A transfer front output flange and method of machining

Abstract

The application provides a kind of front output flange of transfer and processing method, belong to part processing technical field;Including: first heat treatment to blank and second heat treatment to the front output flange to be processed after processing;Adopt rough machining and finish machining mode to turn the front output flange to be processed;Adjust original coordinate system using preset compensation calculation method;Adopt preset indexing method to mill flange, several spherical grooves and threaded connection hole in turn;According to preset gear parameter, process spline;Carry out third heat treatment;Then process fourth end face and third journal;When satisfying preset condition, according to second preset processing parameter, process first inner hole;Form part by sequentially hard turning the front output flange to be processed.The present application solves the problem of lack of mature processing technology for front output flange in the prior art, and at the same time ensures the accuracy of the part, reduces the processing time and improves the production efficiency.

Description

TECHNICAL FIELD

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

[0002] A four-wheel drive transfer case is an important rotating part widely used in 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 tooth parts. Improving the control ability of the core technology of the four-wheel drive transfer case is an important goal of technological innovation.

[0003] Document CN105583590A discloses a processing method for a cylindrical gear shaft made of 4Cr5MoSiV1. The key processing technology is as follows: (1) melt and die-cast the cylindrical gear shaft blank. First, preheat the central furnace, put the ingredients into the furnace to obtain alloy melt, then put the alloy melt into the holding furnace, apply a rotating magnetic field to the outside of the holding furnace to make the alloy melt generate induced eddy current, use a feeding magnetic field generator to pump the alloy melt into the holding furnace of the die-casting machine and keep it in a nitrogen atmosphere for 30s-15min, then perform hot die casting, control the temperature at 500-550℃, input the alloy melt into the die-casting mold for die casting, and the temperature of the die-casting mold is 100-200 degrees; (2) rough machining of the cylindrical gear shaft, turning the end face, turning the outer circle, drilling the center hole, turning the other end face and outer circle, and introducing lubricating liquid during machining to spray it on the workpiece surface and the tool head to prevent the formation of mechanical tumors and carry away the heat generated during machining, and then performing fine machining with a surface roughness of Ra=0.5-1.3μm; (3) aging treatment of the fine-machined cylindrical gear shaft, using pre-quenching method, first water solution cooling and then air cooling, and then tempering treatment, using low temperature (200-250℃) tempering to make the hardness 60-62HRC; (4) carburizing treatment, medium temperature gas carburizing, i.e. dropping acetone as carburizing agent in the gas carburizing furnace, controlling the temperature at 830-850℃, keeping for 1.4-2.5h, slow cooling, and carburizing depth of 0.8-1.2mm; (5) corrosion protection treatment, a corrosion inhibitor mixed by acid, alkali and salt, the corrosion concentration is HCl 0.3-3%, H3PO4 10-20%, H2SO4 50-70%, NCl4 4-5%, KaNO3 7-10%, Ni(NO3)2 3-5%, alkyl alcohol amide 3-5%, hexamethylenetetramine 0.1-0.2%, and the rest is water, wherein H2SO4 acts as an oxidizing agent, alkyl alcohol amide as an active agent, and hexamethylenetetramine as a corrosion inhibitor. The corrosion inhibitor is stirred and mixed uniformly and then sprayed on the surface of the cylindrical gear shaft, the coating thickness is 10-15μm, and then air dried after washing with clean water.

[0004] In a scheme of a cylindrical gear shaft machining method using 4Cr5MoSiV1 as the material, the technical problem to be solved is that some turbine shafts or bevel gear shafts not only have large vibration, energy loss affecting work, and long time causing oil leakage and other problems, but also affect the normal work of the machine, often causing the work to have to stop for maintenance, and the production efficiency is reduced. The measure adopted is to provide a hot pressure casting forming method to improve the use characteristics of the gear, and no improvement method or technical innovation is provided in the machining aspect, this method can solve the above problems, but is limited to ordinary cylindrical gear machining with low precision requirements, and is limited to 4Cr5MoSiV1 material gear machining, and is not suitable for precision parts such as four-wheel drive divider machining.

