Production method of casting and casting

Abstract

The invention provides a casting production method and a casting. The production method of the casting comprises the following steps that a mold is manufactured, specifically, the mold is manufactured, a cavity is formed in the mold, and the shape of the cavity is consistent with that of the casting to be produced; and raw material preparation: smelting a metal stock solution. And pouring is conducted, specifically, a metal stock solution is injected into the mold, and a casting is formed. And post-treatment is conducted, specifically, a casting formed through pouring is treated. Wherein the pouring step comprises the following steps: vacuum adsorption: placing a manufactured mold on a centrifugal pouring machine, vacuumizing the mold, and keeping the vacuum degree, so that a cavity is in a negative pressure state. And centrifugal pouring is conducted, specifically, a centrifugal pouring machine is started, after the centrifugal pouring machine rotates to the preset rotating speed, the metal stock solution in the pouring heat preservation furnace is injected into the mold through a pouring system, the cavity is fully filled with the metal stock solution, and a casting is formed. According to the casting production method and the casting, the production efficiency can be optimized, and the casting quality can be improved.

Description

Technical Field

[0001] The present application relates to the field of casting technology, and in particular to a method for producing a casting and a casting. Background Art

[0002] In the current production process of new energy vehicles, body structural parts such as the rear floor and front cabin are often manufactured by stamping, welding, etc. For more complex large structural parts, there are many restrictions on part design, long connection processes, high investment costs and long manufacturing cycles.

[0003] Therefore, it is necessary to provide an improved method for producing a casting and a casting to solve the above problems. Summary of the invention

[0004] The present application provides a casting production method and a casting that optimizes production efficiency and improves casting quality.

[0005] The present application discloses a method for producing a casting, comprising the following steps: Mould making: making a mould, forming a cavity inside the mould, the shape of the cavity is consistent with the shape of the casting to be produced; Raw material preparation: smelting metal liquid; Pouring: injecting metal liquid into the mold to form a casting; Post-processing: Processing of castings formed by pouring; Wherein, the pouring step comprises the following steps: Vacuum adsorption: Place the finished mold on the centrifugal casting machine, evacuate the mold and maintain the vacuum degree so that the cavity is in a negative pressure state; Centrifugal pouring: Start the centrifugal pouring machine. After the centrifugal pouring machine rotates to the preset speed, the smelted metal liquid is injected into the mold through the pouring system so that the metal liquid fully fills the mold cavity to form a casting.

[0006] Furthermore, the pouring step further comprises a pressurizing step: When the metal concentrate is injected into the mold through the pouring system, pressurized gas is provided to the pouring system through the pressurizing device.

[0007] Furthermore, in the vacuum adsorption step, the vacuum degree of the cavity is 30-500 mbar; In the centrifugal casting step, the preset rotation speed of the centrifugal casting machine is 50-200 rpm.

[0008] Furthermore, the mold is composed of a plurality of sand cores, and the internal chambers of the plurality of sand cores and the gaps between different sand cores together form the mold cavity; The molding step includes a core making step: The sand, resin and catalyst are mixed according to the set ratio, and the mixed sand is made into sand cores using a core making machine.

[0009] Furthermore, after the core making step, the molding step further includes an assembling step: The plurality of sand cores are placed in an assembly device, the plurality of sand cores are positioned by a positioning device of the assembly device, and the positions of the plurality of sand cores are fixed by a locking device of the assembly device to form a mold.

[0010] Furthermore, the molding step further comprises a barrel filling step: placing the entire mold into a protective barrel and fixing and sealing the protective barrel; and / or, The post-processing step comprises the following steps: Air cooling: Cool the casting under the wrapping of sand core; Sand cleaning: After the casting has cooled to a certain temperature, separate the mold from the retaining barrel, then separate the sand core from the casting and take out the casting.

[0011] Furthermore, after the sand cleaning step, the post-processing step also includes a used sand recovery step: the used sand separated from the casting is processed and regenerated to form sand material, which is reused in the molding step.

[0012] Furthermore, after the post-processing step, the casting production method further comprises a processing step, and the processing step comprises the following steps: Machining and assembly: Process the castings through machines and assemble the parts; Cleaning: Remove machining residues and surface oxides from castings.

