New energy automobile rotary transformer end cover and die

Abstract

The invention relates to a new energy automobile rotary transformer end cover and a die, the end cover comprises a thin-wall flange section and a cylinder section, the thin-wall flange section is installed on the periphery of the cylinder section, an annular support plate is arranged in the cylinder section close to the thin-wall flange section, the outer diameter of the annular support plate is matched with the inner diameter of the cylinder section, and the outer diameter of the annular support plate is matched with the inner diameter of the cylinder section. A circular opening is formed in the annular supporting plate, a plurality of protruding parts are evenly distributed on the periphery of the thin-wall flange section, and a plurality of reinforcing ribs are arranged between the thin-wall flange section and the cylinder section. The invention provides a new developed product, relates to a manufacturing process of a rotary transformer end cover of a new energy automobile in the technical field of pressing dies, and can meet the requirements of no leakage, no cold shut, no skin clamping, no crack and no penetrability defect under the condition that the test pressure is greater than 30kPa. The defects of composition segregation, oxidation slag inclusion and the like are avoided, the internal structure of the casting is uniform, and the condition of coarse grains is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and particularly to a resolver end cover and a mold for a new energy vehicle. Background Art

[0002] In recent years, with the rapid development of industries such as aerospace, new energy vehicles, and communication equipment, the lightweight aluminum alloy die-casting industry has entered the fast lane of development driven by intelligent transformation and green manufacturing. As a near-net shaping and high-production-efficiency casting method, aluminum alloy die-casting is widely used in the production of industries such as automobiles, motorcycles, hardware, and toys.

[0003] A resolver is a commonly used position component in new energy motor control. The function of the resolver is to accurately measure the position, speed, and rotation direction of the motor rotor, transmit these signals to the electronic control, and control the motor by the control algorithm of the software. The principle of the resolver is to input a high-frequency sine signal, that is, an excitation signal, to the rotor coil. By receiving the high-frequency induction signal feedback from the induced resolver rotor in the coil, the corresponding sine and cosine information can be obtained through processing, and the absolute position of the stator can be obtained through software parsing.

[0004] Due to the contradiction between the weight defect of the power battery of new energy vehicles and the energy density requirement, the lightweight requirement is particularly urgent in the vehicle component subsystem. The aluminum alloy high-pressure die-casting process has high production efficiency, good airtightness of the finished product, and can form products with complex structures. At the premise of ensuring product functional safety and achieving lightweight, higher requirements are put forward for die-cast aluminum alloy and its process at the present stage. Summary of the Invention

[0005] In view of the above-mentioned technical problems, a resolver end cover and a mold for a new energy vehicle are provided.

[0006] The technical means adopted by the present invention are as follows:

[0007] A resolver end cover for a new energy vehicle includes a thin-wall flange section and a cylindrical section. The thin-wall flange section is installed on the outer periphery of the cylindrical section. An annular support plate is provided inside the cylindrical section close to the thin-wall flange section. The outer diameter of the annular support plate matches the inner diameter of the cylindrical section. The inside of the annular support plate is a circular opening. A plurality of protrusions are evenly distributed on the outer periphery of the thin-wall flange section. A plurality of reinforcing ribs are provided between the thin-wall flange section and the cylindrical section.

[0008] Further, a hole is provided in the protrusion as a bolt assembly hole. The protrusion is a circular ring structure. The thin-wall flange section is a circular ring structure. The outer circumferential surface of the protrusion intersects with the outer circumferential surface of the thin-wall flange section, and the outer circumferential surface of the thin-wall flange section smoothly transitions to the outer circumferential surface of the protrusion.

[0009] Further, the point on the outer circumferential surface of the raised portion closest to the center of the thin-walled flange section is taken as the lower starting point of the reinforcing rib. The end of the right-angled side is connected to the cylindrical section, and the other right-angled side is arranged along the height direction of the cylindrical section. A number of semi-circular protrusions are arranged outside the outer circumferential surface at the top of the cylindrical section, and they are arranged along the height direction of the cylindrical section as the reinforcing column structure. The starting point of the other right-angled side is arranged on the reinforcing column, and the starting point position of the other right-angled side is set based on the inclination angle of the hypotenuse. The inclination angle of the reinforcing rib is 30°.

[0010] Further, the material of the motor resolver end cover die casting is ADC12.

[0011] Further, the casting blank has a machining allowance of at least 2 mm at the top of the cylindrical section, and the specification of the machining allowance is the same as the shape of the cylindrical section and the semi-circular protrusions thereon.

[0012] The present invention also discloses a mold for preparing the above-mentioned resolver end cover of a new energy vehicle, including a movable mold and a stationary mold. A concave mold cavity is arranged in the middle of the stationary mold, and a convex mold table adapted to the concave mold cavity is arranged on the movable mold. A pouring gate is arranged on the stationary mold, and the setting of the mold runner corresponds to the resolver end cover of the new energy vehicle. A number of slag pockets are arranged on the movable mold, and the several slag pockets arranged on the thin-walled flange section are connected with an exhaust passage. A cylindrical section slag pocket is also arranged inside the cylindrical section.

