Casting method based on chilling block device

Abstract

The invention discloses a casting method based on a chilling block device. The casting method at least comprises a molding procedure and a pouring procedure. In the molding procedure, when a sand core and a sand mold are manufactured, a plurality of chilling blocks and a cooling pipeline assembly connected with the chilling blocks are arranged at the thick and large section and / or hot spot corresponding to a casting cavity; the main body part of the cooling pipeline assembly is embedded in the chilling block, and the two ends of the cooling pipeline assembly extend out of the sand core or the sand mold respectively and are exposed in the air; and in the pouring process, air enters one end of the cooling pipeline assembly and forms negative pressure, so that the other end of the cooling pipeline assembly sucks air or a cold source, the air pressure of the air inflow is adjusted along with pouring, and after pouring is completed, air inflow continues for a period of time, and then air inflow is gradually stopped. According to the method, deeper chilling can be formed, regulation and control of a matrix structure in the casting process are enhanced, the number of graphite is increased, the matrix structure lamellar distance is refined, and the casting performance is improved.

Description

Technical Field

[0001] The invention relates to the technical field of casting, and in particular to a casting method based on a chilling iron device. Background Art

[0002] The cooling speed of the composition and solidification process is the two aspects that affect the performance and organization of the casting. Under the condition of a certain composition, the cooling speed of the solidification process is the most important control direction, which determines the quality of the casting structure. The cooling and solidification process of machine tool castings and ultra-thick large-section ductile iron will cause graphite distortion and growth due to long solidification, which seriously deteriorates the mechanical properties. Therefore, it is necessary to actively explore the cooling and cooling conditions during the solidification process to give appropriate rapid cooling to solve the above-mentioned graphite distortion problem.

[0003] Although there are cooling methods such as chilled iron, air cooling, and water cooling, the cooling of special castings during the solidification process mainly relies on chilled iron. However, chilled iron can only chill the cast iron locally or partially, and cannot continuously chill the casting for a long time, so it is easy to produce differences and lead to problems such as abnormal graphite and color difference in the casting. Control technologies such as air cooling and water cooling are difficult to implement, and improper handling can easily cause casting defects or even safety accidents. Summary of the invention

[0004] The purpose of the present invention is to provide a casting method based on a chilling device to solve the problems existing in the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is: A casting method based on a chilling iron device, the casting method at least comprising a molding process and a pouring process; In the molding process, when making the sand core and the sand mold, a plurality of chillers and a cooling pipe assembly connecting the plurality of chillers are arranged corresponding to the thick and large sections and / or the hot spots of the casting cavity; the main body of the cooling pipe assembly is embedded and installed in the chiller, and the two ends of the cooling pipe assembly extend out of the sand core or the sand mold respectively and are exposed to the air; During the pouring process, one end of the cooling pipe assembly takes in air and forms negative pressure, so that the other end inhales air or a cold source. The air pressure of the air is adjusted as the pouring proceeds, and after the pouring is completed, the air intake continues for a period of time and then is gradually closed.

[0006] In the molding process, the casting method based on the quenching chiller device not only arranges chillers for the thick and large sections and / or hot spots of the casting, but also connects a cooling pipe assembly to the chiller, which can greatly exert the cooling and heat conduction effects of the chiller during the pouring and solidification molding of the casting, allowing the chiller to conduct the heat absorbed by itself, and can also form a deeper level of quenching, thereby strengthening the regulation of the matrix structure during the casting process, achieving an increase in the amount of graphite, refinement, and refinement of the matrix structure layer spacing, and improving the performance of the casting.

[0007] This method not only takes into account the heat exchange between the chiller and the molten iron in cooling the casting, but also takes into account the heat exchange of the chiller itself. Moreover, this method can be applied to the sand box molding and pit molding production processes of large iron castings. It can be used for the production of castings weighing several tons or even tens of tons, and it can reduce the difficulty of implementation, allowing it to be used smoothly in actual production.

