Differential shell and transmission gear integrated structure made of ADI material and manufacturing method of differential shell and transmission gear integrated structure

Abstract

The invention provides an ADI material differential shell and transmission gear integrated structure and a manufacturing method thereof, and relates to the field of new energy automobile transmission systems.The method comprises the steps that S1, a mold is designed and manufactured, specifically, a special mold is designed and manufactured according to the design requirement of the differential shell and transmission gear integrated structure; s2, raw material preparation: preparing an ADI material; s3, casting is conducted, specifically, a resin sand molding process is adopted, an ADI material is poured into a mold, the pouring temperature and speed are controlled, and the performance and quality of a casting are ensured; s4, a casting is cleaned, and a casting blank is obtained; s5, rough machining is conducted on the cast blank; s6, the roughly machined workpiece obtained in the step S5 is subjected to heat treatment; and S7, finish machining is conducted on the workpiece obtained in the step S6. The integrated design is adopted, the number of parts and the machining difficulty are reduced, and the production efficiency is improved; and the integrated structure has higher strength and wear resistance while ensuring light weight, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of new energy vehicle transmission systems, and specifically to an integrated structure of an ADI material differential housing and a transmission gear and a manufacturing method thereof. Background Art

[0002] The differential is an important component in the automobile transmission system. Its main function is to allow the left and right wheels to rotate at different speeds when the vehicle turns, thereby ensuring the vehicle's driving stability and maneuverability. Because the power of the traditional differential is transmitted vertically, it is usually composed of components such as the differential housing, the horn gear, and the planetary gear. These components are mostly split due to structural reasons and assembled together by bolting or welding. The split structure generally has the following shortcomings: First, there are many parts, complex assembly, and low production efficiency; second, the connection parts are prone to loosening or fatigue fracture, which affects the reliability and service life of the differential. In recent years, with the demand for lightweight and high performance of automobiles, especially the rapid development of new energy vehicles, the integrated design of differentials has gradually attracted attention. For example, Changshu Meiqiao has obtained a patent for a main reduction gear and differential housing integrated welded differential. This integrated design reduces the number of parts and improves assembly efficiency and structural strength. However, welding deformation is extremely difficult to control, welding stress is not easy to release, and the strength around the weld is reduced due to ablation, which makes it difficult to improve manufacturing accuracy, poor performance stability, and high manufacturing costs. Most of the existing integrated differentials are made of steel or aluminum alloy, which have a series of problems such as heavy weight or insufficient strength. In addition, with the rapid development of new energy vehicles, the drive motor is directly mounted on the bridge body, and the power input direction becomes parallel transmission. The basin angle gears that are difficult and expensive to process are replaced by cylindrical gears that are widely used and easy to process. It has become a general trend that the separate structure of the housing and the transmission gear is replaced by an integrated structure.

[0003] ADI (Austempered Ductile Iron or Austempered Ductile Iron) material is a high-strength, high-toughness ductile iron material with excellent mechanical properties and wear resistance, and is lighter than steel. It is an ideal new alternative material for automotive parts. In the United States, the application rate of ADI materials has accounted for more than 15% of metal materials, while the share of ADI materials in my country in metal materials is only about 1.1%. Therefore, ADI materials not only have broad application prospects in China, but will also occupy an important position worldwide.

[0004] The main advantages of ADI materials are as follows:

[0005] 1. Excellent mechanical properties

[0006] 1. ADI material has high strength and elongation. The highest known tensile strength can reach 1600Mp and the highest elongation can reach 16%. It has excellent dynamic mechanical properties and is superior to forged steel, cast steel, and micro-alloyed steel.

[0007] 2. High fatigue strength, fatigue resistance remains unchanged after millions of alternating loads.

[0008] 3. Good wear resistance. The ADI material contains spherical graphite, which can reduce the friction coefficient and operating temperature. It has high surface hardness and excellent wear resistance. When used in gear transmission, it can effectively reduce tooth surface wear and pitting failure, and prevent tooth breakage.

[0009] (II) Excellent physical properties

[0010] 1. Sound absorption and noise reduction. The graphite in the material has a good sound absorption effect and produces little noise during operation. When used in gear transmission, it can effectively reduce transmission noise and alleviate noise pollution.

[0011] 2. Excellent shock absorption performance. The elastic modulus of ADI material is 20% lower than that of steel. It can quickly absorb vibrations, make the machine parts operate smoothly, and reduce the vibration of the whole machine.

[0012] 3. Excellent low temperature resistance, can still work normally at -80℃, good low temperature toughness, and can adapt to work in high-cold areas.

[0013] (III) Economic and process advantages

[0014] 1. Low cost. ADI material is cheaper than cast steel, forged steel and cast aluminum of the same weight. When the cost is calculated based on yield strength, ADI is the most economical material.

[0015] 2. Small specific gravity. Parts of the same volume are about 10% lighter than forged steel, which helps to reduce the weight of components and the entire machine.

[0016] 3. There are various casting processes and parts shapes: the traditional clay sand and water glass modeling methods can be used, or the more advanced resin sand, lost foam, V-method casting and other processes can be used; the casting process is relatively simple to realize the shapes of parts with complex shapes, which has obvious advantages.

[0017] (IV) Environmental and application advantages

[0018] 1. Environmental protection: the production process has little impact on the environment and is a green engineering material.

[0019] 2. Widely used, it can be used for crankshafts, gears, high-pressure hydraulic valve blocks, high-performance housing parts, etc., and can replace traditional steel, cast steel, forged steel and ordinary ductile iron and other materials;

[0020] After thorough inquiry, there are currently no public reports on the use of ADI materials in the integrated structure of differential housings and cylindrical gears. Summary of the invention

[0021] The present invention provides an integrated structure of a differential housing and a transmission gear made of ADI material and a manufacturing method thereof, so as to solve the technical problems raised by the above-mentioned background technology.