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

[0006] The purpose of the present application is to provide a divider front output flange and a machining method, which overcomes the problem of lack of mature machining process for the front output flange in the prior art, and the specific scheme is as follows:

[0007] A divider front output flange machining method, comprising the following steps:

[0008] Step 1: first heat treating the blank in a forging manner, rough machining the first heat treated blank to form a front output flange to be machined, and second heat treating the front output flange to be machined;

[0009] Step 2: rough machining and finish machining 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 front output flange to be machined;

[0010] Step 3: obtaining an error compensation value by a preset compensation calculation method, 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, sequentially milling the flange, the plurality of spherical grooves, and the threaded connection hole by a preset indexing method;

[0012] Step 5: processing the second journal of the front output flange to be machined according to a preset gear parameter to form a spline;

[0013] Step 6: third heat treating the front output flange to be machined;

[0014] Step 7: processing the fourth end face and the third journal of the third heat treated front output flange to be machined according to a first preset machining parameter;

[0015] Step 8: When the preset condition is met, the first inner hole is machined according to the second preset machining parameter;

[0016] Step 9: The first shaft journal, the second shaft journal, the third shaft journal, the fourth shaft journal, the third end face and the fourth end face of the pre-machining output flange are precisely hard turned to form a pre-input flange.

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

[0018] The blank in the forging mode is normalized and high-temperature tempered until the hardness of the blank reaches the preset hardness value;

[0019] The first heat-treated blank is roughly machined to form a pre-machining output flange with shaft end faces, shaft outer circles, step faces, tooth outer circles and tooth end faces; wherein the shaft end faces reserve a first machining allowance; the shaft outer circles, step faces, tooth outer circles and tooth end faces reserve a second machining allowance;

[0020] The pre-machining output flange is aged and high-temperature tempered.

[0021] In some embodiments, the step 2 includes:

[0022] The first end face is turned, and the machined first end face is used as a first reference surface to machine the center hole of the first end face;

[0023] The third end face, the fourth end face, the first shaft journal, the second shaft journal, the third shaft journal and the fourth shaft journal are machined; wherein the first shaft journal, the second shaft journal and the fourth shaft journal reserve a third machining allowance; the third shaft journal reserves a fourth machining allowance; the third end face and the fourth end face reserve a fifth machining allowance;

[0024] When the runout of any shaft journal is less than a first preset value, the second end face is machined; wherein the first end face, the second end face, the third end face, the fourth end face, the first shaft journal, the second shaft journal, the third shaft journal and the fourth shaft journal are precisely machined according to the first preset parameter;

[0025] The second end face is used as a second reference surface to machine the first inner hole; wherein the first inner hole is precisely machined according to the second preset parameter and reserves a sixth machining allowance;

[0026] The fifth shaft journal is machined, wherein the fifth shaft journal is precisely machined based on the first preset parameter.

[0027] In some embodiments, the step 3 includes:

[0028] The turning is switched to milling machining, any one of the to-be-machined threaded connection holes is tested and machined, and the coordinate value of the test hole is measured;

[0029] Coordinate values of the first inner hole machined by turning are acquired, and the coordinate values of the first inner hole machined by turning are taken as reference points;

[0030] The difference between the coordinate values of the test hole and the coordinate values of the first inner hole is calculated by subtraction compared with a preset standard value, and an error compensation value is acquired;

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

[0032] In some embodiments, the step 4 comprises:

[0033] The rotation axis origin is set, the rotation axis indexing function is started, and the first ball head milling cutter is called to machine a plurality of flanges;

[0034] The second ball head milling cutter is called to machine a plurality of spherical grooves;

[0035] The bottom hole of the threaded connection hole is machined, and the threaded hole is tapped.

[0036] In some embodiments, the step 6 comprises:

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

[0038] Step 610: the carburizing temperature is set to 980-1000℃; the carburizing gas is fed in the low-pressure carburizing stage; wherein the carburizing gas is acetylene with a purity of 96%;

[0039] Step 611: keep for 30min-60min under a preset pressure;

[0040] Step 612: the gas in the vacuum chamber is extracted until the high vacuum degree in the vacuum chamber reaches the vacuum diffusion stage;

[0041] Step 613: repeat steps 610-612 until the hardening layer depth, surface hardness and core hardness of the pre-machining output flange meet the design values.

