Casting process for high-wear-resistance vermicular graphite cast iron one-way stable diverter valve body casting

Abstract

The invention discloses a casting process for a high-wear-resistance vermicular graphite cast iron one-way stable diverter valve body casting, and relates to the technical field of casting. An upper mold box and a lower mold box are manufactured, and meanwhile a core mold used for forming a fluid channel of the valve body casting is manufactured; the core mold is installed at the preset position of a shell of the lower molding box, the upper molding box and the lower molding box are fixed together, and a molding cavity is defined between the upper molding box and the lower molding box; molten metal is cast into the cavity, after cooling forming, the core mold generates elastic shrinkage deformation, and then the core mold is detached from the lower mold box; and the upper molding box is detached to be separated from the lower molding box, then the casting is taken out, and the pouring gate is treated. According to the invention, the core mold capable of elastically shrinking is arranged, so that the surface of the core mold is not contacted with the inner wall of the fluid channel of the casting through the elastic shrinkage of the core mold after the casting is cooled and formed, and the casting can be quickly demolded during demolding, so that the production takt is improved.

Description

Technical Field

[0001] The present invention relates to the field of casting technology, and particularly to a casting process for a high-wear-resistant vermicular graphite cast iron single-way stable flow splitting valve body casting. Background Art

[0002] Castings are metal formed objects obtained by various casting methods, that is, the smelted liquid metal is injected into a pre-prepared mold by pouring, injection, suction or other casting methods. After cooling, through subsequent processing means such as grinding, the obtained objects have a certain shape, size and performance. There are various classification methods for castings: according to the different metal materials used, they are divided into steel castings, iron castings, copper castings, aluminum castings, magnesium castings, zinc castings, titanium castings, etc., and each type of casting can be further divided into different types according to its chemical composition or metallographic structure. For example, iron castings can be divided into gray iron castings, ductile iron castings, vermicular graphite iron castings, malleable iron castings, alloy iron castings, etc.; according to the different mold forming methods, castings can be divided into ordinary sand mold castings, metal mold castings, die castings, centrifugal castings, continuous casting parts, investment castings, ceramic mold castings, electroslag remelting castings, bimetallic castings, etc. Among them, ordinary sand mold castings are the most widely used, accounting for about 80% of the total output of all castings, and non-ferrous metal castings such as aluminum, magnesium, and zinc are mostly die castings.

[0003] A single-way stable flow splitting valve (abbreviated as single-stable valve) is an important flow control valve, mainly used in hydraulic systems, especially in the steering systems of mobile vehicles and multi-way systems of motors requiring stable rotational speeds. Definition: A single-way stable flow splitting valve is a flow control valve that divides the oil supplied by the pump into two paths and ensures that the output flow of one path is basically constant under various working conditions. Function: Ensure that when the vehicle driving speed changes, the normal operation of the steering system is not affected by the change of the pump oil supply or the change of the working load of the two-way actuating components. It can also be used in multi-way systems of motors requiring stable rotational speeds to provide a stable flow output.

[0004] As Figure 5 shown, the basic structure of the flow splitting valve at least includes a valve body 200 and a fluid passage 300 opened on the valve body 200. In the prior art, when casting a single-way stable flow splitting valve casting, for the casting link of the fluid passage of the flow splitting valve, a core mold needs to be used; during the casting process, the shape and size of the core mold determine the final shape of the fluid passage, so that the required fluid passage 300 is formed on the valve body 200; after casting, the core mold needs to be withdrawn from the valve body. However, in actual operation, due to the overly tight contact between the core mold and the inner wall of the cast fluid passage 300, the demolding process is extremely difficult. This not only increases the operation difficulty and reduces the production efficiency, but also may cause damage to the casting due to forced demolding, affecting the quality and performance of the casting, and further affecting the normal use of the entire flow splitting valve, seriously restricting the production and development of the single-way stable flow splitting valve. Summary of the Invention

[0005] The purpose of the present invention is to provide a casting process for a single - path stable flow - dividing valve body casting made of high - wear - resistant vermicular graphite cast iron to solve the problems presented in the above - mentioned background technology.