[0013] Furthermore, the cleaning step includes ultrasonic alkaline cleaning and cleaning, acid cleaning and cleaning.

[0014] Furthermore, after the machining step, the processing step further includes a waste metal recycling step: The old metal separated from the casting in the machining assembly step is processed to be made into metal raw material, which is put into the raw material preparation step for reuse.

[0015] Further, after the post-processing step, the processing step further includes the following steps: Plating: forming a coating on the surface of the casting; Passivation: An oxide film is formed on the surface of the casting to obtain the finished casting.

[0016] Furthermore, in the raw material preparation step, the metal raw material is placed in a melting furnace to be smelted into a metal stock solution, and the metal stock solution is transferred to a pouring and holding furnace in the form of a ladle.

[0017] Further, the metal raw material is steel; In the raw material preparation step, alloy elements also need to be added to the metal stock solution.

[0018] Furthermore, the components of the metal stock solution and their weight percentage contents are: C: 0.9-1.5%; Mn: 11-15%; Si: 0.3-0.8%; Re: 0.05-0.3%; S: <0.04%; P: <0.07%.

[0019] The present application also discloses a casting, which is made by the production method as described above.

[0020] Furthermore, the main body of the casting is a thin-walled structure, and the casting forms a closed thin-walled cavity.

[0021] Furthermore, the wall thickness of the thin-walled structure is 0.8-2.5 mm.

[0022] The production method and castings of the present application enhance the fluidity of the metal stock by using vacuum adsorption during the production process, so that the flow of the metal stock in the cavity is more sufficient; by using centrifugal pouring, the filling of the metal stock in the cavity is made more uniform and compact, which is beneficial to improving the strength of the casting. When producing complex castings with thin-walled structures, the combination of vacuum adsorption and centrifugal pouring is beneficial to the molding of the complex casting structure, ensuring that the metal liquid is evenly filled in the thin wall, while reducing the porosity or cold shut problems caused by the uneven flow of the metal stock, thereby improving the quality of the casting. In addition, the production method of the casting of the present application realizes the one-piece molding of the casting through vacuum centrifugal pouring, improves production efficiency, and meets the requirements of lightweight design.

[0023] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the specification and, together with the description, serve to explain the principles of the specification.

[0025] Figure 1 It is a flow chart of the production method of the casting of the present application.

[0026] Figure 2 yes Figure 1 Flowchart of step S200 in FIG.

[0027] Figure 3 It is a schematic diagram of the sand core assembly of one embodiment of the casting of the present application.

[0028] Figure 4 yes Figure 3 A cross-sectional view of a casting of an embodiment of the present invention.

[0029] Figure 5 It is a schematic diagram of sand core assembly when the casting of the present application is a front engine room.

[0030] Figure 6 yes Figure 5 A perspective view of the mid-front cabin.

[0031] Figure 7 It is a three-dimensional view when the casting of the present application is a front floor.

[0032] Figure 8 yes Figure 7 Cross-section of the central channel.

[0033] Description of Figure Numbers: 11. First sand core; 12. Second sand core; 13. Third sand core; 14. Fourth sand core; 20. Cavity; 21. Casting gate; 30. Thin-walled cavity; 31. First sub-cavity; 32. Second sub-cavity; 33. Third sub-cavity; 41. Base sand core; 42. Upper sand core; 43. Rear sand core; 44. Internal sand core; 45. External sand core; 50. Front engine room; 51. Inner area of ​​longitudinal beam; 52. Front part of front enclosure and upper area of ​​wheel arch; 53. Rear area of ​​front enclosure; 54. Longitudinal beam cavity area; 55. Outer area of ​​longitudinal beam and lower area of ​​wheel arch; 60. Thin-walled structure; 70. Front floor; 71. Central channel; 711. Outer wall of channel; 712. Inner wall of channel; 72. Door sill beam; 73. Seat cross beam; 74. Front floor panel. DETAILED DESCRIPTION

[0034] Here, the technical solutions in the embodiments (or "implementation methods") of the present application will be described clearly and completely in conjunction with the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0035] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0036] Next, the embodiments of this specification are described in detail.

[0037] like Figure 1As shown, the present application provides a method for producing a casting, comprising the following steps: Step S100, mold making: making a mold. A cavity is formed in the mold, and the shape of the cavity is consistent with the shape of the casting to be produced.