[0042] In some embodiments, the step 6 further comprises:

[0043] The pre-machining output flange of the third heat treatment is micro-deformation straightened and center hole lapping processed with the first inner hole and the center hole as reference until the runout of any one journal detected is less than a second preset value.

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

[0045] Adopt the double top end way to fix the input flange before processing, and rough machining and hard turning are carried out on the third shaft neck and the fourth end face according to the first preset machining parameter; wherein, the third shaft neck reserves the first excess amount;

[0046] Correspondingly, the step 8 comprises:

[0047] Clamp the third shaft neck, and take the fourth end face as the axial positioning reference; when the detected arbitrary shaft neck runout is less than the third preset value, the first inner hole is precisely machined according to the second preset machining parameter.

[0048] In some embodiments, the step 9 comprises:

[0049] Step 901: adopt the double top end way to clamp the input flange before processing;

[0050] Step 902: precisely hard turning is carried out on the fourth end face;

[0051] Step 903: according to the axial compensation method, an axial compensation value is obtained;

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

[0053] Step 905: according to the compensated origin coordinate, the third end face, the first shaft neck, the third shaft neck and the fourth shaft neck are respectively precisely hard turned; wherein, the first end face, the third end face, the first shaft neck, the third shaft neck and the fourth shaft neck are precisely hard turned according to the third preset machining parameter;

[0054] Step 906: a external turning tool with a preset angle as the main offset angle is called, and the spline of the second shaft neck is precisely hard turned according to the fourth preset machining parameter; wherein, the external turning tool adopts a left-hand tool, and the machining direction sequence is set as: from the spindle to the tailstock direction.

[0055] On the other hand, the application provides a transfer front output flange applied to the method; the transfer front output flange specifically comprises:

[0056] The front output flange shaft with the first inner hole arranged in the middle; the upper section shape of the first inner hole is in the shape of a horn;

[0057] The front output flange shaft sequentially comprises the first shaft neck, the second shaft neck, the third shaft neck, the fourth shaft neck and the fifth shaft neck from left to right; wherein, the left end face of the first shaft neck is the first end face; the left end face of the third shaft neck is the third end face; the left end face of the fourth shaft neck is the fourth end face; the transition shaft neck with the inclined surface structure is further arranged between the fourth shaft neck and the fifth shaft neck;

[0058] The outer surface of the second shaft neck is provided with a spline; the outer surface of the third shaft neck is provided with a snap ring groove; the right end of the fifth shaft neck is uniformly provided with a plurality of flanges on the circumferal side, and the right end face of the fifth shaft neck is uniformly provided with a plurality of threaded connection holes; wherein, the threaded connection holes are provided with a spherical groove between each other.

[0059] Compared with the prior art, the beneficial effects of the present application are:

[0060] The present application provides a kind of front output flange of transfer case and processing method, by first heat treatment to forging blank, and the blank of heat treatment is made to form before processing front output flange, heat treatment again, to comprehensively improve the comprehensive mechanical properties of material;Second, the rough and finish machining of before processing front output flange, then machining spline, then carburizing, heat treatment, finally heat treated hard, complete the machining of parts.In the process of machining, the machining process of turning and milling is used, which greatly shortens the product manufacturing process chain, improves production efficiency, and overcomes the problems of blind hole carburizing and surface carbonization that cannot be solved by traditional atmosphere heat carburizing, ensures that fine metallographic structure and uniform carburizing layer are obtained during heat treatment process, so as to improve the accuracy of spline and the overall strength of the part, and then realize the lightweight and long service life of the product, and improve the performance of NVH. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 It is front output flange processing method flow chart of transfer case;

[0062] Figure 2 It is end surface schematic view of front output flange of transfer case;

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

[0064] In order to make the purpose, technical scheme and advantages of the present application clearer, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Figures 1-3 Further detailed description will be made to the present application, obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

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

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

[0067] As Figure 1 shown, the application provides a kind of front output flange machining method of transfer, comprising the following steps:

[0068] Step 1: first heat treatment is carried out to blank using forging method, rough machining is carried out to the blank of first heat treatment to form the front output flange to be processed, and second heat treatment is carried out to the front output flange to be processed;

[0069] Step 2: 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 front output flange to be processed are turned using rough machining and finish machining method;

[0070] Step 3: error compensation value is obtained using preset compensation calculation method, and original coordinate system is adjusted based on error compensation value to form milling machining coordinate system;

[0071] Step 4: based on milling machining coordinate system, flange, a plurality of spherical grooves and threaded connection holes are sequentially milled and processed using preset indexing method;

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

[0073] Step 6: third heat treatment is carried out to the front output flange to be processed;

[0074] Step 7: the fourth end face and the third journal of the front output flange to be processed after third heat treatment are processed according to first preset machining parameter;

[0075] Step 8: when preset condition is met, the first inner hole is processed according to second preset machining parameter;

[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 precisely hard turned to form the front input flange.