[0008] Furthermore, the chiller has a cooling working surface, which is arranged toward the casting cavity, and the chiller and the main body of the cooling pipeline assembly are both pre-buried in the sand core or the molding sand of the sand mold.

[0009] Furthermore, when making sand cores and sand molds, the chiller is pre-assembled and connected with the cooling pipe assembly and placed in the molding sand; or the cooling pipe assembly is first arranged according to a path, and then the chiller is placed in sequence on the main part of the cooling pipe assembly; and the sand is dropped while the placement is performed to carry out molding.

[0010] Furthermore, when making the sand core and the sand mold, a temperature sensor is pre-embedded in the molding sand near the chiller so as to monitor the temperature near the chiller in real time.

[0011] Furthermore, the time for continuous air intake after pouring is completed is several minutes, several hours or several days.

[0012] Furthermore, the cold iron is provided with a groove on at least one side outside the cooling working surface; the cooling pipe assembly includes a heat exchange tube, and an air outlet pipe connected to one end of the heat exchange tube, the air outlet pipe is provided with an air inlet pipe at the end close to the intersection with the heat exchange tube, the inner diameter of the air inlet pipe and the inner diameter of the heat exchange tube are both smaller than the inner diameter of the air outlet pipe, and the heat exchange tube is matched and connected with the groove.

[0013] It is convenient to open the groove on the surface of the chill, and the heat exchange tube can be well connected. The groove serves as a cooling groove and can exchange heat with the cooling medium flowing through the heat exchange tube, allowing the cooling medium to take away the heat, thereby reducing the temperature of the chill, that is, forming a chill, so that the casting is cooled faster, especially the molten iron in the thick section and hot node can be cooled quickly to achieve a balanced cooling and solidification speed with other parts.

[0014] The cooling pipe assembly can form a suction effect with Bernoulli effect by setting the heat exchange tubes, the air inlet pipes and the air outlet pipes with different inner diameters, realize and strengthen the flow of cooling media such as wind, water, oil, etc. in the heat exchange tubes, take away the heat absorbed by the cold iron in the molten iron (or casting), so that the cold iron can be continuously cooled.

[0015] Furthermore, the central axis of the air outlet pipe is perpendicular to the central axis of the heat exchange pipe, or the air outlet pipe is arranged on the heat exchange pipe at an angle; the air inlet pipe and the air outlet pipe are arranged coaxially.

[0016] Furthermore, the air inlet pipe is connected to the air compressor through a hose and is provided with a control valve, one end of the heat exchange tube is exposed to the air or connected to a cold source through a pipeline; the wind pressure of the air inlet pipe is 0.4-0.8MPa.

[0017] Furthermore, the heat exchange tube is a retractable cooling tube structure, and / or the end of the heat exchange tube away from the air outlet pipe is detachably connected to a spliced ​​extension tube, so that the length of the heat exchange tube can be flexibly adjusted to adapt to the production of castings of different lengths.

