A camshaft production process

Abstract

This invention discloses a camshaft manufacturing process, comprising the following steps: S1: Determine the blank, clarifying the machining allowance, dimensional tolerance values, and shape of the blank; S2: Determine the positioning datum of the blank, first determining the rough machining datum and the finish machining datum, and then selecting the rough datum based on the analysis and clarification of the finish machining datum; S3: Rough machining, using milling and lathe equipment to rough machine the blank, cutting out the outer contour shapes of the cam and spindle according to the rough machining datum, and then grinding the camshaft dimensions; S4: Finish machining, first positioning the blank using locating keys, and then using a grinding machine to precisely machine the outer cylindrical surface, cam groove, and oil hole of the camshaft. In this invention, the use of locating keys to position the blank can improve the machining quality of the camshaft, and at the same time, the improved quenching process solves the problems of excessive hardened layer depth difference and quality of soft strips in the transition zone, as well as the problems of camshaft quenching cracking, soft strips, and peeling at the edges and corners.

Description

Technical Field

[0001] This invention relates to the field of camshaft manufacturing technology, and more specifically to a camshaft manufacturing process. Background Technology

[0002] Patent document (CN106837453B) discloses a combined hollow camshaft, including a camshaft body and a combined cam and signal wheel mounted on the camshaft body. Both the combined cam and signal wheel have mounting holes for installation on the camshaft body. The camshaft body, the cam base circle portion of the combined cam, and the toothed portion of the signal wheel are all connected and fixed by a pin structure. The manufacturing process includes the following steps: casting a hollow camshaft body; machining blind holes on the journal corresponding to the cam on the camshaft body; machining stepped holes on the combined cam corresponding to the blind holes on the camshaft body; pressing cam rivets into the corresponding holes on the combined cam and the camshaft body; machining fixing holes on the toothed portion of the signal wheel; machining blind holes on the camshaft body corresponding to the fixing holes; and pressing tapered pins into the fixing holes and corresponding blind holes on the signal wheel. This reduces the difficulty and cost of the manufacturing process. However, it cannot improve the machining quality of camshafts, and it cannot solve the problems of excessive hardened layer depth difference, quality issues of soft strip in transition zone, camshaft quenching cracks, soft strip and edge peeling. Summary of the Invention

[0003] In order to overcome the above-mentioned technical problems, the present invention aims to provide a camshaft manufacturing process that can improve the machining quality of camshaft by using a positioning key to position the blank. At the same time, the improved quenching process solves the problems of excessive hardened layer depth difference, quality of soft strip in transition zone, camshaft quenching cracking, soft strip and peeling at the edges and corners.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A camshaft manufacturing process includes the following steps:

[0006] S1: Determine the blank, and clarify the machining allowance, dimensional tolerance values ​​and shape of the blank;

[0007] S2: Determine the positioning datum of the blank. First, determine the roughing datum and the finishing datum. Then, based on the analysis and clarification of the finishing datum, select the roughing datum.

[0008] S3: Rough machining, the blank is rough machined by milling machine and lathe equipment, the outer contour shape of the cam and the main shaft is cut according to the rough machining reference, and then the camshaft size is ground.

[0009] S4: Precision machining. First, the blank is positioned by a locating key, and then the outer cylindrical surface, cam groove and oil hole of the camshaft are precisely machined by a grinding machine.

[0010] S5: Heat treatment, which alters the microstructure and properties of the camshaft through heating and cooling.

[0011] S6: Inspection and Adjustment. The camshaft is inspected for size, shape and surface quality using various inspection equipment. If dimensional deviations or shape problems are found in the camshaft during the inspection process, an adjustment process is carried out. The adjustment process corrects the camshaft by grinding or cutting to complete the process.

[0012] Preferably, the positioning reference for determining the blank is determined by positioning the blank through the two center holes of the blank.

[0013] Preferably, the step of first positioning the blank using a positioning key includes:

[0014] Set the clamping surface of the grinding machine to an outer diameter of 22mm, and fix the worktable with the chuck of the grinding machine to support the positions with diameters of 32mm and 47.5mm.