[0077] Specifically:

[0078] In one specific embodiment, the present application forms the output flange before processing by making the blank, and rough and finish machining the output flange before processing, then machining the spline, then carburizing, heat treatment, and finally hard turning after heat treatment to complete the processing of the part, which overcomes the lack of mature processing technology for the front output flange in the prior art, can greatly reduce the processing time while ensuring the accuracy of the part, effectively improve the production efficiency, and effectively reduce the production cost.

[0079] Optionally, the first heat treatment of the blank in the forging manner, the rough machining of the first heat treated blank to form the output flange before processing, and the second heat treatment of the output flange before processing, specifically include:

[0080] Step 101: normalizing and high temperature tempering treatment of the blank in the forging manner until the hardness of the blank reaches the preset hardness value;

[0081] Step 102: rough machining of the first heat treated blank to form the output flange before processing with shaft end face, shaft outer circle, step surface, tooth outer circle and tooth end face; wherein the shaft end face has a first machining allowance; the shaft outer circle, step surface, tooth outer circle and tooth end face have a second machining allowance;

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

[0083] Specifically, in step 101, the blank is forged by FAS3420H material, and the forged blank is normalized and high temperature tempered 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 the output flange before processing with shaft end face, shaft outer circle, step surface, tooth outer circle and tooth end face; wherein the shaft end face is the end face at both ends of the output flange before processing, the shaft end face has a machining allowance of 3mm, the rest has a machining allowance of 2mm, the overall surface roughness is Ra3.2, and the coaxiality of the workpiece at both ends is less than 0.04mm.

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

[0086] Optionally, 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 before machining are turned by rough machining and finish machining, specifically comprising:

[0087] Step 201: turning the first end face, and taking the machined first end face as the first reference surface, and machining the center hole of the first end face.

[0088] In step 201, the fifth journal is clamped by the machine chuck, the center frame is auxiliary supported by the reference A, the first end face is turned by calling the turning tool with the main offset angle of 75 degrees, the machined first end face is taken as the axial reference surface, and the center hole is machined at the center point of the first end face by calling the B4 type center drill.

[0089] Step 202: machining 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 the third machining allowance; the third journal reserves the fourth machining allowance; the third end face and the fourth end face reserve the fifth machining allowance.

[0090] In step 202, the workpiece is tightly pressed by the tail seat center, the center frame is loosened, and the third end face, the fourth end face, the first journal, the second journal, the third journal and the fourth journal are machined by calling the external turning tool; wherein the first journal, the second journal and the fourth journal reserve 0.3mm machining allowance; the third journal reserves 0.6mm machining allowance; the third end face and the fourth end face reserve 0.15mm machining allowance; so as to facilitate subsequent heat treatment machining.

[0091] Step 203: machining the second end face when the runout of any journal is less than the first preset value; 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 finish machined according to the first preset parameter.

[0092] In step 203, the chuck hard jaw is switched to the soft jaw to clamp the output flange before machining; wherein the soft jaw clamps the third journal; when the runout of any journal is less than 0.015mm, the second end face is turned by calling the external turning tool with the angle of 75 degrees, so as to ensure the total length precision requirement of the part.

[0093] Step 204: taking the second end face as the second reference surface, and machining the first inner hole; wherein the first inner hole is finish machined according to the second preset parameter, and reserves the sixth machining allowance.

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

[0095] Step 205: processing the fifth journal, wherein the fifth journal is finished based on the first preset parameter.

[0096] In step 205, a main offset angle 93-degree cylindrical turning tool is called to turn the outer diameter of the fifth journal.

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

[0098] Further, the parameter of the first inner hole is obtained through a large number of process tests, which can effectively eliminate the vibration of thin-walled deep hole turning.