[0018] Furthermore, the cooling pipeline assembly is multiple, and the heat exchange pipe is also provided with a plurality of heat exchange branches at intervals. By matching multiple pipelines and heat exchange branches, its application range can be further improved, and it can be better used in the production of large castings.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. In the casting process, the present casting method based on the quenching cold iron device not only arranges cold irons for the thick and large sections and / or hot nodes of the casting, but also has a cooling pipe assembly connected to the cold iron, which can greatly exert the cooling and heat conduction effects of the cold iron during the pouring and solidification molding of the casting, so that the cold iron can also conduct the heat absorbed by itself, and can also form a deeper level of quenching, strengthen the regulation of the matrix structure during the casting process, and realize the increase of graphite quantity and refinement and refinement of the matrix structure layer spacing, thereby improving the performance of the casting; 2. In cooling the casting, the present method not only considers the heat exchange between the cold iron and the molten iron, but also considers the heat exchange of the cold iron itself, and the present method can be used in the sand box molding and pit molding production processes of large iron castings, which can reduce the difficulty of implementation; 3. It is more convenient to open the groove on the surface of the cold iron, and it can also be well connected to the heat exchange tube. The groove As a cooling trough, it can exchange heat with the cooling medium flowing through the heat exchange tube, allowing the cooling medium to take away the heat, thereby reducing the temperature of the cold iron and accelerating the cooling of the casting; 4. The cooling pipe assembly can form a suction effect with a Bernoulli effect through the arrangement of the heat exchange tubes, the air inlet pipes and the air outlet pipes with different inner diameters, realize and strengthen the flow of cooling media such as wind, water, oil, etc. in the heat exchange tubes, take away the heat absorbed by the cold iron (or castings), so that the cold iron can continue to be quenched; 5. When the cold iron and cooling pipeline arrangement scheme of this method is adopted, the heat is taken away by suction, and heat is dissipated without adversely affecting the castings or causing related defects. Even if there are gaps at the joints, the wind will not enter the sand core, sand mold and cavity due to the negative pressure suction; 6. After air cooling of this method, the pearlite content in the body structure of the ultra-thick and slow-cooling casting test block is significantly increased, by at least 5% to 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the cold iron body of the present invention; Figure 2 Another structural schematic diagram of the cold iron body of the present invention; Figure 3 It is a schematic diagram of the structure of the cooling assembly of the present invention; Figure 4 It is a partial schematic diagram of the cold iron body and the cooling assembly used in conjunction with each other in the present invention (looking upward from the bottom of the cold iron); Figure 5 A partial schematic diagram (top view) of another arrangement of the cold iron body and the cooling assembly of the present invention; Figure 6 It is a structural schematic diagram of the connection between the heat exchange tube and the splicing tube of the present invention; Figure 7 Another structural schematic diagram of the heat exchange tube and the splicing tube connected to each other in the present invention; Figure 8 Another schematic diagram of the structure of the cooling assembly of the present invention; Fig. 9 is a metallographic diagram of a comparative chiller (without a cooling pipe assembly) in this embodiment; Fig.10 The metallographic diagram of the test example chiller (with cooling pipe assembly) in this embodiment; Fig.11 This is a metallographic image of the comparative coated sand chilled iron (without cooling pipe assembly) in this embodiment; Fig.12 This is a metallographic diagram of the test example coated sand chiller (with cooling pipe assembly) in this embodiment; Fig.13 is a metallographic image of a comparative casting test block (without a cooling pipe assembly) in this embodiment; Fig.14 The metallographic image of the test casting block (with cooling pipe assembly) of the test example in this embodiment; Fig.15 The metallographic image of the comparative casting test block (cold iron coated sand, without cooling pipe assembly) in this embodiment; Fig.16 The metallographic image of the test casting block (cold iron coated sand, plus cooling pipe components) of the test example in this embodiment; In the figure: 1, cold iron; 101, groove; 102, cooling working surface; 2, heat exchange tube; 3, air outlet pipe; 4, air inlet pipe; 5, hose; 6, spliced ​​extension pipe; 7, flange edge; 8, sealing gasket; 9, tongue and groove structure; 10, heat exchange branch pipe; 11, sand mold; 12, casting cavity. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0023] A casting method based on a chilling iron device, the casting method at least comprising a molding process and a pouring process; In the molding process, Figure 1 to Figure 5 As shown, when making sand cores and sand molds, a plurality of chillers 1 and a cooling pipe assembly connecting the plurality of chillers 1 are arranged corresponding to the thick and large sections and / or hot spots of the casting cavity 12; the main body of the cooling pipe assembly is embedded and installed in the chiller 1, and the two ends extend out of the sand core or sand mold respectively and are exposed to the air; During the pouring process, one end of the cooling pipe assembly takes in air and forms negative pressure, so that the other end can inhale air or a cold source. The air pressure is adjusted as the pouring proceeds. After the pouring is completed, the air intake continues for a period of time during the casting cooling stage and then is gradually closed.