[0006] To achieve the above - mentioned purpose, the present invention provides the following technical solutions: A casting process for a single - path stable flow - dividing valve body casting made of high - wear - resistant vermicular graphite cast iron, comprising: Determine the structural parameters of the valve body; Select a combined sand mold as the casting parting type, and manufacture the upper mold box and the lower mold box. At the same time, manufacture a core mold for forming the fluid passage of the valve body casting; Install the core mold at a predetermined position on the outer shell of the lower mold box, and dock the upper mold box and the lower mold box to fix the upper mold box and the lower mold box together, and form a cavity between the upper mold box and the lower mold box; Pour molten metal into the cavity. After cooling and forming, the core mold undergoes elastic shrinkage deformation, and then the core mold is disassembled from the lower mold box; Disassemble the upper mold box to separate it from the lower mold box, then take out the casting, and process the pouring gate.

[0007] Furthermore, a shell core is also provided between the upper mold box and the lower mold box.

[0008] Furthermore, the molten metal includes the following components by weight percentage: Carbon 3.5% - 3.8%, silicon 2.0% - 2.5%, manganese 0.5% - 0.8%, phosphorus ≤ 0.1%, sulfur ≤ 0.05%, ruthenium ≤ 0.002%.

[0009] Furthermore, the surface of the formed casting is polished and ground, and the interior of the casting is inspected for cracks.

[0010] Furthermore, after the casting is cooled and formed, the casting is heat - treated, and the heat - treatment methods include normalizing or tempering.

[0011] Furthermore, the normalizing temperature is controlled at 900°C to 950°C, and then rapidly cooled.

[0012] Furthermore, the tempering temperature is controlled at 900°C to 950°C, and then slowly cooled in the air.

[0013] Further, the core mold includes a main core mold and a flange portion coaxially and fixedly connected to one end of the main core mold. The flange portion is detachably connected to the outer wall of the lower mold box. A mounting hole in the form of a through hole is coaxially opened at the end of the main core mold. A sliding column is slidably engaged and mounted in the mounting hole. A tapered section and a column section are coaxially and fixedly connected to the end of the sliding column in sequence end to end. The outer diameter of the tapered section increases sequentially in the direction away from the sliding column. A tapered hole is coaxially opened at one end of the main core mold away from the sliding column. The tapered hole is used in cooperation with the tapered section. Two deformation grooves in the form of notches are opened on the periphery of the main core mold. Two compensation strip plates are fixedly connected to the end of the column section away from the tapered section. The compensation strip plates are matched with the deformation grooves.

[0014] Further, a cylinder is mounted on the outer wall of the flange portion. The cylinder rod of the cylinder is drivingly connected to the sliding column.

[0015] Further, a wedge block is fixedly connected to the inner wall of the tapered hole adjacent to the sliding column. A convex block is fixedly connected to the end of the compensation strip plate away from the column section. The convex block and the wedge block are used in cooperation.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the technical solution involved in the present invention, a core mold structure with elastic shrinkage characteristics is specially designed. During the casting process of the casting, the core mold is in an expanded state to accurately fill the internal space of the fluid channel of the casting, ensuring that the shape and size of the fluid channel of the casting meet the design requirements; After the casting is cooled and formed, the core mold undergoes elastic shrinkage deformation. As the core mold shrinks, its surface gradually disengages from the inner wall of the fluid channel of the casting, and no longer has a tightly fitting state; This elastic shrinkage characteristic plays a key role in the demolding process. In the traditional demolding process, due to the tight fit between the core mold and the inner wall of the fluid channel of the casting, a large external force is often required during demolding, and it is easy to cause damage to the surface of the casting or slow demolding speed; in the present invention, since there is no contact between the core mold and the inner wall of the fluid channel of the casting, during demolding, only a small external force needs to be applied, and the casting can be quickly and smoothly removed from the mold. This not only greatly improves the demolding efficiency, reduces the demolding time, but also effectively avoids the damage that may occur to the casting during demolding, thereby significantly improving the rhythm of the entire production process and significantly increasing the production efficiency.