[0099] The error compensation value is obtained by using a preset compensation calculation method in step 3, and the original coordinate system is adjusted based on the error compensation value to form a milling machining coordinate system, which specifically includes:

[0100] Step 301: switching from turning to milling machining, performing bottom hole machining on any one of the to-be-processed threaded connection holes, and measuring the coordinate value of the bottom hole;

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

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

[0103] Step 304: adjusting the original coordinate system based on the error compensation value to form a milling machining coordinate system.

[0104] First of all, it needs to be pointed out that due to the precision error of tool measurement before processing and the thermal deformation in the processing process and other factors, plus the milling shaft and turning shaft of the turning and milling combined equipment itself has certain error, thus causing the position precision error when switching from turning to milling. In order to eliminate the error, the preset compensation calculation method is used to obtain the error compensation value, and the precision compensation is carried out, so as to ensure the position precision of turning elements and milling elements in the same sequence processing.

[0105] In step 301, any one of the threaded connection holes to be processed is selected, and the test hole milling of the threaded connection hole to be processed is carried out according to the coordinates on the drawing. The coordinate value of the bottom hole of the milling processing is measured by using the measuring head;

[0106] In step 302, the coordinate value of the first inner hole of the turning processing is measured by using the measuring head, and the coordinate value of the first inner hole of the turning processing is taken as the 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 and rear direction) and Y axis (up and down direction) on the equipment; wherein the difference between the diameter of the test hole and the diameter of the bottom hole of the threaded connection hole to be processed is greater than the preset difference value; wherein the preset difference value is a critical value for correcting the maximum error compensation value. That is, the error compensation value is less than or equal to the preset difference value.

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

[0109] Step 304: According to the error compensation value, the original coordinate system is corrected to form a milling processing coordinate system.

[0110] It can be understood that after the X and Y axis offset correction compensation, the milling tool is called to process the milling elements, which can effectively ensure the position precision of the parts and avoid the production of unqualified parts.

[0111] The step 4 based on the milling processing coordinate system adopts a preset indexing method to mill the flange, a plurality of spherical grooves and threaded connection holes in turn, which specifically includes:

[0112] Step 401: Set the rotation axis origin, start the rotation axis indexing function, and call the first ball end mill to process a plurality of flanges;

[0113] Step 402: Call the second ball end mill to process a plurality of spherical grooves;

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

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

[0116] Optionally, in step 5, the second journal of the output flange to be processed is processed to form a spline according to the preset gear parameters; specifically, a gear hobbing machine is used to perform gear hobbing on the spline 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] Table 1 is as follows:

[0118]

[0119] Optionally, step 6 involves performing a third heat treatment on the output flange before machining, specifically including:

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

[0121] Step 610: Set the carburizing temperature to 980-1000℃; introduce carburizing gas during the low-pressure carburizing stage; wherein the carburizing gas is acetylene with a purity of 96%;

[0122] Step 611: Maintain the pressure at the preset level (600 Pa) for 30-60 minutes;

[0123] Step 612: Extract gas from the vacuum chamber until the high vacuum level in the vacuum chamber reaches the 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 machining, after low-pressure vacuum carburizing and quenching, is 0.6-0.9 mm (CHD550HV1), with a surface hardness of (80-83) HRA and a core hardness of (320-450) HV30. This heat treatment process can effectively improve the deformation behavior of parts, increase the carburizing temperature, reduce the time of intermittent processing, and greatly reduce gas and energy consumption. It also overcomes the problems of blind hole carburizing and surface carbonization that cannot be solved by traditional atmospheric hot carburizing.

[0126] Further, the step 6 is followed by: after the heat treatment of the workpiece, micro-deformation straightening and center hole fine grinding processing are performed to reduce the influence of heat treatment deformation on the workpiece. The center hole and the first inner hole are used as the reference. For the corrected workpiece, the runout of any shaft journal needs to be less than 0.02mm.