[0038] The mold of the present application is composed of a plurality of sand cores, and the internal chambers of the plurality of sand cores and the gaps between different sand cores together form the mold cavity.

[0039] The design of multiple sand cores forming the cavity enables the mold of the present application to cast a variety of parts with complex structures and complex cavities, and can achieve higher precision and details. In particular, in the production of castings that require hollow or inner cavities (such as pipes, channels, etc.), the combination of sand cores provides greater flexibility. Multiple sand cores combined together can accurately form the required internal shape, reduce secondary processing after casting, reduce process and processing costs, and effectively improve the overall efficiency of casting production. By forming a mold with multiple sand cores, molding in one go, simplifying the design and shortening the manufacturing cycle.

[0040] Specifically, the molding step also includes the following steps: Step S101, core making: sand material, resin and catalyst are mixed according to a set ratio, and the mixed sand is made into a sand core using a core making machine.

[0041] During the core making process, the core box must first be installed in the core making machine. The core box is usually composed of two parts, the upper and lower parts, to accommodate the sand core. The upper and lower core boxes are put together to provide the required space for sand core manufacturing. After that, the mixed sand is shot into the core box through the sand shooting equipment. At this time, the sand has a certain cohesiveness and can fix the shape. While shooting the sand, a catalyst (such as a curing agent, hardener, etc.) is blown in to promote the rapid hardening of the sand core to achieve sufficient strength for subsequent operations.

[0042] After that, the formed single sand core is immersed in the coating. The coating is usually a high-temperature refractory material (such as bauxite, silica sand, etc.), which can increase the heat resistance and strength of the sand core so that the sand core can resist the erosion of the metal liquid during the casting process. After the coating is applied, it needs to be dried to remove moisture and enhance the adhesion of the coating. The drying temperature and time need to be controlled within a certain range to ensure that the coating on the surface of the sand core is uniform and crack-free.

[0043] Step S102, assembling: placing a plurality of sand cores in an assembly device, positioning the plurality of sand cores by a positioning device of the assembly device, and fixing the positions of the plurality of sand cores by a locking device of the assembly device to form a mold.

[0044] Multiple sand cores can be connected into a whole by gluing, welding or mechanical connection. The combined sand cores constitute the cavity of the entire casting. When assembling the sand cores, they must be limited to each other to avoid dislocation under the action of centrifugal force during the pouring process.

[0045] When the casting to be manufactured is a thin-walled structure with a closed cavity, the sand core includes at least one inner core and at least two outer cores, the outer surface of the inner core is the same as the inner contour of the closed cavity, and a pouring port is formed between two adjacent outer cores.

[0046] like Figure 3 and Figure 4 In the illustrated embodiment, the sand core includes a first sand core 11, a second sand core 12, a third sand core 13 and a fourth sand core 14. The first sand core 11, the second sand core 12 and the third sand core 13 are outer cores, which are identical to the outer contour of the casting. The fourth sand core 14 is an inner core, which is identical to the inner contour of the thin-walled cavity 30 in the casting. The first sand core 11, the second sand core 12, the third sand core 13 and the fourth sand core 14 together form a mold cavity 20. A pouring port 21 is formed between the first sand core 11 and the third sand core 13 to allow the metal stock to flow in during the pouring process.

[0047] like Figure 5 and Figure 6 As shown, when the casting is a front engine compartment 50 of a vehicle, the sand core may include a base sand core 41, an upper sand core 42, a rear sand core 43, a pair of inner sand cores 44, and a pair of outer sand cores 45. The base sand core 41 corresponds to the shape of the inner side region 51 of the longitudinal beam of the front engine compartment 50, the upper sand core 42 corresponds to the shape of the front enclosure front part and the upper region 52 of the wheel cover of the front engine compartment 50, the rear sand core 43 corresponds to the shape of the rear area 53 of the front enclosure of the front engine compartment 50, the pair of inner sand cores 44 correspond to the shapes of the longitudinal beam cavity regions 54 on both sides of the front engine compartment 50, and the pair of outer sand cores 45 correspond to the shapes of the outer side of the longitudinal beam and the lower region 55 of the wheel cover on both sides of the front engine compartment 50. The cavity formed by the base sand core 41, the upper sand core 42, the rear sand core 43, the pair of inner sand cores 44, and the pair of outer sand cores 45 is consistent with the shape of the front engine compartment 50.