[0017] 2. In the present invention, after the casting is formed, a heat treatment process will be further carried out on it. Heat treatment is an important means to improve the performance of the casting, and its main purpose is to eliminate the internal stress generated during the casting process; During the casting process, due to the uneven cooling shrinkage of the molten metal, various internal stresses will be generated inside the casting, such as thermal stress, phase transformation stress, etc. If these internal stresses are not eliminated in time, a series of problems will occur during the subsequent use of the casting, such as casting deformation, cracking, etc., seriously affecting the quality and service life of the casting; By performing heat treatment on the casting, such as using normalizing, tempering and other processes, the internal tissue structure of the casting can be transformed, releasing and eliminating internal stresses. At the same time, heat treatment can also refine the grains of the casting, improve the mechanical properties such as strength, hardness and toughness of the casting, reduce the possibility of crack generation, thereby ensuring that the quality and performance of the casting meet the design requirements and improving the reliability and stability of the casting.

[0018] 3. In the present invention, the main core mold is a mold for forming the fluid channel of the valve body. Its forming and function realization rely on a set of delicate mechanical structures. Specifically, the movement of the entire structure is driven by the contraction of the cylinder rod of the cylinder; When the cylinder rod contracts, it will drive the sliding column connected to it to move. During the movement of the sliding column, the conical section on it will slide along a specific conical hole. Due to the shape matching of the conical hole and the conical section, as the sliding column moves, the conical section will gradually expand the main core mold; At the same time, the compensation strip on the main core mold will also be deformed under the expansion action of the conical section and snap into the pre-designed deformation groove. This design enables the periphery of the main core mold to maintain a relatively smooth and complete state during the expansion process, avoiding casting defects caused by incomplete structure; Finally, through such mechanical movement and structural deformation, the main core mold can accurately form the shape of the fluid channel of the valve body, and its smooth and complete periphery can ensure the inner wall quality of the fluid channel of the casting, enabling the casting to meet the performance requirements of fluid flow during subsequent use, thereby realizing the function of the main core mold as a mold for forming the fluid channel of the valve body. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the overall structure of the core mold in the embodiment of the present invention; Figure 2 is Figure 1 a schematic diagram of the positional relationship after partial structures in Figure 3 is Figure 2 an enlarged schematic diagram of the partial structure at A in Figure 4 is Figure 1 an exploded decomposition schematic diagram of the structure in Figure 5 is a schematic diagram of the overall structure of a single-way stable flow divider valve in the prior art.

[0020] In the figure, the descriptions of each reference numeral are as follows: 100, core mold; 101, cylinder; 102, flange part; 103, main core mold; 104, compensation strip; 105, end cover; 106, column section; 107, sliding column; 108, tapered section; 109, bump; 110, wedge; 111, deformation groove; 112, tapered hole; 200, valve body; 300, fluid passage. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Please refer to Figures 1-5 ; The present invention provides a technical solution: a casting process for a high-wear-resistant vermicular graphite cast iron single-way stable flow-dividing valve body casting, including the following steps: Step 1. Determine the structural parameters of the valve body. According to the design drawings of the valve body, determine the parameters such as the size, shape, and material of the casting. This step is the basis of the entire casting process to ensure that the casting meets the design requirements. Specifically, it is necessary to accurately determine a number of key parameters of the casting based on the design drawings of the valve body. In terms of size parameters, it is necessary to clarify the specific values of the length, width, and height of the valve body. For example, the length of the valve body may be 300 mm, the width may be 200 mm, and the height may be 150 mm. At the same time, it is also necessary to determine the detailed dimensions such as the diameter and thickness of each key part. For example, the inlet diameter of the valve body may be 50 mm, the outlet diameter may be 40 mm, and the wall thickness of some key parts may be 10 mm, etc. In terms of shape parameters, it is necessary to comprehensively grasp the overall shape of the valve body and the relative position relationship of each part. The valve body may include complex curved surfaces, inclined surfaces, chamfers, etc. geometric features. For example, there may be a curved surface transition with a radian of 30° in some parts, or a 45° inclined surface design, etc. The selection of material parameters needs to consider multiple factors. According to the material markings on the design drawings, combined with the use environment, performance requirements of the valve body, and the feasibility of the casting process, etc. If the valve body is applied in a high-temperature and high-pressure environment, stainless steel or alloy steel with excellent heat resistance, corrosion resistance, and high strength may be selected. If there are strict weight restrictions, lightweight materials such as aluminum alloy will be a suitable choice.

