Camshaft, manufacturing method thereof and engine

Abstract

The invention relates to the technical field of engine parts, and discloses a cam shaft, a preparation method thereof and an engine. The cam shaft comprises a shaft body and a cam arranged on the shaft body; the shaft body is made of aluminum alloy, and the aluminum alloy is prepared from the following components in percentage by mass: 0.20 to 0.40 percent of Mn, 0.25 to 0.45 percent of Cu, 0.02 to 0.10 percent of Ti, 0.07 to 0.18 percent of Zr, 5.20 to 7.20 percent of Zn, 1.20 to 2.20 percent of Mg, 0.07 to 0.35 percent of Re and the balance of aluminum; the cam is made of steel or aluminum alloy; when the cam is made of aluminum alloy, the cam and the shaft body are the same in component, the shaft body and the cam are integrally formed, a hard anodic oxidation layer is arranged on the surface of the cam, and tiny holes are formed in the hard anodic oxidation layer and blocked by Teflon. The camshaft provided by the invention has the characteristic of light weight on the premise of meeting the use requirements of an engine.

Description

Technical Field

[0001] The invention relates to the technical field of engine parts, and in particular to a camshaft and a preparation method thereof, and an engine. Background Art

[0002] The camshaft is one of the key components of the engine, and its performance directly affects the engine's working efficiency. Traditional camshafts are mostly made of materials such as cast iron or alloy steel. Although they have high strength, they are heavy and have an adverse effect on the overall weight and fuel economy of the engine.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The object of the present invention is to provide a camshaft, a preparation method thereof and an engine.

[0005] The present invention is achieved in that:

[0006] In a first aspect, the present invention provides a camshaft, comprising a shaft body and a cam arranged on the shaft body;

[0007] The material of the shaft body is a first aluminum alloy, and the composition of the first aluminum alloy is as follows by mass percentage: Mn 0.20-0.40%, Cu 0.25-0.45%, Ti 0.02-0.10%, Zr 0.07-0.18%, Zn 5.20-7.20%, Mg 1.20-2.20%, Re 0.07-0.35%, unavoidable impurities ≤ 0.40% and the balance of aluminum; Re includes Sc, La and Ce, wherein the total mass percentage of La and Ce is 0.07-0.1%, and the balance is Sc;

[0008] The material of the cam is steel or a second aluminum alloy;

[0009] When the material of the cam is the second aluminum alloy, the second aluminum alloy has the same composition as the first aluminum alloy, the shaft and the cam are integrally formed, the surface of the cam has a hard anodized layer, the hard anodized layer has tiny holes, and the tiny holes are blocked by Teflon.

[0010] In an optional embodiment, the hard anodized layer has a thickness of 40 to 60 μm.

[0011] In an optional embodiment, the steel material is 40Cr;

[0012] Optionally, the cam is mounted on the shaft body by interference fit;

[0013] Optionally, Re is at least one of La and Ce;

[0014] Optionally, Re is Sc, La and Ce, the total mass percentage of La and Ce is 0.07-0.1%, and the balance is Sc.

[0015] In a second aspect, the present invention provides a method for preparing a camshaft as in the above-mentioned embodiment, when the material of the cam is steel, comprising:

[0016] A cylindrical shaft body and a cam with a mounting hole are provided. At room temperature, the diameter of the mounting hole is smaller than the diameter of the shaft body. After the cam is heated, the diameter of the mounting hole can be greater than or equal to the outer diameter of the shaft body.

[0017] The heated cam is sleeved on a cylindrical shaft at room temperature, and the cam is cooled to achieve an interference fit with the shaft.

[0018] In an optional embodiment, the preparation method of the shaft body comprises: placing an aluminum alloy ingot in a die of an extruder for extrusion molding, during the extrusion process, maintaining the die temperature at 490-500° C. for 2.5-3.5 hours, the billet temperature at 480-490° C., the die barrel temperature at 440-450° C., the outlet temperature at 495-505° C., and obtaining a rough blank after cooling;

[0019] The rough blank is quenched and aged according to the T6 heat treatment process, and then straightened.

[0020] In a third aspect, the present invention provides a method for preparing a camshaft according to the aforementioned embodiment, when the material of the cam is the second aluminum alloy, comprising:

[0021] A camshaft rough blank is prepared by forging the aluminum alloy raw material;

[0022] The rough camshaft blank is subjected to quenching and aging treatment according to the T6 heat treatment process, and then fine-processed to obtain the initial camshaft product;

[0023] The cam portion of the initial camshaft is subjected to hard anodizing treatment to form a hard anodized layer on the surface of the cam portion;

[0024] A Teflon coating is applied on the surface of the hard anodized layer.

[0025] In an optional embodiment, before the hard oxidation treatment, the method further includes: applying oil or glue to the surface of the camshaft primary product except the cam portion, and then baking to form a protective layer;

[0026] Clean the cam part to remove oil and impurities on the surface.

[0027] In an optional embodiment, the hard oxidation treatment method includes:

[0028] The cam part is used as the anode and placed in the electrolyte to form a hard anodized layer under the action of direct current. The current density is 2.5-3.5A / dm 2 The electrolyte is sulfuric acid, the concentration of sulfuric acid is 100-150 g / L, the bath temperature is -10-0°C, and the time is 1-2 hours.