[0024] In the molding process, the casting method based on the quenching chiller device not only arranges chillers for the thick and large sections and / or hot spots of the casting, but also connects a cooling pipe assembly to the chiller, which can greatly exert the cooling and heat conduction effects of the chiller during the pouring and solidification molding of the casting, allowing the chiller to conduct the heat absorbed by itself, and can also form a deeper level of quenching, thereby strengthening the regulation of the matrix structure during the casting process, achieving an increase in the amount of graphite, refinement, and refinement of the matrix structure layer spacing, and improving the performance of the casting.

[0025] This method not only takes into account the heat exchange between the chiller and the molten iron in cooling the casting, but also takes into account the heat exchange of the chiller itself. Moreover, this method can be applied to the sand box molding and pit molding production processes of large iron castings. It can be used for the production of castings weighing several tons or even tens of tons, and it can reduce the difficulty of implementation, allowing it to be used smoothly in actual production.

[0026] The basic structure of cast iron is determined by chemical composition and cooling rate. When the composition is constant, the decisive factor affecting the matrix structure is the cooling rate. Especially for cast iron materials that require pearlite matrix structure, it is necessary to strengthen the overall chilling effect and chilling speed, and adjust them to implement rapid chilling. The chill used in the casting process can be further chilled at an adjustable depth to make the chill play a positive role in the casting process.

[0027] For example, the matrix structure of QT600-3 is ductile iron mainly composed of pearlite, which is required to have the characteristics of high strength and high stiffness, medium toughness and plasticity, wear resistance and good casting process performance. However, the thick and large sections often fail to meet the performance requirements due to slow cooling, graphite distortion, tissue lamella spacing, coarse grains and other problems. The casting method based on the quenching cold iron device can well meet the above high-end requirements and solve the above-mentioned problems such as graphite distortion, tissue lamella spacing, coarse grains, and ultimately achieve the increase in graphite quantity, refinement and refinement of the matrix tissue lamella spacing, and improve the performance of castings.

[0028] This method is also conducive to the directional solidification of the casting. These chills are set at different positions. By adjusting the wind pressure, the heat exchange efficiency and heat exchange intensity between the cooling pipe assembly and the chill can be controlled, so that different wall thicknesses of the casting can be cooled and solidified synchronously, and solidified sequentially from the outside to the inside.

[0029] The chiller and the cooling pipe assembly are preset in the sand core and / or sand mold during the molding process, and do not increase the workload in operation. After the casting cavity is molded, the two ends of the cooling pipe assembly extend out from the sand box or pit to connect to an external blowing or negative pressure device; the cooling method of the cooling pipe assembly is not to blow air into the main part, but to rely on the negative pressure at one end to suck air to allow the main part to exchange heat with the chiller.

[0030] Further, such as Figure 1 As shown in Fig. 2, the chiller 1 has a cooling working surface 102, which is arranged toward the casting cavity 12 to exchange heat with the molten iron or the casting; the chiller 1 and the main body of the cooling pipeline assembly are pre-buried in the sand core or the sand mold. Both the sand core and the sand mold are made of molding sand (such as resin sand, coated sand, etc.).

[0031] Furthermore, when making sand cores and sand molds, small and medium-sized parts can be placed in a pre-connected manner, and the chiller and the cooling pipe assembly can be assembled and connected together in advance and placed in the molding sand; for large castings, the cooling pipe assembly can be arranged according to the path first, and then the chiller can be placed in sequence on the main part of the cooling pipe assembly; both methods can be used for shaping while placing and dropping sand. They are placed in the sand and need to be buried in the sand. Generally, only the cooling working surface of the chiller will be exposed in the mold cavity.