[0023] The above series of steps for determining the structural parameters of the valve body constitute the solid foundation of the entire casting process. Only by ensuring that the parameters such as the size, shape, and material of the casting are accurate can a solid and reliable basis be provided for subsequent mold design, casting process formulation, casting process control, and casting quality inspection, etc., so as to ensure that the finally cast valve body fully meets the design requirements.

[0024] Step 2: Select the combined sand mold as the casting parting type and fabricate the lower mold box. According to the overall structure of the casting and the requirements of subsequent casting processes, accurately design the dimensions, shape, and internal structure of the lower mold box. During fabrication, select high-quality molding sand materials and, in accordance with the established process flow, perform precise molding through a molding machine to ensure that the dimensional accuracy and surface quality of the lower mold box meet the requirements, laying a solid foundation for the subsequent casting process; Design and fabricate the intermediate body core. Based on the structural characteristics and process requirements of the casting, use professional 3D design software to perform detailed 3D modeling of the intermediate body core, determine its shape, dimensions, and internal channel structure. During the fabrication process, adopt advanced core-making techniques, select suitable core-making materials, and fabricate a structurally stable and dimensionally accurate intermediate body core through precise core-making equipment; Then, fabricate the upper mold box according to the intermediate body core. The design of the upper mold box needs to perfectly match the lower mold box and the intermediate body core to ensure good sealing and positioning during mold closing. The fabrication process is similar to that of the lower mold box, and equal attention is paid to the control of dimensional accuracy and surface quality; After completing the above preparatory work, perform the assembly and positioning of the casting. Carefully place the prefabricated runner core into the predetermined position inside the lower mold box, ensuring that the position of the runner core is accurate and error-free to guarantee the smoothness of the runner during the subsequent casting process. Then, in accordance with the predetermined assembly sequence, assemble the intermediate body core in turn and place it steadily into the predetermined position inside the lower mold cavity; during the assembly process, use special positioning tools and jigs to ensure the position accuracy and stability of the intermediate body core; at the same time, in order to form the fluid channel 300 of the valve body 200 casting during the casting process, a core mold 100 is fabricated in this application. The design of the core mold 100 fully considers the shape, dimensions, and surface quality requirements of the fluid channel 300 and is fabricated using high-precision processing techniques. After the intermediate body core is assembled in place, place the core mold 100 accurately into the corresponding position to ensure that it can stably form the required fluid channel 300 during the casting process.

[0025] Step 3: When performing the casting forming operation, accurately install the carefully fabricated core mold 100 at the predetermined position on the outer shell of the lower mold box. Before installation, the operator will carefully check the marks on the outer shell of the lower mold box and the designed installation position of the core mold 100 to ensure that the two are perfectly matched. During the installation process, use special positioning tools such as positioning pins and positioning blocks to slowly and steadily place the core mold 100 into the predetermined position and firmly fix it with fasteners such as bolts and buckles to prevent displacement during the subsequent mold closing and casting processes.

[0026] After the installation of the core mold 100 is completed, the docking work of the upper mold box and the lower mold box begins. The operator will slowly lift the upper mold box according to the predetermined operation process to accurately align it with the lower mold box. During the docking process, by observing the alignment marks on the upper and lower mold boxes, such as engraved lines, marking points, etc., ensure that both are accurate in the horizontal and vertical directions. At the same time, use special guiding devices, such as guide columns, guide sleeves, etc., to guide the smooth descent of the upper mold box to avoid collisions or misalignments during the docking process.