[0013] Further, one mold is provided with one pouring gate and produces two of the above-mentioned resolver end covers of new energy vehicles at the same time. One or two main runners are arranged between the pouring gate and the concave mold cavity;

[0014] The number of raised portions on the thin-walled flange section is six. Taking the uppermost raised portion during the pouring process as the first raised portion and counting clockwise, five slag pockets are respectively arranged at the positions between the first raised portion and the second raised portion, between the second raised portion and the third raised portion, between the fourth raised portion, the fifth raised portion and the sixth raised portion, and between the sixth raised portion and the first raised portion. The main runner is arranged at the position between the fourth raised portion and the fifth raised portion. When two are set, the second main runner is arranged at the position between the third raised portion and the fourth raised portion.

[0015] Further, the whole mold is water-cooled. The stationary mold is cooled by two-in and two-out direct-through circulating water cooling; the movable mold is cooled by single-point high-pressure water at the center of the cylinder.

[0016] Furthermore, the moving die single-point high-pressure water cooling pipeline includes a water inlet, a water outlet, an inner pipe, an outer pipe, a diverter, and a sealing ring. The outer pipe is sleeved outside the inner pipe. The water inlet is connected to the inner pipe, and the output end of the inner pipe is connected to the diverter, which sprays on the part of the mold that needs to be cooled. This part is 15 millimeters away from the bottom plane of the slag pocket. The high-pressure water is diverted at the cross groove on the top of the diverter and spirally returns along the outer wall of the diverter and the inner wall of the mating surface of the mold, and returns to the water return port of the bottom diverter. The water return port is connected to the outer pipe, and the water outlet is connected to the output end of the outer pipe. The bottom of the diverter and the outer surface of the mold adopt a double O-ring sealing form.

[0017] Furthermore, the filling speed of the mold is controlled at 25 - 30 m / s.

[0018] Furthermore, the test pressure of the formed resolver end cover for new energy vehicles > 30 kPa, without leakage, cold shut, laps, cracks, and any penetrative defects; without composition segregation, oxide inclusion defects, and the internal structure of the casting is uniform.

[0019] Compared with the prior art, the present invention has the following advantages: The resolver end cover with a thin-walled flange barrel structure is a newly developed product, involving the manufacturing process of the resolver end cover for new energy vehicles in the field of die casting technology, especially the manufacturing and die design of aluminum alloy die-casting products with a thin-walled flange barrel structure. The structure and die design of this resolver end cover can meet the conditions of no leakage, cold shut, laps, cracks, and any penetrative defects under the test pressure > 30 kPa; without composition segregation, oxide inclusion and other defects, and the internal structure of the casting is uniform, preventing the occurrence of grain coarsening.

[0020] The present invention designs a reinforcing rib with a certain thickness and an inclination angle of 30° between the bolt hole and the top surface of the barrel. This reinforcing rib can improve the filling effect, prevent defects such as gas entrapment and cold shut, and at the same time improve the stiffness of the casting, preventing defects such as deformation and cracking of the resolver end cover during use.

[0021] By designing the gate and filling speed, the flow form of the molten metal is significantly changed, changing from a jet filling method along the thin shell to a filling method close to the full wall thickness. This gate structure is beneficial to preventing gas entrapment and sticking to the mold, and improving the mold life and casting quality.

[0022] Through numerical simulation analysis, a machining allowance of 2 millimeters is added to the ring on the barrel top surface. On the one hand, the impurities and gas at the front end of the aluminum liquid filling are concentrated in the 2-millimeter ring space, serving as the function of the slag pocket. At the same time, the increased alloy liquid raises the temperature of the local mold, avoiding the occurrence of defects such as cold shut and cracks. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is the front view of the resolver end cover.

[0025] Figure 2 It is the axonometric view of the resolver end cover.

[0026] Figure 3 It is the product wall thickness analysis diagram using UG software.

[0027] Figure 4 It is the schematic diagram of increasing the machining allowance at the flange barrel top of the die-cast blank in Embodiment 3.

[0028] Figure 5 It is the schematic diagram of the single-gate die-casting gating system for two parts in one mold in Embodiment 1.

[0029] Figure 6 It is the physical diagram of the product after machining the casting in Embodiment 1.

[0030] Figure 7 It is the physical diagram of the root blowhole defect of some unqualified parts in Embodiment 1.

[0031] Figure 8 It is for Figure 7 The 200-times enlarged view.

[0032] Figure 9 It is for Figure 7 The 500-times enlarged view.

[0033] Figure 10 It is the physical diagram of the barrel top crack defect of some unqualified parts in Embodiment 1.

[0034] Figure 11 It is the physical diagram of the cold lap defect at the rib of some unqualified parts in Embodiment 1.

[0035] Figure 12 It is the numerical simulation analysis diagram of the filling process in Embodiment 1, where (a) is at 0.4300 seconds, (b) is at 0.4389 seconds, and (c) is at 0.4434 seconds.

[0036] Figure 13 It is the schematic diagram of the internal gas entrainment in the casting during the filling process in Embodiment 1.

[0037] Figure 14 It is the pressure contour map in Embodiment 1.

[0038] Figure 15 This is the coagulation analysis diagram of Example 1.

[0039] Figure 16 This is a front view of the double gate solution of Example 2.

[0040] Figure 17 This is a reverse view of the double gate solution of Example 2.