[0029] In an optional embodiment, the method of coating the Teflon coating on the surface of the hard anodized layer comprises:

[0030] The cam product with a hard anodized layer is placed in a sealing solution and soaked at 85-90° C. for 10-20 minutes. The sealing solution contains Teflon, and the concentration of the Teflon is 4-6 g / L.

[0031] In a fourth aspect, the present invention provides an engine, comprising a camshaft according to the aforementioned embodiment;

[0032] When the engine is a diesel engine, the cam is made of steel;

[0033] When the engine is a gasoline engine, the material of the cam is the second aluminum alloy.

[0034] The present invention has the following beneficial effects:

[0035] The camshaft provided by the present invention can greatly reduce the weight of the camshaft because the shaft body is made of aluminum alloy. After it is installed on the engine, the working efficiency of the engine can be significantly improved. The aluminum alloy provided by the present invention is based on the existing 7 series aluminum alloy. In order to obtain a camshaft that can be applied to the engine, the content of the main chemical elements therein is optimized, and rare earth elements are added. The addition of Sc can increase the recrystallization temperature by 150-200°C to improve the strength of the alloy. The addition of lanthanum and cerium mixed rare earths can improve the intergranular corrosion and stress corrosion performance, improve the corrosion resistance of aluminum alloys, and improve the salt spray corrosion performance of aluminum alloys; in addition, by utilizing the characteristics of rare earth elements with high hydrogen absorption performance, adding trace amounts of lanthanum and cerium mixed rare earths can improve the porosity problem in the casting. Therefore, adding an appropriate amount of multiple rare earth elements in this application can improve the mechanical properties of aluminum alloys such as hardness, strength and elongation. The yield strength of the camshaft provided by the present invention is greater than 500MPa, the tensile strength is greater than 520MPa, and the elongation is greater than or equal to 12%, which can meet the use requirements of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A schematic structural diagram of a camshaft provided in an embodiment of the present invention.

[0038] Icon: 100- camshaft; 110- shaft body; 120- cam; 130- journal; 140- flange; 150- camshaft position sensor signal plate. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0040] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0041] The camshaft, the method for manufacturing the camshaft and the engine provided by the embodiments of the present invention are described in detail below.

[0042] The working contents of the camshaft are;

[0043] 1. Control valve opening and closing: The camshaft, through the shape and position of the cam on it, pushes the valve to open and close on time, so that the cylinder can take in and exhaust air on time. The early opening and late closing of the intake and exhaust valves are to ensure sufficient intake and complete exhaust.

[0044] 2. Impact on engine performance: The design of the camshaft directly affects the engine's power output, fuel economy and emission performance. The side of the cam is egg-shaped, and its design purpose is to ensure sufficient intake and exhaust of the cylinder, while taking into account the durability of the engine and the smoothness of operation.

[0045] 3. Realize valve timing: In theory, in the intake stroke, when the piston moves from the top dead center to the bottom dead center, the intake valve opens and the exhaust valve closes; in the exhaust stroke, when the piston moves from the bottom dead center to the top dead center, the intake valve closes and the exhaust valve opens. But in reality, in order to increase the amount of air intake in the cylinder, the intake valve needs to be opened earlier and closed later; similarly, in order to make the exhaust gas in the cylinder more clean, the exhaust valve also needs to be opened earlier and closed later.

[0046] 4. Improve combustion efficiency: The camshaft can optimize the combustion process, improve fuel utilization, reduce fuel consumption, and reduce harmful emissions by controlling the opening time and lift of the valve.

[0047] Considering that the camshaft itself is heavy and has an adverse effect on the overall weight and fuel economy of the engine, the inventor tried to use aluminum alloy as the manufacturing material of the camshaft. Aluminum alloy can be considered as a manufacturing material for the camshaft due to its advantages such as low density, high specific strength, and good processing performance. However, the strength and elongation of ordinary aluminum alloys are difficult to meet the requirements under engine working conditions. Therefore, how to improve the strength and elongation of aluminum alloys while maintaining the weight advantage so that the camshaft meets the use requirements of the engine is the first problem that needs to be solved when using aluminum alloys as materials.

[0048] The camshaft 100 provided in the embodiment of the present invention comprises a shaft body 110 and a cam 120 disposed on the shaft body 110;

[0049] The material of the shaft body is a first aluminum alloy, and the composition of the first aluminum alloy is as follows by mass percentage: Mn 0.20-0.40%, Cu 0.25-0.45%, Ti 0.02-0.10%, Zr 0.07-0.18%, Zn 5.20-7.20%, Mg 1.20-2.20%, Re 0.07-0.35%, unavoidable impurities ≤ 0.40% and the balance of aluminum; Re includes Sc, La and Ce, wherein the total mass percentage of La and Ce is 0.07-0.1%, and the balance is Sc;

[0050] The material of the cam 120 is steel or the second aluminum alloy;

[0051] When the material of the cam is the second aluminum alloy, the second aluminum alloy has the same composition as the first aluminum alloy, the shaft and the cam are integrally formed, the surface of the cam has a hard anodized layer, the hard anodized layer has tiny holes, and the tiny holes are blocked by Teflon.