[0022] In order to solve the above technical problems, the present invention discloses a method for manufacturing an integrated structure of a differential housing and a transmission gear made of ADI material, comprising:

[0023] Step S1: mold design and manufacturing: design and manufacture a dedicated mold according to the design requirements of the integrated structure of the differential housing and the transmission gear;

[0024] Step S2: Raw material preparation: preparing ADI material;

[0025] Step S3: Casting: Using resin sand molding technology, pour the ADI material into the mold, control the pouring temperature and speed to ensure the performance and quality of the casting;

[0026] Step S4: cleaning the casting to obtain a casting blank;

[0027] Step S5: performing rough machining on the casting blank;

[0028] Step S6: heat treating the rough-machined workpiece obtained in step S5;

[0029] Step S7: finishing the workpiece obtained in step S6.

[0030] Preferably, in step S2: the chemical composition of the ADI material comprises by weight percentage:

[0031] C: 3.3-3.9%; Si: 1.7-2.3%; Mn: <0.2%; S: <0.02%; P: <0.035%; Mg: 0.02-0.05; Cu: 0-0.3%; Ni: 0.3-1.5%; the rest is Fe;

[0032] In step S2, the melting temperature of the ADI material is 1530°C-1560°C; after melting, the material is allowed to stand at high temperature and then subjected to slag removal treatment; spheroidization is performed by the injection method, and the amount of spheroidizing agent added is 1.1-1.3%; the amount of inoculant added is 0.5-0.9%, and the amount of covering agent added is 0.4-1.0%.

[0033] Preferably, the pouring temperature is 1390°C to 1420°C; a semi-closed pouring system is used, and the area ratio of the ingates, runners and sprues is: 0.8: (1.2-1.5): 1; the pouring speed must be controlled during pouring to keep the filling stable and avoid secondary oxidation and air entrainment;

[0034] The castings are required to have a spheroidization rate of 3 or above and a graphite particle count of no less than 100 / mm 2; The metallographic matrix structure is mainly ferrite, pearlite or austenite according to needs.

[0035] Preferably, the casting cleaning includes: cutting the gate and riser, removing the flash and shot blasting to make the casting surface neat and smooth;

[0036] The rough machining includes: rough machining of shape, size and tooth profile;

[0037] The finishing includes: finishing the surface shape of the workpiece obtained in step S6, the size required by the drawing and the tooth shape, ensuring the dimensional accuracy, position accuracy and surface roughness, and removing the heat treatment deformation.

[0038] Preferably, the heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, heat preservation, and isothermal quenching;

[0039] In the isothermal quenching heat treatment:

[0040] The heating temperature is 750℃-990℃; the heating rate is controlled at 100-150℃ / hour before reaching 600℃;

[0041] The heat preservation time is 50-100 minutes;

[0042] In isothermal quenching, the isothermal temperature is 250°C-430°C, and the isothermal time is 50-90 minutes.

[0043] Preferably, the step S1 comprises:

[0044] Step S11: Drawing analysis: by interpreting and analyzing the three-dimensional model and two-dimensional drawings of the workpiece, clarify the technical requirements, accuracy, tolerance of the casting, and understand the workpiece geometry, design basis, dimensions of each part, and surface requirements;

[0045] Step S12: Determine the mold solution: comprehensively consider the number and arrangement of cavities, parting surface selection, gating system design, and exhaust system design;

[0046] Step S13: Make mold drawings: First, make an overall design, draw a mold assembly drawing, clarify the assembly relationship of each component in the mold, and then disassemble and draw component drawings to clarify size requirements and materials;

[0047] Step S14: Organize relevant experts and technicians to conduct centralized review, and conduct detailed review of the structural principle, processing technology and manufacturing operation safety of the mold to ensure that the performance is met and the manufacturing operation is convenient;

[0048] Step S15: manufacturing and assembly, according to the mold drawings that have been reviewed and adjusted, manufacturing and assembly are completed;

[0049] Step S16: Inspection and acceptance: Carry out detailed inspection on the mold cavity size and position accuracy to ensure that they meet the design requirements; then carry out functional inspection, through actual pouring test, check whether the mold's pouring performance, exhaust effect, and casting quality meet the design requirements.

[0050] Preferably, the heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, heat preservation, and isothermal quenching;

[0051] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat treated is divided into a number of target sub-heating temperature sections, and each target sub-heating temperature section is heated in a corresponding target temperature rise rate range of the workpiece to be heat treated;

[0052] In the batch heat treatment in step S6, the set furnace temperature of the heating furnace is set to a value within the target furnace temperature range during the heating stage;

[0053] The process of determining the target furnace temperature range includes:

[0054] Step S61: determining a target temperature rise rate range of the workpiece to be heat treated in each target sub-heating temperature section;

[0055] Step S62: determining a first furnace temperature range corresponding to each target sub-heating temperature segment based on the maximum temperature of each target sub-heating temperature segment, the minimum temperature of the target sub-heating temperature segment, the target temperature rise rate range of the workpiece to be heat-treated in the target sub-heating temperature segment, and the heating model of the heating furnace;

[0056] Step S63: determining the heating matching degree of the first integer temperature based on the matching degree between the first integer temperature and the first furnace temperature range corresponding to each target sub-heating temperature segment and the temperature rise rate difference between adjacent target sub-heating temperature segments at the first integer temperature; the first integer temperature is an integer temperature in the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the largest temperature;

[0057] Step S64: Determine the first integer temperature whose heating matching degree is greater than or equal to the preset matching degree as the required integer temperature, and determine the target furnace temperature range based on the required integer temperature.