[0041] Figure 18 These are numerical simulation analysis diagrams of the filling process of Example 2, where (a) is 0.4300 seconds, (b) is 0.4389 seconds, and (c) is 0.4434 seconds.

[0042] Figure 19 This is a schematic diagram of the high pressure point cooling structure of Example 4.

[0043] Figure 20 These are coagulation analysis diagrams of Example 4, wherein (a) is the coagulation at 6.55 seconds, (b) is the coagulation at 8.94 seconds, and (c) is the coagulation at 10.52 seconds.

[0044] Figure 21 This is a graph showing the speed analysis results of the gate position sensor in Example 4.

[0045] Figure 22 This is a physical picture of the moving mold part of Example 2.

[0046] Figure 23 This is a physical picture of the static mold part of Example 2.

[0047] Figure 24 This is an X-ray image of the product with runner produced in Example 4.

[0048] Figure 25 This is a wire cutting sectioning position diagram of the parts produced in Example 4.

[0049] Figure 26 This is a metallographic micrograph of the parts produced in Example 4.

[0050] In the figure: 1. thin-walled flange section; 2. cylindrical section; 3. annular support plate; 4. raised portion; 5. reinforcing ribs; 6. machining allowance; 7. slag bag; 8. cylindrical section slag bag; 9. exhaust duct; 10. pouring port; 11. main pouring channel; 12. water inlet; 13. water outlet; 14. outer tube; 15. inner tube; 16. sealing ring; 17. diverter. DETAILED DESCRIPTION

[0051] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0052] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. The description of at least one exemplary embodiment is actually illustrative only and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0053] It should be noted that the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and / or their combinations.

[0054] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the description. In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0055] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of the present invention. The orientation words "inner, outer" refer to the inside and outside relative to the contour of each component itself.

[0056] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper", etc. can be used here to describe the spatial positional relationship between a device or feature shown in a figure and other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figure for the device. For example, if the device in the attached drawing is inverted, a device described as "above or over other devices or structures" will then be positioned "below or under other devices or structures". Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations are made for the spatial relative descriptions used here.

[0057] In addition, it should be noted that the use of terms such as "first", "second", etc. to define components is only for the convenience of differentiating the corresponding components. Without additional statements, the above terms have no special meanings, and thus should not be construed as limiting the protection scope of the present invention.

[0058] As Figure 1 shown, an embodiment of the present invention discloses a resolver end cover for a new energy vehicle, which includes a thin-walled flange section 1 and a cylindrical section 2. The thin-walled flange section is installed on the outer peripheral part of the cylindrical section. An annular support plate 3 is arranged inside the cylindrical section near the thin-walled flange section. The outer diameter of the annular support plate matches the inner diameter of the cylindrical section. The inside of the annular support plate is a circular opening. A plurality of protruding parts 4 are evenly distributed on the outer peripheral part of the thin-walled flange section. A plurality of reinforcing ribs 5 are arranged between the thin-walled flange section and the cylindrical section.

[0059] Further, holes are provided in the protruding parts as bolt assembly holes. The protruding parts are of a circular ring structure. The thin-walled flange section is of a circular ring structure. The outer circumferential surface of the protruding part intersects with the outer circumferential surface of the thin-walled flange section, and the outer circumferential surface of the thin-walled flange section smoothly transitions to the outer circumferential surface of the protruding part.

[0060] Further, the point on the outer circumferential surface of the protruding part closest to the center of the thin-walled flange section is used as the lower starting point of the reinforcing rib. The end of the right-angle side is connected to the cylindrical section, and the other right-angle side is arranged along the height direction of the cylindrical section. A plurality of semi-circular protrusions are arranged outside the outer circumferential surface at the top of the cylindrical section, which are arranged along the height direction of the cylindrical section as reinforcing column structures. The starting point of the other right-angle side is arranged on the reinforcing column, and the starting point position of the other right-angle side is set based on the inclination angle of the hypotenuse. The inclination angle of the reinforcing rib is 30°.

[0061] Further, the material of the die-cast part of the motor resolver end cover is ADC12.

[0062] The geometric model of the motor resolver end cover is shown in Figure 1 , Figure 2 . In this embodiment, the contour dimensions of the casting are The volume is approximately 110.2 cm 3 , the mass is 0.286 Kg. The overall casting is a thin-walled flange barrel structure. The inner hole diameter of the casting cylinder is for installing the motor bearing. It is required that there should be no air holes larger than 0.5 mm on the machined surface. The height of the inner hole of the cylinder is 38 mm and the thickness is 4.5 mm. The 6 bolt assembly holes around the casting flange are evenly distributed on the circumference. The flange thickness is 5.0 mm. Its lower surface is the assembly reference and measurement reference for the resolver end cover. As Figure 2 shown, a reinforcing rib with a thickness of 3.5 mm and an inclination angle of 30° is designed between the bolt hole and the top surface of the cylinder. This reinforcing rib can improve the filling effect, prevent defects such as gas entrapment and cold lap, and at the same time improve the stiffness of the casting, preventing deformation and cracks and other defects during the use of the resolver end cover. The maximum wall thickness is located at the junction of the flange and the cylinder, and the maximum thickness is 9.0 mm, improving the working stiffness of the casting. The minimum wall thickness is 2.3 mm, and the wall thickness difference is relatively large. As Figure 3 shown, shrinkage cavities, air holes and other casting defects are likely to occur at the junction of the maximum and minimum wall thicknesses of the casting. Therefore, it is necessary to cooperate with the mold and specific processes mentioned later to meet the established indicators.