[0052] The camshaft provided by the present invention can greatly reduce the weight of the camshaft because the shaft body is made of aluminum alloy. After it is installed on the engine, the working efficiency of the engine can be significantly improved. The aluminum alloy provided by the present invention is based on the existing 7 series aluminum alloy. In order to obtain a camshaft that can be applied to the engine, the content of the main chemical elements therein is optimized, and rare earth elements are added. The addition of Sc can increase the recrystallization temperature by 150-200°C to improve the strength of the alloy. The addition of lanthanum and cerium mixed rare earths can improve the intergranular corrosion and stress corrosion performance, improve the corrosion resistance of aluminum alloys, and improve the salt spray corrosion performance of aluminum alloys; in addition, by utilizing the characteristics of rare earth elements with high hydrogen absorption performance, adding trace amounts of lanthanum and cerium mixed rare earths can improve the porosity problem in the casting. Therefore, adding an appropriate amount of multiple rare earth elements in this application can improve the mechanical properties of aluminum alloys such as hardness, strength and elongation. The yield strength of the camshaft provided by the present invention is greater than 500MPa, the tensile strength is greater than 520MPa, and the elongation is greater than or equal to 12%, which can meet the use requirements of the engine.

[0053] The unavoidable impurities mentioned above are, for example, Fe, Si and Cr, wherein Fe≤0.20%, Si≤0.10% and Cr≤0.10%.

[0054] Optionally, when the cam 120 is made of steel, the steel is 40Cr to provide it with better strength;

[0055] Optionally, when the cam 120 is made of steel, in order to ensure the stability of the assembly of the cam 120 and the shaft body 110 , the cam 120 is installed on the shaft body 110 through interference fit.

[0056] Alternatively, if Figure 1 As shown, the camshaft 100 includes, in addition to the shaft body 110 and the cam 120, a core shaft, a journal, a flange, etc. Specifically, Figure 1 In the structure shown, the parts arranged on the shaft body are the shaft body 110, the cam 120, the flange 140, the journal 130, and the camshaft position sensor signal disk 150. The structure of the camshaft 100 belongs to the prior art and will not be described in detail here. When the cam 120 is made of steel and assembled with the shaft body 110 by interference fit, the other parts on the shaft body can also be made of the same material as the cam 120 and assembled on the shaft body 110 in the same way. When the cam 120 and the shaft body 110 are both made of aluminum alloy and the two are integrally formed, the core shaft, the journal and the flange can also be made of the same material as the cam 120 and be integrally formed with the cam 120.

[0057] The method for preparing the camshaft 100 provided in the embodiment of the present invention, when the material of the cam 120 is steel, comprises:

[0058] A cylindrical shaft body 110 and a cam 120 having a mounting hole are provided. At room temperature, the diameter of the mounting hole is smaller than the diameter of the shaft body 110. After the cam 120 is heated, the diameter of the mounting hole can be greater than or equal to the outer diameter of the shaft body 110.

[0059] The heated cam 120 is sleeved on the cylindrical shaft body 110 at room temperature, and the cam 120 is interference-fitted with the shaft body 110 after cooling.

[0060] Specifically, the preparation method is:

[0061] S1. Squeeze

[0062] At high temperature, the alloy ingot passes through the die of the extruder to extrude the aluminum alloy shaft 110. During the extrusion process, the die temperature is maintained at 490-500°C (e.g., 490°C, 495°C, or 500°C), and the temperature is kept for 2.5-3.5h (2.5h, 3h, or 3.5h), the billet temperature is 480-490°C (480°C, 485°C, or 490°C), the die barrel temperature is 440-450°C (e.g., 440°C, 445°C, or 450°C), the outlet temperature is 495-505°C (e.g., 495°C, 500°C, or 505°C), and a rough blank is obtained after cooling.

[0063] Optionally, the cooling method is mainly water flow, and the straightening rate is 1-3%, which can effectively eliminate the bending, twisting or other shape defects of the material generated in the previous processing process, improve the appearance of the material, improve the mechanical properties of the conduit, and reduce the residual stress inside the material.

[0064] S2. Heat treatment

[0065] The rough blank is quenched and aged according to the T6 heat treatment process, and the mechanical properties of the product are tested.

[0066] S3, Straightening

[0067] After extrusion, aluminum alloy may be bent and needs to be straightened.

[0068] S4. Inspection

[0069] The aluminum alloy after extrusion is subjected to quality inspection, including dimensional accuracy, surface quality, mechanical properties, etc. After the above steps, a shaft body 110 with a complex shape and fine structure is obtained.

[0070] S5. Assembly

[0071] Assemble the various parts such as the mandrel, the steel cam 120, the journal, the flange, etc. At room temperature, there is an interference between the hole of the external part and the outer diameter of the internal shaft body 110. Before assembly, the internal shaft body 110 is cooled, and the cam 120 is heated according to the actual situation to eliminate the interference.

[0072] The combined aluminum alloy camshaft 100 manufactured by the method is about 50% lighter than the conventional steel camshaft 100.