[0058] Preferably, the heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, heat preservation, and isothermal quenching;

[0059] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat treated is divided into a number of target sub-heating temperature sections, and each target sub-heating temperature section is heated in a corresponding target temperature rise rate range of the workpiece to be heat treated;

[0060] The heating process of the workpiece to be heat treated is divided into several target sub-heating temperature sections including:

[0061] Step S611: taking the median of the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the maximum temperature as the second furnace temperature, setting the set furnace temperature of the heating furnace to the second furnace temperature, performing a heating test on the workpiece to be heat-treated for testing, and collecting the surface temperature of the workpiece to be heat-treated for testing for multiple times during the heating test;

[0062] Step S612: constructing a time-test workpiece surface temperature variation curve based on the surface temperature of the workpiece to be heat treated collected in step S611;

[0063] Step S613: dividing the time-test surface temperature variation curve of the workpiece to be heat-treated into a plurality of first sub-temperature sections at preset temperature intervals, and determining the average temperature rise rate of each first sub-temperature section;

[0064] Step S614: Based on step S613, the target sub-heating temperature segment is determined, the target sub-heating temperature segment is composed of continuous first sub-temperature segments, and the absolute value of the difference between the average temperature rise rates of any two first sub-temperature segments of the target sub-heating temperature segment is less than or equal to the first preset temperature rise rate, and the absolute value of the difference between the average temperature rise rates of adjacent first sub-temperature segments in the target sub-heating temperature segment is less than or equal to the second preset temperature rise rate.

[0065] Preferably, during step S3, the molten iron is filtered through a filter and then injected into the mold, a pressure sensor 1 is provided on the feed side of the filter to detect the molten iron pressure at the corresponding position, and a pressure sensor 2 is provided on the discharge side of the filter to detect the molten iron pressure at the corresponding position;

[0066] The pouring process of a single workpiece is divided into several pouring sections, each pouring section corresponds to a different total pouring amount range, the memory stores a mapping table of the total pouring amount range of molten iron in the mold and the target pouring speed range, and the control device is electrically connected to the memory, the pressure sensor 1, the pressure sensor 2, and the molten iron pouring control device respectively;

[0067] Batch casting process, the casting process of each workpiece includes:

[0068] Step S31: obtaining the parameters of the molten iron to be poured and a mapping table of the total pouring amount range of the molten iron in the mold and the target pouring speed range, wherein the parameters of the molten iron include: the viscosity of the molten iron and the temperature of the molten iron;

[0069] Step S32: obtaining a target pouring speed range corresponding to the current pouring section, and determining a first ratio corresponding to the current pouring section; the first ratio corresponding to the current pouring section is a ratio of an average detection value of the pressure sensor 2 corresponding to a previous pouring section of the current pouring section to an average detection value of the pressure sensor 1;

[0070] Step S33: based on the first ratio corresponding to the current casting section and the ratio of the parameter of the molten iron in the current casting section to the corresponding standard parameter of the molten iron, the target casting speed range corresponding to the current casting section is corrected to obtain a corrected casting speed range corresponding to the current casting section;

[0071] Step S34: During the pouring process of the current pouring section, the molten iron pouring control device is controlled to operate so that the actual pouring speed of the molten iron is within the corrected pouring speed range corresponding to the current pouring section.

[0072] The invention also discloses an integrated structure of a differential housing and a transmission gear made of an ADI material, which is manufactured by adopting the manufacturing method of the integrated structure of a differential housing and a transmission gear made of an ADI material.

[0073] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] 1. Simplified structure and improved efficiency: The integrated design optimizes the internal and external shape of the shell, reducing the number of parts and the difficulty of processing; the assembly process is reduced and the complexity is reduced, which improves production efficiency.

[0076] 2. Performance improvement and cost reduction: The high strength and high toughness of ADI materials enable the integrated structure to have higher strength and wear resistance while ensuring lightweight; reduce component damage, extend service life, extend the effective working time of the whole machine, increase economic benefits, and reduce downtime losses and component replacement costs.

[0077] 3. Enhanced reliability: integrated molding reduces the number of connection parts, reduces the risk of loosening and fatigue fracture, and increases the service life of the differential.

[0078] 4. Cost reduction: By optimizing the design and manufacturing process, the material and processing costs are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0080] Figure 1 It is a schematic flow chart of the manufacturing method of the present invention;

[0081] Figure 2 The structure of the three-dimensional model of the present invention is shown in FIG. Figure 1 ;

[0082] Figure 3The structure of the three-dimensional model of the present invention is shown in FIG. Figure 2 ;

[0083] Figure 4 The structure of the two-dimensional model of the present invention is shown in FIG. Figure 1 ;

[0084] Figure 5 The structure of the two-dimensional model of the present invention is shown in FIG. Figure 2 . DETAILED DESCRIPTION

[0085] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0086] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present invention. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions and technical features between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0087] The present invention provides the following embodiments:

[0088] The present invention aims to provide an integrated structure of a differential case and a transmission gear using ADI material and a manufacturing method thereof, so as to solve the problems of the existing differential having a complex structure, heavy weight, complicated assembly process, easy loosening of connection parts, complex anti-loosening measures, and insufficient strength.

