Front output flange of transfer case and machining method

Abstract

The invention provides a transfer case front output flange and a machining method, and belongs to the technical field of part machining. Comprising the steps that first heat treatment is conducted on a blank, and second heat treatment is conducted on a machined to-be-machined output flange; turning the to-be-machined output flange in a rough machining and finish machining manner; adjusting the original coordinate system by adopting a preset compensation calculation method; sequentially milling the flange, the plurality of spherical grooves and the threaded connecting holes by adopting a preset indexing method; a spline is machined according to preset gear parameters; performing third heat treatment; then, a fourth end face and a third journal are machined; when the preset condition is met, the first inner hole is machined according to a second preset machining parameter; and the output flanges to be machined are sequentially subjected to hard turning to form parts. The technical problem that in the prior art, a mature machining process for the front output flange is lacked is solved, the part precision is guaranteed, meanwhile, the machining time is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of transfer case parts processing, and in particular to a transfer case front output flange and a processing method thereof. Background Art

[0002] The four-wheel drive transfer case is an important rotating component widely used in mid-to-high-end four-wheel drive vehicles. The core technology of the four-wheel drive transfer case assembly lies in the processing technology of the shaft and gear parts. At present, there is a lack of mature processing technology in China, and foreign technology is basically introduced, and it has not been fully digested and absorbed. In particular, the key technologies of lightweight, service life, and NVH of parts have become a problem that hinders the rapid development of domestic independent automobile brands. Improving the control of the core technology of the four-wheel drive transfer case is an important goal of technological innovation.

[0003] Document CN105583590A discloses a method for processing a cylindrical gear shaft using 4Cr5MoSiV1 as a material. The key technologies of the processing process are as follows: (1) Melting the die-cast cylindrical gear shaft blank, first preheating the central furnace, placing the ingredients into the furnace to obtain a molten alloy, then placing the molten alloy into a holding furnace, applying a rotating magnetic field to the periphery of the molten alloy to generate induced eddy currents in the molten alloy, and using a feed magnetic field generator to pump the molten alloy into the holding furnace of the die-casting machine and keep it warm for 30 seconds to 15 minutes in a nitrogen atmosphere. Then, hot die casting is performed, the temperature is controlled at 500-550℃, the alloy melt is input into the die casting mold for die casting, and the temperature of the die casting mold is 100-200 degrees; (2) the cylindrical gear shaft is rough-machined, the end face is turned, the outer circle is turned, the center hole is drilled, and the other end face and outer circle are turned. During the processing, lubricating fluid is introduced and sprayed on the surface of the workpiece and the tool head to prevent the formation of mechanical tumors and take away the heat generated by the processing. The surface roughness is Ra=0.5-1.3μm; (3) the cylindrical gear shaft after fine processing is Aging treatment is performed by pre-quenching method, first cooling with aqueous solution and then air cooling, and then tempering treatment is performed, and low temperature (200-250℃) tempering is used to make its hardness 60-62HRC; (4) Carburizing treatment is performed by medium temperature gas carburizing, that is, acetone is dripped into the gas carburizing furnace as a carburizing agent, the temperature is controlled at 830-850℃, the temperature is kept for 1.4-2.5h, and the carburizing depth is slowly cooled to 0.8-1.2mm; (5) Anticorrosive treatment is a kind of anticorrosive agent made of acid, alkali and salt, and the anticorrosive concentration is HCl0. 3-3%, H3PO4 10-20%, H2SO4 50-70%, NCl4-5%, KaNO3 7-10%, Ni(NO3)2 3-5%, alkyl alcohol phthalamide 3-5%, hexamethylenetetramine 0.1-0.2%, and the rest is water, wherein H2SO4 acts as an oxidant, alkyl alcohol phthalamide acts as an active agent, and hexamethylenetetramine is a preservative. The preservative is stirred and mixed evenly and then sprayed on the surface of the cylindrical gear shaft. The coating thickness is 10-15μm, and then it is air-dried in the air after being rinsed with clean water.

[0004] In a method for processing cylindrical gear shafts made of 4Cr5MoSiV1, the technical problem to be solved is that "some turbine shafts or bevel gear shafts not only have large vibrations, energy loss and affect work, but also cause oil leakage and other problems in the machine, which also affect the normal operation of the machine, often forcing the machine to be stopped for maintenance, resulting in reduced production efficiency". The measure adopted is to provide a hot die casting method to improve the use characteristics of the gears, and no improvement methods or technical innovations are provided in terms of mechanical processing. Although this method can solve the above problems, it is limited to the processing of ordinary cylindrical gears with low gear precision requirements, and is limited to the processing of gears made of 4Cr5MoSiV1, and is not suitable for the processing of precision parts such as four-wheel drive transfer cases.