[0032] The cooling working surface 102 of the chill 1 is also provided with a sand coating, the thickness of which should be controlled below 6 mm, that is, when the chill is buried, the cooling working surface is also covered with sand, and according to its placement, the sand coating is flush with the outer surface of the sand core or sand mold, and then refractory paint is applied together to form a refractory coating. The purpose of such a setting is to play the chilling role of the chill while preventing the molten iron just poured into the cavity from melting the chill or adhering to the chill, so as not to reduce the cooling effect of the chill, and also to prevent the chill from sticking to the casting after the casting is solidified and formed, which is difficult to clean, and even causes surface quality problems of the casting.

[0033] By analyzing the temperature of the resin sand after pouring around the casting cavity, it is found that there is an overheated resin sand area around 1040℃ near the casting. The temperature is higher than its phase change temperature (873℃), which causes the quartz sand to undergo phase change, which is not conducive to the solidification process of the molten iron, and will lead to aggravated sand cracks. The intrusion of molten iron is easy to cause sintering. Then comes the temperature area of ​​900-400℃. As the temperature gradually dissipates, no phase change occurs, and the solid remains basically the same as the original sand; the temperature of the outer layer of resin sand is lower than 100℃, which is basically the same as the normal resin sand area. Therefore, the high-temperature molten iron is first transmitted to the contacting molding sand layer, and the highest temperature is 3-6mm, so a 3-6mm covering sand layer is designed.

[0034] Furthermore, when making sand cores and sand molds, a temperature sensor is embedded in the molding sand near the chiller 1 to monitor the temperature of the molding sand near the chiller in real time, thereby determining the heat exchange condition of the chiller to adjust the wind pressure.

[0035] Furthermore, the time (the period of time) for continuous air intake after pouring is completed is several minutes, several hours or several days.

[0036] In terms of structure, combined Figure 1 to Figure 3 As shown, the cold iron 1 is provided with a groove 101 on at least one side outside the cooling working surface 102; the cooling pipeline assembly includes a heat exchange tube 2, and an air outlet pipe 3 connected to one end of the heat exchange tube 2, the air outlet pipe 3 is provided with an air inlet pipe 4 at the end close to the intersection with the heat exchange tube 2, the inner diameter of the air inlet pipe 4 and the inner diameter of the heat exchange tube 2 are both smaller than the inner diameter of the air outlet pipe 3, and the heat exchange tube 2 is matched and connected with the groove 101.

[0037] It is convenient to open the groove 101 on the surface of the cold iron 1, and it can also be well connected to the heat exchange tube 2. The groove 101 serves as a cooling groove and can exchange heat with the cooling medium flowing through the heat exchange tube 2, allowing the cooling medium to take away the heat, thereby reducing the temperature of the cold iron, that is, forming a chill, so that the casting is cooled faster, especially the molten iron in the thick section and hot node can be cooled quickly to achieve a balanced cooling and solidification speed with other parts.

[0038] The cooling pipe assembly can form a suction effect with Bernoulli effect by setting the heat exchange tube 2, the air inlet pipe 4 and the air outlet pipe 3 with different inner diameters, realize and strengthen the flow of cooling media such as wind, water, oil, etc. in the heat exchange tube, take away the heat absorbed by the cold iron in the molten iron (or casting), so that the cold iron can be continuously cooled.

[0039] Specifically, the cross-sectional size of the air inlet pipe 4 is smaller than the cross-sectional size of the air outlet pipe 3, and the cross-sectional size of the air inlet pipe 4 is equivalent to or one level larger than the cross-sectional size of the heat exchange pipe 2; since the inner diameter of the air inlet pipe is smaller and the inner diameter of the air outlet pipe is larger, when the wind enters the air outlet pipe from the air inlet pipe, the wind suddenly changes from a small cavity high speed and low pressure state to a large cavity low speed and high pressure state (relatively speaking), forming a negative pressure, and the negative pressure can draw the cooling medium at the other end of the heat exchange pipe, allowing the cooling medium to enter the air outlet pipe after passing through the heat exchange pipe, and then be discharged together with the wind. In this process, the cooling medium takes away the heat of the cold iron to cool the cold iron.

[0040] The Bernoulli effect suction method adopted in this method has significant advantages over other cold iron cooling methods.