[0089] Embodiment 1, as Figure 1-Figure 5 As shown, an embodiment of the present invention provides a method for manufacturing an integrated structure of a differential housing and a transmission gear made of ADI material, comprising:

[0090] Step S1: mold design and manufacturing: design and manufacture a special mold according to the design requirements of the integrated structure of the differential housing and the transmission gear; the mold precision can reach micron level;

[0091] Step S2: Raw material preparation: Select high-purity ADI materials to ensure the uniformity and performance consistency of the materials; specifically: select the raw materials of ADI materials for smelting;

[0092] Step S3: Casting: Using resin sand molding technology, pour the ADI material into the mold, control the pouring temperature and speed to ensure the performance and quality of the casting;

[0093] Step S4: cleaning the casting to obtain a casting blank;

[0094] Step S5: performing rough machining on the casting blank;

[0095] Step S6: heat treating the rough-machined workpiece obtained in step S5; performing isothermal quenching heat treatment on the rough-machined integrated differential case and cylindrical gear workpiece to improve the strength and toughness of the material and meet the performance requirements of the workpiece;

[0096] Step S7: finishing the workpiece obtained in step S6.

[0097] Specifically, in step S2: the chemical composition of the ADI material includes by weight percentage:

[0098] C: 3.3-3.9%; Si: 1.7-2.3%; Mn: <0.2%; S: <0.02%; P: <0.035%; Mg: 0.02-0.05; Cu: 0-0.3%; Ni: 0.3-1.5%; the rest is Fe;

[0099] In step S2, the melting temperature of the ADI material is 1530°C-1560°C; after melting, the material is allowed to stand at high temperature and then subjected to slag removal treatment; spheroidization is performed by the injection method, and the amount of spheroidizing agent added is 1.1-1.3%; the amount of inoculant added is 0.5-0.9%, and the amount of covering agent added is 0.4-1.0%.

[0100] Specifically, the pouring temperature is 1390℃~1420℃; a semi-closed pouring system is used, and the area ratio of the inner runner, the cross runner and the straight runner is: 0.8: (1.2~1.5): 1; the pouring speed must be controlled during pouring to keep the filling stable and avoid secondary oxidation and air entrainment;

[0101] The castings are required to have a spheroidization rate of 3 or above and a graphite particle count of no less than 100 / mm 2 ; The metallographic matrix structure is mainly ferrite, pearlite or austenite according to needs.

[0102] Specifically, casting cleaning includes: cutting the gate, riser, removing the flash and shot blasting to make the casting surface neat and smooth;

[0103] The rough machining includes: rough machining of shape, size and tooth profile;

[0104] The finishing includes: finishing the surface shape, the dimensions required by the drawing, and the tooth shape of the workpiece obtained in step S6 to ensure the dimensional accuracy, positional accuracy, and surface roughness, and to remove the heat treatment deformation.

[0105] Specifically, the heat treatment in step S6 is an isothermal quenching heat treatment (ADI isothermal quenching heat treatment), and the isothermal quenching heat treatment includes: heating, heat preservation, and isothermal quenching (cooling by isothermal quenching);

[0106] In the isothermal quenching heat treatment:

[0107] The heating temperature is 750℃-990℃ (temperature range of the workpiece after heating); the heating rate (temperature rise rate) is controlled at 100-150℃ / hour before reaching 600℃;

[0108] According to the size and performance requirements of the workpiece, the insulation time is 50-100 minutes;

[0109] In isothermal quenching, the isothermal temperature is 250°C-430°C (temperature of the isothermal quenching medium), and the isothermal time is 50-90 minutes.

[0110] Specifically, the step S1 includes:

[0111] Step S11: Drawing analysis: by interpreting and analyzing the three-dimensional model and two-dimensional drawings of the workpiece, clarify the technical requirements, accuracy, tolerance, etc. of the casting, and understand the workpiece geometry, design basis, dimensions of each part, and surface requirements;

[0112] Step S12: Determine the mold solution: comprehensively consider aspects such as the number and arrangement of cavities, parting surface selection, gating system design, and exhaust system design;

[0113] Step S13: Make mold drawings: First, make an overall design, draw a mold assembly drawing, clarify the assembly relationship of each component in the mold, and then disassemble and draw component drawings to clarify size requirements and materials;

[0114] Step S14: Centralized review: After the design is completed, the company's technical center organizes relevant experts and technicians to conduct a centralized review, and conducts a detailed review of the mold's structural principles, processing technology, and manufacturing operation safety to ensure that it meets the performance requirements and is easy to manufacture;

[0115] Step S15: manufacturing and assembly, according to the mold drawings that have been reviewed and adjusted, manufacturing and assembly are completed;

[0116] Step S16: Inspection and acceptance: Carry out detailed inspection on the mold cavity size and position accuracy (three-coordinate measuring instrument and other inspection equipment can be used) to ensure that it meets the design requirements; then carry out functional inspection, through actual pouring test, check whether the pouring performance, exhaust effect and casting quality of the mold meet the design requirements.

[0117] The present invention also discloses an integrated structure of an ADI material differential housing and a transmission gear, comprising: a differential housing including a cylindrical gear is made of ADI material, and has a high-strength and high-toughness tooth shape and size to meet transmission requirements; the integrated structure of the differential housing and the transmission gear of the ADI material is manufactured by the manufacturing method; the transmission gear and the differential housing are cast into an integrated blank through optimized design, and the parts are manufactured through the processes of mold design and manufacturing---raw material preparation---casting---casting cleaning---rough machining---ADI isothermal quenching heat treatment---fine machining, so as to ensure structural strength and transmission accuracy.

[0118] In the present invention, after isothermal quenching, the integrated differential housing obtains excellent comprehensive performance, with a tensile strength of ≥1200Mp, which is better than the tensile strength of 1080Mp of 20CrMnTi, a common gear material, after carburizing and quenching; and an elongation of ≥10%, which is equivalent to the elongation of 20CrMnTi after carburizing and quenching.

[0119] The beneficial effects of the above technical solution are:

[0120] 1. Simplified structure and improved efficiency: The integrated design optimizes the internal and external shape of the shell, reducing the number of parts and the difficulty of processing; the assembly process is reduced and the complexity is reduced, which improves production efficiency.