[0027] After the upper mold box and the lower mold box are accurately docked, use a suitable fixing method to firmly fix the two together. Common fixing methods include using bolts and nuts for fastening, or using a hydraulic clamping device for clamping. During the fastening process, operate according to the predetermined torque value to ensure that the connection between the upper mold box and the lower mold box is firm and reliable, and there will be no loosening or separation during the casting process.

[0028] With the fixation of the upper mold box and the lower mold box, a cavity for casting the casting is formed between them. At this time, it is necessary to inspect the cavity to ensure that its dimensional accuracy, shape, and surface quality meet the design requirements. The inspection content includes whether the dimensions of the cavity are consistent with the design drawings, whether the surface of the cavity is flat and smooth, and whether there are defects such as cracks and pores. If any problems are found in the cavity, they need to be adjusted and repaired in time to ensure the smooth progress of the subsequent casting process.

[0029] Through the above series of rigorous and meticulous operations, the docking and fixation of the upper mold box and the lower mold box are completed, making full preparations for the forming of the casting.

[0030] Step 4: Pour the high wear-resistant vermicular graphite cast iron molten metal into the cavity. The molten metal includes the following components by weight percentage: Carbon 3.5% - 3.8%, silicon 2.0% - 2.5%, manganese 0.5% - 0.8%, phosphorus ≤ 0.1%, sulfur ≤ 0.05%, ruthenium ≤ 0.002%. The content of ruthenium is trace. By improving the composition of the molten metal, the obtained casting has good wear resistance. Vermicular graphite cast iron has good wear resistance and corrosion resistance. Under friction and wear conditions, vermicular graphite cast iron shows a low wear rate and is especially suitable for occasions with high wear resistance requirements. In addition, vermicular graphite cast iron with improved composition ratio shows good corrosion resistance in non-oxidizing acid and alkali environments. Especially due to the addition of ruthenium, its corrosion resistance at high temperatures is further enhanced.