[0073] The method for preparing the camshaft 100 provided in the embodiment of the present invention, when the material of the cam 120 is the second aluminum alloy, comprises:

[0074] A camshaft 100 rough blank is produced by forging the aluminum alloy raw material;

[0075] The rough camshaft 100 is subjected to quenching and aging treatment according to the T6 heat treatment process, and then fine-processed to obtain the initial camshaft 100 product;

[0076] The cam 120 of the first product of the camshaft 100 is subjected to hard anodizing treatment to form a hard anodized layer on the surface of the cam 120;

[0077] A Teflon coating is applied on the surface of the hard anodized layer.

[0078] Specifically, the preparation method is:

[0079] S1. Forging

[0080] The aluminum alloy raw material is forged into a camshaft 100 rough blank and rough-machined.

[0081] S2. Heat treatment

[0082] The camshaft 100 rough blank is subjected to quenching and aging treatment according to the T6 heat treatment process.

[0083] S3, finishing

[0084] After the heat treatment is completed, the aluminum alloy camshaft 100 is finely processed to obtain a primary camshaft 100.

[0085] Specifically, grinding is used, which is the most efficient and accurate camshaft 100 processing method.

[0086] S4, hard anodizing

[0087] (1) The parts of the camshaft 100 that do not require hard anodizing are coated with oil or glue using a fine brush and then placed in an oven for baking to form a protective layer to prevent them from being oxidized during the hard anodizing process.

[0088] The oil is a synthetic oil or lubricant that is resistant to high temperatures and corrosion;

[0089] The applied glue is specifically selected from epoxy resin structural adhesive, 3M special masking tape, and PPI masking tape.

[0090] (2) The cam 120 of the first camshaft 100 is subjected to surface cleaning treatment to remove surface oil and impurities.

[0091] The specific method of surface cleaning is polishing or brushing. This step ensures that the surface of the cam 120 to be hard anodized is clean, providing a good foundation for subsequent anodizing.

[0092] (3) Anodizing

[0093] The cam 120 is used as an anode and placed in an electrolyte to form a hard anodized layer under the action of direct current. The current density is 2.5 to 3.5 A / dm 2 (2.5A / dm 2 、3A / dm 2 or 3.5A / dm 2 ), the electrolyte is sulfuric acid, the sulfuric acid concentration is 100-150g / L (for example, 100g / L, 125g / L or 150g / L), the bath temperature is -10-0°C (optimally -8°C), the time is 1-2h (optimally 1.5h), and a hard anodized layer with a thickness of 40-60μm (for example, 40μm, 50μm or 60μm) is obtained to obtain a first intermediate product.

[0094] (4) Washing

[0095] The first intermediate product is placed in a water washing tank for ultrasonic treatment to remove impurities such as sulfuric acid carried on the first intermediate product.

[0096] S5. Sealing

[0097] After the hard anodizing treatment, although a hard anodized layer is formed, there are tiny pores on the hard anodized layer. In order to improve the adverse effect of the tiny pores on the corrosion resistance, the first intermediate product is subjected to Teflon sealing treatment to form a Teflon coating on its surface, thereby obtaining a second intermediate product.

[0098] The specific sealing method is to place the washed first intermediate product in a sealing tank, wherein the tank contains a sealing solution, wherein the sealing solution is a solution in which Teflon is dissolved, and the concentration of Teflon is 4 to 6 g / L (e.g., 4 g / L, 5 g / L, or 6 g / L). The temperature of the solution in the tank is controlled to be 85 to 90° C. (e.g., 85° C., 88° C., or 90° C.), and the first intermediate product is immersed therein for 10 to 20 minutes (preferably 15 minutes), and then dried to form a Teflon coating on the surface of the first intermediate product.

[0099] Teflon is a polymer material with excellent high temperature resistance, corrosion resistance and anti-adhesion properties. Teflon sealer can fill the tiny holes and defects in the anodized film to form a continuous and uniform protective film, further improving the wear resistance and anti-adhesion properties of the camshaft 100. At the same time, Teflon sealer can also reduce the friction coefficient between the camshaft 100 and other components, reducing energy loss and wear.

[0100] S6. Post-processing

[0101] The second intermediate product is rinsed with deionized water and dried to remove possible residual solutions and contaminants on the surface, and to remove the protective layer on the surface of the portion that does not require hard anodizing treatment, thereby obtaining a finished camshaft 100.

[0102] The mechanical properties of the camshaft 100 manufactured by the method are as follows: tensile strength of 550-650MPa (e.g., 550MPa, 600MPa or 650MPa), and it passes the wear resistance test. The aluminum alloy camshaft not only reduces weight by about 65% compared to conventional steel aluminum alloy camshafts, but also has excellent mechanical properties and wear resistance, and can meet the needs of modern engines for high-performance, lightweight components. In addition, the manufacturing method of the present invention is simple, easy to operate, low-cost and easy to achieve industrial large-scale production.

[0103] The engine provided by the embodiment of the present invention includes the camshaft 100 provided by the embodiment of the present invention.

[0104] Optionally, when the engine is a diesel engine, the cam 120 is made of steel.

[0105] Optionally, when the engine is a gasoline engine, the material of the cam 120 is the second aluminum alloy.

[0106] Example 1

[0107] like Figure 1 As shown, this embodiment provides a camshaft 100, which includes a shaft body 110 and a plurality of cams 120, a journal 130, and a flange 140 arranged on the shaft body 110. The shaft body 110 is made of aluminum alloy, and the materials of other components are steel.

