Integrated Structure of ADI Material Differential Housing and Transmission Gear and Its Manufacturing Method

Abstract

The present invention provides an integrated structure of an ADI material differential housing and a transmission gear and its manufacturing method, which relates to the field of new energy vehicle transmission systems. The method includes: 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; Step S2: Raw material preparation: Prepare ADI materials; Step S3: Casting: Adopt the resin sand molding process to pour the ADI materials into the mold, and control the pouring temperature and speed to ensure the performance and quality of the casting; Step S4: Clean the casting to obtain a casting blank; Step S5: Rough machine the casting blank; Step S6: Heat-treat the workpiece obtained in Step S5; Step S7: Finish machine the workpiece obtained in Step S6. The present invention adopts an integrated design, reduces the number of components and the processing difficulty, and improves the production efficiency; while ensuring lightweight, the integrated structure has higher strength and wear resistance, and reduces the cost.

Description

Technical Field

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

[0002] The differential is an important component in the vehicle drive system. Its main function is to allow the left and right wheels to rotate at different speeds when the vehicle turns, thereby ensuring the driving stability and controllability of the vehicle. In traditional differentials, since the power is transmitted vertically, it is usually composed of components such as a differential housing, bevel pinion, and planetary gears. Due to structural reasons, most of these components adopt a split design and are assembled together by means of bolt connection or welding. The split structure generally has the following deficiencies: First, the number of components is large, the assembly is complex, and the production efficiency is low; second, the connection parts are prone to looseness or fatigue fracture, affecting the reliability and service life of the differential. In recent years, with the requirements of vehicle lightweight and high performance, especially the rapid development of new energy vehicles, the integrated design differential 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 components, improves the assembly efficiency and structural strength. However, it is extremely difficult to control the welding deformation, the welding stress is not easily released, and the strength around the weld is reduced due to ablation, resulting in difficulties in improving the manufacturing accuracy, poor performance stability, and high manufacturing costs. Most of the existing integrated differentials use steel or aluminum alloy materials, having a series of problems such as large weight or insufficient strength; and with the rapid development of new energy vehicles, the drive motor is directly assembled on the axle body, and the power input direction becomes parallel transmission. The bevel pinion with high processing difficulty and high cost is replaced by the widely used and simply processed cylindrical gear, and it has become an irresistible trend that the split structure of the housing and transmission gears is replaced by an integrated structure.

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

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

[0005] (1) Excellent mechanical properties

[0006] 1. The strength and elongation rate of ADI material are very high. It is known that the highest tensile strength can reach 1600Mp, and the highest elongation rate can reach 16%. It has excellent dynamic mechanical properties, which are more excellent than those of forged steel, cast steel, and micro-alloyed steel.

[0007] 2. High fatigue strength, and the anti-fatigue property remains unchanged after millions of alternating loads.

[0008] 3. Good wear resistance. There are spherical graphite in ADI materials, which can reduce the friction coefficient and operating temperature, with high surface hardness and excellent abrasion resistance. When used in gear transmission, it can effectively reduce tooth surface wear and pitting failure, and prevent tooth fracture, etc.

[0009] (II) Excellent physical properties

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

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

[0012] 3. Excellent low-temperature performance. It can still work normally at -80°C, with good low-temperature toughness, and can adapt to work in alpine regions.

[0013] (III) Economic and technological advantages

[0014] 1. Low cost. The price of ADI material is lower than that of cast steel, forged steel and cast aluminum of the same weight. When calculating the cost based on the 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 parts and the whole machine.

[0016] 3. Diversity in casting process and part shape: Traditional clay sand and water glass molding methods can be used, and currently more advanced processes such as resin sand, lost foam casting, and V-process casting can also be used. It is relatively simple to realize the shape of parts with complex shapes by casting process, and the advantages are obvious.

[0017] (IV) Environmental and application advantages

[0018] 1. Environmental protection. The production process has little impact on the environment, and it belongs to green engineering materials.

[0019] 2. Wide application. 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 sufficient inquiry, there is currently no public report on the application of ADI material in the integrated structure of differential housing and cylindrical gear. 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 process, 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 as required.

[0035] Preferably, the cleaning of the casting includes: cutting the gate and riser, removing the flash and shot peening, so that the surface of the casting is neat and smooth;

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

[0037] The finish machining includes: finish machining the surface shape, the dimensions required by the drawing and the tooth profile of the workpiece obtained in step S6, ensuring the dimensional accuracy, positional accuracy and surface roughness, and removing the heat treatment deformation.