[0031] After cooling and forming, elastic shrinkage deformation is generated by the core mold 100, and then the core mold 100 is disassembled from the lower mold box. Specifically, the core mold 100 includes a main core mold 103 and a flange portion 102 coaxially fixed to one end of the main core mold 103. The flange portion 102 is detachably connected to the outer wall of the lower mold box by screws. A mounting hole in the form of a through hole is coaxially opened at the end of the main core mold 103. A sliding column 107 is slidably engaged and installed in the mounting hole. A tapered section 108 and a column section 106 are coaxially fixed to the end of the sliding column 107 in sequence end to end. The outer diameter of the tapered section 108 increases sequentially in the direction away from the sliding column 107. A tapered hole 112 is coaxially opened at one end of the main core mold 103 away from the sliding column 107. The tapered hole 112 is used in cooperation with the tapered section 108. The outer diameter of the column section 106 is smaller than the maximum inner diameter of the tapered section 108 and larger than the minimum outer diameter of the tapered section 108, so that the column section 106 has a certain space for axial movement along the main core mold 103 in the tapered hole 112. Two deformation grooves 111 in the form of notches are opened on the periphery of the main core mold 103. Two compensation strip plates 104 are fixed to the end of the column section 106 away from the tapered section 108. One end of the compensation strip plate 104 in the length direction is fixed to the end of the column section 106, and when it is subjected to a squeezing force along the inner side of the radial direction of the column section 106, the compensation strip plate 104 matches the deformation groove 111. A cylinder 101 is installed on the outer wall of the flange portion 102. The cylinder rod of the cylinder 101 is drivingly connected to the sliding column 107. A wedge block 110 is fixed to the inner wall of the tapered hole 112 adjacent to the sliding column 107. A convex block 109 is fixed to the end of the compensation strip plate 104 away from the column section 106. The convex block 109 and the wedge block 110 are used in cooperation; During casting, the cylinder rod of the cylinder 101 is in a contracted state. Refer to Figure 2 , the sliding column 107 will move in the direction of the cylinder 101, and the tapered section 108 will slide in the tapered hole 112, and the tapered section 108 will generate a squeezing force on the inner wall of the tapered hole 112, so that the main core mold 103 is elastically expanded to Figure 1 state, that is, the diameter of the whole main core mold 103 is consistent. At the same time, the compensation strip plate 104 also moves in the direction of the cylinder 101, so that the inclined surfaces of the convex block 109 and the wedge block 110 generate relative sliding, and the compensation strip plate 104 generates elastic deformation toward the outer side of the radial direction of the main core mold 103, or in other words, the two compensation strip plates 104 will expand with the connection with the column section 106 as the axis, and the compensation strip plate 104 will be stuck into the deformation groove 111, thereby compensating the deformation groove 111, so that the periphery of the main core mold 103 is smooth and complete. In addition, an end cover 105 is coaxially fixed to the end of the column section 106 away from the tapered section 108, so that after the tapered section 108 moves in place in the direction of the cylinder 101, the end cover 105 can seal the maximum inner diameter end of the tapered hole 112; After the casting is formed and cooled, the valve body 200 is formed. The cylinder rod of the cylinder 101 extends, causing the tapered section 108 to move in the reverse direction. At this time, the convex block 109 and the wedge block 110 are disengaged from contact. The compensation strip 104 will restore its deformation by itself, that is, it will change from the original unfolded state to the folded state and retract into the tapered hole 112. The main core mold 103 also gradually restores its deformation, that is, the outer diameter of the main core mold 103 decreases successively in the direction adjacent to the cylinder 101, and the contact area between the periphery of the main core mold 103 and the inner wall of the casting fluid passage 300 is reduced. Then, the flange portion 102 is disassembled, and then the main core mold 103 is taken out of the lower mold box. Additionally, further, the width dimension of the compensation strip 104 can be set to decrease successively in the direction away from the tapered section 108, so that when the compensation strip 104 is in the deformed state, the influence on the deformation of the deformation groove 111 is small.

[0032] Step 5: Disassemble the upper mold box to separate it from the lower mold box, then take out the casting, and grind the casting gate. Grind and polish the surface of the formed casting, and detect cracks inside the casting. For example, X-rays or ultrasonic waves can be used for crack detection; the specific operation of this process is as follows: First, operate on the casting mold to safely disassemble the upper mold box from the overall mold structure, ensuring that the mold parts and the casting not yet taken out inside are not damaged during the disassembly process. During the disassembly process, professional tools such as suitable wrenches and crowbars need to be used, and the correct disassembly sequence and operation specifications should be followed to avoid mold deformation or casting damage caused by improper operation. After the upper mold box is completely separated from the lower mold box, carefully check the separation part to confirm that there are no residual connections or obstacles.

[0033] Subsequently, carefully take out the preliminarily formed casting from the lower mold box. When taking out the casting, appropriate taking-out tools and methods need to be selected according to the shape, size, and material characteristics of the casting. For some castings with complex shapes or large volumes, lifting equipment or special fixtures may be needed to ensure that the casting is not damaged during the taking-out process.

[0034] After the casting is taken out, grind the casting gate part. Since the casting gate will form excess metal protrusions or burrs during the casting process, these not only affect the appearance quality of the casting but may also affect subsequent processing and use. Therefore, grinding tools such as grinders and sandpapers need to be used to carefully grind the casting gate to make its surface flat and smooth, and naturally transition to the main body surface of the casting.

[0035] After finishing the grinding of the casting gate, the overall surface of the formed casting is ground and polished. The grinding process can be divided into three stages: rough grinding, medium grinding, and fine grinding. Different grit sandpapers or grinding wheels are used respectively to gradually remove the rough parts, oxide scales, and minor defects on the surface of the casting. During the grinding process, a uniform force and appropriate grinding direction need to be maintained to avoid grinding marks or over-grinding in local areas. After grinding, a polishing machine or polishing paste is used to polish the surface of the casting to make its surface meet certain smoothness requirements and present a good appearance effect.