[0108] The specific composition of aluminum alloy is as follows:

[0109] Fe 0.10%, Si 0.05%, Mn 0.30%, Cu 0.30%, Ti 0.06%, Zr 0.12%, Zn 6.20%, Mg 1.70%, Sc 0.1%, La 0.05%, Ce 0.05%, Cr 0.05%, and the balance is aluminum.

[0110] The grade of steel is 40Cr.

[0111] The preparation method is:

[0112] At high temperature, the alloy ingot passes through the die of the extruder to extrude an aluminum alloy shaft 110 with a diameter of 28.5 mm. During the extrusion process, the die temperature is maintained at 495°C for 3 hours, the billet temperature is 485°C, the die barrel temperature is 445°C, the outlet temperature is 500°C, and a rough embryo is obtained after cooling.

[0113] The rough blank is quenched and aged according to the T6 heat treatment process. The specific operation steps and parameters are: water penetration, aging: temperature 120℃, time 24h.

[0114] After that, straightening, inspection and parts assembly are performed to obtain the camshaft 100 .

[0115] Example 2

[0116] The present embodiment provides a camshaft 100 , which includes a shaft body 110 and a plurality of cams 120 , a journal and a flange arranged on the shaft body 110 . The shaft body 110 is made of aluminum alloy, and the materials of other components are steel.

[0117] The specific composition of aluminum alloy is as follows:

[0118] Fe 0.20%, Si 0.10%, Mn 0.20%, Cu 0.45%, Ti 0.1%, Zr 0.07%, Zn 7.20%, Mg 1.20%, Sc 0.07%, La 0.035%, Ce 0.035%, Cr 0.10%, and the balance is aluminum.

[0119] The grade of steel is 40Cr.

[0120] The preparation method is:

[0121] At high temperature, the alloy ingot passes through the die of the extruder to extrude an aluminum alloy shaft 110 with a diameter of 28.5 mm. During the extrusion process, the die temperature is maintained at 490°C for 3.5 hours, the billet temperature is 490°C, the die barrel temperature is 440°C, the outlet temperature is 495°C, and a rough embryo is obtained after cooling.

[0122] The rough blank is subjected to quenching and aging treatment according to the T6 heat treatment process, and the specific operation steps and parameters are the same as those in Example 1.

[0123] After that, straightening, inspection and parts assembly are performed to obtain the camshaft 100 .

[0124] Example 3

[0125] The present embodiment provides a camshaft 100 , which includes a shaft body 110 and a plurality of cams 120 , a journal and a flange arranged on the shaft body 110 . The shaft body 110 is made of aluminum alloy, and the materials of other components are steel.

[0126] The specific composition of aluminum alloy is as follows:

[0127] Fe 0.05%, Si 0.02%, Mn 0.40%, Cu 0.25%, Ti 0.02%, Zr 0.18%, Zn 5.20%, Mg 2.20%, Sc 0.10%, La 0.05%, Ce 0.02%, Cr 0.01%, and the balance is aluminum.

[0128] The grade of steel is 40Cr.

[0129] The preparation method is:

[0130] At high temperature, the alloy ingot passes through the die of the extruder to extrude an aluminum alloy shaft 110 with a diameter of 28.5 mm. During the extrusion process, the die temperature is maintained at 480°C for 2.5 hours, the billet temperature is 500°C, the die barrel temperature is 450°C, the outlet temperature is 505°C, and a rough blank is obtained after cooling.

[0131] The rough blank is subjected to quenching and aging treatment according to the T6 heat treatment process, and the specific operation steps and parameters are the same as those in Example 1.

[0132] After that, straightening, inspection and parts assembly are performed to obtain the camshaft 100 .

[0133] Example 4

[0134] This embodiment provides a camshaft 100, which includes a shaft body 110 and a plurality of cams 120, a journal and a flange arranged on the shaft body 110. The shaft body 110 and the cams 120 arranged thereon and other parts are integrally formed and are made of aluminum alloy.

[0135] The specific composition of the aluminum alloy is the same as that of the aluminum alloy in Example 1.

[0136] The preparation method is specifically as follows:

[0137] The aluminum alloy raw material is forged into a rough blank and rough-machined, and then the camshaft rough blank is quenched and aged according to the T6 heat treatment process;

[0138] The specific operation steps and parameters of the quenching and aging treatment are the same as those in Example 1.

[0139] After the heat treatment is completed, the aluminum alloy camshaft is finely processed to obtain the initial camshaft product;

[0140] For the parts of the camshaft that do not need hard anodizing treatment, use a fine brush to apply epoxy resin structural adhesive and then bake it in an oven at 95°C to form a protective layer;

[0141] The cam 120 of the camshaft 100 is polished, and then the cam 120 is used as an anode and placed in an electrolyte to form a hard anodized layer under the action of direct current. The current density is 3A / dm 2 , the electrolyte is sulfuric acid, the sulfuric acid concentration is 120g / L, the bath temperature is -8°C, the time is 1.5h, and a hard anodized layer with a thickness of 50μm is obtained to obtain a first intermediate product;

[0142] The first intermediate product is placed in a water washing tank for ultrasonic treatment to remove impurities such as sulfuric acid carried by the first intermediate product;

[0143] The washed first intermediate product is placed in a sealing tank, in which there is a sealing solution, which is a solution in which Teflon is dissolved, and the concentration of Teflon is 5g / L. The temperature of the solution in the tank is controlled to be 88°C, and the first intermediate product is immersed in it for 15 minutes, and then dried to form a Teflon coating on the surface of the first intermediate product;

[0144] The second intermediate product is cleaned in a cleaning solution, rinsed with deionized water and dried to obtain a finished camshaft 100.

