Casting method for engine cylinder block

Abstract

The invention discloses an engine cylinder block casting method. The engine cylinder block casting method comprises the following steps that sand core parts needed for forming a casting mold are prepared; wherein the sand core part comprises a bottom plate core, a cylinder barrel core, a front end core, a rear end core, a left side core, a right side core, a water jacket core, an oil duct core, a top cover core and a patch core; assembling the cylinder barrel core on the bottom plate core to obtain a combined core; wherein three positioning references which are triangularly arranged and are positioned on the same horizontal plane are arranged on the bottom plate core; coating and drying the combined core and other sand core parts; a cylinder sleeve is prepared, and shot blasting and preheating treatment are conducted on the cylinder sleeve; hoisting the dried combined core on a metal bottom plate, and sequentially assembling the sand core parts and the cylinder sleeve according to a preset assembling sequence to obtain a casting mold; preparing molten aluminum; molten aluminum is poured into the casting mold; the engine cylinder block manufacturing method has the advantages that the design precision of the casting mold is improved, and the forming quality of the cylinder block is improved.

Description

Technical Field

[0001] This application relates to the technical field of engine cylinder block casting, and particularly to a method for casting an engine cylinder block. Background Art

[0002] According to the structure of the engine cylinder block, a casting mold with a corresponding cavity structure needs to be designed for pouring and forming. Since there are many complex oil cavities and water cavities combined on the engine cylinder block casting, the production of the cylinder block casting is difficult, and the requirement for the design accuracy of the mold is relatively high. However, the existing engine cylinder block casting process has relatively low process accuracy in the preparation stage of the casting mold, resulting in an impact on the subsequent forming quality of the cylinder block. Summary of the Invention

[0003] The main purpose of this application is to provide a method for casting an engine cylinder block, aiming to solve the technical problem of relatively low process accuracy in the preparation stage of the existing engine cylinder block casting process.

[0004] To achieve the above purpose, this application provides a method for casting an engine cylinder block, including the following steps:

[0005] Prepare each core part required to form the casting mold; wherein, the core parts include a bottom plate core, a cylinder core, a front end core, a rear end core, a left side core, a right side core, a water jacket core, an oil passage core, a top cover core, and a repair core;

[0006] Assemble the cylinder core on the bottom plate core to obtain a combined core; wherein, three positioning references arranged in a triangle and located on the same horizontal plane are provided on the bottom plate core;

[0007] Apply coating and drying to the combined core and the remaining core parts;

[0008] Prepare the cylinder liner and perform shot peening and preheating treatment on the cylinder liner;

[0009] Lift the dried combined core onto the metal bottom plate, and sequentially assemble each core part and the cylinder liner according to a preset assembly sequence to manufacture the casting mold; wherein, the cylinder liner is sleeved on the cylinder core;

[0010] Prepare molten aluminum;

[0011] Pour the molten aluminum into the casting mold;

[0012] Perform post-treatment on the casting mold to manufacture the engine cylinder block.

[0013] Optionally, assembling the cylinder core on the bottom plate core to obtain a combined core includes:

[0014] Select multiple cylinder cores and pre-tighten them on the core assembly tool to manufacture an integral cylinder core; wherein, the integral cylinder core has two groups of cylinder groups arranged symmetrically in a V shape;

[0015] A detection template is sleeved on two groups of cylinder barrels; wherein, the detection template is used to detect the top cylinder center distance, the bottom cylinder center distance and the height difference of the two groups of cylinder barrels;

[0016] The integral cylinder barrel core with the detection template is hoisted onto the bottom plate core and assembled to obtain a combined core.

[0017] Optionally, prepare a cylinder liner and perform shot peening and preheating treatments on the cylinder liner, including:

[0018] Prepare a cylinder liner and perform shot peening on the surface of the cylinder liner. The diameter of the steel shot is 0.3 - 0.5 mm, and the shot peening time is 10 - 15 minutes;

[0019] Then perform preheating treatment on the cylinder liner. The preheating temperature is 500 - 600 °C, and the time from the cylinder liner being taken out of the preheating furnace to pouring is controlled within 3 - 5 minutes.

[0020] Optionally, prepare molten aluminum, including:

[0021] Select an appropriate amount of aluminum ingot raw materials for melting to obtain molten aluminum;

[0022] Transfer the molten aluminum to a holding furnace;

[0023] Take a sample of the molten aluminum for analysis to obtain the magnesium content in the composition of the molten aluminum;

[0024] If the magnesium content is lower than the preset standard content, add magnesium blocks to the molten aluminum; wherein, the addition amount of magnesium blocks = (0.4% - magnesium content) × weight of the molten aluminum, and the standard content is 0.35 - 0.45%;

[0025] When the magnesium content reaches the standard content, add a grain refiner, a slagging agent and a modifier to the molten aluminum in sequence;

[0026] Start a degasser to refine and degas the molten aluminum and add a refining agent of 0.2% ± 0.02;

[0027] Then perform slagging treatment on the molten aluminum, and add a covering agent of 0.1% - 0.15% to finally obtain qualified molten aluminum.

[0028] Optionally, the modifier is potassium fluozirconate, and the potassium fluozirconate is 0.18 - 0.3% of the total amount of the molten aluminum.

[0029] Optionally, the parameters for refining and degassing are: argon gas flow rate 1.2 - 2.2 m 3 / h; degassing temperature 730 - 740 °C; initial rotational speed of the graphite rotor 1000 - 1200 rpm, lasting for 1 - 2 min; stable rotational speed of the graphite rotor 400 - 500 rpm; degassing time 20 - 25 min.

[0030] Optionally, pour the molten aluminum into a casting mold, including:

[0031] Grasp the metal base plate by a manipulator to grasp the entire casting mold to a pouring machine;

[0032] Cooperate the casting mold with a clamping sleeve box on the pouring machine to pour molten aluminum into the casting mold.

[0033] Optionally, the pouring parameters of the pouring machine are as follows: the first-stage pouring pressure is 110 mbar, the time is 6 s; the second-stage pouring pressure is 200 mbar, the time is 4 s; the third-stage pouring pressure is 250 mbar, the time is 2 s; the fourth-stage pouring pressure is 350 mbar, the time is 3 s; the fifth-stage pouring pressure is 580 mbar, the time is 4 s; the pressure holding time is 600 s; the suspension pressure is 65 mbar, and the suspension holding time is 600 s.