[0127] In step 7: the fourth end face of the third heat-treated output flange before machining and the third shaft neck are machined according to the first preset machining parameter, specifically including:

[0128] Step 701: The input flange before machining is fixed by using double center method, and the third shaft neck and the fourth end face are rough machined according to the first preset machining parameter; wherein the third shaft neck is reserved with a first excess amount; Specifically: a 93-degree main offset angle external cylindrical cutter is used, and a PCBN material blade is used to hard turn the third shaft neck and the fourth end face corresponding to the reference B, wherein the third shaft neck is left with a 0.15mm excess amount for subsequent fine machining. The benefits of this design are: the third shaft neck outer diameter and the fourth end face are used as the turning positioning reference, which can ensure that the perpendicularity of the third shaft neck and the fourth end face is less than 0.003mm, and the coaxiality of the first shaft neck and the fourth shaft neck relative to the references A and B is less than 0.02mm; the first preset machining parameter is: cutting speed v=180m / min, feed rate f is 0.07mm / r, and cutting depth ap is 0.1mm.

[0129] The step 8 includes:

[0130] Step 801: The third shaft neck is clamped, and the fourth end face is used as the axial positioning reference. When the detected runout of any shaft neck is less than a third preset value, the first inner hole is fine machined according to the second preset machining parameter.

[0131] In step 801, the chuck jaw is replaced with a soft jaw to clamp the third shaft neck, and the fourth end face is used as the axial positioning reference. When the runout of the machined shaft neck is less than 0.01mm, an inner hole boring cutter is called, a C-shaped blade RE0.4 and a PCBN material blade are installed, and the first inner hole with a 0.2mm excess amount left in the above step 2 is fine machined according to the second preset parameter. The second preset parameter is: cutting speed v=120m / min, feed rate f is 0.1mm / r, and cutting depth ap is 0.12mm. The benefits of this design are: the inner hole roundness of the first inner hole can be ensured to be less than 0.003mm, and the runout relative to the reference B is less than 0.015mm.

[0132] Optionally, the step 9 includes:

[0133] Step 901: The input flange before machining is clamped by using double center method;

[0134] Step 902: The fourth end face is precisely hard turned;

[0135] Step 903: According to the axial compensation method, an axial compensation value is obtained;

[0136] Step 904: According to the axial compensation value, the origin coordinate of the milling machining coordinate system is compensated;

[0137] Step 905: According to the compensated origin coordinate, precision hard turning is performed on the third end face, the first shaft neck, the third shaft neck, and the fourth shaft neck, respectively; wherein the third end face, the fourth end face, the first shaft neck, the third shaft neck, and the fourth shaft neck are precision hard turned according to the third preset machining parameter;

[0138] Step 906: A cylindrical turning tool with a main offset angle of a preset angle is called, and the spline of the second shaft neck is precision hard turned according to the fourth preset machining parameter; wherein the cylindrical turning tool adopts a left-hand tool, and the machining direction sequence is set as: from the spindle to the tailstock direction.

[0139] In step 903, the first inner hole is taken as a positioning reference, the fourth end face is machined first, and a measuring head is used to measure the first distance between the fourth end face and the third end face; the difference between the first distance and the preset distance value is calculated, the difference is taken as the axial compensation value, and the Z-axis origin coordinate of the milling machining coordinate system is corrected.

[0140] In step 905, a 93-degree main offset angle cylindrical turning tool is called, a PCBN material blade is used to perform precision hard turning on the first shaft neck, the third shaft neck, the fourth shaft neck, and the third end face, to ensure that the machining surface roughness is Ra0.4, the shaft neck roundness is 0.003mm, the cylindricality is 0.005mm, and the coaxiality of the first shaft neck and the third shaft neck is 0.005mm. The third preset machining parameter is: cutting speed v=180m / min, feed amount f is 0.07mm / r, and cutting depth ap is 0.1mm. The advantage is that this parameter can effectively control the part surface roughness Ra to be between 0.2-0.3. The hard turning process does not need to use cutting fluid for cooling, and the machining process is more green and environmentally friendly compared with grinding.

[0141] In step 906, a 75-degree main offset angle cylindrical turning tool is called, a C-shaped blade RE0.8, a PCBN material, and a negative rake angle are used. The advantage is that the tool toughness and the resistance to intermittent machining impact can be improved. At the same time, the tool direction is selected as a left-hand tool, and the machining direction sequence is set as the spindle to the tailstock direction. The advantage of this machining method is that it can reduce the self-excited vibration caused by cutting force, effectively improve the system rigidity, provide better part roughness, and increase the tool life by 3 times. The fourth preset machining parameter (i.e. intermittent hard turning cutting parameter) is set as: cutting speed v=130m / min, feed amount f is 0.1mm / r, and cutting depth ap is 0.05mm.