[0145] Example 5

[0146] This embodiment provides a camshaft 100, which includes a shaft body 110 and a plurality of cams 120, a journal and a flange arranged on the shaft body 110. The shaft body 110 and the cams 120 arranged thereon and other parts are integrally formed and are made of aluminum alloy.

[0147] The specific composition of the aluminum alloy is the same as that of the aluminum alloy in Example 2.

[0148] The preparation method is specifically as follows:

[0149] The aluminum alloy raw material is forged into a rough blank and rough-machined, and then the camshaft 100 rough blank is quenched and aged according to the T6 heat treatment process;

[0150] The specific operation steps and parameters of quenching and aging treatment are the same as those in Example 1;

[0151] After the heat treatment is completed, the aluminum alloy camshaft 100 is finely processed to obtain a primary camshaft 100;

[0152] For the parts of the camshaft 100 that do not need hard anodizing treatment, use a fine brush to apply epoxy resin structural adhesive and then put it into an oven to bake at 95°C to form a protective layer;

[0153] The cam 120 of the camshaft 100 is polished, and then the cam 120 is used as an anode and placed in an electrolyte to form a hard anodized layer under the action of direct current. The current density is 2.5A / dm 2 , the electrolyte is sulfuric acid, the sulfuric acid concentration is 150g / L, the bath temperature is 0°C, the time is 1h, and a hard anodized layer with a thickness of 40μm is obtained to obtain a first intermediate product;

[0154] The first intermediate product is placed in a water washing tank for ultrasonic treatment to remove impurities such as sulfuric acid carried by the first intermediate product;

[0155] The washed first intermediate product is placed in a sealing tank, in which there is a sealing solution, which is a solution containing Teflon, and the concentration of Teflon is 5g / L. The temperature of the solution in the tank is controlled to be 85°C, and the first intermediate product is immersed in it for 20 minutes, and then dried to form a Teflon coating on the surface of the first intermediate product;

[0156] The second intermediate product is cleaned in a cleaning solution, rinsed with deionized water and dried to obtain a finished camshaft 100.

[0157] Example 6

[0158] This embodiment provides a camshaft 100, which includes a shaft body 110 and a plurality of cams 120, a journal and a flange arranged on the shaft body 110. The shaft body 110 and the cams 120 arranged thereon and other parts are integrally formed and are made of aluminum alloy.

[0159] The specific composition of the aluminum alloy is the same as that of the aluminum alloy in Example 3.

[0160] The preparation method is specifically as follows:

[0161] The aluminum alloy raw material is forged into a rough blank and rough-machined, and then the camshaft 100 rough blank is quenched and aged according to the T6 heat treatment process;

[0162] The specific operation steps and parameters of quenching and aging treatment are the same as those in Example 1;

[0163] After the heat treatment is completed, the aluminum alloy camshaft 100 is finely processed to obtain a primary camshaft 100;

[0164] For the parts of the camshaft 100 that do not need hard anodizing treatment, use a fine brush to apply epoxy resin structural adhesive and then put it into an oven to bake at 95°C to form a protective layer;

[0165] The cam 120 of the camshaft 100 is polished, and then the cam 120 is used as an anode and placed in an electrolyte to form a hard anodized layer under the action of direct current. The current density is 3.5A / dm 2The electrolyte is sulfuric acid, the concentration of sulfuric acid is 100 g / L, the bath temperature is -10°C, the time is 2 hours, and a hard anodized layer with a thickness of 60 μm is obtained to obtain a first intermediate product;

[0166] The first intermediate product is placed in a water washing tank for ultrasonic treatment to remove impurities such as sulfuric acid carried by the first intermediate product;

[0167] The washed first intermediate product is placed in a sealing tank, in which there is a sealing solution, which is a solution containing Teflon, and the concentration of Teflon is 5g / L. The temperature of the solution in the tank is controlled to be 90°C, and the first intermediate product is immersed in it for 10 minutes, and then dried to form a Teflon coating on the surface of the first intermediate product;

[0168] The second intermediate product is cleaned in a cleaning solution, rinsed with deionized water and dried to obtain a finished camshaft 100.

[0169] Comparative Example 1

[0170] This embodiment is basically the same as the embodiment 1, except that lanthanum and cerium are replaced by equal amounts of erbium.

[0171] Comparative Example 2

[0172] This comparative example provides an integrally formed steel camshaft 100 , the structure of which is the same as that of the above-mentioned embodiments.

[0173] The steel material is the same as that of the cam 120 in the first embodiment.

[0174] Comparative Example 3

[0175] This comparative example is basically the same as Example 3, except that the Mn content in the aluminum alloy composition is 0.7%.