[0048] Step S103, barreling: the mold is placed in a protective barrel as a whole, and the protective barrel is fixed and sealed.

[0049] The protective barrel is usually made of metal or high-strength material with good compression resistance. It can protect the sand core and prevent the sand core from deformation or cracks.

[0050] Step S200, raw material preparation: smelting metal liquid.

[0051] In the raw material preparation step, the metal raw material is placed in a melting furnace to be smelted into a metal stock solution, and the metal stock solution is transferred to a pouring and holding furnace in the form of a ladle.

[0052] Specifically, in the present application, the melting furnace in the raw material preparation process is a medium frequency furnace. The metal raw material is steel, which can effectively reduce the cost.

[0053] In the raw material preparation step, alloy elements need to be added to the metal stock solution to achieve the component configuration requirements required for molding. In this embodiment, the components and their weight percentage contents of the metal stock solution are: C: 0.9-1.5%; Mn: 11-15%; Si: 0.3-0.8%; Re: 0.05-0.3%; S: <0.04%; P: <0.07%.

[0054] The metal stock solution of this embodiment adds 11-15% Mn to make the liquidus temperature of the alloy reach 1377°C and the solidus temperature reach 1195°C, which is far lower than the melting point of iron 1538°C, greatly improving the fluidity of the metal stock solution during the casting process. On this basis, by adding 0.05-0.3% Re elements, the harmful effects of elements such as S and P can be effectively reduced. Secondly, the organization of steel can also be improved, and the comprehensive mechanical properties of steel can be improved. When the casting is used in a vehicle, during the high-speed collision deformation process of the vehicle, the casting will rapidly undergo plastic deformation, inducing strong work hardening. During this process, the austenite structure will undergo a martensitic phase transformation, producing a large number of hardened layers to further improve the safety of the vehicle.

[0055] Specifically, Figure 2 As shown, the smelting of the metal raw liquid also includes the following steps: Step S201, heating and deoxidation: During the heating process, the viscosity of the alkaline slag is continuously adjusted, the fluidity and melting point of the slag are observed, and a small amount of Ca-Si powder (the addition amount is 0.1%-0.2%), or other Fe-Si powder, AL powder is added to the slag surface to diffuse and deoxidize the molten steel (a small amount of CaF2 or refractory brick waste particles can also be used to adjust the viscosity of the slag).

[0056] Step S202, alloying: When the temperature rises to 1540°C, electrolytic manganese can be added. It is worth noting that when adding electrolytic manganese, it should be added in batches and stages, and the amount added each time should match the melting rate to prevent "sinking" and composition control deviation caused by excessive addition. Only 85%-90% of the rough amount is added in advance, and it is decided whether to continue adding after the test results come out. In addition, the added alloy should be careful not to contact the slag liquid, otherwise it will affect the metal recovery rate.

[0057] Step S203, adding C, Si, Re elements: making the element content reach a preset ratio, then stirring the metal stock solution to make it uniform; taking samples, and making final adjustments based on the sampling results.

[0058] Step S204, deoxidation and steel tapping: When the temperature of the raw metal reaches about 1500°C, continue to diffuse deoxidation on the slag surface to reduce the oxygen content in the raw metal, and decide whether to change the slag according to needs. When the color of the slag becomes lighter and whiter, it indicates that the oxides are reduced and the deoxidation reaction of the raw metal is almost completed, and the alloy elements are adjusted. Perform final deoxidation, insert 0.10% Al, and wait for about 2 minutes to tap the steel and obtain the raw metal.

[0059] When the metal is smelted, the liquid metal will be transferred to the pouring and holding furnace through the ladle. A ladle is a container used to temporarily store and transport liquid metal. It is usually made of high-temperature resistant materials and can maintain the temperature of the metal and prevent heat loss. The pouring and holding furnace is usually equipped with a temperature control device to maintain a constant temperature to ensure that the metal does not solidify or over-oxidize. Transferring the metal to the pouring and holding furnace can effectively maintain the temperature and fluidity of the metal for the next pouring operation.