[0034] Optionally, post-treat the casting mold to obtain an engine cylinder block, including:

[0035] Cool the casting mold, perform shakeout and percussion treatment in sequence to obtain a cylinder block blank;

[0036] Saw cut, heat treat, perform material inspection, mill the surface, rough clean, perform dimensional inspection, sandblast, shot blast, finish clean and perform appearance inspection on the cylinder block blank in sequence, and finally obtain an engine cylinder block.

[0037] Optionally, the process parameters of the heat treatment are as follows: the solution furnace loading temperature ≤ 300 °C, the aging furnace loading temperature ≤ 100 °C, the heating rate ≤ 100 °C / h, and the number of solution treatments for a single casting does not exceed 3 times.

[0038] The beneficial effects that can be achieved by this application are as follows:

[0039] In this application, the cylinder core and the bottom plate core are first assembled into a combined core as a whole, and then enter the subsequent coating and drying processes, which can reduce the number of core assembly times of separately coating and drying each core part and then assembling them, thereby reducing the precision error. There are three positioning references arranged in a triangle and located on the same horizontal plane on the bottom plate core, which can determine a positioning plane, so as to accurately position the bottom surface of the cylinder block blank to be formed, facilitate positioning the height direction of the cylinder block blank, and the cylinder core can facilitate positioning the length and width directions of the cylinder block blank. Compared with the existing cylinder block blank where the X, Y, and Z direction references are all located on the top surface of the cylinder block, the positioning accuracy is higher, the consistency of blank casting is good, and the blank quality is improved. Then, assemble each core part and cylinder liner in sequence according to the preset assembly order to obtain a high-precision casting mold. Subsequently, prepare molten aluminum and pour it, and perform post-treatment on the casting mold, and finally an engine cylinder block can be obtained. Therefore, based on the optimization of the core assembly order and the optimized design of the positioning reference structure, this application can greatly improve the process precision and product quality. Brief Description of the Drawings

[0040] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0041] Figure 1 It is a schematic flow chart of a method for casting an engine cylinder block in an embodiment of the present application;

[0042] Figure 2 It is a schematic flow chart during the prefabrication of a prefabricated combined core in an embodiment of the present application;

[0043] Figure 3 It is a schematic flow chart when assembling each core part and cylinder liner in sequence according to a preset assembly sequence to obtain a casting mold in an embodiment of the present application;

[0044] Figure 4 It is a schematic structural diagram of a compression sleeve box in an embodiment of the present application.

[0045] Reference Numerals:

[0046] 110 - cylinder core, 120 - bottom plate core, 130 - metal bottom plate, 140 - front end core, 150 - cylinder liner, 160 - left side core, 170 - oil passage core, 180 - rear end core, 190 - top cover core, 210 - water jacket core, 220 - right side core, 230 - patch core, 240 - inspection template, 250 - core assembly tooling, 260 - compression sleeve box.

[0047] The realization of the objectives, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0049] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0050] In this application, unless otherwise clearly specified and defined, terms such as "connection" and "fixation" shall be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of this application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes Scenario A, or Scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0052] Embodiment

[0053] Referring to Figures 1 - 4 , this embodiment provides a method for casting an engine cylinder block, including the following steps:

[0054] Prepare each core part required to form the casting mold; among them, the core parts include a bottom plate core 120, a cylinder core 110, a front end core 140, a rear end core 180, a left side core 160, a right side core 220, a water jacket core 210, an oil passage core 170, a top cover core 190, and a repair core 230;

[0055] Assemble the cylinder core 110 on the bottom plate core 120 to obtain a combined core; among them, three positioning references arranged in a triangle and located on the same horizontal plane are provided on the bottom plate core 120;

[0056] Apply coating and drying to the combined core and the remaining core parts;

[0057] Prepare the cylinder liner 150 and perform shot peening and preheating treatments on the cylinder liner 150;

[0058] Lift the dried combined core onto the metal bottom plate 130 and sequentially assemble each core part and the cylinder liner 150 according to a preset assembly sequence to manufacture the casting mold; among them, the cylinder liner 150 is sleeved on the cylinder core 110;

[0059] Prepare molten aluminum;

[0060] Pour the molten aluminum into a casting mold;

[0061] Perform post-treatment on the casting mold to obtain an engine cylinder block.

[0062] In this embodiment, first, the cylinder barrel core 110 and the bottom plate core 120 are integrally assembled to form a combined core, and then the subsequent coating and drying processes are carried out. This can reduce the number of assembly times of each sand core part when it is individually coated, dried, and then assembled, thereby reducing the precision error. Moreover, three positioning references arranged in a triangle and located on the same horizontal plane are provided on the bottom plate core 120, which can determine a positioning plane, thereby accurately positioning the bottom surface of the cylinder block blank to be formed, facilitating the positioning of the height direction of the cylinder block blank. The cylinder barrel core 110 can facilitate the positioning of the length and width directions of the cylinder block blank. Compared with the existing cylinder block blank where the X, Y, and Z direction references are all located on the top surface of the cylinder block, the positioning accuracy is higher, the consistency of the blank casting is good, and the quality of the blank is improved. Then, each sand core part and the cylinder liner 150 are assembled in sequence according to the preset assembly order to obtain a high-precision casting mold. Subsequently, molten aluminum is prepared and poured, and post-treatment is performed on the casting mold. Finally, the engine cylinder block can be obtained. Therefore, based on the optimization of the core assembly order and the optimized design of the positioning reference structure in this embodiment, the process precision can be significantly improved, and the product quality can be enhanced.

[0063] Specifically, the preparation process conditions of the front-end core 140, the rear-end core 180, the left-side core 160, and the right-side core 220 are as follows:

[0064] (1) Equipment used: Sanxin RLA + 65 cold box core shooter.

[0065] (2) The operator should be familiar with the equipment operation steps and the PC operation steps before core shooting operation, operate according to the equipment safety operation regulations, and pay attention to safety during the operation.

[0066] (3) Before starting work, the mold should be inspected and cleaned. It can start molding production only when it is qualified; sharp metal objects such as files shall not be used for cleaning, and sharp wooden pieces or bamboo pieces must be used for cleaning.