[0176] Comparative Example 4

[0177] This comparative example is basically the same as Example 2, except that the Cu content in the aluminum alloy composition is 0.7%.

[0178] Comparative Example 5

[0179] This comparative example is basically the same as Example 2, except that the Ti content in the aluminum alloy composition is 0.2%.

[0180] Comparative Example 6

[0181] This comparative example is basically the same as Example 3, except that the content of Zr element in the aluminum alloy composition is 0.3%.

[0182] Comparative Example 7

[0183] This comparative example is basically the same as Example 2, except that the content of Zn element in the aluminum alloy composition is 8%.

[0184] Comparative Example 8

[0185] This comparative example is basically the same as Example 3, except that the Mg content in the aluminum alloy composition is 3%.

[0186] Comparative Example 9

[0187] This comparative example is basically the same as Example 2, except that the aluminum alloy composition does not contain the Mn element.

[0188] Comparative Example 10

[0189] This comparative example is basically the same as Example 3, except that the aluminum alloy composition does not contain the Ti element.

[0190] Comparative Example 11

[0191] This comparative example is basically the same as Example 2, except that the aluminum alloy composition does not contain the Zr element.

[0192] Experimental example

[0193] The performance of the camshaft 100 prepared in each embodiment and comparative example was tested, and the specific test contents were as follows:

[0194] The strength test is carried out using the GB / T 228.1-2021 method.

[0195] Record the test results in Table 1.

[0196] Table 1 Test results of various embodiments and comparative examples

[0197]

[0198]

[0199] It can be seen from the above table that the cam 120 of the camshaft 100 made in each embodiment of the present invention has better strength and elongation.

[0200] Comparing Comparative Example 1 with Example 1, since all rare earth elements in Comparative Example are cerium, the yield strength and tensile strength of the camshaft obtained are significantly deteriorated, indicating that adding lanthanum and cerium to the rare earth elements can increase the strength of the camshaft compared with adding only cerium;

[0201] Comparing Comparative Example 2 with Example 2, Comparative Example 2 is a full steel camshaft, and although its strength is better than that of Example 1, its elongation is significantly worse. Since the camshaft drives the opening and closing of the valve, under the premise that the strength meets the use requirements, the better elongation can further extend its service life. Therefore, compared with Comparative Example 2, Example 2 undoubtedly has the characteristic of long service life; in addition, since the camshaft of Example 2 is made of aluminum alloy, which is lighter than steel, the camshaft of Example 2 is used in the engine with a smaller engine load;

[0202] Comparing Comparative Example 3 with Example 3, the manganese content in Comparative Example 3 is higher, and the yield strength and tensile strength of Comparative Example 3 are significantly lower than those of Example 3, indicating that the manganese content in the aluminum alloy is not within the range required by the present invention, which will reduce the strength;

[0203] Comparing Comparative Example 4 with Example 2, the copper content in the aluminum alloy in Comparative Example 4 is higher, and the yield strength and tensile strength of Comparative Example 4 are significantly lower than those of Example 2, indicating that the copper element in the aluminum alloy is not within the range required by the present invention, which will reduce the strength;

[0204] Comparing Comparative Example 5 with Example 2, the titanium content in the aluminum alloy in Comparative Example 5 is higher, and the yield strength and tensile strength of Comparative Example 5 are significantly lower than those of Example 2, indicating that the titanium element in the aluminum alloy is not within the range required by the present invention, which will reduce the strength;

[0205] Comparing Comparative Example 6 with Example 3, the zirconium content in the aluminum alloy in Comparative Example 6 is relatively high, and the yield strength and tensile strength of Comparative Example 6 are significantly lower than those of Example 2, indicating that the zirconium element in the aluminum alloy is not within the range required by the present invention, which will reduce the strength;

[0206] Comparing Comparative Example 7 with Example 2, the zinc content in the aluminum alloy in Comparative Example 7 is higher, and the yield strength and tensile strength of Comparative Example 7 are significantly lower than those of Example 2, indicating that the zinc element in the aluminum alloy is not within the range required by the present invention, which will reduce the strength;

[0207] Comparing Comparative Example 8 with Example 3, the aluminum alloy in Comparative Example 8 has a higher magnesium content, and the yield strength and tensile strength of Comparative Example 8 are significantly lower than those of Example 3, indicating that the magnesium element in the aluminum alloy is not within the range required by the present invention, which will reduce the strength;

[0208] Comparing Comparative Example 9 with Example 2, the aluminum alloy in Comparative Example 9 does not contain manganese, and the yield strength and tensile strength of Comparative Example 9 are significantly lower than those of Example 2, indicating that the aluminum alloy does not contain manganese, which will reduce the strength;

[0209] Comparing Comparative Example 10 with Example 3, the aluminum alloy in Comparative Example 10 does not contain titanium. The yield strength, tensile strength and elongation of Comparative Example 10 are significantly lower than those of Example 3, indicating that the absence of titanium in the aluminum alloy will reduce the strength and elongation.

[0210] Comparing Comparative Example 11 with Example 2, the aluminum alloy in Comparative Example 11 does not contain zirconium element. The yield strength, tensile strength and elongation of Comparative Example 11 are significantly lower than those of Example 2, indicating that the absence of zirconium in the aluminum alloy will reduce the strength and elongation.