[0060] It is understandable that there is no particular order in which step S100 and step S200 should be performed. Step S100 and step S200 can be performed in sequence or simultaneously.

[0061] Step S300, pouring: injecting metal liquid into a mold to form a casting.

[0062] Wherein, the pouring step comprises the following steps: Step S301, vacuum adsorption: placing the finished mold on a centrifugal casting machine, evacuating the mold and maintaining the vacuum degree so that the cavity is in a negative pressure state.

[0063] By vacuuming, it is ensured that there is no air or bubbles in the cavity, avoiding the formation of pores or other defects due to the presence of gas during the pouring process. Vacuum adsorption can effectively enhance the fluidity and wettability of the metal stock in the cavity, ensuring that the metal stock can quickly and evenly fill every detail of the cavity, which is particularly suitable for the production of complex-shaped castings and thin-walled structures.

[0064] In some cases, the assembled sand core mold can be loaded into a protective barrel, and then the protective barrel is transported to the centrifugal casting machine for fixing. In some cases, the protective barrel can be fixed on the centrifugal casting machine first, and then the assembled mold can be placed in the protective barrel for fixing.

[0065] Step S302, centrifugal pouring: start the centrifugal pouring machine, and after the centrifugal pouring machine rotates to a preset speed, inject the metal stock in the pouring and holding furnace into the mold through the pouring system, so that the metal stock fully fills the mold cavity to form a casting.

[0066] Centrifugal force helps drive the metal to flow along the walls of the mold, allowing the metal to quickly and evenly fill the entire cavity. Due to the centrifugal force, the casting is usually more dense and the probability of pores and other defects is greatly reduced.

[0067] After the metal stock is injected into the mold, the centrifugal casting machine needs to keep rotating for a certain period of time before stopping. During the centrifugal casting process, the vacuum adsorption operation must also be continued to maintain the vacuum degree in the cavity so that the metal stock can fully fill the mold.

[0068] Step S303, pressurization: when the metal stock solution is injected into the mold through the pouring system, the pressurizing device provides pressurized gas to the pouring system.

[0069] The pressurized gas provided by the booster device can improve the fluidity and filling capacity of the metal stock, especially when casting complex molds or molds with narrow cavities. Air pressurization can help the metal stock better overcome the resistance of complex areas in the mold, ensure complete filling of the cavity, and achieve the molding of castings with high complexity or thin-walled structures.

[0070] It is understandable that during the pouring process, the vacuuming operation is performed on one side of the metal stock liquid (i.e., the side close to the inside of the cavity), and the pressurization operation is performed on the other side of the metal stock liquid (i.e., the side close to the outside of the mold). Therefore, pressurization and vacuum adsorption do not affect each other, and the pressurization operation will not damage the vacuum degree during the pouring process.

[0071] By combining vacuum adsorption with centrifugal pouring, the metal stock liquid has higher fluidity and stronger filling capacity during the pouring process, and can fill well even in a narrow cavity to form a thin-walled structure. For large or complex cavity castings, it can also ensure fast filling, improve the quality of the castings and improve production efficiency.

[0072] During the pouring process, process conditions such as the vacuum degree of the mold cavity, the rotation speed of the centrifugal pouring machine, and the rotation time can be flexibly set according to the production needs of different castings and the actual situation during production. In some embodiments, in the vacuum adsorption step, the vacuum degree of the mold cavity is 30-500mbar. In the centrifugal pouring step, the preset rotation speed of the centrifugal pouring machine is 50-200rpm.

[0073] It is worth noting that in the present application, the raw material preparation step and the pouring step are carried out separately. Compared with smelting and pouring at the same time, the casting production method of the present application can better control the temperature of the metal stock solution, avoid affecting the final casting quality due to temperature fluctuations during the pouring process, and improve the stability of the pouring quality. Secondly, the alloying elements can also be fully and evenly mixed during the raw material preparation process to ensure that the alloy composition of the metal stock solution meets the design requirements, especially for high-precision, high-quality castings, and improve the quality of the castings. In addition, the raw material preparation step is carried out separately from the pouring step, and the time, temperature and other parameters of metal smelting and pouring can be adjusted according to actual needs to improve the flexibility of production. This method allows each link in the production process to be independently regulated, thereby improving the quality of castings and the stability of production.