[0005] Based on the above content, it can be seen that there is currently a lack of effective solutions. Summary of the invention

[0006] The purpose of this application is to provide a transfer case front output flange and a processing method, which overcomes the problem of lack of mature processing technology for the front output flange in the prior art. The specific solution is as follows:

[0007] A method for processing a front output flange of a transfer case comprises the following steps:

[0008] Step 1: performing a first heat treatment on the forged blank, performing rough processing on the blank subjected to the first heat treatment to form an output flange before processing, and performing a second heat treatment on the output flange before processing;

[0009] Step 2: rough machining and finishing are used to turn the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, the fourth journal, the fifth journal and the first inner hole of the output flange to be machined;

[0010] Step 3: Using a preset compensation calculation method to obtain an error compensation value, and adjusting the original coordinate system based on the error compensation value to form a milling machining coordinate system;

[0011] Step 4: Based on the milling machining coordinate system, the flange, several spherical grooves and threaded connection holes are milled in sequence using a preset indexing method;

[0012] Step 5: According to the preset gear parameters, the second journal of the output flange to be processed is processed to form a spline;

[0013] Step 6: Perform a third heat treatment on the output flange before processing;

[0014] Step 7: Processing the fourth end surface of the output flange to be processed and the third journal according to the first preset processing parameters;

[0015] Step 8: When the preset conditions are met, the first inner hole is processed according to the second preset processing parameters;

[0016] Step 9: The first journal, the second journal, the third journal, the fourth journal, the third end face and the fourth end face of the front output flange to be processed are precision hard turned to form the front input flange.

[0017] In some specific embodiments, the step 1 specifically includes:

[0018] Performing normalizing and high-temperature tempering treatment on the forged blank until the hardness of the blank reaches a preset hardness value;

[0019] The blank subjected to the first heat treatment is rough-machined to form an output flange to be machined, which has a shaft end face, a shaft outer circle, a step face, a tooth outer circle and a tooth end face; wherein the shaft end face is reserved with a first machining allowance; and the shaft outer circle, the step face, the tooth outer circle and the tooth end face are reserved with a second machining allowance;

[0020] The output flange is subjected to aging treatment and high temperature tempering treatment before processing.

[0021] In some specific embodiments, the step 2 comprises:

[0022] Performing turning processing on the first end surface, and using the processed first end surface as a first reference surface, processing a center hole of the first end surface;

[0023] The third end face, the fourth end face, the first journal, the second journal, the third journal and the fourth journal are processed; wherein the first journal, the second journal and the fourth journal are reserved with a third processing allowance; the third journal is reserved with a fourth processing allowance; the third end face and the fourth end face are reserved with a fifth processing allowance;

[0024] When the runout of any journal is detected to be less than a first preset value, the second end face is processed; wherein the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, and the fourth journal are finely processed according to the first preset parameters;

[0025] The first inner hole is processed by using the second end surface as the second reference surface; wherein the first inner hole is finely processed according to the second preset parameter and a sixth processing allowance is reserved;

[0026] The fifth journal is machined, wherein the fifth journal is finish-machined based on the first preset parameters.

[0027] In some specific embodiments, the step 3 comprises:

[0028] Switch turning to milling, perform test hole processing on any threaded connection hole to be processed, and measure the coordinate value of the test hole;

[0029] Acquire the coordinate value of the first inner hole processed by turning, and use the coordinate value of the first inner hole processed by turning as a reference point;

[0030] Subtract the difference between the coordinate value of the test hole and the coordinate value of the first inner hole from the preset standard value to obtain an error compensation value;

[0031] The original coordinate system is adjusted according to the error compensation value to form the milling machining coordinate system.

[0032] In some specific embodiments, step 4 includes:

[0033] Set the origin of the rotary axis, start the rotary axis indexing function, and use the first ball end mill to process several flanges;

[0034] Using a second ball end milling cutter to process a plurality of spherical grooves;

[0035] Process the bottom hole of the threaded connection hole and tap it.

[0036] In some specific embodiments, step 6 includes:

[0037] Step 61: heat treatment is performed using a low-pressure vacuum carburizing and quenching process, specifically including:

[0038] Step 610: setting the carburizing temperature to 980-1000° C.; feeding carburizing gas during the low-pressure carburizing stage; wherein the carburizing gas is acetylene with a purity of 96%;

[0039] Step 611: Maintaining the preset pressure for 30 min to 60 min;

[0040] Step 612: extracting gas from the vacuum chamber until the high vacuum degree in the vacuum chamber reaches a vacuum diffusion stage;

[0041] Step 613: Repeat steps 610-612 until the hardened layer depth, surface hardness and core hardness of the output flange before processing meet the design values.

[0042] In some specific embodiments, step 6 further includes:

[0043] Taking the first inner hole and the center hole as reference, the output flange to be processed before the third heat treatment is subjected to micro-deformation straightening and center hole fine grinding until the runout of any journal detected is less than the second preset value.

[0044] In some specific embodiments, the step 7 specifically includes:

[0045] The input flange to be processed is fixed by a double center method, and the third journal and the fourth end face are rough-machined and hard-turned according to the first preset processing parameters; wherein the third journal is reserved with a first margin;

[0046] Accordingly, step 8 includes:

[0047] The third journal is clamped, and the fourth end face is used as an axial positioning reference. When the detected runout of any journal is less than the third preset value, the first inner hole is finely machined according to the second preset machining parameters.

