A method for integrated assembly casting of diesel engine body sand core

Abstract

The application provides a diesel engine body sand core integrated combination casting method, which integrally produces an oil-water channel double-pipe integrated sand core with an elongated oil channel and a water channel by designing an integrated core bone with a deformation prevention function, avoids size deviation caused by separate casting of two holes, avoids internal skin seams caused by casting of multiple sand cores, and avoids leakage and oil-water pollution caused by deformation, bending and gaps of cast-in steel pipes; different coating processes are combined on the surface of the oil-water channel double-pipe integrated sand core to improve the cleanliness of the inner wall of the elongated high-temperature cavity channel, and the production efficiency in the cleaning stage is improved; the integrated sand core of the air cavity is produced to improve the internal size and surface quality of the air cavity; the integration of the cylinder hole, the crank cavity and the foot plate elements realizes one-step core production forming of the internal and external shapes of the cylinder hole, the crank cavity and the foot plate, reduces the number of sand cores, guarantees the internal and external size precision and surface quality of the engine body, and improves the efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of diesel engine casting technology, and particularly relates to a diesel engine body sand core integrated combination casting method. BACKGROUND

[0002] Diesel engine has been invented by German for more than 100 years, and has a production and use history of more than 70 years in China. The frontiers of diesel engine design and manufacturing technology have been dominated by European and American countries. For many years, China has been using the way of patent introduction to produce diesel engines. However, while introducing, digesting and absorbing, China has been persistently carrying out original design and process research and development work. In recent years, many original diesel engines with independent intellectual property rights have been successfully developed and put into use in China, and the economic benefit has been greatly improved. The situation that diesel engine power is subject to Europe and the United States has been greatly improved.

[0003] The body is the mother body of the diesel engine, and all parts of the diesel engine are supported by the body. The strength, rigidity, shock resistance and other performances of the body play a decisive role in the normal operation of the whole diesel engine. The body structure is complex, the size precision requirement is high, and the casting technology is difficult. The casting body of large diesel engine is generally produced by high-strength gray cast iron and high-strength ductile cast iron. After more than 60 years of development in China, the manufacturing technology of ductile cast iron has been very mature, and the manufacturing cost is basically close to that of high-strength gray cast iron.

[0004] The lubrication of the moving pairs such as the crankshaft, connecting rod and camshaft of the diesel engine is realized by the lubricating oil provided by the oil channel of the body. The size and quality of the oil channel play a crucial role in the operation of the whole diesel engine. In addition, if the large amount of heat generated by the diesel engine cannot be transferred out of the working part in time, the diesel engine will not work normally. The medium for transferring the heat energy generated by the diesel engine is the water provided by the water channel of the diesel engine. If the pressure and flow of the circulating water are insufficient due to various reasons, the temperature of the working parts of the diesel engine will be high and the diesel engine will not work normally. Therefore, the quality of the oil channel and water channel of the diesel engine body is very important to the whole diesel engine.

[0005] For a long time, the casting sand core of large diesel engine body produced in China is seriously fragmented, the number of sand cores is large, the operation is complicated, the quality of the inner and outer surfaces of the casting is poor, and the size precision is low.

[0006] Defects of the prior art:

[0007] The main oil channel and water channel of the large diesel engine body generally have three forming ways, which are expansion pipe, cast-in steel pipe and sand casting.

[0008] The expansion pipe is a way of embedding a steel pipe between each file to form a main oil channel and water channel by plastic deformation after the body is machined. This way is realized in the mechanical machining stage.

[0009] Both the cast-in steel pipe and the sand casting method are implemented in the blank casting stage. Both methods are implemented in production practice. Generally, the oil passage is cast in the steel pipe more, the water pipe is cast in the sand more, and the oil passage and the water passage are rarely cast in the steel pipe or cast in the sand at the same time, which is mainly due to the fact that the oil passage is formed by machining, and the cooling water passage into each cylinder is often formed by casting.

[0010] The cast-in steel pipe is a method of placing a seamless steel pipe of a certain size at the position of the oil passage or the water passage of the body, and the steel pipe is covered by the molten iron to form an integrated casting hole during pouring.