[0121] 2. Performance improvement and cost reduction: The high strength and high toughness of ADI materials enable the integrated structure to have higher strength and wear resistance while ensuring lightweight; reduce component damage, extend service life, extend the effective working time of the whole machine, increase economic benefits, and reduce downtime losses and component replacement costs.

[0122] 3. Enhanced reliability: integrated molding reduces the number of connection parts, reduces the risk of loosening and fatigue fracture, and increases the service life of the differential.

[0123] 4. Cost reduction: By optimizing the design and manufacturing process, the material and processing costs are reduced.

[0124] Embodiment 2, based on Embodiment 1, the heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment includes: heating, heat preservation, and isothermal quenching in sequence;

[0125] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat treated is divided into a number of target sub-heating temperature sections, and each target sub-heating temperature section is heated according to the target temperature rise rate range of the corresponding workpiece to be heat treated; wherein the target temperature rise rate range of the target sub-heating temperature section before 600°C is between 100-150°C / hour, and the target temperature rise rate range of the target sub-heating temperature section from 600°C to the maximum temperature of the heating process is between 50-80°C / hour;

[0126] In step S6, during the batch heat treatment, the set furnace temperature of the heating furnace is set to a value within the target furnace temperature range during the heating stage (the furnace temperature is set to the same value during the isothermal quenching heat treatment of a single workpiece to be heat treated, and the furnace temperature set by the heating furnace is within the target furnace temperature range);

[0127] The process of determining the target furnace temperature range includes:

[0128] Step S61: determining a target temperature rise rate range of the workpiece to be heat treated in each target sub-heating temperature section (related to the requirements of specific ADI materials, which can be determined based on experiments and / or historical experience, and the quality of the workpiece to be heat treated meets the requirements within the target temperature rise rate range);

[0129] Step S62: determining a first furnace temperature range corresponding to each target sub-heating temperature segment based on the maximum temperature of each target sub-heating temperature segment, the minimum temperature of the target sub-heating temperature segment, the target temperature rise rate range of the workpiece to be heat-treated in the target sub-heating temperature segment, and the heating model of the heating furnace;

[0130] Step S63: determining the heating matching degree of the first integer temperature based on the matching degree between the first integer temperature and the first furnace temperature range corresponding to each target sub-heating temperature segment and the temperature rise rate difference between adjacent target sub-heating temperature segments at the first integer temperature; the first integer temperature is an integer temperature in the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the maximum temperature (the value is different according to different ADI materials);

[0131] Step S64: determining a first integer temperature whose heating matching degree is greater than or equal to a preset matching degree (which can be 1) as a required integer temperature, and determining a target furnace temperature range based on the required integer temperature;

[0132] Determine the temperature range consisting of continuous required integer temperatures as the required temperature range:

[0133] When there are multiple required temperature ranges, determine the required temperature range with the largest average value of the heating matching degree of the required integer temperature as the target furnace temperature range;

[0134] When there is one required temperature range, the required temperature range is determined to be the target furnace temperature range;

[0135] When there is only one required temperature, another heating furnace is selected to redo the process of determining the target furnace temperature range.

[0136] Among them, the first furnace temperature range is ;

[0137] in, is the maximum temperature of the i-th target sub-heating temperature segment; is the minimum temperature of the i-th target sub-heating temperature section; e is a natural constant; h is the total heat transfer coefficient between the workpiece to be heat-treated and the environment in the heating furnace; S is the surface area of ​​a single workpiece to be heat-treated; c is the specific heat capacity of the workpiece to be heat-treated, and m is the mass of a single workpiece to be heat-treated; The minimum value of the target temperature rise rate range of the workpiece to be heat treated in the i-th target sub-heating temperature section; The maximum value of the target temperature rise rate range of the workpiece to be heat treated in the i-th target sub-heating temperature section; the temperature rise rate unit is ° C / hour;

[0138] That is, the heating model of the heating furnace is substituted into The lower limit of the first furnace temperature range obtained;

[0139] The heating matching degree for the first integer temperature is calculated as follows:

[0140] ;

[0141] ;

[0142] is the difference in temperature rise rate between the i-th target sub-heating temperature segment and the i-1-th target sub-heating temperature segment at the j-th first integer temperature; Indicates the minimum value; The absolute value of the furnace temperature error of the heating furnace (can be ±0.5°C, which is different for different heating furnaces); is the jth first integer temperature; , They are the first weight and the second weight respectively (both are greater than 0 and less than 1, and can be 0.7 and 0.3 respectively);

[0143] is the heating matching degree of the jth first integer temperature; M is the total number of divided target sub-heating temperature sections; is the matching degree between the jth first integer temperature and the first furnace temperature range corresponding to the ith target sub-heating temperature segment; is the average temperature rise rate of the i-th target sub-heating temperature section when the furnace temperature of the heating furnace is the j-th first integer temperature; is the average temperature rise rate of the i-1th target sub-heating temperature section when the furnace temperature of the heating furnace is the jth first integer temperature; for The corresponding maximum allowed value ( Based on the specific ADI material and the specific value of i).

[0144] ;

[0145] ;

[0146] is the natural logarithm; is the maximum temperature of the i-1th target sub-heating temperature segment; is the minimum temperature of the i-1th target sub-heating temperature segment; is the natural logarithm;

[0147] The beneficial effects of the above technical solution are:

[0148] The heating matching degree of the first integer temperature is combined with the first integer temperature and the first furnace temperature range matching state corresponding to each target sub-heating temperature segment ( ), and the temperature rise rate difference state of adjacent target sub-temperature segments at the first integer temperature ( ), determine the first integer temperature whose heating matching degree is greater than or equal to the preset matching degree as the required integer temperature, and determine the target furnace temperature range based on the required integer temperature, so as to ensure that the appropriate furnace temperature is selected.