[0048] In some specific embodiments, step 9 includes:

[0049] Step 901: Clamp the input flange to be processed by double centering method;

[0050] Step 902: performing precision hard turning on the fourth end surface;

[0051] Step 903: Obtaining an axial compensation value according to an axial compensation method;

[0052] Step 904: Compensate to the origin coordinate of the milling machining coordinate system according to the axial compensation value;

[0053] Step 905: According to the compensated origin coordinates, precision hard turning is performed on the third end face, the first journal, the third journal, and the fourth journal respectively; wherein the first end face, the third end face, the first journal, the third journal, and the fourth journal are precision hard turned according to the third preset processing parameters;

[0054] Step 906: Call an external cylindrical turning tool with a main deflection angle of a preset angle, and perform precision hard turning on the spline of the second shaft neck according to a fourth preset processing parameter; wherein the external cylindrical turning tool adopts a left-hand tool, and the processing direction sequence is set to: from the main spindle to the tailstock direction.

[0055] On the other hand, the present application provides a transfer case front output flange, which is applied to the method described above; the transfer case front output flange specifically includes:

[0056] A front output flange shaft is provided with a first inner hole in the middle; the upper cross-section of the first inner hole is trumpet-shaped;

[0057] The front output flange shaft includes, from left to right, a first journal, a second journal, a third journal, a fourth journal and a fifth journal; wherein the left end face of the first journal is the first end face; the left end face of the third journal is the third end face; the left end face of the fourth journal is the fourth end face; a transition journal with an inclined surface structure is also provided between the fourth journal and the fifth journal;

[0058] Among them, the outer surface of the second shaft neck is provided with splines; the outer surface of the third shaft neck is provided with a retaining ring groove; a plurality of flanges are evenly arranged on the circumferential edge of the right end of the fifth shaft neck, and a plurality of threaded connection holes are evenly arranged on the circumferential side of the right end face of the fifth shaft neck; wherein spherical grooves are arranged between two adjacent threaded connection holes.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The present invention provides a transfer case front output flange and processing method, which uses a first heat treatment on a forged blank, and forms a front output flange to be processed by manufacturing the heat-treated blank, and then performs heat treatment again, thereby comprehensively improving the comprehensive mechanical properties of the material; secondly, the front output flange to be processed is subjected to rough and fine processing, and then the spline is processed, and then carburizing and heat treatment are performed, and finally hard turning after heat treatment is performed to complete the processing of the part. In the processing process, a turning and milling composite processing technology is adopted, which greatly shortens the product manufacturing process chain and improves production efficiency. Independently developed process methods and process parameters are used for key processes to overcome the blind hole carburizing and surface carbon accumulation problems that cannot be solved by traditional atmosphere hot carburizing, and ensure that the heat treatment process obtains a delicate metallographic structure and a uniform carburized layer, thereby improving the precision of the spline and the overall strength of the part, and then through precision hard turning after heat treatment, the product is lightweight and has a long life, and the NVH performance is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic diagram of the process of processing the front output flange of the transfer case;

[0062] Figure 2 It is a schematic diagram of the end face of the front output flange of the transfer case;

[0063] Figure 3 It is a schematic diagram of the overall structure of the front output flange of the transfer case. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solutions and advantages of this application clearer, the following will be combined with the attached Figure 1-3 The present application is further described in detail. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0065] It should be understood that although the terms first, second, third, etc. may be used to describe in the embodiments of the present application, these descriptions should not be limited to these terms. These terms are only used to distinguish the descriptions. For example, without departing from the scope of the embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0066] Reference Figure 2 As shown in the figure: 1, first end face; 2, second end face; 3, third end face; 4, fourth end face; 5, first shaft neck; 6, second shaft neck; 7, third shaft neck; 8, fourth shaft neck; 9, fifth shaft neck; 10, spherical groove; 11, flange; 12, threaded connection hole; 13, first inner hole.

[0067] like Figure 1As shown, the present application provides a method for processing a front output flange of a transfer case, comprising the following steps:

[0068] Step 1: performing a first heat treatment on the forged blank, performing rough processing on the blank subjected to the first heat treatment to form an output flange before processing, and performing a second heat treatment on the output flange before processing;

[0069] Step 2: rough machining and finishing are used to turn the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, the fourth journal, the fifth journal and the first inner hole of the output flange to be machined;

[0070] Step 3: Using a preset compensation calculation method to obtain an error compensation value, and adjusting the original coordinate system based on the error compensation value to form a milling machining coordinate system;

[0071] Step 4: Based on the milling machining coordinate system, the flange, several spherical grooves and threaded connection holes are milled in sequence using a preset indexing method;

[0072] Step 5: According to the preset gear parameters, the second journal of the output flange to be processed is processed to form a spline;

[0073] Step 6: Perform a third heat treatment on the output flange before processing;

[0074] Step 7: Processing the fourth end surface of the output flange to be processed and the third journal according to the first preset processing parameters;

[0075] Step 8: When the preset conditions are met, the first inner hole is processed according to the second preset processing parameters;

[0076] Step 9: The first journal, the second journal, the third journal, the fourth journal, the third end face and the fourth end face of the front output flange to be processed are precision hard turned to form the front input flange.