[0011] The main problem of the cast-in steel pipe method is that the steel pipe and the body have different materials, and there is a large gap in properties such as melting point and shrinkage rate, which makes it difficult for the steel pipe and the body to better fuse, and a certain gap often appears between the body and the steel pipe, as shown in Figure 9 and 10 In addition, when the camshaft and the crankshaft oil passage are machined, the gap between the steel pipe and the body in the main oil passage will increase due to the drilling pressure, so that there will be lubricating oil between the steel pipe and the body during the operation of the body, and migration will occur. These gaps will retain some metal debris generated during machining, and these metal foreign matters often cause the body to have unknown reasons for cylinder pulling and abnormal wear of the friction pair, which has a very adverse effect on the service life and safe operation of the diesel engine. In addition, the cast-in steel pipe will deform and bend due to insufficient strength and stiffness, so that the wall thickness around the oil passage or the water passage will be locally thinned, and the size of the oil passage or the water passage cannot meet the requirements, as shown in Figure 11 To reduce the deformation of the steel pipe, a certain number of core supports are generally used to fix the steel pipe, but oil or water will seep out along the gap between the core support and the body, which often causes the diesel engine to leak. Diesel engine leakage is a fatal problem in the diesel engine industry in China, and is also one of the main bottlenecks restricting the development of diesel engines in China.

[0012] The sand casting method is to set a sand core at the corresponding position of the oil passage or the water passage of the body, and then clean the sand in the oil passage and the water passage of the body after pouring the molten iron, to finally form the oil passage or the water passage of the body.

[0013] For the method of forming the oil channel and water channel of diesel engine body with sand core, since the oil channel and water channel of large diesel engine body are slender pipes with large length-diameter ratio (length / diameter is generally greater than 20), the rigidity of the sand core is poor, and the sand core will deform due to the change of gravity and buoyancy at different time during pouring. The general solution to this problem is to divide the sand core of the oil channel and water channel into multiple sections, and each section is fixed by using a core support. However, this method results in the formation of many sand core butt joints inside the oil and water pipes, which are difficult to clean due to the small size of the pipes (generally less than 100mm) and the limited space for cleaning tools. In addition, the use of core support often causes oil and water to seep out of the oil and water channels, which often leads to a decrease in water pressure and oil pressure, and the diesel engine cannot work normally.

[0014] Due to the backwardness of mold manufacturing means and the actual situation of worker operation, the types and quantities of sand cores of our large diesel engine body are numerous. Generally, the sand cores of the engine body include cylinder hole sand core, camshaft sand core, air cavity sand core, crank cavity sand core, engine body two side surface sand core, bottom plate sand core, etc., as shown in Figure 12 The size control deviation is large during the process of box matching, there are many skin joints inside and outside the casting, and the cleaning difficulty is large. The residual skin joints after cleaning affect the quality of the inner and outer surfaces of the casting, and the size uniformity and stability of the finished engine body are poor. In addition, a large amount of skin joints consume too much molten iron, which increases the cost of the engine body. Therefore, it is necessary to improve it. SUMMARY

[0015] The technical problem solved by the present application is to provide a diesel engine body sand core integrated combination casting method. The present application designs a whole core bone with a deformation prevention function, and integrally manufactures an oil and water channel double pipe whole sand core with a slender oil channel and water channel, which avoids the size deviation caused by separate casting of two holes, avoids the internal skin joint formed by casting multiple sand cores, and avoids the leakage and oil and water pollution caused by deformation, bending and gap of cast steel pipes. By combining and coating different coating processes on the surface of the oil and water channel double pipe whole sand core, the cleanliness of the inner wall of the slender high-temperature cavity pipe is improved, and the production efficiency at the cleaning stage is improved. By manufacturing a gas cavity whole sand core, the internal size and surface quality of the gas cavity are improved. By integrating the cylinder hole, crank cavity and bottom plate elements, the internal and external shapes of the cylinder hole, crank cavity and bottom plate are formed at one time, the number of sand cores is reduced, the internal and external size precision and surface quality of the engine body are ensured, and the efficiency is improved.