[0149] hour, The value is 1. On the one hand, the jth first integer temperature is within the first furnace temperature range of the ith target sub-heating temperature segment, ensuring that the temperature rise rate of the workpiece to be heat treated is appropriate in the ith target sub-heating temperature segment. On the other hand, the error of the heating furnace is taken into account to ensure that even if there is a slight error in the furnace temperature of the heating furnace, the temperature rise rate still meets the requirements.

[0150] Embodiment 3, based on Embodiment 1, the heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment includes: heating, heat preservation, and isothermal quenching in sequence;

[0151] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat treated is divided into a number of target sub-heating temperature sections, and each target sub-heating temperature section is heated in a corresponding target temperature rise rate range of the workpiece to be heat treated;

[0152] The heating process of the workpiece to be heat treated is divided into several target sub-heating temperature sections including:

[0153] Step S611: taking the median of the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the maximum temperature as the second furnace temperature, setting the set furnace temperature of the heating furnace to the second furnace temperature, performing a heating test on the workpiece to be heat-treated for testing, and collecting the surface temperature of the workpiece to be heat-treated for testing for multiple times during the heating test;

[0154] Step S612: constructing a time-test workpiece surface temperature variation curve based on the surface temperature of the workpiece to be heat treated collected in step S611 (the abscissa is the temperature collection time, and the ordinate is the collected surface temperature of the workpiece to be heat treated);

[0155] Step S613: dividing the time-test surface temperature variation curve of the workpiece to be heat-treated into a plurality of first sub-temperature sections at preset temperature intervals (which may be 0.5°C or 1°C), and determining the average temperature rise rate of each first sub-temperature section;

[0156] Step S614: Based on step S613, the target sub-heating temperature segment is determined, the target sub-heating temperature segment is composed of continuous first sub-temperature segments, and the absolute value of the difference in average temperature rise rates of any two first sub-temperature segments of the target sub-heating temperature segment is less than or equal to the first preset temperature rise rate (set to different values ​​according to different workpieces, such as 16-30°C / hour), and the absolute value of the difference in average temperature rise rates of adjacent first sub-temperature segments in the target sub-heating temperature segment is less than or equal to the second preset temperature rise rate (set to different values ​​according to different workpieces, such as 5-15°C / hour).

[0157] The beneficial effects of the above technical solution are:

[0158] The heating process of the workpiece to be heat treated is divided into several target sub-heating temperature sections, and each target sub-heating temperature section is heated within the corresponding target temperature rise rate range of the workpiece to be heat treated to ensure that the temperature rise of the workpiece to be heat treated at each target sub-heating temperature in the heating process of the workpiece to be heat treated meets the requirements, thereby ensuring the heat treatment quality of the workpiece to be heat treated.

[0159] The median of the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the maximum temperature is taken as the second furnace temperature, the set furnace temperature of the heating furnace is set to the second furnace temperature (which can be ±0.3°C), and a heating test is performed on the workpiece to be heat-treated for testing. During the heating test, the surface temperature of the workpiece to be heat-treated for testing is collected multiple times, and a time-surface temperature change curve of the workpiece to be heat-treated for testing is constructed, so that the actual temperature rise state of the workpiece to be heat-treated under certain conditions (the furnace temperature of the heating furnace is within the preset range of the second furnace temperature) can be determined based on the initial test;

[0160] Then, the target sub-heating temperature sections are divided based on the actual temperature rise state of the workpiece to be heat-treated under certain conditions, and the division is reliable.

[0161] The absolute value of the difference between the average temperature rise rates of any two first sub-temperature segments of the target sub-heating temperature segment is less than or equal to the first preset temperature rise rate, so that the temperature rise rate of each target sub-heating temperature segment is relatively close, ensuring the heat treatment effect.

[0162] Embodiment 4, on the basis of any one of Embodiments 1-3, in step S3, the molten iron is filtered through a filter screen and then injected into the mold, a pressure sensor 1 is provided on the feed side of the filter screen to detect the molten iron pressure at the corresponding position, and a pressure sensor 2 is provided on the discharge side of the filter screen to detect the molten iron pressure at the corresponding position; wherein, the present invention can set the filter screen at a certain position directly above the feed port of the mold;

[0163] The pouring process of a single workpiece is divided into several pouring sections (each pouring section corresponds to a number), each pouring section corresponds to a different total pouring volume range (the total pouring volume is the total amount of molten iron produced by a single workpiece and has been injected into the mold), the memory stores a mapping table of the total pouring volume range of molten iron in the mold-target pouring speed range (which can be obtained based on testing or historical experience), and the control device is electrically connected to the memory, pressure sensor 1, pressure sensor 2, and molten iron pouring control device respectively;

[0164] Batch casting process, the casting process of each workpiece includes:

[0165] Step S31: obtaining the parameters of the molten iron to be poured and a mapping table of the total pouring amount range of the molten iron in the mold and the target pouring speed range, wherein the parameters of the molten iron include: the viscosity of the molten iron and the temperature of the molten iron;

[0166] Step S32: obtaining a target pouring speed range corresponding to the current pouring section, and determining a first ratio corresponding to the current pouring section; the first ratio corresponding to the current pouring section is a ratio of an average detection value of the second pressure sensor corresponding to the previous pouring section of the current pouring section to an average detection value of the first pressure sensor; wherein, when the first ratio is less than a preset value, an alarm is issued;

[0167] Step S33: based on the first ratio corresponding to the current casting section and the ratio of the parameter of the molten iron in the current casting section to the standard parameter of the corresponding molten iron, the target casting speed range corresponding to the current casting section is corrected to obtain a corrected casting speed range corresponding to the current casting section;

[0168] Step S34: During the pouring process of the current pouring section, the molten iron pouring control device is controlled to operate so that the actual pouring speed of the molten iron is within the corrected pouring speed range corresponding to the current pouring section.