[0077] Specifically:

[0078] In a specific embodiment, the present application forms a front output flange to be processed by manufacturing a blank, and performs rough and fine processing on the front output flange to be processed, then processes the spline, and then performs carburizing and heat treatment, and finally performs hard turning after heat treatment to complete the processing of the part, which overcomes the problem of lack of mature processing technology for the front output flange in the prior art, and can greatly reduce the processing time while ensuring the accuracy of the parts, effectively improve production efficiency, and effectively reduce production costs.

[0079] Optionally, the first heat treatment is performed on the forged blank, the rough processing is performed on the first heat treated blank to form an output flange before processing, and the second heat treatment is performed on the output flange before processing, specifically including:

[0080] Step 101: normalizing and high-temperature tempering the forged blank until the hardness of the blank reaches a preset hardness value;

[0081] Step 102: Rough machining the blank after the first heat treatment to form an output flange to be machined, which has a shaft end face, a shaft outer circle, a step surface, a tooth outer circle and a tooth end face; wherein the shaft end face is reserved with a first machining allowance; the shaft outer circle, the step surface, the tooth outer circle and the tooth end face are reserved with a second machining allowance;

[0082] Step 103: Perform aging treatment and high-temperature tempering treatment on the output flange before processing.

[0083] Specifically, in step 101, FAS3420H material is used to forge a blank, and the forged blank is subjected to normalizing and high-temperature tempering treatment to uniform the structure and improve the comprehensive mechanical properties of the material, wherein the hardness of the blank after the first heat treatment is HB170-185.

[0084] In step 102, the blank is rough-machined to form a front output flange to be processed having a shaft end face, a shaft outer circle, a step surface, a tooth outer circle and a tooth end face; wherein the shaft end face is the end face located at both ends of the front output flange to be processed, a 3mm machining allowance is reserved for the shaft end face, and a 2mm machining allowance is reserved for the remaining parts, the overall surface roughness is Ra3.2, and the coaxiality of the two ends of the workpiece is less than 0.04mm.

[0085] In step 103, due to the high cutting removal rate, the output flange before processing formed by rough processing is heat treated again, that is, the output flange before processing is subjected to aging treatment, and a high temperature tempering heat treatment method is used to eliminate the turning internal stress.

[0086] Optionally, the rough machining and fine machining of the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, the fourth journal, the fifth journal and the first inner hole of the output flange to be machined specifically include:

[0087] Step 201: Perform turning processing on the first end surface, and use the processed first end surface as a first reference surface to process a center hole of the first end surface.

[0088] In step 201, the fifth journal is clamped by a machine tool chuck, the center stand assists in supporting the reference A, a turning tool with a main deflection angle of 75 degrees is used to turn the first end face, and the machined first end face is used as the axial reference plane, and a B4 model center drill is used to machine a center hole at the center point of the first end face.

[0089] Step 202: Process the third end face, the fourth end face, the first journal, the second journal, the third journal, and the fourth journal; wherein the first journal, the second journal, and the fourth journal reserve a third machining allowance; the third journal reserves a fourth machining allowance; and the third end face and the fourth end face reserve a fifth machining allowance.

[0090] In step 202, the workpiece is clamped with the tailstock center, the center frame is loosened, and the external cylindrical turning tool is used to process the third end face, the fourth end face, the first shaft neck, the second shaft neck, the third shaft neck, and the fourth shaft neck respectively; wherein, a machining allowance of 0.3 mm is reserved for the first shaft neck, the second shaft neck, and the fourth shaft neck; a machining allowance of 0.6 mm is reserved for the third shaft neck; a machining allowance of 0.15 is reserved for the third end face and the fourth end face; to facilitate subsequent heat treatment processing.

[0091] Step 203: When it is detected that the runout of any journal is less than the first preset value, the second end face is processed; wherein the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, and the fourth journal are finely processed according to the first preset parameters.

[0092] In step 203, firstly, the hard jaws of the chuck are switched to soft jaws to clamp the output flange to be processed; wherein, the soft jaws clamp the third journal; when the runout of any journal is detected to be less than 0.015mm, the outer circle 75-degree turning tool is used to turn the second end face to ensure the overall length accuracy requirement of the part.

[0093] Step 204: Use the second end surface as the second reference surface to process the first inner hole; wherein the first inner hole is finely processed according to the second preset parameters, and a sixth processing allowance is reserved.

[0094] In step 204, the second end surface processed in step 203 is used as the second reference surface, and a guide drill and a gun drill with a diameter of 26 mm are used to pre-drill the bottom hole of the first inner hole, and then the inner hole turning tool is used to turn the contour of the first inner hole, wherein a 0.2 mm machining allowance is reserved for the first inner hole.

[0095] Step 205: Processing the fifth journal, wherein the fifth journal is finish-processed based on the first preset parameters.