[0016] The technical scheme adopted by the present application is a diesel engine body sand core integrated combination casting method, comprising the following steps:

[0017] Step one: first make the oil-water channel double-pipe integral sand core, the air cavity integral sand core, the cylinder hole and the crank cavity bottom foot plate integral sand core, the cam shaft sand core, the air cavity side sand core, the free end sand core and the output end sand core respectively;

[0018] Step two: assemble the sand cores made in step one in the diesel engine body casting mold, specifically,

[0019] 1) Put the air cavity integral sand core into the casting mold, make the two end cores of the air cavity integral sand core flush with the casting mold plane, and lock the air cavity integral sand core and the casting mold at the two locking platforms in the middle lower part;

[0020] 2) Put the cam shaft sand core and the air cavity side sand core into the two sides of the diesel engine body casting mold respectively;

[0021] 3) Put the end head support sand cores of the free end sand core and the output end sand core into the lower part of the two end faces of the diesel engine body casting mold respectively;

[0022] 4) Put the oil-water channel double-pipe integral sand core on the end head support sand cores of the free end sand core and the output end sand core, and make the oil-water channel double-pipe integral sand core flush with the end head support sand cores;

[0023] 5) Put the cylinder hole and the crank cavity bottom foot plate integral sand core on the cam shaft sand core and the air cavity side sand core, and position the length direction by the side core heads of the cam shaft sand core and the air cavity side sand core, and position the width by the lower core heads of the free end sand core and the output end sand core;

[0024] 6) Put the upper sand cores of the two end heads of the free end sand core and the output end sand core on the oil-water channel double-pipe integral sand core respectively; the sand core assembly is completed;

[0025] Step three: pour the molten iron into the diesel engine body casting mold, and form the diesel engine body casting after the molten iron is cooled.

[0026] In further limitation of the above technical solution, the method for manufacturing the oil-water channel double-pipe integral sand core comprises an integral core bone, a core bone reinforcing layer for preventing deformation of the integral core bone and the sand core is arranged in the middle inner cavity of the integral core bone, and a plurality of tapered holes for better combination of the core bone and resin sand are uniformly arranged on the wall of the integral core bone; the integral core bone is placed in a mold to ensure that the core bone and the mold edge have uniform sand intake, and the minimum sand intake is greater than 20 mm; resin sand I is filled into the mold and compacted, and the strength of the resin sand I must be greater than 1.3 MPa; the mold is removed after the resin sand I is hardened for 24 hours, and the surface of the sand core is checked and finished; an anti-cracking coating is brushed on the surface of the sand core, and the thickness is 0.3 mm-0.4 mm; after 1 hour, two layers of anti-cracking cloth are continuously and uniformly wound on the surface of the sand core, and the thickness is 0.2 mm-0.3 mm; after 2 hours, a heat-resistant coating is brushed on the surface of the sand core for two times, the first time is 60-65 Be, and the second time is 40-45 Be, the interval time between the two times is 30 minutes, and the coating thickness is 0.3 mm-0.5 mm; after 1 hour, an anti-oxidation coating is brushed on the surface of the sand core for two times, the alcohol-based Be of the two times is 30-35, the interval time is 30 minutes, and the coating thickness is 0.3 mm-0.5 mm.

[0027] In further limitation of the above technical solution, the diameter of the tapered hole is φ10, the tapered holes are uniformly distributed in the circumferential direction of the integral core bone by 120°, and the length direction interval is 150 mm; the anti-cracking coating is mixed by a certain proportion of repair agent and adhesive; the anti-cracking cloth is a dense asbestos product; the heat-resistant coating is a coating prepared by mixing alcohol-based zirconium powder and chromite powder in a certain proportion; and the anti-oxidation coating is mixed by alcohol-based graphite powder in a certain proportion.

[0028] In further limitation of the above technical solution, the method for manufacturing the gas cavity integral sand core comprises the following steps: two lock core rings and accessories are placed in the middle of a mold in advance, resin sand II with a thickness of 100 mm is placed and compacted, and two core bones I with a certain length and interval are placed; resin sand II with a thickness of 150 mm is placed, and two core bones I with a certain length and interval are placed; a gas outlet fuse is placed between the two core bones I; resin sand II with a thickness of 100 mm is placed and compacted, and one core bone II with a certain length is placed; resin sand II is filled into all spaces and compacted; the mold is removed after being hardened for 24 hours, the surface of the sand core is finished, and alcohol-based silicon dioxide coating is brushed for three times with an interval of 20 minutes, and the Be is 60-65, 40-45 and 30-35 in sequence; and the gas outlet fuse is ignited.