[0067] (4) Quality requirements

[0068] The sand core should be compact and flat; there should be no defects or looseness; there should be no obvious core misalignment, and the core misalignment ≤ 0.2 mm;

[0069] For the exhaust plug and ejector rod parts of the sand core: the protrusion in the cavity part ≤ 0.2 mm; the depression ≤ 0.5 mm; the depression in the core head part ≤ 2 mm, and there should be no protrusion; the outer shape and mating surface ≤ 2 mm, and there should be no protrusion;

[0070] Core repair: For the parts with complete shape but loose surface in the cavity part, use repair paste for repair. Discard the cores with incomplete shape, and no repair is required for the remaining parts.

[0071] Chills are not allowed to be misplaced or omitted.

[0072] (5) Process requirements

[0073] Use a continuous sand mixer to automatically mix new sand or recycled sand of 50 / 100 mesh. The ratio of resin II to component I is 11:9, and the addition ratio of two-component resin (by weight of sand) is 1.6 ± 0.1%;

[0074] Core-making parameters:

[0075]

[0076] The mold can be replenished with mold release agent after every 10 ± 3 parts are produced;

[0077] After the core is shot, check whether the core is qualified, and use repair paste to repair the parts that are not shot tightly;

[0078] Check and clean the mold every 10 parts produced: ① Resin clusters adhering to the mold surface corresponding to the nozzle; ② Whether the exhaust plugs are blocked, complete, and flush with the cavity; ③ Whether there are broken or piled-up cores in the cavity (if so, it is necessary to recheck whether the cores shot in the previous stage are complete), etc.;

[0079] The cores should be placed with the shooting surface facing down. One mold shot at a time is taken as a group. Foam sponges etc. should be padded between the cores to prevent damage, and stacking is prohibited.

[0080] Specifically, the preparation process conditions of the bottom plate core 120 and the top cover core 190 are as follows:

[0081] (1) Equipment used: Sanxin RLA + 40 cold box core shooter.

[0082] (2) The operator should be familiar with the equipment operation steps and the PC operation steps before the core shooting operation, operate in accordance with the equipment safety operation regulations, and pay attention to safety during the operation.

[0083] (3) The mold should be checked and cleaned before work, and production can start only when it is qualified; do not use sharp metal objects such as files for cleaning, and use sharp wooden pieces or bamboo pieces for cleaning.

[0084] (4) Quality requirements

[0085] The shape of the core cavity part is complete, the core is compact, flat, without defects or looseness; for the parts with complete shape but loose surface, use repair paste for repair, and discard the cores with incomplete shape;

[0086] Local non-full shooting is allowed on the back of the sand mold, but there should be no through holes;

[0087] Core exhaust plug and ejector rod parts: For the cavity part, the protrusion ≤ 0.2 mm and the depression ≤ 0.5 mm; for the core head and mating surface, only a depression of 0.2 - 2 mm is allowed, and no protrusion is permitted.

[0088] The reference surface of the bottom plate core blank shall be flat, without depression or protrusion, and no looseness is allowed.

[0089] (5) Process requirements

[0090] Use a continuous sand mixer to automatically mix new sand or recycled sand of 50 / 100 mesh. For resin II, the ratio of component I to component II is 11:9, and the addition ratio of the two-component resin (by weight of sand) is 1.6 ± 0.1%.

[0091] Core-making parameters:

[0092]

[0093] The mold can be replenished with mold release agent after every 10 ± 3 parts are produced.

[0094] After the sand core is shot, 100% inspection shall be carried out to check whether the sand core meets the quality requirements.

[0095] The mold shall be inspected and cleaned every 10 parts produced: ① resin mass adhered to the mold surface corresponding to the nozzle; ② whether the exhaust plug is blocked, intact, and flush with the cavity; ③ whether there are broken or piled-up sand cores in the cavity (pay attention to checking whether the sand cores shot in the early stage are intact), etc.

[0096] The sand core shall be placed with the shooting surface facing down. One mold shot at a time is taken as a group. Foam sponge, etc. shall be padded between the sand cores to prevent damage, and stacking is prohibited.

[0097] Specifically, the preparation process conditions of the cylinder core 110 are as follows:

[0098] (1) Equipment used: Sanxin RLA + 40 cold box core shooter.

[0099] (2) The operator shall be familiar with the equipment operation procedures and the PC operation procedures before the core shooting operation, operate in accordance with the equipment safety operation procedures, and pay attention to safety during the operation.

[0100] (3) Before work, the mold shall be inspected and cleaned. Production can start only after it is qualified; sharp metal objects such as files shall not be used for cleaning, and sharp wooden pieces or bamboo pieces shall be used for cleaning.

[0101] (4) Quality requirements

[0102] The shape of the cavity part of the sand core is complete, the sand core is compact and flat, without defects or looseness; for the parts with complete shape but not compact surface, use repair paste to repair, and the sand cores with incomplete shape shall be scrapped.

[0103] Core exhaust plug and ejector rod parts: Only depressions of 0.2 - 2 mm are allowed, and no protrusions are allowed;

[0104] Mold misalignment ≤ 0.2 mm, flash thickness ≤ 0.3 mm;

[0105] (5) Process requirements

[0106] Use a continuous sand mixer to automatically mix new sand or recycled sand of 50 / 100 mesh. Resin II: Component I ratio is 11:9. The addition ratio of the two-component resin (by weight of sand): 1.6 ± 0.1%;

[0107] Core-making parameters:

[0108]

[0109] The mold can be replenished with release agent after every 10 ± 3 parts are produced;

[0110] Place chill blocks at the designated positions (with magnets) on the main core. Quantity: 2 follow-shaped chill blocks;

[0111] After the sand core is shot, it should be 100% inspected to see if it meets the quality requirements;

[0112] The mold should be inspected and cleaned every 10 parts produced: ① resin clusters adhering to the mold surface corresponding to the nozzle; ② whether the exhaust plug is blocked, intact, and flush with the cavity; ③ whether there are broken or piled-up sand cores in the cavity (pay attention to checking whether the previously shot sand cores are intact), etc.;

[0113] The sand cores should be placed upright with the shooting surface facing down. One mold shot at a time is a group. Foam sponges or the like should be padded between the sand cores to prevent damage, and stacking is prohibited.

[0114] Specifically, the preparation process conditions of the water jacket core 210 are as follows:

[0115] (1) Equipment used: Z8620 core shooter, timer; Tools used: file.

[0116] (2) When operating the equipment, follow the equipment operation procedures and pay attention to safety during the operation.

[0117] (3) Before the core box is powered on for heating, check whether the air pressure is normal, the condition of the mold is good, and whether the exhaust needle is intact without missing or damage, and then the core-making work can be carried out.