[0041] For example, when using hollow chillers, it is impossible to achieve effective connection of the chillers and the implementation process is extremely complicated and increases the workload. The wind enters from one side of the chiller and exits from the other side, which will have adverse effects. Once the wind enters the cavity and then enters the casting, it will cause unnecessary defects such as pores in the casting. When using a chiller with a steel pipe in the middle, the processing of the chiller is large (holes need to be opened), and the sealing of the pipe splicing is very important. Once the connection leaks, the wind will also blow into the sand core, sand mold, and even the cavity, causing additional quality problems for the casting.

[0042] When the cold iron and cooling pipeline arrangement scheme of this method is adopted, the heat is taken away by suction, so as to achieve heat dissipation without bringing adverse effects to the castings and causing related defects. Even if there are gaps at the joints, wind will not enter the sand core, sand mold and cavity due to negative pressure suction.

[0043] Furthermore, the central axis of the air outlet pipe 3 is perpendicular to the central axis of the heat exchange pipe 2, or the air outlet pipe 3 is arranged obliquely on the heat exchange pipe 2; the air inlet pipe 4 is arranged coaxially with the air outlet pipe 3. This arrangement allows the air outlet pipe not to discharge air toward the casting sand box or the pit, which is conducive to the rapid dispersion of the extracted hot air in the external space, rather than gathering near the sand box or the pit.

[0044] Furthermore, the air inlet pipe 4 is connected to the air compressor through a hose 5 and is provided with a control valve, and one end of the heat exchange tube 2 is exposed to the air or connected to a cold source through a pipeline; the wind pressure of the air inlet pipe is 0.4-0.8MPa.

[0045] An air compressor is used to provide compressed air to the air inlet pipe, and the control valve is equipped with a controller to adjust the air pressure entering the air inlet pipe. During the cooling process of the casting, the air pressure can be stabilized at about 0.6MPa. The other end of the heat exchange pipe, that is, the suction end, can directly absorb external cold air for heat exchange, or can be connected to a cooling medium such as water or oil to achieve a better cooling effect.

[0046] Furthermore, the heat exchange tube 2 is a retractable cooling tube structure, and / or one end of the heat exchange tube 2 away from the air outlet pipe 3 is detachably connected to a spliced ​​extension tube 6 .

[0047] For small parts within 3m in length, continuous heat exchange tubes can be used directly; for small and medium-sized parts, such as castings with a length of 3-5m, a retractable cooling tube structure can be used, which can flexibly adjust the length of the heat exchange tube to adapt to the production of castings of different lengths; for large components over 5m or even over 10m, the length of the heat exchange tube can be extended by splicing tubes so that it can be adapted to longer casting cavities.

[0048] like Figure 6 As shown, the ends of the heat exchange tube 2 and the spliced ​​extension tube 6 are provided with flange structures that match each other. The flange edges 7 can be fastened with bolts after being butt-jointed, and a sealing gasket 8 can also be provided between the flange edges 7.

[0049] like Figure 7 As shown, the ends of the heat exchange tube 2 and the spliced ​​extension tube 6 are provided with tongue-and-groove structures 9 that match each other, and are connected by plugging, which is a simple and convenient connection method.

[0050] Furthermore, the cooling pipeline assembly is multiple, such as Figure 8 As shown, a plurality of heat exchange branch pipes 10 are arranged at intervals on the heat exchange pipe 2 .

[0051] According to the large size of the casting, a plurality of cooling pipeline assemblies may be provided, and these cooling pipeline assemblies may be connected in series or in parallel using the heat exchange branch pipes to jointly exert a cooling effect.

[0052] This embodiment also provides a test method for a chilling chill device.

[0053] First, a chill 1 is made, and a groove 101 is formed on one side of the chill. The size (depth×width) of the groove 101 is 20*20mm, 25*25mm, 30*30mm, 35*35mm, 40*40mm, and 50*50mm, etc., and the length runs through the chill horizontally.