[0063] The assembly requirements of this product are relatively strict, and the mechanical property requirements are also very high. The test pressure > 30 kPa, no leakage. No cold lap, laps, cracks, and any penetrating defects; no segregation, oxide inclusions and other defects, and the internal structure of the casting is uniform to prevent grain coarsening, etc.

[0064] Based on the following theoretical principles, the die-casting process is analyzed to design the mold and conduct experiments, numerical simulation analysis and verification, defect detection, and adjust the processing parameters to obtain a resolver end cover that meets the expected values.

[0065] The theoretical basis for the calculation during the solidification process of the product is the unsteady heat conduction partial differential equation:

[0066]

[0067] When the latent heat of crystallization is released and the temperature gradients and liquid fraction of the liquid and solid phases are relatively small, the above equation can be transformed into

[0068]

[0069] where C - specific heat (J.Kg / ℃), ρ - material density (Kg / m 3 ), Q - latent heat of crystallization.

[0070] The initial condition is the temperature distribution within the entire mold cavity starting from the moment when the aluminum alloy die-casting product just begins to solidify, i.e., at t = 0. This condition has an important impact on subsequent mold temperature analysis. When the mold is in a cyclic working state, the initial mold temperature can be set to the working temperature; when in a hot mold state, the initial condition can be set to room temperature, and multiple cycles are required to simulate a relatively accurate result.

[0071]

[0072] For die-casting products, the filling time is short. Usually, the pouring temperature T of such products is taken P .

[0073] Taking the boundary as the contact part of two adjacent different materials at the interface between the product and the mold, the heat flux rate q flowing through the boundary surface is

[0074]

[0075] q—the heat flux rate through the interface between the mold and the molten aluminum; h—the interface exchange coefficient; T1—the temperature on the molten aluminum side; T2—the temperature on the mold side.

[0076] During the solidification process of aluminum alloy, due to the presence of latent heat of crystallization, it is different from the general solidification process. Generally, Q is the heat released per kilogram of aluminum alloy per unit time, as follows:

[0077]

[0078] In the formula: L—the latent heat of crystallization of the aluminum alloy material; ρ—the material density; f L —the solid fraction of the metal material at temperature T.

[0079] The differential equation for the release of heat during metal solidification and crystallization is:

[0080]

[0081] Generally, the main methods for dealing with latent heat are the enthalpy method, the temperature rise method, and the equivalent specific heat method. The enthalpy method and the equivalent specific heat method are applicable to alloys with a certain crystallization temperature range, while the temperature rise method is applicable to pure metals or alloys with eutectic compositions.

[0082] The purpose of analyzing the temperature field during the solidification process is to be able to more accurately predict the location of shrinkage cavities, and prevent the occurrence of shrinkage cavities by reasonably designing the die-casting mold or improving die-casting process parameters (pouring temperature, mold surface temperature, mold cooling water flow rate, etc.), the structure of the gating system, and cooling means.

[0083] Based on the formation mechanism of solidification according to the temperature field, with the temperature field as the calculation basis, common determination methods include the direct simulation method, the isosolideus method, the critical solid fraction method, the temperature gradient method, and NIYAMA (G / R 1 / 2 ) etc.

[0084] The present invention is based on the Niyama method and determines according to the ratio of the temperature gradient G to the square root of the cooling rate R. When the ratio is less than a critical value (about 0.8), shrinkage cavities are generated, and the smaller the ratio, the easier it is to generate shrinkage cavities.

[0085] Temperature gradient

[0086]

[0087] Cooling rate

[0088]

[0089] Where T upper is the liquidus temperature, and T lowwer is the solidus temperature

[0090] According to the Niyama theory, when G / R 1 / 2 ≤M at a certain place when the product solidification is completed, shrinkage cavities and porosity are generated at that place. M is the critical criterion value for shrinkage cavities and porosity. Different alloy compositions have different critical criterion values, which are independent of the size and shape of the product; in the solidification region, the smaller the G / R 1 / 2 criterion value, the greater the tendency to generate shrinkage cavities and porosity; conversely, the smaller the tendency to generate shrinkage cavities and porosity. The Niyama method uses two parameters, the temperature gradient and the cooling rate, not only taking into account the influence of the shape and size of the product, but also being able to accurately evaluate the loss of flow pressure, and has a wide application in defect prediction.

[0091] The above products are prepared based on the following examples.

[0092] Example 1

[0093] In this example, the mold and related processing parameters are designed for the above-designed product. According to the structural characteristics and technical requirements of the part, the casting specific pressure is 80 Mpa, 2 pieces are produced per mold, the safety factor is 1.2, the calculated clamping force is about 2660 KN, and a 350-ton die-casting machine and die-casting mold are used for manufacturing.

[0094] Such as Figure 5As shown in the figure, the mold of this embodiment includes a moving mold and a stationary mold. A concave mold cavity is provided in the middle of the stationary mold, and a convex mold platform adapted to the concave mold cavity is provided on the moving mold. A pouring port 10 is provided on the stationary mold. The setting of the mold runner corresponds to the resolver end cover of the new energy vehicle. A plurality of slag pockets 7 are provided on the moving mold. A plurality of slag pockets provided in the thin-walled flange section are connected to an exhaust passage 9, and a cylindrical section slag pocket 8 is also provided inside the cylindrical section.