[0118] (4) Quality requirements:

[0119] The sand core is complete, tightly compacted without looseness, the surface of the sand core is smooth, and the color is uniform;

[0120] Sand core misalignment ≤ 0.2 mm, pit formed by ejector rod ≤ 0.2 mm, flash thickness ≤ 0.2 mm;

[0121] The exhaust pinholes of the core should be unobstructed but not penetrate through the cavity surface. Check the exhaust pin size for the first piece of each shift:

[0122] Needle Extraction Instructions Water Hole Needle Extraction Size φ2.5 Depth 75±10

[0123] After the nozzle part is polished smoothly, use repair paste to repair the rough surface flat.

[0124] (5) Process requirements:

[0125] Use 680L coated sand to shoot the core;

[0126] Core box working temperature: 230 ± 30 °C; Shooting sand pressure: ≥ 0.4 Mpa; In-mold curing time 40 ± 10 s.

[0127] Spray the mold release agent once every 15 ± 3 parts produced by the mold;

[0128] The process of shooting the core is briefly described as follows:

[0129] Inspect and clean the mold → Heat the mold → Spray the mold release agent → Add the core frame → Close the mold → Shoot sand → Cure in the mold → Demold and take out the core → Inspect and clean the core → Store the core.

[0130] Specifically, the preparation process conditions of the oil channel core 170 are as follows:

[0131] (1) Equipment used: Z8620H core shooter, timer; Tools used: file.

[0132] (2) Operate the equipment according to the equipment operation procedures and pay attention to safety during the operation process.

[0133] (3) Before the core box is powered on for heating, the cooling water should be turned on to cool the "water-cooled sand shooting plate" first. Check whether the air pressure is normal, whether the mold is in good use condition, and whether the exhaust pins are complete without missing or damage. Then the core-making work can be carried out;

[0134] (4) Quality requirements:

[0135] The core is complete, tightly packed without looseness, the surface of the core is smooth and the color is uniform;

[0136] The misalignment of the sand mold ≤ 0.2 mm, the pits formed by the ejector rods ≤ 0.2 mm, and the flash thickness ≤ 0.2 mm;

[0137] The core head and the ejector rods and exhaust plugs on the mating surface are only allowed to be sunken by 0 - 2 mm and are not allowed to protrude;

[0138] The exhaust pinholes of the core should be unobstructed but not penetrate through the cavity surface. Check the exhaust hole size for the first piece of each shift:

[0139] Needle Extraction Instructions Exhaust Needle Extraction Size φ2.5 Depth 75±10

[0140] After the cavity and the nozzle part of the positioning surface are polished flat, use repair paste to repair and level the rough parts on the surface.

[0141] (5) Process requirements:

[0142] Use coated sand with 680L:50AG = 3:1 to shoot the sand core;

[0143] Core box working temperature: 230 ± 30 °C; Sand shooting air pressure: ≥ 0.4 Mpa; In-mold curing time 100 ± 10 s;

[0144] After the mold produces 15 ± 3 parts each time, spray the release agent again;

[0145] The process of shooting the core is briefly described as follows:

[0146] Inspect and clean the mold → Heat the mold → Spray the release agent → Close the mold → Shoot sand → Cure in the mold → Demold and take out the core → Inspect and clean the sand core → Store the sand core.

[0147] After coating, when drying the combined core and the remaining sand cores, the drying process conditions are as follows:

[0148] (1) Tools and inspection tools used: drying furnace (far-infrared sand core drying furnace), XCT-101 millivoltmeter, XWDI-100 automatic temperature measuring instrument.

[0149] (2) Quality requirements:

[0150] Bake the sand cores: all sand cores;

[0151] Place the sand cores on a flat plate or core rack for baking; The size of the sand core exceeding the core rack is not more than 50 mm;

[0152] Heat up: The furnace loading temperature ≤ 140 °C; Heat up to the holding temperature;

[0153] Insulate: The holding temperature is 180 ± 10 °C, and the holding time is 3 ± 0.5 hours;

[0154] Take out of the furnace: Cool in the furnace to ≤ 150 °C before taking out of the furnace, and handle the sand cores gently;

[0155] Do not open the furnace door during the baking process of the sand cores to avoid affecting the baking quality of the sand cores; Keep the baking records of each furnace well;

[0156] Water content of the sand core: ≤ 0.5%.

[0157] As an optional implementation method, assemble the cylinder barrel core 110 on the bottom plate core 120 to obtain a combined core, including:

[0158] Select multiple cylinder barrel cores 110 and pre-tighten them on the core assembly tooling 250 to make an integral cylinder barrel core; Among them, the integral cylinder barrel core has two groups of cylinder barrel groups arranged symmetrically in a V shape;

[0159] A detection template 240 is sleeved on two groups of cylinder barrels; wherein, the detection template 240 is used to detect the top cylinder center distance, bottom cylinder center distance and height difference of the two groups of cylinder barrels.

[0160] The integral cylinder barrel core with the detection template 240 is hoisted onto the bottom plate core 120 and assembled to obtain a combined core.

[0161] In this embodiment, when pre-assembling the cylinder barrel core 110 and the bottom plate core 120, the corresponding number of cylinder barrel cores 110 needs to be designed according to the structure of the cylinder block to be formed (such as V6 cylinder block, V8 cylinder block, V10 cylinder block). Therefore, multiple cylinder barrel cores 110 can be pre-tightened on the core assembling tooling 250 first to prepare an integral cylinder barrel core. The number of cylinder barrels of the integral cylinder barrel core corresponds to the number of cylinder holes of the cylinder block. First, the detection template 240 is sleeved on the two groups of cylinder barrels, and then the integral cylinder barrel core is hoisted onto the bottom plate core 120 and assembled by using a special lifting tool, which can reduce the measurement error caused by installing the detection template 240 after transportation, thereby improving the measurement accuracy, and further improving the assembling accuracy of the combined core, providing a guarantee for the cylinder barrel quality of the subsequent cylinder block.

[0162] As an optional embodiment, preparing the cylinder liner 150 and performing shot peening and preheating treatment on the cylinder liner 150, including:

[0163] Preparing the cylinder liner 150 and performing shot peening treatment on the surface of the cylinder liner 150, the diameter of the steel shot is 0.3 - 0.5 mm, and the shot peening treatment time is 10 - 15 minutes.

[0164] Then, preheating treatment is performed on the cylinder liner 150, the preheating temperature is 500 - 600 °C, and the time from the cylinder liner 150 being taken out of the preheating furnace to pouring is controlled within 3 - 5 minutes.