[0054] The cooling pipe assembly is laid and set in a sand box, the cavity is a rectangular cavity (taking a rectangular test block casting as an example), and the chiller is set around it. At the same time, a set of comparative sand boxes is made, in which the cooling pipe assembly is not set on the chiller around the cavity.

[0055] Through reasonable design, we completed tests such as the placement of sand molds for test blocks of air-cooled chillers, the placement of air-cooled pipes, and the fixation of air-cooled suction heads. We successfully realized the systematic application of the air-cooling device and achieved reliable air-cooling technology of chiller grooving + air-cooling pipes.

[0056] Finally, after the molten iron was poured, the air cooling channel was opened. Through the temperature measurement and temperature monitoring data, it can be seen that the comparison sand box chiller was not air-cooled, and its temperature reached 484.8℃ (red hot state, it is expected that the chiller will be saturated with heat storage after a period of time) 19 minutes after pouring. The test group chilled iron was air-cooled, and its temperature was only 274.5℃ (the chiller has strong heat storage capacity), which is only half the temperature of the comparison chilled iron. At the same time, the air-cooled inlet and outlet temperatures of the cooling pipe assembly were 32℃ and 42.3℃, with a difference of 10℃, indicating that the air cooling effect is outstanding, forming a huge temperature difference. The chilled iron + air cooling has good cooling effect, strong heat conductivity and heat storage capacity, and has a continuous cooling effect.

[0057] The control group did not add air cooling, and the contact surface between the casting and the internal cold iron tank had been oxidized after high-temperature baking. The test example cold iron + air cooling, the contact surface between the casting and the internal cold iron tank had a small amount of oxidation after high-temperature baking. At the same time, the heat exchange tube where the cold iron was placed was intact, and no carbonization or related numerical residues appeared. There was carbon black residue on both sides of the heat exchange tube. Analysis showed that it was the reaction product formed by the high-temperature evaporation of the resin in the cavity, which accumulated on the outside of the pipe under the rapid cooling of the pipe, and did not affect the cooling effect. After actual inspection, the cooling pipeline assembly did not have pits, deformation, damage, etc., and the pipeline integrity was good.

[0058] The graphite morphology of the chilled iron in the test example and the comparative example was further analyzed. The chilled iron after the test was sampled, ground, polished, photographed, and the graphite morphology was compared.

[0059] from Fig. 9 and Fig.10 It can be seen that the graphite size and quantity of the place without air cooling are smaller than that of the place with air cooling by this method, and the overall graphite roundness is not as round as that of the place with air cooling. The graphite of the place with air cooling by this method is obviously refined, rounded, and has a large number and good distribution shape. Therefore, for ductile iron, quenching will increase the diameter, size, quantity and even the roundness of graphite, which will ultimately affect the performance of the casting.

[0060] Graphite morphology analysis of sand-coated chiller. Fig.11 and Fig.12It can be seen that the graphite in the sand-coated chilled iron without air-cooling is less round than that in the sand-coated chilled iron with air-cooling by this method. The quantity is generally the same, but the graphite in the air-cooled area is obviously round and has a good distribution shape. Therefore, for ductile iron, quenching will increase the graphite diameter, size, quantity and even the roundness of the graphite, which is consistent with the previous one.

[0061] The graphite morphology of the casting specimens after the test was further analyzed. Figure 13 to Figure 16 shown.

[0062] After the air cooling of this method is implemented, the heat conducted from the casting is transferred to the cold iron, the cold iron is transferred to the cold iron trough, the cold iron trough is transferred to the heat exchange tube, and then the wind in the air outlet duct takes away the heat to achieve the effect of air cooling. It is basically a heat conduction process, so the cooling effect is good. At the same time, the air cooling after pouring continuously takes away the heat. The continuous quenching effect of the cold iron is strong, which prompts the graphite to begin nucleation and crystallization as soon as it forms nucleus. Under the continuous quenching effect of the cold iron, austenite is further formed to seal the graphite in time, and then further nucleation of graphite is promoted. The further nucleation of graphite also promotes the formation of austenite. In this cycle, the graphite is small and the number is large; while the unquenched cold iron can only perform the quenching effect in the early stage, and can only form partial graphite nucleation, and the subsequent cold iron loses the quenching effect, and the graphite cannot be quickly surrounded and sealed by austenite, and the graphite begins to grow, so that the graphite cannot become smaller, so the number of graphite is relatively small.