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

[0039] In the isothermal quenching heat treatment:

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

[0041] The holding time is 50 - 100 minutes;

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

[0043] Preferably, step S1 includes:

[0044] Step S11: Drawing analysis: By interpreting and analyzing the 3D model and 2D drawing of the workpiece, clarify the technical requirements, accuracy and tolerance of the casting, and understand the geometric shape, design datum, dimensions of each part and surface requirements of the workpiece;

[0045] Step S12: Determine the mold plan: Make a comprehensive consideration from the aspects of the number and arrangement of cavities, the selection of parting surfaces, the design of gating systems and the design of exhaust systems;

[0046] Step S13: Make the mold drawings: First, carry out the overall design, draw the overall assembly drawing of the mold, clarify the assembly relationship of each component in the mold, and then disassemble and draw the component drawings, clarifying the dimensional requirements and materials;

[0047] Step S14: Organize relevant experts and technicians for centralized review, and conduct a detailed review of the structural principle, machining manufacturability and manufacturing operation safety of the mold to ensure that it meets the service performance and is convenient for manufacturing and operation;

[0048] Step S15: Manufacture and assembly, and manufacture and complete the assembly according to the mold drawings completed and adjusted in the joint review;

[0049] Step S16: Inspection and acceptance: The dimensions and positional accuracy of the mold cavity are carefully inspected to ensure compliance with the design requirements. Then, functional inspection is carried out. Through actual casting tests, the casting performance, exhaust effect, and casting quality of the mold are checked to meet the design requirements.

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

[0051] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat-treated is divided into several target sub-heating temperature segments, and each target sub-heating temperature segment is heated under the control of the corresponding target temperature rise speed range of the workpiece to be heat-treated;

[0052] In the batch heat treatment of 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 determination process of the target furnace temperature range includes:

[0054] Step S61: Determine the target temperature rise speed range of the workpiece to be heat-treated for each target sub-heating temperature segment;

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

[0056] Step S63: Based on the matching degree of the first integer temperature with the first furnace temperature range corresponding to each target sub-heating temperature segment and the temperature rise speed difference degree between adjacent target sub-heating temperature segments at the first integer temperature, determine the heating matching degree of the first integer temperature; The first integer temperature is the integer temperature within the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the highest temperature;

[0057] Step S64: Determine the first integer temperature with a heating matching degree 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 isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, holding, and isothermal quenching;

[0059] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat-treated is divided into several target sub-heating temperature segments, and each target sub-heating temperature segment is heated under the control of the corresponding target temperature rise speed range of the workpiece to be heat-treated;

[0060] The division of the heating process of the workpiece to be heat-treated into several target sub-heating temperature segments includes:

[0061] Step S611: Use the median of the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the highest temperature as the second furnace temperature, set the set furnace temperature of the heating furnace to the second furnace temperature, and conduct a heating test on the workpiece to be heat-treated for testing. During the heating test, collect the surface temperature of the workpiece to be heat-treated for testing multiple times;

[0062] Step S612: Construct a time-surface temperature change curve of the workpiece to be heat-treated for testing based on the surface temperature of the workpiece to be heat-treated for testing collected in Step S611;

[0063] Step S613: Divide the time-surface temperature change curve of the workpiece to be heat-treated for testing into several first sub-temperature segments at a preset temperature interval, and determine the average temperature rise rate of each first sub-temperature segment;

[0064] Step S614: Determine the target sub-heating temperature segment based on Step S613. The target sub-heating temperature segment is composed of consecutive first sub-temperature segments, and the absolute value of the difference between the average temperature rise rates of any two first sub-temperature segments in 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 the process of Step S3, the molten iron is filtered through a filter screen and then poured into the mold. A pressure sensor one is arranged on the feed side of the filter screen to detect the molten iron pressure at the corresponding position, and a pressure sensor two is arranged on the discharge side of the filter screen to detect the molten iron pressure at the corresponding position;

[0066] The pouring process of a single workpiece is divided into several pouring segments, each pouring segment corresponding to a different total pouring volume range. The memory stores a mapping table of the total pouring volume range - target pouring speed range of the molten iron in the mold. The control device is electrically connected to the memory, the pressure sensor one, the pressure sensor two, and the molten iron pouring control device respectively;