[0074] Step S400, post-processing: processing the casting formed by pouring.

[0075] Specifically, the post-processing step includes the following steps: Step S401, air cooling: cooling the casting while being wrapped by the sand core.

[0076] Air cooling is usually carried out in a natural environment. The casting is cooled under the wrapping of the sand core, which can evenly dissipate heat. The sand core itself has a certain thermal isolation effect, which can help the casting to cool evenly and avoid defects such as casting deformation or thermal cracks caused by excessive cooling speed.

[0077] Step S402, sand cleaning: after the casting is cooled to a certain temperature, the mold is separated from the retaining barrel, and then the sand core is separated from the casting, and the casting is taken out.

[0078] Sand cleaning can be achieved by a variety of methods, such as vibration sand cleaning, mechanical stripping, airflow cleaning, etc. Sand cleaning can remove sand particles, residual sand cores and other debris on the surface and inside of the casting to obtain the casting and ensure that the surface of the casting is smooth and flawless.

[0079] Step S403, recycling of old sand: treating and regenerating the old sand separated from the casting to make sand material, which is reused in the molding step.

[0080] Recycling old sand can not only reduce production costs, but also realize the recycling of resources and reduce environmental pollution. By returning the old sand to the furnace for roasting, reusable core sand can be obtained, which not only meets environmental protection requirements but also improves economic benefits.

[0081] Furthermore, after the post-processing step, the casting production method further includes a processing step S500. In the processing step, the separated castings are subjected to rough polishing, sawing of pouring and riser, grinding of pouring and riser residues and burrs, fine polishing, etc., and the finished castings after the above processes are boxed into a semi-finished product warehouse.

[0082] Specifically, the processing step includes the following steps: S501, Machining and assembly: Process the castings through machines and assemble the parts.

[0083] Machining methods include CNC machining, laser cutting, etc., which can be used to process the reference holes (such as positioning holes, threaded holes, etc.) and mounting surfaces of parts. Through mechanical processing, the excess material on the surface of the casting is removed so that the casting can accurately meet the design size and tolerance requirements. After that, the processing residue is purged and the parts are assembled, and different parts (such as wire thread sleeves, projection welding nuts, etc.) are assembled into a complete component or system according to the set method.

[0084] S502, cleaning: remove the machining residues and surface oxides of the casting.

[0085] The cleaning steps include ultrasonic alkaline cleaning and cleaning, pickling and cleaning. The present application combines ultrasonic cleaning and alkaline cleaning, uses ultrasonic cleaning equipment, immerses the casting in a solution containing an alkaline cleaning agent, and uses the high-frequency vibration of ultrasound to clean off the processing residues. Cleaning is performed after ultrasonic alkaline cleaning. During pickling, an acidic solution (such as sulfuric acid or hydrochloric acid) is usually used to remove oxides on the surface of the casting. The casting after pickling needs to be further rinsed with clean water to avoid acid residue.

[0086] The cleaning step ensures that the casting surface is clean and free of residual impurities that could affect subsequent plating or passivation treatments, or affect the performance of the assembled component.

[0087] S503, coating: forming a coating on the surface of the casting.

[0088] In the actual production process, different coatings can be applied to the surface of the casting according to different needs.

[0089] Taking hot-dip galvanizing as an example, the casting is first preheated to 150~200℃, and then slowly immersed in a molten zinc bath. The temperature of the zinc bath is usually maintained at around 450~460℃. At this temperature, zinc will react with the surface of the casting to form a coating to improve the corrosion resistance and hardness of the casting.

[0090] S504, passivation: forming an oxide film on the surface of the casting to obtain a finished casting.

[0091] The passivation process usually involves immersing the casting in a passivation solution that contains an oxidant that can promote oxidation reactions on the casting surface and form an oxide film on the casting surface. The oxide film formed by passivation can protect the casting surface from corrosion, extend its service life, and improve its surface wear resistance and oxidation resistance. The oxide film is usually transparent and not easy to fall off.

[0092] The processing steps of this application integrate the traditional machining assembly process section and the surface treatment process section, connect them into a whole line, and merge them into one process flow. At the same time, the workstations are merged, which greatly reduces the process flow, reduces intermediate logistics transfer, site occupation, etc., and improves production efficiency.