[0169] ;

[0170] ;

[0171] is the lower limit of the corrected pouring speed range corresponding to the hth pouring section; is the upper limit of the corrected pouring speed range corresponding to the hth pouring section; is the lower limit of the target pouring speed range of the hth pouring section (under the standard value condition of the ratio of the pressure of the molten iron on the discharge side of the filter screen to the pressure of the molten iron on the feed side of the filter screen); is the upper limit of the target pouring speed range of the hth pouring segment; The viscosity of the molten iron to be poured (each ladle / each furnace of molten iron can be tested only once). is the temperature of the molten iron corresponding to the h-th pouring section (the temperature of the molten iron to be poured can be monitored in real time during the pouring process); , They are standard molten iron viscosity and standard molten iron temperature respectively (the actual molten iron viscosity of the current ADI material at the standard molten iron temperature is determined based on the test as the standard molten iron viscosity; the standard molten iron temperature is determined according to the required temperature range of different ADI materials before pouring, and the value can be the median of the required temperature range of different ADI materials before pouring); It is the standard value of the ratio of the pressure of the molten iron on the discharge side of the filter to the pressure of the molten iron on the feed side of the filter; is the first ratio corresponding to the hth casting section.

[0172] The total pouring amount is measured in weight or volume and can be determined based on monitoring the overall weight of the mold or the reduction in the amount of molten iron being poured in the molten iron pouring equipment.

[0173] The beneficial effects of the above technical solution are:

[0174] When pouring molten iron, different pouring sections pour into different mold areas. Different pouring sections determine matching target pouring speeds according to the structures of the corresponding mold areas. At the target pouring speed, the molding quality of the workpiece in the corresponding mold area is better.

[0175] By setting up the filter, the purity of the poured molten iron is guaranteed, and based on the pressure ratio state of the molten iron after filtration and before filtration of the filter of the previous casting section of the current casting section (the ratio of the average detection value of the pressure sensor 2 to the average detection value of the pressure sensor 1 corresponding to the previous casting section of the current casting section) and the parameter state of the molten iron in the current casting section ( , ) Correct the pouring speed to ensure that the appropriate pouring speed is selected for pouring, thereby ensuring the stability of the pouring quality.

[0176] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for manufacturing an integrated structure of an ADI material differential housing and a transmission gear, characterized in that: include: Step S1: mold design and manufacturing: design and manufacture a dedicated mold according to the design requirements of the integrated structure of the differential housing and the transmission gear; Step S2: Raw material preparation: preparing ADI material; Step S3: Casting: Use resin sand molding technology to pour ADI material into the mold, control the pouring temperature and speed to ensure the performance and quality of the casting; Step S4: cleaning the casting to obtain a casting blank; Step S5: performing rough machining on the casting blank; Step S6: heat treating the rough-machined workpiece obtained in step S5; Step S7: finishing the workpiece obtained in step S6.

2. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: In step S2: the chemical composition of the ADI material includes by weight percentage: C: 3.3-3.9%; Si: 1.7-2.3%; Mn: <0.2%; S: <0.02%; P: <0.035%; Mg: 0.02-0.05; Cu: 0-0.3%; Ni: 0.3-1.5%; the rest is Fe; In step S2, the melting temperature of the ADI material is 1530°C-1560°C; after melting, the material is allowed to stand at high temperature and then subjected to slag removal treatment; spheroidization is performed by the injection method, and the amount of spheroidizing agent added is 1.1-1.3%; the amount of inoculant added is 0.5-0.9%, and the amount of covering agent added is 0.4-1.0%.

3. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: The pouring temperature is 1390℃~1420℃; a semi-closed pouring system is used, and the area ratio of the inner runner, cross runner and straight runner is: 0.8: (1.2~1.5): 1; the pouring speed must be controlled during pouring to keep the filling stable and avoid secondary oxidation and air entrainment; The castings are required to have a spheroidization rate of 3 or above and a graphite particle count of no less than 100 / mm 2 ; The metallographic matrix structure is mainly ferrite, pearlite or austenite according to needs.

4. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: Casting cleaning includes: cutting the gate and riser, removing the flash and shot blasting to make the casting surface neat and smooth; The rough machining includes: shape, size and tooth profile rough machining; The finishing includes: finishing the surface shape of the workpiece obtained in step S6, the size required by the drawing and the tooth shape, ensuring the dimensional accuracy, position accuracy and surface roughness, and removing the heat treatment deformation.

5. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: The heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment includes: heating, heat preservation, and isothermal quenching in sequence; In the isothermal quenching heat treatment: The heating temperature is 750℃-990℃; the heating rate is controlled at 100-150℃ / hour before reaching 600℃; The heat preservation time is 50-100 minutes; In isothermal quenching, the isothermal temperature is 250°C-430°C, and the isothermal time is 50-90 minutes.

6. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: The step S1 comprises: Step S11: Drawing analysis: by interpreting and analyzing the three-dimensional model and two-dimensional drawings of the workpiece, clarify the technical requirements, accuracy, tolerance of the casting, and understand the workpiece geometry, design basis, dimensions of each part, and surface requirements; Step S12: Determine the mold solution: comprehensively consider the number and arrangement of cavities, parting surface selection, gating system design, and exhaust system design; Step S13: Make mold drawings: First, make an overall design, draw a mold assembly drawing, clarify the assembly relationship of each component in the mold, and then disassemble and draw component drawings to clarify size requirements and materials; Step S14: Organize relevant experts and technicians to conduct centralized review, and conduct detailed review of the structural principle, processing technology and manufacturing operation safety of the mold to ensure that the performance is met and the manufacturing operation is convenient; Step S15: manufacturing and assembly, according to the mold drawings that have been reviewed and adjusted, manufacturing and assembly are completed; Step S16: Inspection and acceptance: Carry out detailed inspection on the mold cavity size and position accuracy to ensure that they meet the design requirements; then carry out functional inspection, through actual pouring test, check whether the mold's pouring performance, exhaust effect, and casting quality meet the design requirements.

7. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: The heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment includes: heating, heat preservation, and isothermal quenching in sequence; In the isothermal quenching heat treatment, the heating process of the workpiece to be heat treated is divided into a number of target sub-heating temperature sections, and each target sub-heating temperature section is heated in a corresponding target temperature rise rate range of the workpiece to be heat treated; In step S6, during the batch heat treatment, the set furnace temperature of the heating furnace is set to a value within the target furnace temperature range during the heating stage; The process of determining the target furnace temperature range includes: Step S61: determining a target temperature rise rate range of the workpiece to be heat treated in each target sub-heating temperature section; Step S62: determining a first furnace temperature range corresponding to each target sub-heating temperature segment based on the maximum temperature of each target sub-heating temperature segment, the minimum temperature of the target sub-heating temperature segment, the target temperature rise rate range of the workpiece to be heat-treated in the target sub-heating temperature segment, and the heating model of the heating furnace; Step S63: determining the heating matching degree of the first integer temperature based on the matching degree between the first integer temperature and the first furnace temperature range corresponding to each target sub-heating temperature segment and the temperature rise rate difference between adjacent target sub-heating temperature segments at the first integer temperature; the first integer temperature is an integer temperature in the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the largest temperature; Step S64: Determine the first integer temperature whose heating matching degree is greater than or equal to the preset matching degree as the required integer temperature, and determine the target furnace temperature range based on the required integer temperature.

8. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: The heat treatment in step S6 is an isothermal quenching heat treatment, and the isothermal quenching heat treatment includes: heating, heat preservation, and isothermal quenching in sequence; In the isothermal quenching heat treatment, the heating process of the workpiece to be heat treated is divided into a number of target sub-heating temperature sections, and each target sub-heating temperature section is heated in a corresponding target temperature rise rate range of the workpiece to be heat treated; The heating process of the workpiece to be heat treated is divided into several target sub-heating temperature sections including: Step S611: taking the median of the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the maximum temperature as the second furnace temperature, setting the set furnace temperature of the heating furnace to the second furnace temperature, performing a heating test on the workpiece to be heat-treated for testing, and collecting the surface temperature of the workpiece to be heat-treated for testing for multiple times during the heating test; Step S612: constructing a time-test workpiece surface temperature variation curve based on the surface temperature of the workpiece to be heat treated collected in step S611; Step S613: dividing the time-test surface temperature variation curve of the workpiece to be heat-treated into a plurality of first sub-temperature sections at preset temperature intervals, and determining the average temperature rise rate of each first sub-temperature section; Step S614: Based on step S613, the target sub-heating temperature segment is determined, the target sub-heating temperature segment is composed of continuous first sub-temperature segments, the absolute value of the difference between the average temperature rise rates of any two first sub-temperature segments of the target sub-heating temperature segment is less than or equal to the first preset temperature rise rate, and the absolute value of the difference between the average temperature rise rates of adjacent first sub-temperature segments in the target sub-heating temperature segment is less than or equal to the second preset temperature rise rate.

9. The method for manufacturing the integrated structure of differential housing and transmission gear made of ADI material according to claim 1, characterized in that: During step S3, the molten iron is filtered through the filter and then injected into the mold. A pressure sensor 1 is provided on the feed side of the filter to detect the molten iron pressure at the corresponding position, and a pressure sensor 2 is provided on the discharge side of the filter to detect the molten iron pressure at the corresponding position. The pouring process of a single workpiece is divided into several pouring sections, each pouring section corresponds to a different total pouring amount range, the memory stores a mapping table of the total pouring amount range of molten iron in the mold and the target pouring speed range, and the control device is electrically connected to the memory, the pressure sensor 1, the pressure sensor 2, and the molten iron pouring control device respectively; Batch casting process, the casting process of each workpiece includes: Step S31: obtaining the parameters of the molten iron to be poured and a mapping table of the total pouring amount range of the molten iron in the mold and the target pouring speed range, wherein the parameters of the molten iron include: the viscosity of the molten iron and the temperature of the molten iron; Step S32: obtaining a target pouring speed range corresponding to the current pouring section, and determining a first ratio corresponding to the current pouring section; the first ratio corresponding to the current pouring section is a ratio of an average detection value of the pressure sensor 2 corresponding to a previous pouring section of the current pouring section to an average detection value of the pressure sensor 1; Step S33: based on the first ratio corresponding to the current casting section and the ratio of the parameter of the molten iron in the current casting section to the corresponding standard parameter of the molten iron, the target casting speed range corresponding to the current casting section is corrected to obtain a corrected casting speed range corresponding to the current casting section; Step S34: During the pouring process of the current pouring section, the molten iron pouring control device is controlled to operate so that the actual pouring speed of the molten iron is within the corrected pouring speed range corresponding to the current pouring section.

10. ADI material differential housing and transmission gear integrated structure, characterized by: The differential housing and transmission gear integrated structure made of ADI material is manufactured by the manufacturing method according to any one of claims 1 to 9.

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