1:2, carrying out diluted brush coating, namely, the using amount of the alcohol is 2 times of the mass of the coating.
Example 1
Blanking a camshaft, integrally heating the camshaft by adopting a trolley furnace in a normalizing way, keeping the heating temperature at 850 ℃ for 3h, forcibly cooling the camshaft by adopting a spraying and air-blowing machine after discharging, detecting the hardness of 229HB, machining the camshaft and the diameter of the camshaft, straightening and stress relieving and tempering at 200 ℃. The laser melting quenching adopts 5kW carbon dioxide laser equipment, the diluted white silica light absorption coating is uniformly coated on the cam and shaft diameter surfaces of the cam shaft after cleaning, melting strengthening processing is started after laser positioning, and the process parameters are as follows: the laser power is 3kW, the defocusing amount is 220mm, the scanning speed is 1.4m/min, and the diameter of a light spot is 5mm. And air cooling is carried out after the laser fusing, and the step is finished. The surface hardness of the camshaft is measured to be 657HV, and the depth of a hardened layer is 0.94mm. And (5) performing fine grinding until the size of a finished product is obtained, wherein the machining allowance is 0.07mm.
Example 2
Blanking a camshaft, integrally heating the camshaft by adopting a trolley furnace in a normalizing way, keeping the heating temperature at 890 ℃, keeping the temperature for 3h, forcibly cooling the camshaft by adopting a spraying and air-blowing machine after discharging, detecting the hardness to be 235HB, machining the camshaft and the diameter of the camshaft, straightening and stress-relieving tempering at 200 ℃. The laser melting quenching adopts 5kW carbon dioxide laser equipment, diluted white silica light absorption coating is uniformly coated on the cam and shaft diameter surfaces of the cam shaft after cleaning, melting strengthening processing is started after laser positioning, and the process parameters are as follows: the laser power is 3kW, the defocusing amount is 220mm, the scanning speed is 1.5m/min, and the diameter of a light spot is 5mm. And air cooling is carried out after the laser fusing, and the step is finished. The surface hardness of the camshaft was measured to be 661HV, and the depth of the hardened layer was 1.0mm. And (5) performing fine grinding until the size of a finished product is obtained, wherein the machining allowance is 0.05mm.
Example 3
Feeding a cam shaft, integrally heating by adopting a trolley furnace in the normalizing process, keeping the heating temperature at 880 ℃, preserving the heat for 3 hours, forcibly cooling by adopting a spraying and air-blowing machine after discharging, detecting the hardness to be 232HB, machining the cam shaft and the shaft diameter, straightening, and applying stress relieving tempering at 200 ℃. The laser melting quenching adopts 5kW carbon dioxide laser equipment, the diluted white silica light absorption coating is uniformly coated on the cam and shaft diameter surfaces of the cam shaft after cleaning, melting strengthening processing is started after laser positioning, and the process parameters are as follows: the laser power is 3kW, the defocusing amount is 220mm, the scanning speed is 1.8m/min, and the diameter of a light spot is 5mm. And air cooling is carried out after the laser fusing, and the step is finished. The surface hardness of the camshaft is detected to be 670HV, and the depth of the hardened layer is 1.0mm. And (5) performing fine grinding until the size of a finished product is obtained, wherein the machining allowance is 0.1mm.
Example 4
Blanking a camshaft, integrally heating the camshaft by adopting a trolley furnace in a normalizing way, keeping the heating temperature at 890 ℃, keeping the temperature for 3h, forcibly cooling the camshaft by adopting a spraying and air-blowing machine after discharging, detecting the hardness of 240HB, machining the camshaft and the diameter of the camshaft, straightening and stress relieving and tempering at 200 ℃. The laser melting quenching adopts 5kW carbon dioxide laser equipment, diluted white silica light absorption coating is uniformly coated on the cam and shaft diameter surfaces of the cam shaft after cleaning, melting strengthening processing is started after laser positioning, and the process parameters are as follows: the laser power is 3kW, the defocusing amount is 220mm, the scanning speed is 1.6m/min, and the diameter of a light spot is 5mm. When the laser melting is carried out, the displacement between the scanning belts is controlled, for example, the interval between two scanning belts is set to be 3mm, the second scanning belt is started, the third scanning belt is controlled to be air-cooled after the laser melting is carried out, and the laser melting scanning step is finished. The surface hardness of the camshaft is measured to be 660HV, and the depth of the hardened layer is 0.96mm. And (5) performing fine grinding until the size of a finished product is obtained, wherein the machining allowance is 0.1mm. The cam of the finished camshaft is provided with three laser scanning belts, the friction surface of the whole cam is hard and soft, the hardened belt can play a role in hardness and abrasion resistance, the soft belt can store oil to play a role in lubrication and reduce the abrasion loss, and the soft belts between the scanning belts are in surface contact, so that the oil storage, cooling and lubrication are facilitated.