[0029] In further limitation of the above technical solution, the method for manufacturing the cylinder hole and crankshaft cavity bottom foot plate integral sand core comprises the following steps: three-dimensional software is used to optimize and integrate the cylinder hole sand core, the crankshaft cavity sand core and the bottom foot plate sand core, so that the cylinder hole part, the inside and outside of the crankshaft cavity, the upper and lower and side surfaces of the two side bottom foot plates form the cylinder hole and crankshaft cavity bottom foot plate integral sand core.

[0030] The advantages of the present application compared with the prior art are:

[0031] 1、The scheme avoids the size deviation caused by the separate casting of two holes, improves the size precision of the relative position of the two pipelines, avoids the internal skin joint formed by the casting of multiple sand cores, greatly improves the cleaning efficiency, avoids the leakage and oil and water pollution caused by the deformation, bending and gap of the cast-in steel pipe, and improves the safety and reliability of the diesel engine;

[0032] 2、The scheme improves the high-temperature resistance and high-temperature strength of the sand core, makes the sand core cleaning more convenient, improves the cleanliness of the inner wall of the slender high-temperature cavity pipeline, improves the production efficiency in the cleaning stage, and avoids the sand sticking caused by high-temperature sintering, so that the inner surfaces of the oil channel and the water channel are smoother and cleaner;

[0033] 3、The scheme changes the previous mode of multiple sand cores and core supports, avoids the leakage caused by the use of core supports, improves the internal size of the gas cavity, and improves the compactness of the machine body; the gas cavity sand core is integrally cast, avoids the skin joint formed by the casting of multiple sand cores, improves the production efficiency, and improves the surface quality inside the gas cavity;

[0034] 4、The scheme integrates the cylinder hole, the crank cavity and the foot plate elements, realizes one-time core making of the internal and external shapes of the cylinder hole, the crank cavity and the foot plate, forms an integrated sand core of the cylinder hole, the crank cavity and the foot plate, reduces the number of sand cores by 2 / 3 compared with the previous mode, improves the efficiency, and ensures the internal and external size precision and surface quality of the machine body;

[0035] 5、Since the cylinder hole, the crank cavity and the foot plate elements are integrally cast by one sand core, the influence of human factors is avoided, the size precision of the machine body is greatly improved, the skin joint between the sand cores is avoided, the surface quality of the casting is greatly improved, the consumption of manpower and material resources in the processes of core making and skin joint cleaning is reduced, and the production cost is greatly reduced;

[0036] 6、The scheme forms a casting mold by combining sand cores, controls the chemical composition and pouring temperature by reasonable batching, and finally ensures the performance of the machine body by controlling the heating and cooling speed, holding temperature and time of heat treatment. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a schematic diagram of the overall structure of the present application;

[0038] Figure 2 is a left view of the present application; Figure 1

[0039] Figure 3 is a structural sectional view of A-A direction of the present application; Figure 1

[0040] Figure 4 is a structural sectional view of B-B direction of the present application; Figure 1

[0041] Figure 5 is a structural front view of the oil and water channel double tube integral sand core in the present application;

[0042] Figure 6 is a structural left view of the oil and water channel double tube integral sand core in the present application;

[0043] Figure 7 is a structural schematic view of the gas cavity integral sand core in the present application;

[0044] Figure 8 is a structural schematic view of the cylinder hole and crank cavity bottom foot plate integral sand core in the present application;

[0045] Figure 9 is a structural schematic view of the body and steel pipe cracking in the prior art;

[0046] Figure 10 is an enlarged schematic view of the structure of Ⅰ in Figure 9

[0047] Figure 11 is a structural schematic view of the steel pipe deformation casted in the body in the prior art;

[0048] Figure 12 is a structural schematic view of the body sand core assembly in the prior art. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0050] ​​​​It has to be understood that, in the present text, the terms "comprising", "including", or any other variant thereof, are intended to cover non-exclusive inclusions, such that processes, methods, articles, or devices that comprise a list of elements are not limited to those elements, but are also inclusive of other elements not expressly listed, or inherent to such processes, methods, articles, or devices. Without further limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or device that includes the defined element.

[0051] Reference is made to Figures 1-8 for a detailed description of embodiments of the application.

[0052] A sand core integrated combined casting method for a diesel engine block, the embodiment taking the manufacture of a 6-cylinder L-type diesel engine block as an example for illustration.