[0036] Finally, crack detection is carried out on the inside of the casting. Cracks are one of the common defects in castings and can seriously affect the strength and service life of the casting. To ensure the quality of the casting, advanced detection techniques are required to conduct a comprehensive inspection of the inside of the casting. Among them, X-ray detection and ultrasonic detection are two commonly used crack detection methods. X-ray detection utilizes the penetrability of X-rays to clearly display the location, shape, and size of cracks, pores, and other defects inside the casting; ultrasonic detection, on the other hand, detects whether there are abnormal conditions such as cracks inside the casting through the propagation characteristics of ultrasonic waves in the casting. The inspectors need to select appropriate detection methods and parameters according to the specific situation of the casting to ensure the accuracy and reliability of the detection results. After the detection is completed, the detection results are recorded and analyzed in detail. For castings with defects such as cracks, timely repair or scrapping treatment is required to ensure the product quality.

[0037] Step 6: After the casting has completed the cooling and forming process, it is necessary to further perform heat treatment operations on it to optimize its internal organizational structure and thereby improve the comprehensive performance of the casting. The main heat treatment methods are normalizing and tempering, and different treatment methods are applicable to different performance requirements and casting material characteristics.

[0038] During the normalizing process, first, the casting needs to be accurately heated to a specific temperature range, that is, 900°C to 950°C. To ensure the accuracy of temperature control, a high-precision temperature measurement device, such as a thermocouple thermometer, is used to monitor the temperature change of the casting in real-time. When the temperature of the casting reaches the set range, it needs to be maintained at this temperature for sufficient and uniform heating to fully austenitize the internal structure of the casting. This process usually needs to last for a certain period of time, and the specific time depends on factors such as the thickness, shape, and material of the casting; After heating, the casting needs to be quickly cooled. The rapid cooling method can adopt water cooling or oil cooling, etc., and the specific choice depends on the material and performance requirements of the casting. For example, for some high-carbon steel castings, water cooling can more effectively obtain fine pearlite structure, thereby improving the hardness and strength of the casting. During the cooling process, the cooling rate and time need to be strictly controlled to avoid defects such as cracks in the casting caused by uneven cooling or too fast cooling speed.

[0039] The tempering process also requires heating the casting to a temperature range of 900°C to 950°C and maintaining it at this temperature for appropriate heat preservation to ensure that the internal structure of the casting is fully transformed. Different from the normalizing process, after the heating in the tempering process is completed, the casting needs to be placed in the air and allowed to cool slowly naturally; The slow cooling process helps to eliminate the internal stress generated during the previous processing of the casting (such as casting, heat treatment, etc.), reducing the risk of deformation or cracking of the casting during use. At the same time, the tempering process can also improve the cutting performance of the casting, making it easier to perform operations such as cutting and drilling during subsequent machining processes, and improving the machining efficiency and quality.

[0040] After completing the heat treatment process, to further improve the surface quality and performance of the casting, a series of surface treatment operations can be carried out on it.

[0041] Shot blasting treatment: Use high-speed jet sand grains to impact the surface of the casting to remove the scale, rust, impurities, etc. generated during the heat treatment process on the surface. Shot blasting treatment can not only effectively clean the surface of the casting, but also increase the surface roughness of the casting to a certain extent, improving the adhesion between the coating and the casting surface. When carrying out shot blasting treatment, it is necessary to select appropriate parameters such as the type of sand grains, particle size, and jet pressure according to the material and surface requirements of the casting to ensure the best treatment effect.

[0042] Coating an anti-corrosion coating: For the possible corrosion problems that the casting may face in a specific use environment, an anti-corrosion coating can be coated on the surface of the casting after shot blasting treatment. There are many types of anti-corrosion coatings, such as paint, epoxy resin coating, galvanized layer, etc. The specific selection needs to be comprehensively considered according to factors such as the use environment of the casting, corrosive medium, and corrosion resistance requirements. Coating an anti-corrosion coating can effectively prevent the corrosive medium from contacting the surface of the casting, extend the service life of the casting, and improve its corrosion resistance in a specific environment.