[0067] In the batch pouring process, the pouring process of each workpiece includes:

[0068] Step S31: Obtain the parameters of the molten iron to be poured currently and the mapping table of the total pouring volume range - target pouring speed range of the molten iron in the mold. The parameters of the molten iron include: the viscosity of the molten iron, the temperature of the molten iron;

[0069] Step S32: Obtain the target pouring speed range corresponding to the current pouring segment, and determine the first ratio corresponding to the current pouring segment; the first ratio corresponding to the current pouring segment is the ratio of the average detection value of the pressure sensor two corresponding to the previous pouring segment of the current pouring segment to the average detection value of the pressure sensor one;

[0070] Step S33: Based on the first ratio corresponding to the current casting section and the ratio of the parameters of the molten iron in the current casting section to the standard parameters of the corresponding molten iron, correct the target pouring speed range corresponding to the current casting section to obtain the corrected pouring speed range corresponding to the current casting section;

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

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

[0073] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments.

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

[0075] 1. Structural simplification and efficiency improvement: By adopting an integrated design and optimizing the internal and external shape structures of the housing, the number of components and the processing difficulty are reduced; the assembly process is reduced and the complexity is decreased, improving the production efficiency.

[0076] 2. Performance improvement and cost reduction: Due to the high strength and high toughness characteristics of the ADI material, the integrated structure has higher strength and wear resistance while ensuring light weight; the damage of components is reduced, the service life is long, the effective working time of the whole machine is extended, the economic benefit is increased, and the downtime loss and the cost of replacing components are reduced.

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

[0078] 4. Cost reduction: Through optimizing the design and manufacturing process, the material and processing costs are reduced. Description of the Drawings

[0079] The 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 to the present invention. In the drawings:

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

[0081] Figure 2 is a schematic structure of the three-dimensional model of the present invention Figure 1 ;

[0082] Figure 3Structural schematic of the three-dimensional model of the present invention Figure 2 ;

[0083] Figure 4 Structural schematic of the two-dimensional model of the present invention Figure 1 ;

[0084] Figure 5 Structural schematic of the two-dimensional model of the present invention Figure 2 。 Specific embodiments

[0085] The following is a description of the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0086] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes, and do not particularly refer to the meaning of order or sequence. Nor are they used to limit the present invention. They are merely 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 quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions and technical features between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions 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 made of ADI material and its manufacturing method to solve the problems of the existing differential, such as complex structure, large weight, cumbersome assembly process, easy loosening of the connection part, complex anti-loosening measures, and insufficient strength.

[0089] Example 1, as Figures 1-5 shown, the present invention provides a manufacturing method for an integrated structure of an ADI material differential case and a transmission gear, including:

[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 case and the transmission gear; the mold accuracy can reach the micron level;

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

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

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

[0094] Step S5: Rough machine the casting blank;

[0095] Step S6: Heat-treat the workpiece obtained in Step S5; Isothermal quenching heat treatment is carried out on the rough-machined integrated workpiece of the differential case and cylindrical gear to improve the strength and toughness of the material and meet the usage performance requirements of the workpiece;

[0096] Step S7: Finish machine the workpiece obtained in Step S6.

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

[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, perform slag removal treatment after high-temperature standing; spheroidization is carried out by the in-pouring method of spheroidizing agent, and the addition amount of the spheroidizing agent is 1.1 - 1.3%; the addition amount of the inoculant is 0.5 - 0.9%, and the addition amount of the covering agent is 0.4 - 1.0%.

[0100] Specifically, the pouring temperature is 1390°C ~ 1420°C; adopt a semi-closed gating system, and the area ratio of the ingate, cross gate and sprue is: 0.8: (1.2 ~ 1.5): 1; during pouring, the pouring speed must be controlled to keep the filling smooth and avoid secondary oxidation and gas entrainment;

[0101] The casting is required to have a spheroidization rate of more than grade 3, and the number of graphite particles is not less than 100 per mm 2 ; The metallographic matrix structure is mainly ferrite, pearlite or austenite according to needs.