[0093] Further, after the machining step, the processing step further includes the following steps: S505, recycling of old metals: processing the old metals separated from the castings in the machining and assembly steps to make metal raw materials, which are put into the raw material preparation step for reuse.

[0094] During the machining and assembly process, some castings may produce waste, debris or unused metal parts. These waste metal materials can be recycled and processed into metal raw materials, which can be put back into the production process of raw material preparation to achieve the recycling of resources.

[0095] The present application also provides a casting, which is made by the production method as described above.

[0096] like Figure 4 As shown, the main body of the casting is a thin-walled structure 60, and the casting forms a closed thin-walled cavity 30. The wall thickness of the thin-walled structure 60 is 0.8-2.5 mm.

[0097] Figure 7 The front floor 70 of the vehicle is formed in one piece, and the main body of the front floor 70 is a thin-walled structure 60. The front floor 70 includes a central channel 71 extending along the length direction of the vehicle body, a pair of sill beams 72, and a seat cross beam 73 extending along the width direction of the vehicle body. The central channel 71 intersects with the seat cross beam 73, and the top wall structure of the central channel 71 and the seat cross beam 73 at the intersection is the same. The central channel 71, the pair of sill beams 72, and the seat cross beam 73 are all formed with a thin-walled cavity 30 structure.

[0098] like Figure 8 As shown, the central channel 71 includes a channel outer wall 711 and a channel inner wall 712. Both sides of the channel outer wall 711 are connected to the front floor panel 74, and the channel outer wall 711 and the front floor panel 74 together form a closed thin-walled cavity 30. The channel inner wall 712 extends from one side of the channel outer wall 711 into the thin-walled cavity 30 and is connected to the other side of the channel outer wall 711.

[0099] Figure 8In the illustrated embodiment, a channel inner wall 712 divides the thin-walled cavity 30 into three closed sub-cavities, namely the first sub-cavity 31, the second sub-cavity 32 and the third sub-cavity 33. The arrangement of the channel inner wall 712 enables the central channel 71 to form a double-layer structure, wherein the first sub-cavity 31 and the second sub-cavity 32 are located in the upper layer of the central channel 71, and the third sub-cavity 33 is located in the lower layer of the central channel 71. The first sub-cavity 31 and the second sub-cavity 32 are spaced a certain distance apart, and the middle portion of the channel outer wall 711 is recessed downward, connecting the first sub-cavity 31 and the second sub-cavity 32.

[0100] By using vacuum adsorption and centrifugal pouring to improve the filling conditions, and using sand cores as molds to provide complex and diverse cavity designs, the casting production method of the present application can not only produce Figure 4 The simple casting structure shown can also produce Figure 6 , Figure 7 and Figure 8 The complex casting structure shown. And the minimum wall thickness of the casting can reach 0.8mm. The casting production method of the present application can be integrally molded into various thin-walled castings, which improves the quality of the castings and greatly simplifies and shortens the manufacturing cycle.

[0101] The production method and castings of the present application enhance the fluidity of the metal stock by using vacuum adsorption during the production process, so that the flow of the metal stock in the cavity is more sufficient; by using centrifugal pouring, the filling of the metal stock in the cavity is made more uniform and compact, which is beneficial to improving the strength of the casting. When producing complex castings with thin-walled structures, the combination of vacuum adsorption and centrifugal pouring is beneficial to the molding of the complex casting structure, ensuring that the metal liquid is evenly filled in the thin wall, while reducing the porosity or cold shut problems caused by the uneven flow of the metal stock, thereby improving the quality of the casting. In addition, the production method of the casting of the present application realizes the one-piece molding of the casting through vacuum centrifugal pouring, improves production efficiency, and meets the requirements of lightweight design.