[0095] Furthermore, in this embodiment, one mold is provided with one pouring port and two of the resolver end covers of the new energy vehicle are produced simultaneously. In this embodiment, one main runner 11 of the pouring port and the concave mold cavity is provided;

[0096] The number of convex portions of the thin-walled flange section is six. Taking the uppermost convex portion during the pouring process as the first convex portion and counting clockwise, five of the slag pockets are respectively arranged at the positions between the first convex portion and the second convex portion, between the second convex portion and the third convex portion, between the fourth convex portion, the fifth convex portion and the sixth convex portion, and between the sixth convex portion and the first convex portion. The main runner is arranged at the position between the fourth convex portion and the fifth convex portion.

[0097] The single-gate die-casting pouring system of one mold with two parts in Embodiment 1 is as Figure 5 shown. The basic wall thickness of the casting is 4.5 mm. Referring to its sealing property requirements, the recommended in-gate speed in the manual is set to 40 m / s to 45 m / s. According to the principle of constant flow rate through the in-gate, it is calculated that the cross-sectional area of the in-gate for a single casting is 160 mm 2 , the diameter of the piston of the injection rod is 60 mm, and the injection speed of the injection rod is taken as 3.5 m / s. The secondary injection acceleration ratio can be obtained as 8.75. According to the principle of mass conservation, the length of the pressure chamber is designed to be 495 mm, and the filling degree of the pressure chamber is 35.4%. ADC12 is a eutectic alloy, the eutectic temperature is about 577 °C, the liquidus temperature is 580 °C, and the solidus temperature is 515 °C. According to experience, the initial temperature of the die-casting mold is designed to be 180 ± 10 °C, the pouring temperature of the ADC12 aluminum liquid is 665 ± 10 °C, the whole mold is water-cooled, the inlet water temperature is set to 25 °C, and the outlet water temperature is 35 °C. The product after production in Embodiment 1 is as Figure 6 shown. After producing several batches, the overall qualified rate is relatively high, and Embodiment 1 can be used as a mold for normal product production.

[0098] In addition, the unqualified parts in Embodiment 1 are also analyzed. Among them, the main defects are as Figure 7The shrinkage holes shown are concentrated in the thick wall where the straight barrel and the flange meet. The single hole size is less than 0.5mm, honeycomb-shaped, mostly dark gray and irregular in shape. It is judged that the shrinkage holes are the majority, and their location is the 9mm thickest part of the casting wall. The shrinkage hole defect is caused by uneven cooling. The local thickness of the flange and the cylinder junction reaches 9mm. Due to local heat nodes, filling turbulence, poor exhaust and other factors, this area is prone to shrinkage holes, shrinkage and component segregation.

[0099] like Figure 8 As shown in Figure 2, by using an upright metallographic microscope NM950 to magnify 200 times to observe local defects, it was found that the diameter of the shrinkage cavity can reach 270 microns, and the grain size of α-Al is 40-57 microns, as shown in Figure 2. Figure 9 As shown, through 500 times magnification observation with a metallographic microscope, it can be found that there are many sharp polygonal and blocky single crystal silicon and needle-shaped iron phases near the shrinkage area. This casting organization not only splits the crystal structure and reduces the mechanical properties of the product, but also reduces the corrosion resistance of the parts.

[0100] like Figure 10 As shown in the figure, part of the defects are cracks at the top of the barrel. After analysis, the main reason for the tiny cracks at the top of the barrel is that the temperature of the aluminum liquid decreases at the end of pouring and the fluidity is poor. At the same time, the mold temperature is insufficient, and the tensile stress of the casting is too large during the shrinkage and solidification process, resulting in cracks.

[0101] Another part of the defects is the flow marks of the reinforcement and cold insulation, such as Figure 11 As shown in the figure, flow marks occur on the outer surface of the six reinforcing ribs. They are lines without obvious directionality produced when the aluminum alloy liquid metal flows in the mold. These lines are usually different in color from the metal matrix and may appear together with cold shut in severe cases. Flow marks not only affect the appearance of the casting, but also cause peeling defects in the subsequent shot blasting process.

[0102] The causes of flow marks and cold shut are low mold temperature and turbulence at the intersection of aluminum liquid filling: low mold temperature will cause uneven metal liquid flow and easily produce flow marks. When the temperature of aluminum alloy mold is lower than 180℃, flow mark defects are prone to occur.

[0103] A simulation analysis was performed to verify the problems existing in Example 1, based on a numerical simulation analysis of the filling process using the ANYCASTING 6.0 casting software.