[0063] After adopting the air cooling method, the pearlite content in the matrix structure of the casting test block is significantly increased, by at least 5% to 20%. The new suction method of the method can achieve a better air cooling effect and can form a continuous chilling effect.

[0064] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A casting method based on a chilling chiller, characterized in that: The casting method at least includes a molding process and a pouring process; In the molding process, when making the sand core and the sand mold, a plurality of chillers and a cooling pipe assembly connecting the plurality of chillers are arranged corresponding to the thick and large sections and / or the hot spots of the casting cavity; the main body of the cooling pipe assembly is embedded and installed in the chiller, and the two ends of the cooling pipe assembly extend out of the sand core or the sand mold respectively and are exposed to the air; During the pouring process, one end of the cooling pipe assembly takes in air and forms negative pressure, so that the other end inhales air or a cold source. The air pressure of the air is adjusted as the pouring proceeds, and after the pouring is completed, the air intake continues for a period of time and then is gradually closed.

2. The casting method based on the chilling device according to claim 1, characterized in that: The chiller has a cooling working surface, which is arranged toward the casting cavity. The chiller and the main body of the cooling pipeline assembly are both pre-buried in the sand core or the sand of the sand mold.

3. The casting method based on the chilling device according to claim 1, characterized in that: When making sand cores and sand molds, the chiller is pre-assembled and connected with the cooling pipe assembly and placed in the molding sand; or the cooling pipe assembly is first arranged according to a path, and then the chiller is sequentially placed on the main part of the cooling pipe assembly; and the sand is dropped while the sand is placed to perform molding.

4. The casting method based on the chilling device according to claim 1, characterized in that: When making sand cores and sand molds, a temperature sensor is pre-embedded in the molding sand close to the chill.

5. The casting method based on the chilling device according to claim 1, characterized in that: The duration of continuous gas inflow after pouring can be minutes, hours or days.

6. The casting method based on the chilling device according to claim 1, characterized in that: The cold iron is provided with a groove on at least one side outside the cooling working surface; the cooling pipe assembly includes a heat exchange tube, and an air outlet pipe connected to one end of the heat exchange tube, the air outlet pipe is provided with an air inlet pipe at the end close to the intersection with the heat exchange tube, the inner diameter of the air inlet pipe and the inner diameter of the heat exchange tube are both smaller than the inner diameter of the air outlet pipe, and the heat exchange tube is matched and connected with the groove.

7. The casting method based on the chilling device according to claim 6, characterized in that: The central axis of the air outlet pipe is perpendicular to the central axis of the heat exchange pipe, or the air outlet pipe is arranged on the heat exchange pipe in an inclined manner; the air inlet pipe and the air outlet pipe are arranged coaxially.

8. The casting method based on the chilling device according to claim 6, characterized in that: The air inlet pipe is connected to the air compressor through a hose and is provided with a control valve. One end of the heat exchange pipe is exposed to the air or connected to a cold source through a pipeline. The wind pressure of the air inlet pipe is 0.4-0.8MPa.

9. The casting method based on the quenching chiller device according to claim 6, characterized in that: The heat exchange tube is a retractable cooling tube structure, and / or one end of the heat exchange tube away from the air outlet tube is detachably connected to a spliced ​​extension tube.

10. The casting method based on the chilling device according to claim 6, characterized in that: There are multiple cooling pipeline assemblies, and a plurality of heat exchange branch pipes are arranged at intervals on the heat exchange pipe.

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