[0211] In summary, the camshaft provided by the present invention can greatly reduce the weight of the camshaft because the material of the shaft body is aluminum alloy. After installing it on the engine, the working efficiency of the engine can be significantly improved. The aluminum alloy provided by the present invention is based on the existing 7 series aluminum alloy. In order to obtain a camshaft that can be applied to the engine, the content of the main chemical elements therein is optimized, and rare earth elements are added. The addition of Sc can increase the recrystallization temperature by 150-200°C to improve the strength of the alloy. The addition of lanthanum and cerium mixed rare earths can improve the intergranular corrosion and stress corrosion performance, improve the corrosion resistance of aluminum alloys, and improve the salt spray corrosion performance of aluminum alloys; in addition, by utilizing the characteristics of rare earth elements with high hydrogen absorption performance, adding trace amounts of lanthanum and cerium mixed rare earths can improve the porosity problem in the casting. Therefore, adding an appropriate amount of multiple rare earth elements in this application can improve the mechanical properties of aluminum alloys such as hardness, strength and elongation. The yield strength of the camshaft provided by the present invention is greater than 500MPa, the tensile strength is greater than 520MPa, and the elongation is greater than or equal to 12%, which can meet the use requirements of the engine.

[0212] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A camshaft, characterized in that: It comprises a shaft body and a cam arranged on the shaft body; The material of the shaft body is a first aluminum alloy, and the composition of the first aluminum alloy is as follows, by mass percentage: Mn 0.20-0.40%, Cu 0.25-0.45%, Ti 0.02-0.10%, Zr 0.07-0.18%, Zn 5.20-7.20%, Mg 1.20-2.20%, Re 0.07-0.35%, unavoidable impurities ≤ 0.40% and the balance of aluminum; Re includes Sc, La and Ce, wherein the total mass percentage d of La and Ce is 0.07-0.1%, and the balance is Sc; The material of the cam is steel or the second aluminum alloy; When the material of the cam is the second aluminum alloy, the second aluminum alloy has the same composition as the first aluminum alloy, the shaft and the cam are integrally formed, the surface of the cam has a hard anodized layer, the hard anodized layer has tiny holes, and the tiny holes are blocked by Teflon.

2. The camshaft according to claim 1, characterized in that The thickness of the hard anodized layer is 40-60 μm.

3. The camshaft according to claim 1, characterized in that: The steel material is 40Cr; Optionally, the cam is mounted on the shaft body by interference fit.

4. A method for preparing a camshaft according to claim 1 or 3, characterized in that: When the material of the cam is steel, it includes: Providing a cylindrical shaft body and a cam having a mounting hole, wherein at room temperature, the diameter of the mounting hole is smaller than the diameter of the shaft body, and after the cam is heated, the diameter of the mounting hole can be greater than or equal to the outer diameter of the shaft body; The heated cam is sleeved on the cylindrical shaft body at room temperature, and the cam is cooled to achieve interference fit with the shaft body.

5. The preparation method according to claim 4, characterized in that: The preparation method of the shaft body comprises: placing an aluminum alloy ingot in a die of an extruder for extrusion molding, during the extrusion process, maintaining the die temperature at 490-500° C. for 2.5-3.5 hours, the billet temperature at 480-490° C., the die barrel temperature at 440-450° C., the outlet temperature at 495-505° C., and obtaining a rough blank after cooling; The rough blank is subjected to quenching and aging treatment according to the T6 heat treatment process, and then straightened.

6. A method for preparing a camshaft according to claim 1 or 2, characterized in that: When the material of the cam is the second aluminum alloy, it includes: A camshaft rough blank is prepared by forging the aluminum alloy raw material; The rough camshaft blank is subjected to quenching and aging treatment according to the T6 heat treatment process, and then fine-processed to obtain a primary camshaft product; The cam portion of the camshaft product is subjected to hard anodizing treatment to form a hard anodized layer on the surface of the cam portion; A Teflon coating is coated on the surface of the hard anodized layer.

7. The preparation method according to claim 6, characterized in that: Before the hard oxidation treatment is performed, the method further includes: applying oil or glue to the surface of the camshaft product except the cam portion, and then baking to form a protective layer; The cam part is cleaned to remove oil and impurities on the surface.

8. The preparation method according to claim 6, characterized in that: Hard anodizing treatment methods include: The cam part is used as an anode and placed in an electrolyte to form a hard anodized layer under the action of direct current. The current density is 2.5-3.5A / dm 2 The electrolyte is sulfuric acid, the concentration of sulfuric acid is 100-150 g / L, the bath temperature is -10-0°C, and the time is 1-2 hours.

9. The preparation method according to claim 6, characterized in that: The method for coating the Teflon coating on the surface of the hard anodized layer comprises: The cam product with a hard anodized layer is placed in a sealing solution and soaked at 85-90° C. for 10-20 minutes. Teflon is dissolved in the sealing solution, and the concentration of the Teflon is 4-6 g / L.

10. An engine, characterized in that: comprising the camshaft as claimed in claim 1; When the engine is a diesel engine, the material of the cam is the steel material; when the engine is a gasoline engine, the material of the cam is the second aluminum alloy.

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