[0165] In this embodiment, the processing technology of the cylinder liner 150 is optimized. A thin needle-shaped cylinder liner can be used, and the time from the cylinder liner 150 being taken out of the preheating furnace to pouring is strictly controlled. If the time is less than 3 minutes, the temperature of the cylinder liner 150 is high, and shrinkage porosity defects are likely to occur. If the time is greater than 5 minutes, the temperature of the cylinder liner 150 is low, resulting in poor fluidity of the molten aluminum and the bonding rate of the cylinder liner 150 being less than 95%, thereby further improving the quality of the casting mold.

[0166] Specifically, the process conditions for performing shot peening treatment on the surface of the cylinder liner 150 further include: selecting cylinder liners with correct dimensions, 6 cylinder liners for each cylinder block; the cylinder liners are prohibited from contacting pollutants such as oil stains and moisture; the shot peening time: 15 - 20 min; the cylinder liners are placed vertically upward; when cleaning, the steel shot, dust, etc. on the surface of the cylinder liners are blown clean with compressed air.

[0167] Specifically, the process conditions for preheating the cylinder liner 150 also include: selecting cylinder liners with correct dimensions, 6 cylinder liners for each cylinder block; the cylinder liners are prohibited from contacting pollutants such as oil stains, moisture, and dust; the cylinder liners are placed in a triangular pattern, 3 on each side; ensure that the temperature of the cylinder liner when leaving the furnace is 600 ± 20 °C (dark red).

[0168] It should be noted that when heating the cylinder liner 150, induction heating can be used. The heating time is only 200 s. The short heating time reduces the thickness of the oxide layer on the surface of the cylinder liner 150, which is beneficial to improving the fitting rate of the cylinder liner 150.

[0169] Specifically, assemble each core part and the cylinder liner 150 in sequence according to the preset assembly order to manufacture the casting mold. The assembly order is: combine the front-end core 140, install the cylinder liner 150, combine the rear-end core 180, combine the top cover core 190, combine the left and right water jacket cores 210, combine the right-side core 220, combine the patch core 230; the requirements for core assembly (hereinafter referred to as mold closing) are as follows:

[0170] (1) Before mold closing, a 100% quality inspection should be carried out on the cores to be poured during the shift; check and clean the coating accumulation on all cores, especially pay attention to the mating surfaces of each core head;

[0171] (2) The mold closing process is carried out on a special platform. A preliminary mold closing must be carried out. After the preliminary closing, check and clean the surface of the cavity, and pay attention to preventing damage to the cores;

[0172] (3) Cores for mold closing: After the cores are dried and taken out of the furnace, pouring should be completed in a timely manner to ensure that the temperature of the cores before pouring is 40 - 80 °C;

[0173] (4) Any loose, fallen-off, or damaged cores found during mold closing should be replaced; the water jackets and oil passage cores to be replaced should be preheated after drying;

[0174] (5) Time control for mold closing: The waiting time from the cylinder liner leaving the furnace to pouring ≤ 5 minutes;

[0175] (6) Cylinder liner temperature control: The temperature of the cylinder liner when leaving the furnace is 600 ± 20 °C (dark red). After the 6 cylinder liners are placed on the cores, the temperature of the cylinder liner ≥ 420 °C.

[0176] As an optional implementation method, preparing molten aluminum includes:

[0177] Select an appropriate amount of aluminum ingot raw materials for melting to obtain molten aluminum;

[0178] Transfer the molten aluminum to a holding furnace;

[0179] Take a sample of the molten aluminum for analysis to obtain the magnesium content in the composition of the molten aluminum;

[0180] If the magnesium content is lower than the preset standard content, add magnesium blocks to the molten aluminum; where the addition amount of magnesium blocks = (0.4% - magnesium content) × weight of molten aluminum, and the standard content is 0.35 - 0.45%;

[0181] When the magnesium content reaches the standard content, add a grain refiner, a drossing agent, and a modifier to the molten aluminum in sequence; where the modifier is potassium fluozirconate, and the potassium fluozirconate is 0.18 - 0.3% of the total amount of molten aluminum;

[0182] Start the degasser to refine and degas the molten aluminum and add a refining agent of 0.2% ± 0.02;

[0183] Then perform drossing treatment on the molten aluminum, and add a covering agent of 0.1% - 0.15%, and finally obtain qualified molten aluminum.

[0184] In this embodiment, when preparing the molten aluminum, 0.18 - 0.3% potassium fluozirconate is added to the molten aluminum, and the magnesium content is controlled at 0.35 - 0.45%. Through the control of these two key chemical components, it is ensured that the leakage rate caused by shrinkage porosity defects after product forming is less than 2%, and the leakage rate is lower than 0.5% after one-time impregnation, which can further improve the product forming quality.

[0185] Specifically, the process conditions for melting the molten aluminum are as follows:

[0186] (1) Tools used: gas melting furnace, drossing ladle, sampling ladle, etc.; iron tools must be clean and coated and dried before entering the molten aluminum.

[0187] (2) Process and quality requirements

[0188] The furnace charge is prepared with ZL101A aluminum ingots. The single addition ratio of the first-class return charge does not exceed 40% of the total furnace charge, and it is not allowed to add the second-class and below return charges. Before adding materials to each shift, check and clean the foreign matters such as oxide scale and aluminum dross on the surface of the crucible;

[0189] All aluminum ingots and return charges should be cleaned thoroughly to remove oxides, slag inclusions, chips, sand, oil stains, water stains, etc., and preheated to 250°C - 300°C and kept warm for 1 - 3 hours (preheating with the furnace is allowed) before entering the furnace. It is prohibited to directly add normal-temperature aluminum ingots and return charges into the molten aluminum;

[0190] Control the melting temperature: the temperature of the molten aluminum in the furnace is 730 - 770°C;

[0191] After the molten aluminum melts into a liquid, put the thermocouple into the crucible in time to monitor the temperature of the molten aluminum. After the temperature of the molten aluminum rises to 710°C, sprinkle the drossing agent and skim off the aluminum dross. It is necessary to sprinkle a covering agent (0.05% - 0.1% of the total melt) on the surface of the molten aluminum to isolate the melt from the air, and clean it up before pouring;

[0192] Pouring temperature: 750 - 770°C (gravity, low pressure);

[0193] After melting in each shift, clean the oxide scale, aluminum slag and other foreign matters on the surface of the crucible;

[0194] Pour one spectral specimen in front of the pouring furnace, make furnace number marks, submit for inspection. If aluminum-silicon alloy needs to be added, please complete the addition before turning the water. After sampling and analyzing qualified again, turn the water.