[0096] In step 205, an external cylindrical turning tool with a main deflection angle of 93 degrees is used to turn the outer diameter of the fifth journal.

[0097] It should be noted that steps 201 to 205 all use two processes of rough machining and fine machining; wherein the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, the fourth journal, and the fifth journal are finely machined according to the first preset parameters, the parameters are: cutting speed v=280m / min, feed rate f is 0.1mm / r, and cutting depth ap is 0.25mm. The first inner hole is finely machined according to the second preset parameters, the parameters are: cutting speed v=250m / min, feed rate f is 0.13mm / r, and cutting depth ap is 0.6mm.

[0098] Furthermore, the present application has undergone a large number of process tests on the parameters of the first inner hole, which can effectively eliminate the vibration of thin-wall deep hole turning.

[0099] In step 3, a preset compensation calculation method is used to obtain an error compensation value, and the original coordinate system is adjusted based on the error compensation value to form a milling machining coordinate system, specifically including:

[0100] Step 301: Switch turning to milling, perform bottom hole processing on any threaded connection hole to be processed, and measure the coordinate value of the bottom hole;

[0101] Step 302: Acquire the coordinate value of the first inner hole processed by turning, and use the coordinate value of the first inner hole processed by turning as a reference point;

[0102] Step 303: Subtract the difference between the coordinate value of the bottom hole and the coordinate value of the first inner hole from the preset standard value to obtain an error compensation value;

[0103] Step 304: Adjust the original coordinate system according to the error compensation value to form a milling machining coordinate system.

[0104] First of all, it should be explained that due to the accuracy errors in tool measurement before processing and factors such as thermal deformation during processing, as well as certain errors in the milling axis and turning axis of the turning-milling composite equipment itself, position accuracy errors are generated when switching from turning to milling. In order to eliminate the errors, a preset compensation calculation method is used to obtain the error compensation value and perform accuracy compensation, thereby ensuring the position accuracy of turning elements and milling elements in the same sequence processing.

[0105] In step 301, any threaded connection hole to be processed is selected, and a test hole milling process is performed on the threaded connection hole to be processed according to the coordinates on the drawing, and the coordinate value of the milling bottom hole is measured by using a probe;

[0106] In step 302, a probe is used to measure the coordinate value of the first inner hole processed by turning, and the coordinate value of the first inner hole processed by turning is used as a reference point.

[0107] In step 303, the difference between the coordinate value of the test hole and the coordinate value of the first inner hole is calculated, and the difference is subtracted from the preset standard value to obtain the error compensation value of the X axis (front-to-back direction) and the Y axis (up-down direction) on the device; wherein the difference between the diameter of the test hole and the bottom hole diameter of the threaded connection hole to be processed is greater than the preset difference; wherein the preset difference is a critical value for correcting the existing maximum error compensation value. That is, the error compensation value is less than or equal to the preset difference.

[0108] In this embodiment, the threaded connection hole to be processed is M8, the bottom hole diameter is 6.75 mm, and the test hole diameter is 6 mm.

[0109] Step 304: Correct the original coordinate system according to the error compensation value to form a milling machining coordinate system.

[0110] It can be understood that by correcting and compensating the X and Y axis offsets and then calling the milling tool to process the milling elements, the position accuracy of the parts can be effectively guaranteed and the generation of defective parts can be avoided.

[0111] The step 4 described in which the flange, a plurality of spherical grooves and threaded connection holes are milled in sequence by using a preset indexing method based on the milling machining coordinate system specifically includes:

[0112] Step 401: setting the origin of the rotation axis, starting the rotation axis indexing function, and calling the first ball end milling cutter to process a number of flanges;

[0113] Step 402: using a second ball end milling cutter to process a plurality of spherical grooves;

[0114] Step 403: Process the bottom hole of the threaded connection hole and tap it.

[0115] For example, set the origin of the rotary axis (the workpiece rotation spindle in the milling function), start the rotary axis indexing function (or C-axis indexing), call a 12mm diameter ball end milling cutter to process three flanges, call a 20mm diameter ball end milling cutter to add 6 spherical grooves. Call a 6.75mm diameter drill to drill 6 M8*1.25 threaded holes, and call an M8*1.25 tap for tapping.

[0116] Optionally, in step 5, according to preset gear parameters, the second shaft neck of the output flange before processing is processed to form a spline; specifically, the spline is hobbed using a gear hobbing machine according to the gear parameters in Table 1 to ensure the accuracy requirements of the spline. After the gear hobbing is completed, the gear needs to be chamfered to remove burrs.

[0117] Among them, Table 1 is as follows:

[0118]

[0119] Optionally, in step 6, the output flange before processing is subjected to a third heat treatment, specifically comprising:

[0120] Step 61: heat treatment is performed using a low-pressure vacuum carburizing and quenching process, specifically including:

[0121] Step 610: setting the carburizing temperature to 980-1000° C.; feeding carburizing gas during the low-pressure carburizing stage; wherein the carburizing gas is acetylene with a purity of 96%;

[0122] Step 611: Maintaining at a preset pressure (600 Pa) for 30 min to 60 min;

[0123] Step 612: extracting gas from the vacuum chamber until the high vacuum degree in the vacuum chamber reaches a vacuum diffusion stage;

[0124] Step 613: Repeat steps 610-612 until the hardened layer depth, surface hardness and core hardness of the output flange before processing meet the design values.