[0015] Place the blank on the center rest of the grinding machine, push it into the tip using the center hole of the helical gear, and put the small end of the blank into the chuck. Rotate the blank to make the positioning key and the keyway fit together.

[0016] The hydraulic system causes the chuck's three-jaw chuck to grip the reinforced surface of the 22mm outer diameter and hold the 32mm and 47.5mm outer diameters in place, thus completing the positioning.

[0017] Preferably, the heat treatment includes:

[0018] Pretreatment involves cleaning to remove surface dirt, impurities, and grease;

[0019] Heating is performed through methods such as flame heating, resistance heating, and induction heating, with a heating temperature of 700℃ to 900℃ and a heating time of 45-55 minutes, followed by cooling through methods such as blowing air or spraying.

[0020] Quenching involves first heating the material, then rapidly cooling it down using a coolant during the heating process.

[0021] Tempering involves reheating the quenched camshaft and holding it at a temperature below Ac1 for more than 2 hours, followed by natural cooling to complete the heat treatment.

[0022] Preferably, the sensing via a sensor includes:

[0023] The camshaft is placed vertically, and the two sides of the base circle of the sensor are raised by 4mm.

[0024] The axial and radial clearances between the effective coil of the sensor and the parts are controlled. The clearance between the sensor and the tip of the camshaft is adjusted to 10mm, the clearance between the sensor and the lifting part of the camshaft is adjusted to 4.5mm, and the clearance between the sensor and the base circle of the camshaft is adjusted to 5mm to complete the sensing.

[0025] Preferably, the coolant is a 10%–12% AQ251 water-soluble quenching cooling medium, used at a temperature of 20–30°C, and sprayed at a pressure of 1.2 MPa.

[0026] The beneficial effects of this invention are:

[0027] 1. Using locating keys to position the blank can improve the machining quality of the camshaft. At the same time, the improved quenching process can solve the problems of excessive hardened layer depth difference, quality of soft strip in transition zone, camshaft quenching cracking, soft strip and peeling at the edges. Attached Figure Description

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1 As shown, a camshaft manufacturing process includes the following steps:

[0032] S1: Determine the blank, and clarify the machining allowance, dimensional tolerance values ​​and shape of the blank;

[0033] It should be explained that, in this embodiment of the invention, the camshaft itself experiences complex stress conditions. In actual operation, the load it bears is alternating, and the temperature is often not constant. To ensure its strength and toughness meet usage requirements, it needs an internal fibrous structure; therefore, the blank is determined to be a casting. Based on the actual usage of the camshaft and the corresponding technical requirements, the actual tolerance grade of this part is determined to be ordinary. Further calculation and analysis of the camshaft can basically determine the outer dimensions of the blank: L = 228 mm, D = 45 mm.

[0034] S2: Determine the positioning datum of the blank. First, determine the roughing datum and the finishing datum. Then, based on the analysis and clarification of the finishing datum, select the roughing datum.

[0035] It should be explained that, in this embodiment of the invention, the rough machining datum needs to have a high degree of surface smoothness, and the surface must be free of burrs, rough edges, and surface defects. This rough datum surface can be determined as the φ28 and φ40 surfaces of the shaft. First, the two end faces of the camshaft are machined, and then these are used as the fine datum for subsequent machining processes. For the camshaft part, according to the calculation requirements of its part drawing, the fine machining datum is determined to be the top holes on both end faces of the camshaft. Many surfaces of the part can be used as datums for corresponding machining. Determining the datum also requires adhering to the principle of "datum uniformity," which facilitates safer and more reliable clamping operations, simplifies the machining process, and makes the fixture structures involved in the actual machining of the camshaft more similar, saving time spent manufacturing different fixtures and completing the machining of more surfaces in a single clamping. This method can meet the needs of mass production, facilitate the use of high-efficiency special-purpose machine tools for large-scale production, and ensure improved machining accuracy of each surface of the camshaft.