[0195] Control points: The control standards for the chemical composition of the specimen are as shown in Table 1 below:

[0196] Table 1

[0197]

[0198] The process conditions for aluminum transfer are as follows:

[0199] (1) Tools used: ladle for turning water, overhead crane.

[0200] (2) Process and quality requirements

[0201] Before turning the water, check and clean the oxide scale, aluminum slag and other foreign matters in the ladle;

[0202] Set the temperature of the ladle dryer to 790±30°C. After preheating, the temperature in the ladle for turning water ≥550°C;

[0203] After each turning of the water, it is necessary to clean the oxide scale, aluminum slag and other foreign matters in the ladle;

[0204] Before the aluminum liquid is transferred into the holding furnace, use slag remover to remove the surface floating slag.

[0205] Specifically, the process conditions for modifying the aluminum water are as follows:

[0206] (1) Tools used: low-pressure casting holding furnace, slag spoon; iron tools must be clean and coated and dried before entering the aluminum liquid. Operation process: preheat the iron tools to 150 - 200°C before brushing → brush evenly → preheat and dry.

[0207] (2) Process and quality requirements

[0208] After adding aluminum liquid in each shift, immediately sprinkle slag remover to clean the oxide scale, aluminum slag and other foreign matters on the surface of the holding furnace crucible and the surface of the aluminum liquid, and then add other furnace charges;

[0209] Take one spectral specimen in front of the furnace for analysis after turning the water. The control standards for the chemical composition are as shown in Table 2 below:

[0210] Table 2

[0211]

[0212] If it cannot be refined immediately after the water transfer, wait. After skimming the slag, sprinkle a covering agent to isolate the air. Refinement treatment: temperature 730°C ± 10°C, the addition amount of the refining agent (AlTi5B1) is 0.15 - 0.18% of the total amount of new aluminum liquid;

[0213] Modification treatment: temperature 730°C ± 10°C, the addition amount of the modifier is 0.18 - 0.3% of the total amount of new aluminum liquid, and the modification time is 20 minutes;

[0214] After modification, add a slagging agent to remove the floating slag on the surface of the aluminum liquid, and then immediately start the degassing and refining process;

[0215] The modifier, refining agent, refining agent, covering agent, magnesium ingots, etc. need to be dried and preheated before being put into the furnace.

[0216] The overall process flow is: slagging in the water transfer ladle → transferring water to the holding furnace → adding the refining agent → adding a slagging agent to skim the slag → adding the modifier → sampling the composition → starting the degasser to degas and adding 0.2% ± 0.02 refining agent → skimming the slag → sprinkling 0.1% - 0.15% covering agent → standing for 10 minutes → taking a test bar sample → skimming the slag → covering the furnace lid.

[0217] As an alternative implementation method, the parameters for refining and degassing are: argon gas flow rate 1.2 - 2.2m 3 / h; degassing temperature 730 - 740°C; initial rotational speed of the graphite rotor 1000 - 1200 rpm, lasting for 1 - 2 min; stable rotational speed of the graphite rotor 400 - 500 rpm; degassing time 20 - 25 min. By optimizing the parameters of refining and degassing, the quality of the aluminum liquid is further improved, that is, the quality of the casting cylinder block is improved.

[0218] Specifically, the process conditions for refining and degassing are as follows:

[0219] (1) Tools used: low-pressure casting holding furnace, degasser, slagging ladle; iron tools must be clean and coated before entering the aluminum liquid.

[0220] (2) Job quality requirements

[0221] Before degassing, after skimming the floating slag on the surface of the aluminum liquid, sprinkle a covering agent, and check and clean the aluminum slag, scale, etc. on the graphite rotor and baffle of the degasser;

[0222] The graphite rotor is lowered to 20 - 100 mm from the surface of the aluminum liquid and preheated for ≥ 10 minutes;

[0223] Refining and degassing parameters:

[0224] During the lifting process of the degassing machine, argon gas needs to be constantly supplied to prevent the rotor from being blocked by molten aluminum; there should be no aluminum dross on the surface of the molten aluminum before the rotor enters the molten aluminum, and the refining agent has been sprinkled; at the beginning of degassing, the rotor needs to rotate at high speed to generate a vortex in the molten aluminum to suck the refining agent into the molten aluminum. When degassing is stable, the bubbles on the surface of the molten aluminum should be dispersed and no large bubbles should emerge; after degassing is completed, immediately add 0.1 - 0.3% of the weight of the molten aluminum of aluminum-free sodium dross agent - AZ6 to skim off the slag, then sprinkle a small amount of covering agent to isolate the melt from the air, and then let it stand for 10 - 12 minutes; detect the degassing effect, and the density equivalent ≤ 2.24%. The sampling position of the in-furnace degassing sample is 150 - 300 mm below the surface of the molten aluminum. Pour 6 - 10 mechanical property samples once per shift, and the mold temperature is 260 - 380 °C.

[0225] As an alternative implementation, pouring molten aluminum into a casting mold includes:

[0226] Grasp the metal bottom plate 130 by a manipulator to grasp the entire casting mold to the pouring machine;

[0227] Cooperate with the casting mold through the clamping sleeve box 260 on the pouring machine to pour the molten aluminum into the casting mold.

[0228] In this implementation, by assembling cores on the metal bottom plate 130 and then grasping and pouring as a whole by the manipulator (the interface on the metal bottom plate 130 can be grasped), the pouring machine is equipped with a clamping sleeve box 260. Mechanical limit mechanisms, clamping force control mechanisms, and synchronous clamping mechanisms are provided around and on the upper part of the clamping sleeve box 260, which will not damage the casting mold. In addition, the clamping sleeve box also has a communication interface with the casting machine. If the position of the clamping sleeve box 260 is not in place, the casting machine will not enter the pouring program, avoiding problems such as aluminum leakage and product size deviation. The clamping sleeve box 260 can provide a reliable clamping force to the casting mold to prevent molten aluminum leakage during pouring. At the same time, due to the use of the synchronous clamping sleeve box process, the casting sand position is minimized to the greatest extent, and the sand-aluminum ratio is less than 5. After pouring is completed, it is grasped and placed into the cooling line, and automated pouring can be achieved.