[0102] Specifically, the casting cleaning includes: through processes such as cutting the gating and riser, removing the flash and shot blasting cleaning, etc., to make the surface of the casting neat and smooth;

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

[0104] The finish machining includes: performing finish machining on the surface shape, the dimensions required by the drawing, the tooth profile, etc. of the workpiece obtained in step S6 to ensure dimensional accuracy, position accuracy, and surface roughness, and removing the deformation caused by heat treatment.

[0105] Specifically, the heat treatment in step S6 is austempering heat treatment (ADI austempering heat treatment), and the austempering heat treatment sequentially includes: heating, holding, and austempering (cooling by austempering).

[0106] In the austempering heat treatment:

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

[0108] According to the size and service performance requirements of the workpiece, the holding time is 50 - 100 minutes.

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

[0110] Specifically, step S1 includes:

[0111] Step S11: Drawing analysis: By interpreting and analyzing the 3D model and 2D drawing of the workpiece, clarify the technical requirements, accuracy, tolerances, etc. of the casting, and understand the geometric shape, design datum, dimensions of each part, and surface requirements of the workpiece.

[0112] Step S12: Determine the mold plan: Make a comprehensive consideration from aspects such as the number and arrangement of cavities, the selection of parting surfaces, the design of gating systems, the design of exhaust systems, etc.

[0113] Step S13: Make mold drawings: First, conduct overall design, draw the overall assembly drawing of the mold to clarify the assembly relationship of each component in the mold, and then disassemble and draw the component drawings to clarify the dimensional requirements and materials.

[0114] Step S14: Centralized review. After the design is completed, the company's technical center organizes relevant experts and technical personnel for centralized review, and conducts a detailed review on the structural principle, machining manufacturability, and manufacturing operation safety of the mold to ensure that it meets the service performance and is convenient for manufacturing and operation.

[0115] Step S15: Manufacturing and assembly. According to the mold drawings that have been reviewed and adjusted in place, manufacture and complete the assembly.

[0116] Step S16: Inspection and acceptance: The cavity dimensions and positional accuracy of the mold are carefully inspected (inspection equipment such as a coordinate measuring machine can be used) to ensure compliance with the design requirements; then functional inspection is carried out. Through actual casting tests, the casting performance, exhaust effect, and casting quality of the mold are checked to meet the design requirements.

[0117] The present invention also discloses an integrated structure of an ADI material differential housing and a transmission gear, including: a differential housing made of ADI material and containing cylindrical gears, having high-strength and high-toughness tooth shapes and dimensions to meet the transmission requirements; manufactured by the manufacturing method of the integrated structure of the ADI material differential housing and the transmission gear; the transmission gear and the differential housing are integrally cast into a blank through optimized design, and after mold design and manufacturing - raw material preparation - casting - casting cleaning - rough machining - ADI isothermal quenching heat treatment - finish machining and other processes, the component manufacturing is completed to ensure structural strength and transmission accuracy.

[0118] In the present invention, after isothermal quenching, the integral differential housing obtains excellent comprehensive properties, with a tensile strength ≥ 1200Mp, which is superior to the tensile strength of 1080Mp after carburizing and quenching of the commonly used gear material 20CrMnTi; the elongation rate ≥ 10%, which is equivalent to the elongation rate after carburizing and quenching of 20CrMnTi.

[0119] The beneficial effects of the above technical solutions are as follows:

[0120] 1. Structural simplification and efficiency improvement: By adopting an integrated design and optimizing the internal and external shape structures of the housing, the number of components and the processing difficulty are reduced; the assembly process is reduced and the complexity is lowered, improving the production efficiency.

[0121] 2. Performance improvement and cost reduction: Due to the high-strength and high-toughness characteristics of the ADI material, the integrated structure has higher strength and wear resistance while ensuring lightweight; the damage of components is reduced, the service life is long, the effective working time of the whole machine is extended, the economic benefit is increased, and the downtime loss and the cost of replacing components are reduced.

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

[0123] 4. Cost reduction: Through optimized design and manufacturing processes, the material and processing costs are reduced.