[0125] Specifically, the hardened layer depth of the input flange before processing treated by low-pressure vacuum carburizing and quenching process is CHD550HV1 0.6-0.9mm, the surface hardness is (80-83) HRA, and the core hardness is (320-450) HV30. This heat treatment process can effectively improve the deformation behavior of parts, increase the carburizing temperature, reduce the time of intermittent treatment, greatly reduce gas and energy consumption, and overcome the blind hole carburizing and surface carbon accumulation problems that cannot be solved by traditional atmosphere hot carburizing.

[0126] Furthermore, after step 6, it also includes: performing micro-deformation straightening and center hole finishing treatment on the workpiece after the heat treatment is completed, so as to reduce the influence of the heat treatment deformation on the workpiece, and taking the center hole and the first inner hole as the reference, for the corrected workpiece, the runout of any section of the shaft neck needs to be less than 0.02mm.

[0127] In step 7: the fourth end surface and the third journal of the output flange to be processed before the third heat treatment are processed according to the first preset processing parameters, specifically including:

[0128] Step 701: Use a double center method to fix the input flange to be processed, and perform rough machining hard turning on the third journal and the fourth end face according to the first preset machining parameters; wherein, the third journal reserves the first margin; specifically: use a 93-degree main deflection angle external turning tool and a PCBN material blade to hard turn the third journal and the fourth end face corresponding to the reference B, wherein the third journal reserves a margin of 0.15mm for subsequent fine machining. The advantages of this design are: using the outer diameter of the third journal and the fourth end face as the turning positioning reference, it can ensure that the verticality of the third journal and the fourth end face is less than 0.003mm, and the coaxiality of the first journal and the fourth journal relative to the references A and B is less than 0.02mm; the first preset machining parameters are: cutting speed v = 180m / min, feed rate f is 0.07mm / r, and cutting depth ap is 0.1mm.

[0129] The step 8 comprises:

[0130] Step 801: Clamp the third journal and use the fourth end face as an axial positioning reference. When the detected runout of any journal is less than a third preset value, finish machining the first inner hole according to second preset machining parameters.

[0131] In step 801, the chuck jaws are replaced with soft jaws to clamp the third journal, and the fourth end face is used as the axial positioning reference; when the runout of the processed journal is detected to be less than 0.01mm, the inner hole boring tool, C-type blade RE0.4, PCBN material blade, is called, and the second preset parameters are installed to perform fine machining on the first inner hole with a 0.2mm margin in the above step 2. Among them, the second preset parameters are: cutting speed v=120m / min, feed rate f is 0.1mm / r, and cutting depth ap is 0.12mm. The advantage of this design is that it can ensure that the inner hole roundness at the first inner hole is less than 0.003mm, and the runout relative to the reference B is less than 0.015mm.

[0132] Optionally, step 9 includes:

[0133] Step 901: Clamp the input flange to be processed by double centering method;

[0134] Step 902: performing precision hard turning on the fourth end surface;

[0135] Step 903: Obtaining an axial compensation value according to an axial compensation method;

[0136] Step 904: Compensate to the origin coordinate of the milling machining coordinate system according to the axial compensation value;

[0137] Step 905: According to the compensated origin coordinates, the third end face, the first journal, the third journal, and the fourth journal are respectively subjected to precision hard turning; wherein the third end face, the fourth end face, the first journal, the third journal, and the fourth journal are subjected to precision hard turning according to the third preset processing parameters;

[0138] Step 906: Call an external cylindrical turning tool with a main deflection angle of a preset angle, and perform precision hard turning on the spline of the second shaft neck according to a fourth preset processing parameter; wherein the external cylindrical turning tool adopts a left-hand tool, and the processing direction sequence is set to: from the main spindle to the tailstock direction.

[0139] Among them, in step 903, the first inner hole is used as the positioning reference, the fourth end face is first processed, and the first distance between the fourth end face and the third end face is measured by a probe; the difference between the first distance and the preset distance value is calculated, and the difference is used as the axial compensation value to correct the Z-axis origin coordinates of the milling machining coordinate system.

[0140] In step 905, a 93-degree main deflection angle external cylindrical turning tool and a PCBN material blade are called to perform precision hard turning on the first journal, the third journal, the fourth journal, and the third end face to ensure that the surface roughness Ra0.4, the journal roundness 0.003mm, the cylindricity 0.005mm, and the coaxiality of the first journal and the third journal is 0.005mm. The third preset processing parameters are: cutting speed v=180m / min, feed rate f is 0.07mm / r, and cutting depth ap is 0.1mm. The advantage is that this parameter can effectively control the surface roughness Ra of the part between 0.2-0.3. The hard turning process does not require the use of cutting fluid for cooling, and the processing process is more environmentally friendly than grinding.