[0036] Furthermore, the positioning reference for determining the blank is determined by positioning it through the two center holes of the blank, which can avoid positioning errors caused by changing the positioning reference during subsequent processing.

[0037] S3: Rough machining. The blank is rough machined using milling and lathe equipment. The outer contour shape of the cam and the main shaft is cut according to the rough machining reference. Then the camshaft size is ground. The purpose is to make the size and shape of the camshaft meet the design requirements and ensure its surface finish.

[0038] S4: Precision machining. First, the blank is positioned using a locating key. Then, the outer cylindrical surface, cam groove, and oil hole of the camshaft are precisely machined using a grinding machine. The purpose is to improve the dimensional accuracy and surface quality of the camshaft to meet the product's usage requirements.

[0039] Furthermore, the step of first positioning the blank using a positioning key includes:

[0040] Set the clamping surface of the grinding machine to an outer diameter of 22mm, and fix the worktable with the chuck of the grinding machine to support the positions with diameters of 32mm and 47.5mm.

[0041] Place the blank on the center rest of the grinding machine, push it into the tip using the center hole of the helical gear, and put the small end of the blank into the chuck. Rotate the blank to make the positioning key and the keyway fit together.

[0042] The hydraulic system causes the chuck's three-jaw chuck to grip the reinforced surface of the 22mm outer diameter and hold the 32mm and 47.5mm outer diameters in place, thus completing the positioning.

[0043] It should be explained that, in this embodiment of the invention, although the locating key is not a critical positioning element, it plays a vital driving role in the actual machining process. It ensures a good fit between the locating key and the keyway, causing the chuck to rotate as a whole, thus completing the grinding operation on the camshaft. The accuracy of the locating key directly affects the angular displacement of the camshaft, thereby influencing the performance of the camshaft during subsequent engine applications.

[0044] S5: Heat treatment, which alters the microstructure and properties of the camshaft through heating and cooling.

[0045] Furthermore, the heat treatment includes:

[0046] Pretreatment involves cleaning to remove surface dirt, impurities, and grease;

[0047] Heating is performed through methods such as flame heating, resistance heating, and induction heating, with a heating temperature of 700℃ to 900℃ and a heating time of 45-55 minutes, followed by cooling through methods such as blowing air or spraying.

[0048] It should be explained that, in this embodiment of the invention, the heating temperature and heating time need to be controlled during the heating process to ensure that the camshaft achieves the required heat treatment effect.

[0049] Quenching involves first heating the material, then rapidly cooling it down using a coolant during the heating process.

[0050] It should be explained that, in this embodiment of the invention, quenching is another important step in the heat treatment of the camshaft. After being heated to a certain temperature, the camshaft needs to be rapidly cooled to allow its microstructure to undergo a phase transformation.

[0051] Tempering involves reheating the quenched camshaft and holding it at a temperature below Ac1 for more than 2 hours, followed by natural cooling to complete the heat treatment.

[0052] It should be explained that, in this embodiment of the invention, the camshaft after quenching typically exhibits a certain degree of brittleness. To reduce this brittleness and improve toughness, tempering is required. Tempering is achieved by reheating the camshaft and maintaining it at a specific temperature and time. Tempering can adjust the microstructure of the camshaft, thereby improving its toughness and durability.

[0053] Specifically, the sensing via a sensor includes:

[0054] The camshaft is placed vertically, and the two sides of the base circle of the sensor are raised by 4mm.

[0055] The axial and radial clearances between the effective coil of the sensor and the parts are controlled. The clearance between the sensor and the tip of the camshaft is adjusted to 10mm, the clearance between the sensor and the lifting part of the camshaft is adjusted to 4.5mm, and the clearance between the sensor and the base circle of the camshaft is adjusted to 5mm to complete the sensing.