[0053] Specifically comprising the following steps:

[0054] Step one: first make the oil and water channel double-pipe integral sand core 1, the air cavity integral sand core 2, the cylinder hole and crank cavity bottom foot plate integral sand core 3, the camshaft sand core 4, the air cavity side sand core 5, the free end sand core 6, and the output end sand core 7 respectively;

[0055] The oil and water channel double-pipe integral sand core 1 is made by the method as shown in Figure 5 and 6

[0056] First, design and make the integral core bone 1-1 with sufficient strength and rigidity, in order to ensure that the outer sand core of the core bone has sufficient sand consumption, the integral core bone 1-1 is provided with a core bone reinforcing layer 1-2 in the middle of the inner cavity to prevent the integral core bone 1-1 and the sand core from deforming. In order to make the core bone and the resin sand have better bonding force and avoid the sand core from cracking, a plurality of tapered holes 1-3 for better bonding of the core bone and the resin sand are uniformly arranged on the wall of the integral core bone 1-1, the diameter of the tapered holes 1-3 is φ10, the tapered holes 1-3 are uniformly distributed in the circumferential direction of the integral core bone 1-1 by 120°, and the length direction interval is 150mm.

[0057] ​The whole core bone 1-1 is placed in a mold, ensuring that the core bone and the mold edge have uniform sand allowance, and the minimum sand allowance is greater than 20 mm; resin sand I 1-4 is filled into the mold and compacted, and the strength of the resin sand I 1-4 must be greater than 1.3 MPa; the resin sand I 1-4 is hardened for 24 hours before demolding, and the surface of the sand core is checked and finished; an anti-cracking coating 1-5 is brushed on the surface of the sand core, with a thickness of 0.3 mm-0.4 mm; after 1 hour, two layers of anti-cracking cloth 1-6 are continuously and uniformly wound on the surface of the sand core, with a thickness of 0.2 mm-0.3 mm; after 2 hours, a heat-resistant coating 1-7 is brushed on the surface of the sand core for two times, with a S.G. of 60-65 Be for the first time and a S.G. of 40-45 Be for the second time, with an interval of 30 minutes between the two times, and the coating thickness is 0.3 mm-0.5 mm; after 1 hour, an anti-oxidation coating 1-8 is brushed on the surface of the sand core for two times, with a S.G. of 30-35 Be for both times, with an interval of 30 minutes between the two times, and the coating thickness is 0.3 mm-0.5 mm.

[0058] The anti-cracking coating 1-5 is prepared by mixing a repairing agent and a bonding agent in a certain proportion, and the repairing agent and the bonding agent are configured in a proportion of 8:2; the anti-cracking cloth 1-6 is a dense asbestos product that can be purchased on the market; the heat-resistant coating 1-7 is a coating prepared by configuring alcohol-based zirconium powder and chromite powder in a certain proportion, wherein the zirconium powder and the chromite powder are mixed uniformly in a proportion of 3:7; the anti-oxidation coating 1-8 is prepared by mixing alcohol-based graphite powder in a certain proportion, wherein the graphite powder is 60-70%, the coke powder is 3%, SiC is 1%, the suspending agent is 1-3%, and 30-35% ethanol is added after dry mixing.

[0059] The manufacturing method of the gas cavity whole sand core 2 is as shown in Figure 7

[0060] Two lock core rings and accessories 2-1 are pre-placed in the middle of the mold, resin sand II 2-3 with a thickness of 100 mm is placed and compacted, two core bones I 2-2 with a length of φ45×3500 are placed, and the distance between the core bones is 110 mm; resin sand II 2-3 with a thickness of 150 mm is placed, two core bones I 2-2 with a length of φ45×3500 are placed, and the distance between the core bones I 2-2 is 110 mm; an air outlet fuse 2-5 is placed between the two core bones I 2-2; resin sand II 2-3 with a thickness of 100 mm is placed and compacted, and one core bone II 2-4 with a length of φ45×3100 is placed; resin sand II 2-3 is filled into all spaces and compacted; after hardening for 24 hours, the mold is demolded, the surface of the sand core is finished, and alcohol-based silicon dioxide coating 2-6 is brushed for three times, with an interval of 20 minutes between each time, and the S.G. is 60-65 Be, 40-45 Be, and 30-35 Be in turn; the air outlet fuse 2-5 is ignited.