[0124] Example 2, based on Example 1, in step S6, the heat treatment is isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, holding, and isothermal quenching;

[0125] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat-treated is divided into several target sub-heating temperature segments, and each target sub-heating temperature segment is heated by controlling the target temperature rise speed range of the corresponding workpiece to be heat-treated; among them, the target temperature rise speed range of the target sub-heating temperature segment before 600°C is between 100-150°C / hour, and the target temperature rise speed range of the target sub-heating temperature segment from 600°C to the maximum temperature of the heating process is between 50-80°C / hour;

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

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

[0128] Step S61: Determine the target temperature rise speed range of the workpiece to be heat-treated in each target sub-heating temperature segment (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 under the target temperature rise speed range);

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

[0130] Step S63: 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 speed difference degree between adjacent target sub-heating temperature segments at the first integer temperature, determine the heating matching degree of the first integer temperature; the first integer temperature is the integer temperature in the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the highest temperature (taking different values according to different ADI materials);

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

[0132] Determine the temperature range composed of consecutive required integer temperatures as the required temperature range:

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

[0134] When there is 1 required temperature range, determine the existing required temperature range as the target furnace temperature range;

[0135] When there is only one required temperature, select another heating furnace and re-determine the target furnace temperature range.

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

[0137] Among them, 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 segment; e is the natural constant; h is the total heat transfer coefficient between the workpiece to be heat-treated and the internal environment of 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 speed range of the workpiece to be heat-treated in the i-th target sub-heating temperature segment; The maximum value of the target temperature rise speed range of the workpiece to be heat-treated in the i-th target sub-heating temperature segment; the unit of the temperature rise speed is °C / hour;

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

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

[0140] ;

[0141] ;

[0142] is the temperature rise speed difference degree 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; represents the minimum value; is the absolute value of the error of the furnace temperature of the heating furnace (which can be ±0.5 °C and is set differently according to different heating furnaces); is the j-th first integer temperature; , 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 j-th first integer temperature; M is the total number of divided target sub-heating temperature segments; is the matching degree between the j-th first integer temperature and the first furnace temperature range corresponding to the i-th target sub-heating temperature segment; is the average temperature rise speed of the i-th target sub-heating temperature segment when the furnace temperature of the heating furnace is the j-th first integer temperature; is the average temperature rise rate of the (i - 1)-th target sub-heating temperature segment when the furnace temperature of the heating furnace is the j-th first integer temperature; is the corresponding maximum allowable 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 - 1)-th target sub-heating temperature segment; is the minimum temperature of the (i - 1)-th target sub-heating temperature segment; is the natural logarithm;

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

[0148] The heating matching degree of the first integer temperature combines the matching state of the first integer temperature with the first furnace temperature range 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 ( ), determines the first integer temperature with a heating matching degree greater than or equal to the preset matching degree as the required integer temperature, and determines the target furnace temperature range based on the required integer temperature, so as to ensure the selection of an appropriate furnace temperature.

[0149] When takes the value of 1, on the one hand, it realizes that the j-th first integer temperature is within the first furnace temperature range of the i-th target sub-heating temperature segment, ensuring that the temperature rise rate of the workpiece to be heat-treated is appropriate in the i-th target sub-heating temperature segment. On the other hand, considering the error of the heating furnace, it ensures that even if there is a small error in the furnace temperature of the heating furnace, the temperature rise rate still meets the requirements.

[0150] Example 3, on the basis of Example 1, in step S6, the heat treatment is isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, heat preservation, and isothermal quenching;

[0151] In the isothermal quenching heat treatment, the heating process of the workpiece to be heat-treated is divided into several target sub-heating temperature segments, and each target sub-heating temperature segment is heated under the control of the corresponding target temperature rise rate range of the workpiece to be heat-treated;

[0152] The heating process of the workpiece to be heat-treated being divided into several target sub-heating temperature segments includes:

[0153] Step S611: Take 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, set the set furnace temperature of the heating furnace to the second furnace temperature, and conduct a heating test 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;

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

[0155] Step S613: Divide the time-surface temperature change curve of the workpiece to be heat-treated for testing into several first sub-temperature segments at a preset temperature interval (which can be 0.5 °C or 1 °C), and determine the average temperature rise rate of each first sub-temperature segment;

[0156] Step S614: Determine the target sub-heating temperature segment based on Step S613. The target sub-heating temperature segment is composed of consecutive first sub-temperature segments, and the absolute value of the difference between the average temperature rise rates of any two first sub-temperature segments in the target sub-heating temperature segment is less than or equal to the first preset temperature rise rate (set differently according to different workpieces, such as it can be set to 16 - 30 °C / hour), 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 (set differently according to different workpieces, such as it can be set to 5 - 15 °C / hour).