[0102] It should be noted that the technical solutions or technical features described in the above embodiments can be combined or supplemented with each other without causing conflicts. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the drawings; all modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A method for producing a casting, characterized in that: The following steps are involved: Mould making: making a mould, forming a cavity inside the mould, the shape of the cavity is consistent with the shape of the casting to be produced; Raw material preparation: smelting metal liquid; Pouring: injecting metal liquid into the mold to form a casting; Post-processing: Processing of castings formed by pouring; Wherein, the pouring step comprises the following steps: Vacuum adsorption: Place the finished mold on the centrifugal casting machine, evacuate the mold and maintain the vacuum degree so that the cavity is in a negative pressure state; Centrifugal pouring: Start the centrifugal pouring machine. After the centrifugal pouring machine rotates to the preset speed, the smelted metal liquid is injected into the mold through the pouring system so that the metal liquid fully fills the mold cavity to form a casting.

2. The method for producing a casting according to claim 1, characterized in that: The pouring step also includes a pressurization step: When the metal concentrate is injected into the mold through the pouring system, pressurized gas is provided to the pouring system through the pressurizing device.

3. The method for producing a casting according to claim 1, characterized in that: In the vacuum adsorption step, the vacuum degree of the cavity is 30-500 mbar; In the centrifugal casting step, the preset rotation speed of the centrifugal casting machine is 50-200 rpm.

4. The method for producing a casting according to claim 1, characterized in that: The mold is composed of a plurality of sand cores, and the internal chambers of the plurality of sand cores and the gaps between different sand cores together form the mold cavity; The molding step includes a core making step: The sand, resin and catalyst are mixed according to the set ratio, and the mixed sand is made into sand cores using a core making machine.

5. The method for producing a casting according to claim 4, characterized in that: After the core making step, the molding step further comprises an assembling step: The plurality of sand cores are placed in an assembly device, the plurality of sand cores are positioned by a positioning device of the assembly device, and the positions of the plurality of sand cores are fixed by a locking device of the assembly device to form a mold.

6. The method for producing a casting according to claim 5, characterized in that: The molding step further includes a barrel filling step: placing the entire mold into a protective barrel and fixing and sealing the protective barrel; and / or, The post-processing step comprises the following steps: Air cooling: Cool the casting under the wrapping of sand core; Sand cleaning: After the casting has cooled to a certain temperature, separate the mold from the retaining barrel, then separate the sand core from the casting and take out the casting.

7. The method for producing a casting according to claim 6, characterized in that: After the sand cleaning step, the post-processing step further includes a used sand recovery step: the used sand separated from the casting is processed and regenerated to form sand material, which is reused in the molding step.

8. The method for producing a casting according to claim 1, characterized in that: After the post-processing step, the method for producing the casting further comprises a processing step, wherein the processing step comprises the following steps: Machining and assembly: Process the castings through machines and assemble the parts; Cleaning: Remove machining residues and surface oxides from castings.

9. The method for producing a casting according to claim 8, characterized in that: The cleaning steps include ultrasonic alkali cleaning and cleaning, acid cleaning and cleaning.

10. The method for producing a casting according to claim 8, characterized in that: After the machining assembly step, the processing step also includes a waste metal recovery step: The old metal separated from the casting in the machining assembly step is processed to be made into metal raw material, which is put into the raw material preparation step for reuse.

11. The method for producing a casting according to claim 8, characterized in that: After the post-processing step, the processing step further comprises the following steps: Plating: forming a coating on the surface of the casting; Passivation: An oxide film is formed on the surface of the casting to obtain the finished casting.

12. The method for producing a casting according to claim 1, characterized in that: In the raw material preparation step, the metal raw material is placed in a melting furnace to be smelted into a metal stock solution, and the metal stock solution is transferred to a pouring and holding furnace in the form of a ladle.

13. The method for producing a casting according to claim 12, characterized in that: The metal raw material is steel; In the raw material preparation step, alloy elements also need to be added to the metal stock solution.

14. The method for producing a casting according to claim 1, characterized in that: The components and weight percentage contents of the metal stock solution are: C: 0.9-1.5%; Mn: 11-15%; Si: 0.3-0.8%; Re: 0.05-0.3%; S: <0.04%; P: <0.07%.

15. A casting, characterized in that: The casting is made by the production method of the casting as described in any one of claims 1 to 14.

16. The casting according to claim 15, characterized in that The main body of the casting is a thin-wall structure, and the casting forms a closed thin-wall cavity.

17. The casting according to claim 16, characterized in that The wall thickness of the thin-walled structure is 0.8-2.5 mm.

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