[0061] The manufacturing method of the cylinder hole crank cavity bottom foot plate integrated sand core 3 is as shown in Figure 8 ​​

[0062] The cylinder hole sand core, the crank cavity sand core and the bottom plate sand core are optimized and integrated by using three-dimensional software, so that the cylinder hole part, the inside and outside of the crank cavity, the upper and lower and side of the two side bottom plates form the cylinder hole crank cavity bottom plate integrated sand core 3, the number of the combined body core is reduced by two-thirds, the production efficiency is greatly improved, the size precision of the body is ensured, and the cost is reduced.

[0063] Step two: assemble each sand core prepared in step one in the diesel engine body casting mold, specifically,

[0064] 1) Put the air cavity integrated sand core 2 into the casting mold, so that the two end cores of the air cavity integrated sand core 2 are flush with the planes of the casting mold, and the air cavity integrated sand core 2 is locked with the casting mold at the two locking platforms in the middle lower part;

[0065] 2) Put the camshaft sand core 4 and the air cavity side sand core 5 into the two sides of the diesel engine body casting mold respectively;

[0066] 3) Put the end head support sand core of the free end sand core 6 and the output end sand core 7 into the lower part of the two end faces of the diesel engine body casting mold;

[0067] 4) Put the oil and water channel double pipe integrated sand core 1 on the end head support sand core of the free end sand core 6 and the output end sand core 7, so that the oil and water channel double pipe integrated sand core 1 is flush with the end head support sand core;

[0068] 5) Put the cylinder hole crank cavity bottom plate integrated sand core 3 on the camshaft sand core 4 and the air cavity side sand core 5, and position the length direction by the side core heads of the camshaft sand core 4 and the air cavity side sand core 5, and position the width by the lower core heads of the free end sand core 6 and the output end sand core 7;

[0069] 6) Put the upper sand cores of the two end heads of the free end sand core 6 and the output end sand core 7 on the oil and water channel double pipe integrated sand core 1 respectively; the sand core assembly is completed;

[0070] Step three: after the body is assembled in the casting mold, pouring is carried out, the prepared molten iron with certain chemical composition and temperature is poured into the diesel engine body casting mold, and the diesel engine body casting is formed after the molten iron is cooled.

[0071] The casting process of the method comprises the following steps: smelting, composition control, high-temperature standing treatment, iron liquid spheroidizing treatment, iron liquid inoculation treatment, iron liquid purification treatment, and casting process. The specific method is as follows: 60-70% Q10 pig iron, 20% scrap steel, and 10-20% return material are smelted in a medium-frequency furnace, and the temperature is raised to 1430-1460 DEG C. The iron liquid at a position 80-150 mm below the liquid surface is scooped up with a sample spoon to cast spectroscopic samples and chemical samples for chemical composition analysis. The iron liquid is subjected to standing treatment at 1500 DEG C-1530 DEG C for 10-15 minutes, spheroidizing treatment and first inoculation at 1480 DEG C-1510 DEG C in a dam type spheroidizing ladle, and second inoculation is performed when 2 / 3-3 / 4 of the iron liquid is discharged, and the dosage of the second inoculant is 0.3-0.6% of the total amount of the iron liquid. The iron liquid is poured into a pouring cup containing a third inoculant, and the dosage of the third inoculant is 0.1-0.4% of the amount of the iron liquid. When the temperature of the iron liquid in the pouring cup is 1350-1390 DEG C, the iron liquid control gate is started, and the iron liquid is poured into the casting mold to form a casting after solidification.

[0072] The casting process of the method can adopt the following modes:

[0073] The method is subjected to standing treatment at 1480 DEG C-1520 DEG C for 10-20 minutes before discharging.

[0074] The pouring ladle of the method adopts a dam type pouring ladle, and a sandwich type ladle filling method is adopted. From bottom to top, the layers are spheroidizing agent layer, inoculant layer, carbon additive layer, iron scrap layer, and steel plate. The thickness of the iron scrap layer is 30-40 mm, and the thickness of the steel plate is 10-20 mm.

[0075] The spheroidizing agent in the method is ADLLOY6RE type rare earth magnesium alloy spheroidizing agent, and the particle size is 10-30 mm. The first and second inoculants are a mixture of 75SiFe and Incollin380, and the proportion is half each, and the particle sizes are 3-8 mm and 15-35 mm respectively. The first inoculant is filled in the spheroidizing treatment ladle, and the second inoculant is used for stream inoculation when 3 / 4 of the iron liquid is discharged. The third inoculant is Incollin380, and the particle size is 0.5-1.5 mm. The third inoculant is used for instantaneous inoculation in the pouring cup. The total amount of the inoculants is controlled to be 0.8-1.5% of the weight of the iron liquid.