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

[0158] The heating process of the workpiece to be heat-treated is divided into several target sub-heating temperature segments, and each target sub-heating temperature segment is heated under the control of the corresponding target temperature rise rate range of the workpiece to be heat-treated, so as to ensure that the temperature rise of the workpiece to be heat-treated at each target sub-heating temperature during the heating process of the workpiece to be heat-treated meets the requirements and ensure the heat treatment quality of the workpiece to be heat-treated.

[0159] Take 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, set the set furnace temperature of the heating furnace to the second furnace temperature (which can be ±0.3 °C), conduct a heating test on the workpiece to be heat-treated for testing, collect the surface temperature of the workpiece to be heat-treated for testing multiple times during the heating test, and construct a time-surface temperature change curve of the workpiece to be heat-treated for testing, so as to be able to initially determine 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) based on the test;

[0160] Then, the target sub-heating temperature segments 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 in the target sub-heating temperature segments is less than or equal to the first preset temperature rise rate, so that the temperature rise rates of each target sub-heating temperature segment are relatively close, ensuring the heat treatment effect.

[0162] Example 4, based on any one of Examples 1-3, during the process of step S3, the molten iron is injected into the mold after passing through the filter screen. A pressure sensor one is arranged on the feed side of the filter screen to detect the molten iron pressure at the corresponding position, and a pressure sensor two is arranged on the discharge side of the filter screen to detect the molten iron pressure at the corresponding position; wherein, the filter screen of the present invention can be arranged 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 segments (each pouring segment corresponds to a number), and each pouring segment corresponds to a different total pouring volume range (the total pouring volume is the total amount of molten iron that has been injected into the mold for the production of a single workpiece). The memory stores a mapping table of the total pouring volume range - target pouring speed range of the molten iron in the mold (which can be obtained based on tests or historical experience). The control device is electrically connected to the memory, the pressure sensor one, the pressure sensor two, and the molten iron pouring control device respectively;

[0164] In the batch pouring process, the pouring process of each workpiece includes:

[0165] Step S31: Obtain the parameters of the molten iron to be poured currently and the mapping table of the total pouring volume range - target pouring speed range of the molten iron in the mold. The parameters of the molten iron include: the viscosity of the molten iron and the temperature of the molten iron;

[0166] Step S32: Obtain the target pouring speed range corresponding to the current pouring segment, and determine the first ratio corresponding to the current pouring segment; the first ratio corresponding to the current pouring segment is the ratio of the average detection value of the pressure sensor two corresponding to the previous pouring segment of the current pouring segment to the average detection value of the pressure sensor one; wherein, when the first ratio is less than the preset value, an alarm is given;

[0167] Step S33: Based on the first ratio corresponding to the current pouring segment and the ratio of the parameters of the molten iron in the current pouring segment to the corresponding standard parameters of the molten iron, correct the target pouring speed range corresponding to the current pouring segment to obtain the corrected pouring speed range corresponding to the current pouring segment;

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

[0169] ;

[0170] ;

[0171] is the lower limit of the corrected pouring speed range corresponding to the h-th pouring section; is the upper limit of the corrected pouring speed range corresponding to the h-th pouring section; is the lower limit of the target pouring speed range (under the condition of the standard value of the ratio of the molten iron pressure on the discharge side of the filter screen to the molten iron pressure on the feed side of the filter screen) corresponding to the h-th pouring section; is the upper limit of the target pouring speed range corresponding to the h-th pouring section; is the viscosity of the molten iron to be poured currently (it can be detected only once for each ladle / each heat of molten iron), 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); , are the standard molten iron viscosity and the standard molten iron temperature respectively (based on tests, the actual molten iron viscosity of the current ADI material at the standard molten iron temperature is the standard molten iron viscosity; the standard molten iron temperature is determined according to the required temperature range before pouring of different ADI materials and can take the median value of the required temperature range of different ADI materials before pouring); is the standard value of the ratio of the molten iron pressure on the discharge side of the filter screen to the molten iron pressure on the feed side of the filter screen; is the first ratio corresponding to the h-th pouring section.