[0229] As an alternative implementation, the pouring parameters of the pouring machine are: the pouring pressure in the first stage is 110 mbar, and the time is 6 s; the pouring pressure in the second stage is 200 mbar, and the time is 4 s; the pouring pressure in the third stage is 250 mbar, and the time is 2 s; the pouring pressure in the fourth stage is 350 mbar, and the time is 3 s; the pouring pressure in the fifth stage is 580 mbar, and the time is 4 s; the holding pressure time is 600 s; the suspension pressure is 65 mbar, and the suspension holding time is 600 s.

[0230] In this embodiment, according to the above pouring parameters, the molten aluminum fills the mold smoothly, and there are no defects such as gas entrapment, sand sticking, cold shut, slag inclusion, shrinkage cavity, etc. in the casting; the floating liquid surface is beneficial to reducing the slag inclusion and porosity defects in the casting caused by the secondary oxidation of the molten aluminum, further improving the quality of the cylinder block casting.

[0231] Specifically, the process conditions for pouring are as follows:

[0232] (1) Tools and inspection tools: K-type digital thermometer, low-pressure casting machine.

[0233] (2) Process requirements

[0234] Preheating temperature of the riser tube: 550 - 650 °C. For each furnace, the foreign matters such as oxide scale and aluminum slag on the surface of the thermocouple protection tube, and the inner and outer surfaces of the riser tube shall be cleaned thoroughly.

[0235] Pouring temperature (B): 705 ± 5 °C (digital display), handheld temperature measurement: 705 ± 5 °C (for calibration reference only), and the digital display temperature shall be taken as the standard.

[0236] Before pouring, clean the oxide scale inside the riser tube and the floating slag on the liquid surface inside the riser tube for each piece; clean the mud blocks and sundries on the side wall of the sleeve box, and block the riser tube orifice during cleaning to prevent sundries from falling into the holding furnace.

[0237] Place a filter screen before pouring (the filter screen is clamped by two Φ101 / 178 - 5mm thick sealing rings, and shall be replaced or re-placed after pouring is completed).

[0238] The floating liquid surface is 50 - 150 mm away from the riser tube orifice. Check and adjust for each piece during the pouring process. The 10 mbar pressure value corresponds to a 42.5 mm aluminum column height. Pay attention to the conversion.

[0239] The holding time of the molten aluminum after degassing ≤ 3 hours.

[0240] After each furnace pouring is completed, take 1 post-furnace spectral sample for inspection. The sampling position is 150 - 300 mm below the surface of the molten aluminum. The post-furnace chemical composition control standards are as shown in Table 3 below:

[0241] Table 3

[0242]

[0243] As an optional embodiment, post-treat the casting mold to obtain the engine cylinder block, including:

[0244] Cool the casting mold successively, perform shakeout and sand shaking treatments to obtain the cylinder block blank.

[0245] Saw cut, heat treat, conduct material inspection, mill the surface, perform rough cleaning, dimension inspection, sandblasting, shot peening, fine cleaning and appearance inspection on the cylinder block blank successively, and finally obtain the engine cylinder block.

[0246] Specifically, the process conditions for cooling treatment are as follows: After pouring is completed and at least 1 hour has passed, the external core can be removed by knocking out the mold; during the process of removing the riser, pay attention to the cutting and knocking directions to prevent the pouring riser from being torn and damaged; during the removal of the pouring riser and transportation, the front end face of the casting should be placed upward; when knocking out the mold, it is strictly prohibited to directly knock on the casting body with heavy objects such as hammers; when placing the upper cylinder block, handle it gently to prevent damage; recycle the metal bottom plate and clean the residues such as molding sand, aluminum sheet, and coating on the bottom plate.

[0247] Specifically, the process conditions for shakeout treatment are as follows: Tools used: hammer, pneumatic grinder, polishing machine, iron bar; After pouring is completed for 1 hour, the external core can be removed by knocking out the mold; the shakeout rate of the core on the external surface of the cylinder block is ≥90%; during the process of removing from the rack and loading into the frame, pay attention to the operation method to prevent the cylinder block from being impacted by force, so as to avoid damaging the casting; recycle the chill and locking core screw; when loading into the frame, place it with the bottom facing upward.

[0248] Specifically, the process conditions for vibration sand removal treatment are as follows: Equipment used: high-frequency vibration sanding machine; Before vibration sand removal, the temperature of the casting ≤80°C; during the vibration sand removal process, pay attention to the clamping direction to prevent damage to the casting and equipment; the shakeout rate of the external cavity ≥98%, and the shakeout rate in the water and oil channels ≥95%; during transportation, place the casting with the bottom facing upward; it is strictly prohibited to directly knock on the casting body with heavy objects such as hammers; when placing the upper cylinder block, handle it gently to prevent damage.

[0249] Specifically, the process conditions for sawing are as follows: Tools used: lifting tool, sawing machine; The residual flash of the pouring riser on the bottom surface of the cylinder block ≤3mm, and the residual flash of the pouring riser on the top surface ≤3mm; during the process of removing from the rack and loading into the frame, pay attention to the operation method to prevent the cylinder block from being impacted by force, so as to avoid damaging the casting; when loading into the frame, leave as many hot air circulation channels as possible, the cylinder blocks around should be as close to the material frame as possible, and the distance between the middle cylinder blocks should be as large as possible.

[0250] As an optional implementation method, the process parameters for heat treatment are: the solution furnace loading temperature ≤300°C, the aging furnace loading temperature ≤100°C, the heating rate ≤100°C / h, and the number of solution treatments for a single casting does not exceed 3 times.

[0251] Specifically, the process conditions for heat treatment are as follows: Equipment tools and inspection tools used: solution furnace, aging furnace, scribing platform, center pin, scribing tooling, vernier caliper. Process requirements: Load the furnace with the front end face upward, leave as many hot air circulation channels as possible when loading into the frame, the cylinder blocks around should be as close to the material frame as possible, the distance between the middle cylinder blocks should be as large as possible, and stacking is prohibited. There are at least 6 mechanical property specimens per furnace. Straightening requirements: If the deformation is less than 1mm, no straightening is required; if it exceeds 1mm, mechanical straightening is required, and after straightening, the surface must be inspected by coloring to ensure no cracks; for each heat treatment furnace, take 1 upper cylinder block casting from the upper, middle (center of the material frame, not the edge of the material frame), and lower 3 layers respectively to test the hardness of the casting body, and the hardness of the casting body ≥80HBW; check the water volume in the quenching water tank every day to ensure that the casting is completely submerged in water.