[0104] like Figure 12 (a), (b), (c) Example 1 is a single inner gate of one mold and two parts, with a single gate thickness of 3.0 mm, a length of 55 mm, and a gate cross-sectional area of 160 mm 2From the simulation of ANYCASTING casting software, we can know that the molten metal enters the inner gate at 0.43 seconds of filling, and the filling speed rises rapidly from 0.8 m / s to 40 m / s. The front aluminum liquid jet hits the middle mold core, climbs along the cylindrical core to the top of the barrel, and then turns downward, and merges with the subsequent aluminum liquid entering the gate as shown in Figure 0.4389 seconds, entraining the gas and slag near the gate. At the same time, the middle core will produce defects such as sticking membrane and strain under the impact of high-speed aluminum liquid. Then the aluminum liquid surrounds the two sides of the core to the end, and at 0.4434 seconds, it intersects on the opposite side of the gate. At 0.448 seconds of filling, the high-temperature alloy at the upper end of the opposite side of the thin-walled cylindrical gate moves downward along the middle core and impacts the alloy at the bottom of the flange, causing air entrainment. Figure 13 shown.

[0105] Through the Pressure Cloud Figure 14 It can be seen that at the 0.454th second of filling, when the filling reaches 85%, the pressure near the gate is the largest, reaching 8.4 atmospheres. The pressure at the R angle of the root of the cylinder is large, and the root gas is gathered at the 3 o'clock direction, and the pressure reaches 8.0 atmospheres. The pressure in this part can be solved by adjusting the slag feeding port inside the cylinder. The pressure at the root shows that the gas collection is poor at this part. Through solidification analysis, it can be seen that the root of the cylinder close to the feeding port and the root of the cylinder on the opposite side of the gate are the parts most prone to shrinkage cavities and shrinkage. Through the above analysis, this casting scheme is suitable for the die-casting production of flanged cylindrical thin-walled parts, but there are still certain defects and there is still room for improvement.

[0106] Example 2

[0107] In order to solve the problem of defects in several parts in Example 1, this example uses numerical simulation analysis and combines the actual production experience of cooling water to design another pouring and draining system to improve cooling conditions, optimize the exhaust and slag removal processes, and accurately control process parameters such as injection speed and mold temperature to achieve mass production quality requirements with a pass rate greater than 96%.

[0108] An improvement of this embodiment is that two main runners are provided, and the second main runner is provided between the third protrusion and the fourth protrusion. Figure 16 , Figure 17 shown.

[0109] Double inner gate, gate thickness 2.5mm, gate length of single product 95mm, gate cross-sectional area of single casting 240mm 2, a slag pocket is added at the end of the casting and in the middle between the two gating systems. An exhaust passage is designed at the end of the slag pocket. The mold material is selected as FS438 steel. The heat transfer coefficient between the casting and the mold is set at 1000 W / M.K, and the cooling method is air cooling. The whole mold is water-cooled. The static mold is cooled by two-in and two-out straight-through circulating water cooling. The cooling water channel is 15 mm away from the mold parting surface. The water pipe diameter is 10 mm. The set water flow rate is 2 l / min, the inlet water temperature is set at 25 °C, and the outlet water temperature is 35 °C; the dynamic mold is cooled by single-point high-pressure water, and the layout is at the center of the cylinder. The set water flow rate is 1.5 l / min, the inlet water temperature is set at 25 °C, and the outlet water temperature is 35 °C.

[0110] ANYcasting 6.0 is used to perform variable mesh division on the casting model with hexahedral elements. The total number of volume meshes is 7.35 million. Two sensors are set at the ingate position during the simulation analysis.

[0111] As Figure 18 shown in (a), (b), and (c), the simulation analysis results show that the molten metal enters the ingate at 0.527 s of filling. Due to the increase in the ingate area, the ingate velocity decreases significantly. At 0.538 s of filling, the front ends of the left and right aluminum melts impact the root of the middle mold cylinder core. Part of the aluminum melt merges into the feeding port of the middle slag pocket. The molten metal moves upward along the axial direction of the cylindrical core in the form of full wall thickness. The subsequent molten metal replenishes the circumferential filling in the radial direction. At 0.549 s, the front ends of the molten metal meet at the end on the opposite side of the ingate. Due to the action of the back pressure, part of the aluminum melt flows back to the slag pocket in the middle between the two gating systems.

[0112] It can be seen from the above analysis that due to the design change of the gating system and the decrease in the filling speed, the flow pattern of the molten metal has changed significantly, from the jet filling along the thin shell to the filling close to the full wall thickness. This gating structure is beneficial to preventing gas entrapment and sticking to the mold, and improving the mold life and casting quality.

[0113] Example 3

[0114] On the basis of Example 2, a machining allowance of at least 2 mm is provided at the top of the cylindrical section of the cast blank. The specification of the machining allowance is the same as the shape of the cylindrical section and the semi-circular protrusion thereon. As Figure 4 shown, through numerical simulation analysis and improvement of the casting structure design based on the defects that have occurred, the diameter of the ring on the barrel-shaped top surface is increased by 2 mm. On the one hand, its function is to gather the impurities and gas at the front end of the aluminum melt filling in the 2-mm ring space, acting as a slag pocket. At the same time, the increased alloy liquid raises the temperature of the local mold, avoiding the occurrence of defects such as cold shut and cracks. The machining allowance is removed after casting.