[0043] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A casting process for a high wear-resistant vermicular graphite cast iron single-way stable flow splitting valve body casting, characterized in that, Including: Determine the structural parameters of the valve body; Select a combined sand mold as the casting parting type, and fabricate the upper mold box and the lower mold box. Meanwhile, fabricate a core mold for forming the fluid passage of the valve body casting; Install the core mold at a predetermined position on the outer shell of the lower mold box, and butt the upper mold box and the lower mold box to fix the upper mold box and the lower mold box together. A cavity is formed between the upper mold box and the lower mold box; Pour molten metal into the cavity. After cooling and forming, the core mold undergoes elastic shrinkage deformation, and then the core mold is disassembled from the lower mold box; Disassemble the upper mold box to separate it from the lower mold box, then take out the casting, and process the casting gate.

2. The casting process of a single-way stable flow splitting valve body casting made of high wear-resistant vermicular graphite cast iron according to claim 1, characterized in that, A shell core is also provided between the upper mold box and the lower mold box.

3. The casting process of a single-way stable flow-dividing valve body casting made of high wear-resistant vermicular graphite cast iron according to claim 1, characterized in that, The molten metal includes the following components by weight percentage: Carbon 3.5% - 3.8%, silicon 2.0% - 2.5%, manganese 0.5% - 0.8%, phosphorus ≤ 0.1%, sulfur ≤ 0.05%, ruthenium ≤ 0.002%.

4. The casting process of a single-way stable flow-dividing valve body casting made of high wear-resistant vermicular graphite cast iron according to claim 1, characterized in that, Grind and polish the surface of the formed casting, and detect cracks inside the casting.

5. The casting process of a single-way stable flow-dividing valve body casting made of high wear-resistant vermicular graphite cast iron according to claim 1, characterized in that, After the casting is cooled and formed, the casting is heat-treated. The heat treatment methods include normalizing or tempering.

6. The casting process of a high wear-resistant vermicular graphite cast iron single-way stable flow splitting valve body casting according to claim 5, characterized in that, The normalizing temperature is controlled at 900°C to 950°C, and then it is rapidly cooled.

7. A casting process for a single-channel stable flow-dividing valve body casting made of high wear-resistant vermicular graphite cast iron according to claim 5, characterized in that, The tempering temperature is controlled at 900°C to 950°C, and then it is slowly cooled in the air.

8. A casting process for a high wear-resistant vermicular graphite cast iron single-way stable flow splitting valve body casting according to claim 1, characterized in that, The core mold includes a main core mold and a flange portion coaxially and fixedly connected to one end of the main core mold. The flange portion is detachably connected to the outer wall of the lower mold box. A through-hole-shaped mounting hole is coaxially opened at the end of the main core mold. A sliding column is slidably engaged and installed in the mounting hole. The end of the sliding column is coaxially and fixedly connected with a conical section and a cylindrical section in sequence end to end. The outer diameter of the conical section increases sequentially in the direction away from the sliding column. A conical hole is coaxially opened at one end of the main core mold away from the sliding column. The conical hole is used in cooperation with the conical section. Two notch-shaped deformation grooves are opened on the periphery of the main core mold. Two compensation strip plates are fixedly connected to one end of the cylindrical section away from the conical section. The compensation strip plates match the deformation grooves.

9. The casting process of a single-way stable flow-dividing valve body casting made of high wear-resistant vermicular graphite cast iron according to claim 8, characterized in that, A cylinder is installed on the outer wall of the flange portion. The cylinder rod of the cylinder is drivingly connected to the sliding column.

10. A casting process for a single-channel stable flow-dividing valve body casting made of high wear-resistant vermicular graphite cast iron according to claim 8, characterized in that, A wedge block is fixedly connected to the inner wall of the conical hole adjacent to the sliding column. A convex block is fixedly connected to one end of the compensation strip plate away from the cylindrical section. The convex block and the wedge block are used in cooperation.

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