[0141] In step 906, a 75-degree main deflection angle external cylindrical turning tool is called, with a C-type blade RE0.8, PCBN material, and a negative blade rake angle. The advantage is that the tool toughness and resistance to intermittent machining impact can be improved. At the same time, the tool direction selects a left-hand tool, and the machining direction sequence is set to the spindle to tailstock direction. The benefits of using this machining method are: compared with forehand tool machining, the self-excited vibration caused by the cutting force can be reduced, the system rigidity can be effectively improved, better part roughness can be provided, and the tool life can be increased by 3 times. Among them, the fourth preset machining parameter (i.e., intermittent hard turning cutting parameter) is set as follows: cutting speed v=130m / min, feed rate f is 0.1mm / r, and cutting depth ap is 0.05mm.

[0142] Optionally, the present application further includes step 10; said step 10 specifically includes:

[0143] The surface of the processed front input flange is sprayed, that is, an anti-corrosion coating is sprayed on the surface of the part to improve the corrosion resistance of the part.

[0144] It can be understood that compared with the prior art, the present application overcomes the problem of lack of mature processing technology for the front output flange, and on the basis of innovation, while ensuring the accuracy of parts, uses precision hard turning technology instead of traditional grinding in the process. While ensuring the accuracy of parts, it can greatly reduce the processing time and effectively improve production efficiency. Moreover, the hard turning process does not require the use of cutting fluid, which is more energy-saving and environmentally friendly, and effectively reduces production costs.

[0145] On the other hand, the present application provides a transfer case front output flange, which is applied to the method described above; the transfer case front output flange specifically includes:

[0146] A front output flange shaft is provided with a first inner hole 13 in the middle; the upper cross-section of the first inner hole 13 is trumpet-shaped;

[0147] The front output flange shaft includes, from left to right, a first journal 5, a second journal 6, a third journal 7, a fourth journal 8 and a fifth journal 9; wherein the left end face of the first journal 5 is a first end face 1; the left end face of the third journal 7 is a third end face 3; the left end face of the fourth journal 8 is a fourth end face 4; a transition journal with an inclined surface structure is also provided between the fourth journal 8 and the fifth journal 9;

[0148] The outer surface of the second journal 6 is provided with a spline; the middle of the outer surface of the third journal 7 is provided with a snap ring groove; the right end peripheral edge of the fifth journal 9 is evenly provided with a plurality of flanges 11, and the right end surface peripheral side of the fifth journal 9 is evenly provided with a plurality of threaded connection holes 12; wherein, a spherical groove 10 is provided between two adjacent threaded connection holes 12. It can be understood that the front output flange of the transfer case provided by the present application has a high coaxiality and excellent overall dimensional accuracy, and therefore has a high transmission stability and a long service life, is not prone to spline tooth collapse or shaft breakage, and has a strong practical performance.

[0149] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in a variety of different forms and should not be construed as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art. In the accompanying drawings, for the sake of clarity, the thickness of the layers and regions may be enlarged, and the same reference numerals are used to represent the same devices, and thus their descriptions will be omitted.

Claims

1. A method for processing a front output flange of a transfer case, characterized in that: The following steps are involved: Step 1: performing a first heat treatment on the forged blank, performing rough processing on the blank subjected to the first heat treatment to form an output flange before processing, and performing a second heat treatment on the output flange before processing; Step 2: rough machining and finishing are used to turn the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, the fourth journal, the fifth journal and the first inner hole of the output flange to be machined; Step 3: Using a preset compensation calculation method to obtain an error compensation value, and adjusting the original coordinate system based on the error compensation value to form a milling machining coordinate system; Step 4: Based on the milling machining coordinate system, the flange, several spherical grooves and threaded connection holes are milled in sequence using a preset indexing method; Step 5: According to the preset gear parameters, the second journal of the output flange to be processed is processed to form a spline; Step 6: Perform a third heat treatment on the output flange before processing; Step 7: Processing the fourth end surface of the output flange to be processed and the third journal according to the first preset processing parameters; Step 8: When the preset conditions are met, the first inner hole is processed according to the second preset processing parameters; Step 9: The first journal, the second journal, the third journal, the fourth journal, the third end face and the fourth end face of the front output flange to be processed are precision hard turned to form the front input flange.

2. The method for processing the front output flange of a transfer case according to claim 1, characterized in that: The step 1 specifically includes: Performing normalizing and high-temperature tempering treatment on the forged blank until the hardness of the blank reaches a preset hardness value; The blank subjected to the first heat treatment is rough-machined to form an output flange to be machined, which has a shaft end face, a shaft outer circle, a step face, a tooth outer circle and a tooth end face; wherein the shaft end face is reserved with a first machining allowance; and the shaft outer circle, the step face, the tooth outer circle and the tooth end face are reserved with a second machining allowance; The output flange is subjected to aging treatment and high temperature tempering treatment before processing.