[0142] Optionally, the application further comprises step 10; the step 10 specifically comprises:

[0143] Spraying treatment is performed on the surface of the finished front input flange, that is, a corrosion-resistant coating is sprayed on the surface of the part to improve the corrosion resistance of the part.

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

[0145] On the other hand, the application provides a front output flange of a transfer case, applied to the method; the front output flange of the transfer case specifically comprises:

[0146] The front output flange shaft is provided with a first inner hole 13 in the middle; the upper section shape of the first inner hole 13 is in the shape of a horn;

[0147] The front output flange shaft sequentially comprises a first journal 5, a second journal 6, a third journal 7, a fourth journal 8 and a fifth journal 9 from left to right; 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 a bevel structure is further provided between the fourth journal 8 and the fifth journal 9;

[0148] Wherein, the outer surface of the second journal 6 is provided with a spline; the middle part of the outer surface of the third journal 7 is provided with a snap ring groove; the right end of the fifth journal 9 is uniformly provided with a plurality of flanges 11 on the side edge, and the right end face of the fifth journal 9 is uniformly provided with a plurality of threaded connection holes 12 on the side edge; wherein a spherical groove 10 is provided between every two adjacent threaded connection holes 12. It can be understood that the front output flange of the transfer case provided by the application has high coaxiality and high overall dimensional accuracy, so it has high transmission stability, long service life and strong practicality, and is not prone to spline tooth collapse or shaft fracture.

[0149] Now, exemplary embodiments according to this application will be described in greater detail by referring to the drawings. However, these exemplary embodiments can be implemented in various different forms, and should not be construed as being limited to only the embodiments set forth herein. It should be understood that the embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art, and in the drawings, the thicknesses of layers and regions can be exaggerated for clarity, and the same reference numerals are used throughout the drawings and the same elements are depicted with the same reference numerals, so that a description thereof will not be repeated.

Claims

1. A method of machining a transfer front output flange, characterized by, The method comprises the following steps: Step 1: performing first heat treatment on the blank in a forging manner, rough machining the blank after the first heat treatment to form a pre-machining output flange, and performing second heat treatment on the pre-machining output flange, specifically comprising: performing normalizing and high-temperature tempering treatment on the blank in a forging manner until the hardness of the blank reaches a preset hardness value; Rough machining the blank after the first heat treatment to form a pre-machining output flange having an axial end face, an axial outer circle, a stepped face, a tooth outer circle and a tooth end face; wherein the axial end face is reserved with a first machining allowance; the axial outer circle, the stepped face, the tooth outer circle and the tooth end face are reserved with a second machining allowance; Performing aging treatment and high-temperature tempering treatment on the pre-machining output flange; Step 2: turning the first end face, the second end face, the third end face, the fourth end face, the first shaft neck, the second shaft neck, the third shaft neck, the fourth shaft neck, the fifth shaft neck and the first inner hole of the pre-machining output flange in a rough machining and finish machining manner; Step 3: obtaining an error compensation value by using a preset compensation calculation method, and adjusting an 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, a preset indexing method is used to sequentially mill the flange, a plurality of spherical grooves and a threaded connection hole; Step 5: according to preset gear parameters, the second shaft neck of the pre-machining output flange is machined to form a spline; Step 6: performing third heat treatment on the pre-machining output flange, comprising step 61: performing heat treatment by using a low-pressure vacuum carburizing and quenching process; after the step 6, further comprising: Taking the first inner hole and the center hole as a reference, performing micro-deformation straightening and center hole lapping treatment on the pre-machining output flange after the third heat treatment until the runout of any one of the shaft necks detected is less than a second preset value; Step 7: machining the fourth end face and the third shaft neck of the pre-machining output flange after the third heat treatment according to a first preset machining parameter; Step 8: when a preset condition is met, machining the first inner hole according to a second preset machining parameter; Step 9: precisely hard turning the first shaft neck, the second shaft neck, the third shaft neck, the fourth shaft neck, the third end face and the fourth end face of the pre-machining output flange to form a front output flange, specifically comprising: Step 901: clamping the pre-machining output flange in a double-center method; Step 902: precisely hard turning the fourth end face; Step 903: obtaining an axial compensation value according to an axial compensation method; wherein in the step 903, taking the first inner hole as a positioning reference, the fourth end face is machined first, and a first distance between the fourth end face and the third end face is measured by using a measuring head; calculating the difference between the first distance and a preset distance value, taking the difference as the axial compensation value, and correcting the Z-axis origin coordinate of the milling machining coordinate system; Step 904: compensating to the origin coordinate of the milling machining coordinate system according to the axial compensation value; Step 905: According to the compensated origin coordinates, the third end face, the first journal, the third journal, and the fourth journal are precisely hard turned respectively; wherein, the first end face, the third end face, the first journal, the third journal, and the fourth journal are precisely hard turned according to the third preset machining parameter; in step 905, a 93-degree main offset angle external turning tool is called, a PCBN material blade is used to precisely hard turn the first journal, the third journal, the fourth journal, and the third end face, to ensure that the machining surface roughness is Ra0.4, the journal roundness is 0.003mm, the cylindrical degree is 0.005mm, and the coaxiality of the first journal and the third journal is 0.005mm; Step 906: An external turning tool with a preset angle of main offset angle is called to precisely hard turn the spline of the second journal according to the fourth preset machining parameter; wherein, the external turning tool is a left-handed tool, and the machining direction sequence is set as: from the spindle to the tailstock direction.