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

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

[0174] During molten iron pouring, different pouring sections pour different mold areas. Different pouring sections determine the matching target pouring speed according to the structure of the corresponding mold area. At the target pouring speed, the workpiece forming quality of the corresponding mold area is better;

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

[0176] Obviously, those skilled in the art can make various modifications and variations 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 equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A manufacturing method for an integrated structure of an ADI differential housing and a transmission gear, characterized in that: Including: 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; Step S2: Raw material preparation: Prepare ADI material; Step S3: Casting: Adopt the resin sand molding process, pour the ADI material into the mold, and control the pouring temperature and speed to ensure the performance and quality of the casting; Step S4: Clean the casting to obtain a casting blank; Step S5: Rough machine the casting blank; Step S6: Heat-treat the workpiece obtained in Step S5; Step S7: Finish machine the workpiece obtained in Step S6; In Step S2: The chemical composition of the ADI material by weight percentage includes: 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° - 1560°; after melting, slag removal treatment is carried out after high-temperature standing; spheroidization is carried out by the in-pouring method of spheroidization treatment, the addition amount of the spheroidizing agent is 1.1 - 1.3%; the addition amount of the inoculant is 0.5 - 0.9%, and the addition amount of the covering agent is 0.4 - 1.0%; The pouring temperature is 1390°C to 1420°C; a semi-closed gating system is adopted, and the area ratio of the ingate, cross gate and sprue is: 0.8: (1.2 - 1.5): 1; the pouring speed must be controlled during pouring to keep the filling smooth and avoid secondary oxidation and gas entrainment; The spheroidization rate of the casting should reach level 3 or above, and the number of graphite particles should not be less than 100 per mm 2 ; The metallographic matrix structure is mainly ferrite, pearlite or austenite; The heat treatment in Step S6 is isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, holding, and isothermal quenching; In the isothermal quenching heat treatment, the heating process of the workpiece to be heat-treated is divided into several target sub-heating temperature segments, and each target sub-heating temperature segment is heated according to the corresponding target temperature rise speed range of the workpiece to be heat-treated; In the batch heat treatment of Step S6, the set furnace temperature of the heating furnace is set to the value in the target furnace temperature range during the heating stage; The determination process of the target furnace temperature range includes: Step S61: Determine the target temperature rise speed range of the workpiece to be heat-treated in each target sub-heating temperature segment; Step S62: Determine the first furnace temperature range corresponding to each target sub-heating temperature segment based on the maximum temperature, the minimum temperature of the target sub-heating temperature segment, the target temperature rise speed 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: Determine 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 speed difference degree between adjacent target sub-heating temperature segments at the first integer temperature; the first integer temperature is the integer temperature in the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the highest temperature; Step S64: Determine the first integer temperature with a heating matching degree 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; In the isothermal quenching heat treatment, the heating process of the workpiece to be heat-treated is divided into several target sub-heating temperature segments, and each target sub-heating temperature segment is heated under the control of the corresponding target temperature rise speed range of the workpiece to be heat-treated; The heating process of the workpiece to be heat-treated being divided into several target sub-heating temperature segments includes: Step S611: Using the median value of the allowable range of the maximum heating temperature of the target sub-heating temperature segment with the highest temperature as the second furnace temperature, setting the set furnace temperature of the heating furnace to the second furnace temperature, heating the test workpiece to be heat-treated, and collecting the surface temperature of the test workpiece to be heat-treated multiple times during the heating test; Step S612: Constructing a time-surface temperature change curve of the test workpiece to be heat-treated based on the surface temperature of the test workpiece to be heat-treated collected in Step S611; Step S613: Dividing the time-surface temperature change curve of the test workpiece to be heat-treated into several first sub-temperature segments at a preset temperature interval, and determining the average temperature rise speed of each first sub-temperature segment; Step S614: Determining the target sub-heating temperature segments based on Step S613. The target sub-heating temperature segments are composed of consecutive first sub-temperature segments. The absolute value of the difference between the average temperature rise speeds of any two first sub-temperature segments in the target sub-heating temperature segment is less than or equal to the first preset temperature rise speed, and the absolute value of the difference between the average temperature rise speeds of adjacent first sub-temperature segments in the target sub-heating temperature segment is less than or equal to the second preset temperature rise speed.

2. The manufacturing method of the integrated structure of the ADI material differential housing and the transmission gear according to claim 1, characterized in that: Casting cleaning includes: making the casting surface neat and smooth through processes such as cutting the gating and risers, removing the flash, and shot blasting; The rough machining includes: rough machining of the shape, size, and tooth profile; The finish machining includes: finish machining the surface shape, the dimensions required by the drawing, and the tooth profile of the workpiece obtained in Step S6 to ensure the dimensional accuracy, positional accuracy, and surface roughness, and removing the heat treatment deformation.