The gas distribution camshaft adopts the technical scheme of integral normalizing and laser melting and quenching composite strengthening heat treatment, and is subjected to multi-round process parameter optimization, processing and detection. The surface hardness, effective hardening layer depth, deformation, subsequent processing amount, metallographic structure and other technical indexes are analyzed and compared, and the method is obviously superior to carburizing quenching and medium frequency induction quenching. As shown in fig. 1 and 2, the metallographic structure of the camshaft prepared in example 1 is shown in the drawings, it can be seen from the drawings that the central structure of the camshaft treated by the process of the present application is pearlite + ferrite, the intermediate transition structure is martensite + troostite + ferrite, and the surface structure is ultra-fine martensite, the gas distribution camshaft adopts the process scheme of the overall normalizing and laser melting quenching composite strengthening heat treatment, so that the surface hardness of the finished camshaft can reach above 650HV, the effective hardening depth reaches above 0.9mm, the deformation is only 0.02mm, the subsequent machining allowance is only 0.05-0.1mm, the surface metallographic structure obtains ultra-fine needle-like martensite, and the oil smoke environmental pollution caused by the overall quenching is eliminated. The surface of the finished distribution camshaft obtains high hardness and uniform depth of a hardened layer, and high wear resistance and high fatigue resistance of the product are ensured.
The invention can also be popularized and applied to the improvement of the quality reliability of other parts similar to slender shafts using carburizing quenching and induction quenching processes, and has wider popularization and application range.
Claims (9)
1. A camshaft strengthening treatment process comprises the following steps: blanking, normalizing, mechanical rough machining, straightening, destressing tempering, laser melting quenching strengthening, mechanical finish machining and finished product warehousing, and is characterized in that: normalizing the whole camshaft, strengthening the camshaft and the diameter of the camshaft by laser melting and quenching, keeping the temperature for 3 hours at the normalizing heating temperature of 850-890 ℃, and then discharging from a furnace, carrying out double cooling by adopting spraying and forced air cooling by a fan, and detecting the hardness; the laser fusing equipment comprises a quenching numerical control system, the quenching numerical control system of the laser fusing equipment controls a cam shaft to rotate and move, and a laser fusing scanning belt is arranged on the diameter of a cam and a shaft of a finished product cam shaft.
2. The camshaft strengthening treatment process according to claim 1, wherein: the laser melting and quenching process comprises the following steps:
s1: cleaning the surface of the camshaft;
s2: uniformly brushing a light absorption coating on the surface of the camshaft;
s3: fixing the processed camshaft on laser fusing equipment, and rapidly scanning by using a laser beam to heat the surface of the camshaft to be higher than the melting temperature;
s4: after the laser beam is scanned, the melting layer of the camshaft is subjected to self-condensation solid crystallization.
3. The camshaft strengthening treatment process according to claim 2, wherein: the laser processing system adopts a helium-neon laser for accurate positioning and is matched with a light guide system for laser strengthening processing.
4. A camshaft reinforcement treatment process according to any one of claims 1 to 3, characterized in that: the laser fusing process parameters in the step S3 are as follows: the laser output power is 3kW, the defocusing amount is 220mm, and the scanning speed is 1.4-1.8m/min.
5. The camshaft strengthening treatment process according to claim 1, wherein: and step S3, a servo motor of the quenching numerical control system accurately controls the light guide system to follow up and down, and defocusing amount is kept consistent.
6. The camshaft strengthening treatment process according to claim 2, wherein: the light absorption coating in the step S2 is white silicon dioxide light absorption coating, and the ratio of alcohol to water is 1: dilution was carried out at a ratio of 2.
7. The camshaft strengthening treatment process according to claim 1, wherein: the normalizing is carried out by a trolley furnace.
8. The camshaft strengthening treatment process according to claim 4, wherein: the diameter of the light spot in the laser fusing and quenching process in the step S3 is 5mm.
9. The camshaft strengthening treatment process according to claim 1, wherein: the allowance of mechanical finishing is 0.05-0.1mm.
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