2. The method of claim 1, wherein, The step 2 comprises: Turning the first end face, and taking the machined first end face as a first reference surface to machine a central hole of the first end face; Machining 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 are reserved with a third machining allowance; the third journal is reserved with a fourth machining allowance; the third end face and the fourth end face are reserved with a fifth machining allowance; When the runout of any journal is less than a first preset value, machining the second end face; 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 precisely machined according to the first preset parameter; Taking the second end face as a second reference surface to machine the first inner hole; wherein, the first inner hole is precisely machined according to the second preset parameter and is reserved with a sixth machining allowance; Machining the fifth journal based on the first preset parameter.

3. The method of claim 2, wherein, The step 3 comprises: Switching the turning to milling to machine a test hole of any one to-be-machined threaded connection hole, and measuring the coordinate value of the test hole; Obtaining the coordinate value of the first inner hole machined by turning, and taking the coordinate value of the first inner hole machined by turning as a reference point; Comparing the difference between the coordinate value of the test hole and the coordinate value of the first inner hole with a preset standard value to obtain an error compensation value by subtraction calculation; Adjusting the original coordinate system according to the error compensation value to form a milling machining coordinate system.

4. The method of claim 3, wherein, The step 4 comprises: Setting a rotation axis origin, starting a rotation axis indexing function, and calling a first ball head milling cutter to machine a plurality of flanges; Calling a second ball head milling cutter to machine a plurality of spherical grooves; Machining a bottom hole of the threaded connection hole and tapping.

5. The method of claim 4, wherein, The step 61 specifically comprises: Step 610: setting the carburizing temperature to 980-1000℃; feeding carburizing gas in the low-pressure carburizing stage; wherein, the carburizing gas is acetylene with a purity of 96%; Step 611: maintaining for 30min-60min under a preset pressure; Step 612: extracting the gas in 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.

6. The method for machining the front output flange of a transfer case according to claim 5, characterized in that, Step 7 specifically includes: The output 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 allowance; Accordingly, step 8 includes: The third journal is clamped, and the fourth end face is used as the axial positioning reference. When the detected runout of any journal is less than the third preset value, the first inner hole is precision machined according to the second preset machining parameters.

7. A front output flange of a transfer, characterized by, It is manufactured using the method described in any one of claims 1-6; the front output flange of the transfer case specifically includes: A front output flange shaft with a first inner hole in the middle; the upper cross-sectional shape 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; and a transition journal with a slope structure is also provided between the fourth journal and the fifth journal. The second journal has a spline on its outer surface; the third journal has a retaining ring groove on its outer surface; the fifth journal has a plurality of flanges evenly distributed along its right circumferential edge, and the fifth journal has a plurality of threaded connection holes evenly distributed along its right circumferential edge; and a spherical groove is provided between each pair of adjacent threaded connection holes.

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