3. The manufacturing method of the integrated structure of the ADI material differential housing and transmission gear according to claim 1, wherein: The heat treatment in Step S6 is isothermal quenching heat treatment, and the isothermal quenching heat treatment sequentially includes: heating, holding, and isothermal quenching; In the isothermal quenching heat treatment: The heating temperature is 750°C - 990°C; the heating speed is controlled at 100 - 150°C / hour before reaching 600°C; The holding time is 50 - 100 minutes; In isothermal quenching, the isothermal temperature is 250°C - 430°C, and the isothermal time is 50 - 90 minutes.

4. The manufacturing method of the integrated structure of the ADI material differential housing and the transmission gear according to claim 1, characterized in that: Step S1 includes: Step S11: Drawing analysis: By interpreting and analyzing the three-dimensional model and two-dimensional drawing of the workpiece, clarifying the technical requirements, accuracy, and tolerance of the casting, and understanding the geometric shape, design datum, dimensions of each part, and surface requirements of the workpiece; Step S12: Determining the mold scheme: Considering comprehensively from aspects such as the number and arrangement of cavities, selection of the parting surface, design of the gating system, and design of the exhaust system; Step S13: Making the mold drawings: First, conduct the overall design, draw the overall assembly drawing of the mold to clarify the assembly relationship of each component in the mold, and then disassemble and draw the component drawings to clarify the dimensional requirements and materials; Step S14: Organize relevant experts and technicians for centralized review, and conduct a detailed review of the structural principle, machining processability, and manufacturing operation safety of the mold to ensure that it meets the service performance and is convenient for manufacturing operations; Step S15: Manufacturing and assembly. According to the mold drawings that have been reviewed and adjusted in place, manufacture and complete the assembly; Step S16: Inspection and acceptance: Conduct a detailed inspection of the cavity size and position accuracy of the mold to ensure compliance with the design requirements; then conduct a functional inspection. Through actual pouring tests, check that the pouring performance, exhaust effect, and casting quality of the mold meet the design requirements.

5. The manufacturing method of the integrated structure of the ADI material differential housing and the transmission gear according to claim 1, characterized in that: During step S3, the molten iron is injected into the mold after passing through a filter screen. A pressure sensor 1 is arranged on the feed side of the filter screen to detect the molten iron pressure at the corresponding position, and a pressure sensor 2 is arranged on the discharge side of the filter screen to detect the molten iron pressure at the corresponding position; The pouring process of a single workpiece is divided into several pouring segments, and each pouring segment corresponds to a different total pouring volume range. The memory stores a mapping table of the total pouring volume range - target pouring speed range of the molten iron in the mold. The control device is electrically connected to the memory, pressure sensor 1, pressure sensor 2, and the molten iron pouring control device respectively; In the batch pouring process, the pouring process of each workpiece includes: Step S31: Obtain the parameters of the current molten iron to be poured and the mapping table of the total pouring volume range - target pouring speed range of the molten iron in the mold. The parameters of the molten iron include: the viscosity of the molten iron, the temperature of the molten iron; Step S32: Obtain the target pouring speed range corresponding to the current pouring segment, and determine the first ratio corresponding to the current pouring segment; the first ratio corresponding to the current pouring segment is the ratio of the average detection value of the pressure sensor 2 corresponding to the previous pouring segment of the current pouring segment to the average detection value of the pressure sensor 1; Step S33: Based on the first ratio corresponding to the current pouring segment and the ratio of the parameters of the molten iron in the current pouring segment to the corresponding standard parameters of the molten iron, correct the target pouring speed range corresponding to the current pouring segment to obtain the corrected pouring speed range corresponding to the current pouring segment; Step S34: During the pouring process of the current pouring segment, control the molten iron pouring control device to work so that the actual pouring speed of the molten iron is within the corrected pouring speed range corresponding to the current pouring segment.

6. An integrated structure of an ADI material differential housing and a transmission gear, characterized in that: Manufactured by using the manufacturing method of the integrated structure of the ADI material differential housing and transmission gear as described in any one of claims 1 - 5.

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