[0115] Example 4

[0116] Through numerical simulation analysis, it can be known that the middle part of the bucket solidifies last, and shrinkage cavities are most likely to occur at the rounded corners of the junction between the flange and the cylinder. It is necessary to design a single-point high-pressure cooling at the center of the cylinder in the die-casting mold. The designed cooling water pressure is 10 kg / cm 2 , the designed water flow rate is 2 liters / minute, the inlet water temperature is 25 °C, and the outlet water temperature is 35 °C. It can be calculated that this flow rate meets the cooling requirements of the aluminum alloy. A large amount of cooling water can increase the cooling rate, improve the degree of supercooling, and prevent the generation of shrinkage cavities. As Figure 20 (a), (b), (c) shown. At 6.9 seconds after filling is completed, the gate solidifies. At 8.94 seconds, only the root of the same row remains without solidified material, and solidification is completed at 10.52 seconds.

[0117] Based on Example 2 and / or 3, the entire mold is water-cooled, and the static mold is cooled by a two-in and two-out straight-through circulating water cooling; the single-point high-pressure water cooling of the moving mold is arranged at the center of the cylinder.

[0118] As Figure 19 shown, the single-point high-pressure water cooling pipeline of the moving mold includes an inlet 12, an outlet 13, an inner pipe 15, an outer pipe 14, a diverter 17, and a sealing ring 16. The outer pipe is sleeved outside the inner pipe. The inlet is connected to the inner pipe, and the output end of the inner pipe is connected to the diverter and sprays on the part of the mold that needs to be cooled. This part is 15 mm away from the bottom plane of the slag pocket. The high-pressure water is diverted at the cross groove at the top of the diverter and spirally returns along the outer wall of the diverter and the inner wall of the mating surface of the mold, and returns to the water inlet of the bottom diverter. The water inlet is connected to the outer pipe, and the outlet is connected to the output end of the outer pipe. The bottom of the diverter and the outer surface of the mold adopt a double O-ring sealing form.

[0119] The high-pressure and low-temperature water enters the inner pipe from the inlet white steel pipe and is directly sent to the front end of the diverter and sprayed on the part of the mold that needs to be cooled. This part is 15 mm away from the bottom plane of the slag pocket. The high-pressure water is diverted at the cross groove at the top of the diverter and spirally returns along the outer wall of the diverter and the inner wall of the mating surface of the mold, as shown by the red line in the following figure. It returns to the water inlet of the bottom diverter, and the water enters from the outer surface to the inner surface and flows out to the outlet through the gap between the outer surface of the white steel pipe and the inner wall of the 3 / 8” white steel outer pipe to complete the flowing cooling cycle.

[0120] This high-pressure cooling water cycle has the following characteristics:

[0121] The outer surface of the single-thread stud structure enables the cooling water to have sufficient contact area, ensuring sufficient cooling;

[0122] The distance between the front end of the diverter and the bottom surface of the mold is 15 mm; the inner pipe The cross-sectional area of the inner hole of the white steel pipe is close to the cross-sectional area of the whole process of the channel, ensuring the rational use of space, 10 kg / cm 2 , the designed water flow rate is 2 liters / minute, the water inlet temperature is 25℃, and the water outlet temperature is 35℃.

[0123] The bottom of the diverter and the outer surface of the mold are sealed with double O-rings to ensure that the high-pressure water does not leak. The inner hole is connected with the 3 / 8" white steel pipe vertebral pipe thread, which is easy to install and reliable to use.

[0124] As an optional implementation, different from Example 1, in this embodiment, the mold filling speed is controlled at 25-30 m / s.

[0125] The reason for the excessive porosity is that the two streams of aluminum liquid meet and entrain gas during the flow process. In the die casting process, the aluminum liquid speed is too fast, so that the gas in the cavity cannot be completely and promptly squeezed out of the cavity smoothly, and is drawn into the aluminum liquid by the aluminum liquid flow and cannot be discharged, forming larger pores.

[0126] like Figure 21 As shown in the figure. The speed analysis result of the gate position sensor shows that the speed suddenly increases at 0.523 seconds of filling, from 0.12m / s to 30m / s at 0.556 seconds, and the aging filling is completed in 23 milliseconds. From the above analysis, it can be seen that due to the design change of the gate and the reduction of the filling speed, the flow form of the molten metal has changed significantly, from the injection-type filling along the thin shell to the filling close to the full wall thickness. This gate structure is conducive to preventing the generation of air entrainment and pores.

[0127] Using Examples 2 to 4, Figure 22 , Figure 23 The products produced by the mold shown are Figure 24 From the X-ray images, we can see that there are no visible pores and shrinkage cavities inside the two castings. The slag bag in the center of the cylinder has more pores, which really has a good effect on slag removal and exhaust. At the same time, the slag bag in the middle of the double intersection has white pores, which also plays a role in collecting and exhausting. The effects of these two slag bags are consistent with the results of numerical simulation analysis. Figure 25 In the figure, the bottom is position 1, the right is position 2, the top is position 3, the top left is position 4, the bottom right is position 5, and the bottom left is position 6. The porosity and metallographic structure analysis after cutting are as follows: Figure 26 (a) to (f) correspond to each other as shown.