[0252] It should be noted that material inspection, milling, rough cleaning, dimensional inspection, sandblasting, shot peening, fine cleaning and appearance inspection can be carried out according to the current process, which will not be elaborated here.

[0253] In summary, in this embodiment, by improving the process precision in the preparation stage of the casting mold, combining with the optimization of each process in the preparation of molten aluminum, the synchronous pressing of the sleeve box process, the application of the melting and batching ratio, the strict modification, refining and degassing process, the chills process at each hot spot of the cylinder block, and the control of key processes such as the stable pouring temperature, sand mold temperature, and cylinder liner casting temperature. Taking the V6 aluminum cylinder block as an example, on the basis of a monthly production of 3000 units, the comprehensive casting qualification rate is 98%, the comprehensive qualification rate of the rough machining reaches 95%, the leakage rate is less than 2% without impregnation after machining, and the leakage rate is less than 0.5% after one impregnation, which is much higher than the mass production processing qualification rate of 60 - 75% of foreign similar products.

[0254] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied to other related technical fields, shall be included in the patent protection scope of the present application by the same token.

Claims

1. A method for casting an engine cylinder block, characterized in that: The following steps are involved: Prepare various sand core parts required for forming the casting mold; wherein the sand core parts include a bottom plate core, a cylinder core, a front end core, a rear end core, a left side core, a right side core, a water jacket core, an oil channel core, a top cover core and a patch core; The cylinder core is assembled on the bottom plate core to obtain a combined core; wherein the bottom plate core is provided with three positioning references arranged in a triangle and located on the same horizontal plane; Applying coating and drying to the combined core and the remaining sand core parts; preparing a cylinder liner and performing shot blasting and preheating treatment on the cylinder liner; The dried combined core is hoisted on a metal base plate, and the sand core parts and the cylinder sleeve are assembled in sequence according to a preset assembly sequence to obtain a casting mold; wherein the cylinder sleeve is sleeved on the cylinder core; preparing molten aluminum; pouring molten aluminum into the casting mold; The casting mold is post-processed to obtain an engine cylinder block.

2. The method for casting an engine cylinder block according to claim 1, characterized in that: The step of assembling the cylinder core on the bottom plate core to obtain a combined core comprises: Select a plurality of the cylinder cores and pre-tighten them on a core assembly tool to obtain an integral cylinder core; wherein the integral cylinder core has two cylinder groups symmetrically arranged in a V shape; A detection template is set on the two groups of cylinder assemblies; wherein the detection template is used to detect the top cylinder center distance, bottom cylinder center distance and height difference of the two groups of cylinder assemblies; The integral cylinder core with the test sample is hoisted onto the base plate core and assembled to obtain a combined core.

3. The method for casting an engine cylinder block according to claim 1, characterized in that: The method of preparing the cylinder liner and performing shot blasting and preheating treatment on the cylinder liner comprises: Prepare a cylinder liner and perform shot blasting on the surface of the cylinder liner, the diameter of the steel shot is 0.3-0.5 mm, and the shot blasting time is 10-15 minutes; Then the cylinder liner is preheated at a temperature of 500-600° C. The time from the cylinder liner being preheated out of the furnace to the pouring is controlled at 3-5 minutes.

4. The method for casting an engine cylinder block according to claim 1, characterized in that: The method for preparing molten aluminum comprises: Selecting an appropriate amount of aluminum ingot raw material for melting to obtain aluminum liquid; Transfer molten aluminum to a holding furnace; Sampling and analyzing the molten aluminum to obtain the magnesium content in the composition of the molten aluminum; If the magnesium content is lower than the preset standard content, magnesium blocks are added to the molten aluminum; wherein the amount of magnesium blocks added = (0.4% - magnesium content) × weight of molten aluminum, and the standard content is 0.35-0.45%; When the magnesium content reaches the standard content, adding a refiner, a slag remover and a modifier to the molten aluminum in sequence; Turn on the degasser to refine and degas the molten aluminum and add 0.2%±0.02 refining agent; The molten aluminum is then subjected to slag treatment, and 0.1% to 0.15% of a covering agent is added to finally produce qualified molten aluminum.

5. The method for casting an engine cylinder block according to claim 4, characterized in that: The modifier is potassium fluorozirconate, and the potassium fluorozirconate is 0.18-0.3% of the total amount of aluminum water.

6. The method for casting an engine cylinder block according to claim 4, characterized in that: The parameters of the refining and degassing are: argon flow rate 1.2~2.2m 3 / h; degassing temperature 730~740℃; initial speed of graphite rotor 1000~1200rpm, lasting 1~2min; stable speed of graphite rotor 400~500rpm; degassing time 20~25min.

7. The method for casting an engine cylinder block according to claim 1, characterized in that: The step of pouring molten aluminum into the casting mold comprises: Grab the metal bottom plate by a robot arm to grab the casting mold as a whole to a pouring machine; The compression sleeve on the pouring machine cooperates with the casting mold to pour molten aluminum into the casting mold.

8. The method for casting an engine cylinder block according to claim 7, characterized in that: The pouring parameters of the pouring machine are as follows: the pouring pressure of the first stage is 110 mbar, and the time is 6 s; the pouring pressure of the second stage is 200 mbar, and the time is 4 s; the pouring pressure of the third stage is 250 mbar, and the time is 2 s; the pouring pressure of the fourth stage is 350 mbar, and the time is 3 s; The fifth stage pouring pressure is 580 mbar, the time is 4 s; the holding time is 600 s; the suspension pressure is 65 mbar, and the suspension holding time is 600 s.

9. The method for casting an engine cylinder block according to claim 1, characterized in that: The post-processing of the casting mold to obtain an engine cylinder block includes: The casting mold is subjected to cooling treatment, sand dropping treatment and sand blasting treatment in sequence to obtain a cylinder body blank; The cylinder block blank is subjected to sawing, heat treatment, material inspection, surface milling, rough cleaning, size inspection, sand blasting, shot blasting, fine cleaning and appearance inspection in sequence to finally obtain the engine cylinder block.

10. The method for casting an engine cylinder block according to claim 9, characterized in that: The process parameters of the heat treatment are: solution furnace charging temperature ≤300°C, aging furnace charging temperature ≤100°C, heating rate ≤100°C / h, and the number of solution treatments for a single casting shall not exceed 3 times.

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