[0056] It should be explained that, in this embodiment of the invention, by optimizing the sensor structure and precisely controlling the heating position, the quenching temperature and hardened layer depth at the base circle can be increased while the quenching temperature and hardened layer depth at the camshaft tip can be reduced, effectively ensuring the hardened layer depth. By reasonably controlling the axial and radial clearance between the effective coil of the sensor and the part, the cam heating temperature tends to be uniform, avoiding the quality problems of excessive hardened layer depth difference between the base circle and the cam lift area and soft band in the transition zone caused by excessive temperature difference between the top of the cam lift and the base circle during cam heating.

[0057] Specifically, the coolant is a 10%–12% AQ251 water-soluble quenching cooling medium, with an operating temperature of 20–30°C and a spray pressure of 1.2 MPa.

[0058] It should be explained that, in the embodiments of the present invention, by effectively controlling the concentration, temperature, cooling time and spray pressure of the quenching cooling medium, defects such as quenching cracks, soft bands and peeling at the edges of the parts are reduced.

[0059] S6: Inspection and Adjustment. The camshaft is inspected for size, shape and surface quality using various inspection equipment. If dimensional deviations or shape problems are found in the camshaft during the inspection process, an adjustment process is carried out. The adjustment process corrects the camshaft by grinding or cutting to complete the process.

[0060] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A camshaft production process, characterized by, Includes the following steps: S1: Determine the blank, and clarify the machining allowance, dimensional tolerance values ​​and shape of the blank; S2: Determine the positioning datum of the blank. First, determine the roughing datum and the finishing datum. Then, based on the analysis and clarification of the finishing datum, select the roughing datum. S3: Rough machining, the blank is rough machined by milling machine and lathe equipment, the outer contour shape of the cam and the main shaft is cut according to the rough machining reference, and then the camshaft size is ground. S4: Precision machining. First, the blank is positioned by a locating key, and then the outer cylindrical surface, cam groove and oil hole of the camshaft are precisely machined by a grinding machine. S5: Heat treatment, which alters the microstructure and properties of the camshaft through heating and cooling. S6: Inspection and Adjustment. The camshaft is inspected for size, shape and surface quality using various inspection equipment. If dimensional deviations or shape problems are found in the camshaft during the inspection process, an adjustment process is carried out. The adjustment process corrects the camshaft by grinding or cutting to complete the process. The positioning reference for determining the blank is determined by positioning the blank through the two center holes of the blank. The first step of positioning the blank using positioning keys includes: Set the clamping surface of the grinding machine to an outer diameter of 22mm, and fix the worktable with the chuck of the grinding machine to support the positions with diameters of 32mm and 47.5mm. Place the blank on the center rest of the grinding machine, push it into the tip using the center hole of the helical gear, and put the small end of the blank into the chuck. Rotate the blank to make the positioning key and the keyway fit together. The hydraulic system causes the chuck's three-jaw chuck to grip the reinforced surface of the 22mm outer diameter and hold the 32mm and 47.5mm outer diameters in place, thus completing the positioning. The heat treatment includes: Pretreatment involves cleaning to remove surface dirt, impurities, and grease; Heating is performed using flame heating, resistance heating, and induction heating methods. The heating temperature is 700℃ to 900℃, and the heating time is 45-55 minutes. Cooling is then achieved through air blowing or spraying. Quenching involves first heating the material, then rapidly cooling it using a coolant during the heating process, and sensing the temperature using an inductor. Tempering involves reheating the quenched camshaft and holding it at a temperature below Ac1 for more than 2 hours, followed by natural cooling to complete the heat treatment. The sensing via a sensor includes: The camshaft is placed vertically, and the two sides of the base circle of the sensor are raised by 4mm. The axial and radial clearances between the effective coil of the sensor and the parts are controlled. The clearance between the sensor and the tip of the camshaft is adjusted to 10mm, the clearance between the sensor and the lifting part of the camshaft is adjusted to 4.5mm, and the clearance between the sensor and the base circle of the camshaft is adjusted to 5mm to complete the sensing. The coolant is a 10%–12% AQ251 water-soluble quenching cooling medium with a working temperature of 20–30°C and a spray pressure of 1.2 MPa.

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