[0128] After taking slices on the product, polishing them, and etching them in a 10% caustic soda solution, and then inspecting them under a 100-fold magnification of an AX10 Zeiss metallographic microscope, there are obvious black non-reflective air shrinkage holes and cavities in the metallographic picture of Example 1, and there are densely distributed small pores around them. The porosity is 8%. The white and bright α-aluminum tissue morphology is mostly dendritic crystal tissue, and this crystal morphology results in weak mechanical strength; the aluminum-silicon alloy is diffusely distributed around the α-aluminum, and it can be seen from the metallographic picture that the proportion of massive α-aluminum is relatively small;

[0129] In the improved metallographic picture, the black air shrinkage holes and cavities are significantly reduced. After detection, the porosity is 3.5%. The white and bright α-aluminum tissue morphology is mostly fine spherical or massive crystals. Fewer air shrinkage holes and more spherical tissue structures will produce higher mechanical strength.

[0130] The test pressure of the formed resolver end cover of the new energy vehicle is > 30 kPa, without leakage, cold shut, laps, cracks, and any penetrative defects; without segregation, oxide slag inclusions defects, and the internal structure of the casting is uniform.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A resolver end cover for a new energy vehicle, characterized in that, It includes a thin-walled flange section and a cylindrical section. The thin-walled flange section is installed on the outer peripheral part of the cylindrical section. An annular support plate is provided inside the cylindrical section near the thin-walled flange section. The outer diameter of the annular support plate matches the inner diameter of the cylindrical section. The inside of the annular support plate is a circular opening. A number of protruding parts are evenly distributed on the outer peripheral part of the thin-walled flange section. A number of reinforcing ribs are provided between the thin-walled flange section and the cylindrical section.

2. The resolver end cover of the new energy vehicle according to claim 1, wherein A hole is opened in the protruding part as a bolt assembly hole. The protruding part is of a circular ring structure. The thin-walled flange section is of a circular ring structure. The outer circumferential surface of the protruding part intersects with the outer circumferential surface of the thin-walled flange section. The outer circumferential surface of the thin-walled flange section smoothly transitions to the outer circumferential surface of the protruding part.

3. The resolver end cover of the new energy vehicle according to claim 1, wherein, The point on the outer circumferential surface of the protruding part closest to the center of the thin-walled flange section is used as the lower starting point of the reinforcing rib. The end of the right-angled side is connected to the cylindrical section. The other right-angled side is arranged along the height direction of the cylindrical section. A number of semi-circular protrusions are provided outside the outer circumferential surface at the top of the cylindrical section. They are arranged along the height direction of the cylindrical section and serve as a reinforcing column structure. The starting point of the other right-angled side is set on the reinforcing column. The starting point position of the other right-angled side is set based on the inclination angle of the hypotenuse. The inclination angle of the reinforcing rib is 30°.

4. The resolver end cover of the new energy vehicle according to claim 1, characterized in that, The material of the motor resolver end cover die casting is ADC12.

5. The resolver end cover of the new energy vehicle according to claim 1, wherein, The casting blank has a machining allowance of at least 2 mm at the top of the cylindrical section. The specification of the machining allowance is the same as the shape of the cylindrical section and the semi-circular protrusions thereon.

6. A mold for manufacturing the resolver end cover of the new energy vehicle according to any one of claims 1 to 5, characterized in that It includes a moving die and a stationary die. A female die cavity is provided in the middle of the stationary die. A male die platform adapted to the female die cavity is provided on the moving die. A pouring gate is provided on the stationary die. The setting of the mold runner corresponds to the resolver end cover of the new energy vehicle. A number of slag traps are provided on the moving die. The slag traps provided on the thin-walled flange section are connected to an exhaust channel. A cylindrical section slag trap is also provided inside the cylindrical section.

7. The mold according to claim 6, characterized in that, One mold is provided with one pouring gate and produces two resolver end covers of the new energy vehicle at the same time. One or two main runners are provided between the pouring gate and the female die cavity. The number of protruding parts on the thin-walled flange section is six. Taking the uppermost protruding part during the pouring process as the first protruding part and counting clockwise, five slag traps are respectively arranged at the positions between the first protruding part and the second protruding part, between the second protruding part and the third protruding part, between the fourth protruding part, the fifth protruding part and the sixth protruding part, and between the sixth protruding part and the first protruding part. The main runner is arranged at the position between the fourth protruding part and the fifth protruding part. When two are set, the second main runner is arranged at the position between the third protruding part and the fourth protruding part.

8. The mold according to claim 6, characterized in that, The whole mold is water-cooled. The stationary die is cooled by two-in and two-out direct-through circulating water cooling. The moving die is cooled by single-point high-pressure water with a layout at the center of the cylinder.

9. The mold according to claim 6, characterized in that, The moving die single-point high-pressure water cooling pipeline includes a water inlet, a water outlet, an inner pipe, an outer pipe, a diverter and a sealing ring. The outer pipe is sleeved outside the inner pipe. The water inlet is connected to the inner pipe, and the output end of the inner pipe is connected to the diverter, which sprays on the part of the die that needs to be cooled. This part is 15 millimeters away from the bottom plane of the slag pocket. The high-pressure water is divided by the cross groove at the top of the diverter and spirally returns along the outer wall of the diverter and the inner wall of the mating surface of the die, and returns to the water return port of the bottom diverter. The water return port is connected to the outer pipe, and the water outlet is connected to the output end of the outer pipe. The bottom of the diverter and the outer surface of the die adopt a double O-ring sealing form.

10. The mold according to claim 6, characterized in that, The mold filling speed is controlled at 25 - 30 m / s.

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