3. The method for processing the front output flange of a transfer case according to claim 2, characterized in that: The step 2 comprises: Performing turning processing on the first end surface, and using the processed first end surface as a first reference surface, processing a center hole of the first end surface; The third end face, the fourth end face, the first journal, the second journal, the third journal and the fourth journal are processed; wherein the first journal, the second journal and the fourth journal are reserved with a third processing allowance; the third journal is reserved with a fourth processing allowance; the third end face and the fourth end face are reserved with a fifth processing allowance; When the runout of any journal is detected to be less than a first preset value, the second end face is processed; wherein the first end face, the second end face, the third end face, the fourth end face, the first journal, the second journal, the third journal, and the fourth journal are finely processed according to the first preset parameters; The first inner hole is processed by using the second end surface as the second reference surface; wherein the first inner hole is finely processed according to the second preset parameter and a sixth processing allowance is reserved; The fifth journal is machined, wherein the fifth journal is finish-machined based on the first preset parameters.

4. The method for processing the front output flange of a transfer case according to claim 3, characterized in that: The step 3 comprises: Switch turning to milling, perform test hole processing on any threaded connection hole to be processed, and measure the coordinate value of the test hole; Acquire the coordinate value of the first inner hole processed by turning, and use the coordinate value of the first inner hole processed by turning as a reference point; Subtract the difference between the coordinate value of the test hole and the coordinate value of the first inner hole from the preset standard value to obtain an error compensation value; The original coordinate system is adjusted according to the error compensation value to form the milling machining coordinate system.

5. The method for processing the front output flange of a transfer case according to claim 4, characterized in that: The step 4 comprises: Set the origin of the rotary axis, start the rotary axis indexing function, and use the first ball end mill to process several flanges; Using a second ball end milling cutter to process a plurality of spherical grooves; Process the bottom hole of the threaded connection hole and tap it.

6. The method for processing the front output flange of a transfer case according to claim 5, characterized in that: The step 6 comprises: Step 61: heat treatment is performed using a low-pressure vacuum carburizing and quenching process, specifically including: Step 610: setting the carburizing temperature to 980-1000° C.; feeding carburizing gas during the low-pressure carburizing stage; wherein the carburizing gas is acetylene with a purity of 96%; Step 611: Maintaining the preset pressure for 30 min to 60 min; Step 612: extracting gas from the vacuum chamber until the high vacuum degree in the vacuum chamber reaches a vacuum diffusion stage; Step 613: Repeat steps 610-612 until the hardened layer depth, surface hardness and core hardness of the output flange before processing meet the design values.

7. The method for processing the front output flange of a transfer case according to claim 6, characterized in that: After step 6, the following steps are also included: Taking the first inner hole and the center hole as reference, the output flange to be processed before the third heat treatment is subjected to micro-deformation straightening and center hole fine grinding until the runout of any journal detected is less than the second preset value.

8. The method for processing the front output flange of a transfer case according to claim 7, characterized in that: The step 7 specifically includes: The input flange to be processed is fixed by a double center method, and the third journal and the fourth end face are rough-machined and hard-turned according to the first preset processing parameters; wherein the third journal is reserved with a first margin; Accordingly, step 8 includes: The third journal is clamped, and the fourth end face is used as an axial positioning reference. When the detected runout of any journal is less than the third preset value, the first inner hole is finely machined according to the second preset machining parameters.

9. The method for processing the front output flange of a transfer case according to claim 8, characterized in that: The step 9 comprises: Step 901: Clamp the input flange to be processed by double centering method; Step 902: performing precision hard turning on the fourth end surface; Step 903: Obtaining an axial compensation value according to an axial compensation method; Step 904: Compensate to the origin coordinate of the milling machining coordinate system according to the axial compensation value; Step 905: According to the compensated origin coordinates, precision hard turning is performed on the third end face, the first journal, the third journal, and the fourth journal respectively; wherein the first end face, the third end face, the first journal, the third journal, and the fourth journal are precision hard turned according to the third preset processing parameters; Step 906: Call an external cylindrical turning tool with a main deflection angle of a preset angle, and perform precision hard turning on the spline of the second shaft neck according to a fourth preset processing parameter; wherein the external cylindrical turning tool adopts a left-hand tool, and the processing direction sequence is set to: from the main spindle to the tailstock direction.

10. A transfer case front output flange, characterized in that: The method applied to any one of claims 1 to 9; the transfer case front output flange specifically comprises: A front output flange shaft is provided with a first inner hole in the middle; the upper cross-section of the first inner hole is trumpet-shaped; The front output flange shaft includes, from left to right, a first journal, a second journal, a third journal, a fourth journal and a fifth journal; wherein the left end face of the first journal is the first end face; the left end face of the third journal is the third end face; the left end face of the fourth journal is the fourth end face; a transition journal with an inclined surface structure is also provided between the fourth journal and the fifth journal; The outer surface of the second journal is provided with a spline; the outer surface of the third journal is provided with a snap ring groove; the right end circumferential edge of the fifth journal is evenly provided with a plurality of flanges. A plurality of threaded connection holes are evenly arranged on the circumference of the right end surface of the fifth journal; wherein, Spherical grooves are arranged between two adjacent threaded connection holes.

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