[0076] The iron liquid pouring of the method adopts a bottom pouring system, and the liquid level rising speed of the iron liquid in the casting mold is 20 mm / s, the pouring time is 100-120 seconds, and the pouring weight is 14 tons.

[0077] The fuse, ADLLOY6RE type rare earth magnesium alloy spheroidizing agent, 75SiFe, and Incollin380 inoculant used in the method can be purchased in the market.

[0078] The following is a test verification embodiment for manufacturing a 6-cylinder L-shaped diesel engine body using the method.

[0079] The material used in the implementation is QT400-15A nodular cast iron, and the smelting ingredient control is shown in Table 1. The main chemical component control in the smelting process in the inventive example is shown in Table 2. The pouring temperature, time and other parameter control in the inventive example is shown in Table 3.

[0080] By comparing the test results with the standard parameters of the main evaluation indicators, it can be seen that the QT400-15A with different components above all meet the performance requirements of the diesel engine body. At the same time, the inventive cast engine body does not leak in the water channel and oil channel after a 1.5 MPa, 30-minute water pressure test. The engine body is checked and processed, and the size and shape meet the requirements. Therefore, the modeling, smelting and pouring process of the diesel engine body is feasible.

[0081] Table 1: Smelting ingredient control

[0082]

[0083] Table 2: Smelting chemical components

[0084] C Si Mn P S 3.3-3.9 1.2-1.8 0.2-0.6 ≤0.035 ≤0.020 Cu Ni Cr Mo Ti ＜0.1 ＜0.1 ＜0.05 ＜0.05 ≤0.020

[0085] Table 3: Pouring parameter control

[0086]

[0087] The present application avoids the size deviation caused by separate casting of two holes, avoids the internal skin seam caused by casting of multiple sand cores, avoids the leakage and oil and water pollution caused by deformation, bending and gap of cast-in steel pipes, etc. by designing an integral core bone with a deformation prevention function, and by one-time integral production of an oil and water channel double-pipe integral sand core with an elongated oil channel and water channel. The cleanliness of the inner wall of the elongated high-temperature cavity pipe is improved by combining different coating processes on the surface of the oil and water channel double-pipe integral sand core, and the production efficiency in the cleaning stage is improved. The internal size and surface quality of the air cavity are improved by making an air cavity integral sand core. The internal and external shapes of the cylinder hole, crank cavity and foot plate elements are formed at one time by integrating the cylinder hole, crank cavity and foot plate elements, reducing the number of sand cores, ensuring the internal and external size precision and surface quality of the engine body, and improving the efficiency.

[0088] It will be obvious to a person skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments and can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. The embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference signs in the claims should be considered as limiting the scope of the claims to the identity of the reference signs therein.

[0089] Furthermore, it should be understood that although the description is made on the basis of the embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method of integrated sand core and block casting of a diesel engine block, characterized by: It comprises the following steps: Step one: first make the oil-water channel double-pipe integral sand core (1), the air cavity integral sand core (2), the cylinder hole and the crank cavity bottom foot plate integral sand core (3), the camshaft sand core (4), the air cavity side sand core (5) and the free end sand core (6) and the output end sand core (7) respectively; Step two: assemble the sand cores made in step one in the diesel engine body casting mold, specifically, 1) place the air cavity integral sand core (2) in the casting mold, make the two end cores of the air cavity integral sand core (2) flush with the casting mold plane, lock the air cavity integral sand core (2) and the casting mold at the two lower locking platforms in the middle; 2) place the camshaft sand core (4) and the air cavity side sand core (5) in the two sides of the diesel engine body casting mold respectively; 3) place the lower end core support sand cores of the free end sand core (6) and the output end sand core (7) into the lower part of the two end faces of the diesel engine body casting mold; 4) place the oil-water channel double-pipe integral sand core (1) on the lower end core support sand cores of the free end sand core (6) and the output end sand core (7), make the oil-water channel double-pipe integral sand core (1) flush with the lower end core support sand cores; 5) place the cylinder hole and the crank cavity bottom foot plate integral sand core (3) on the camshaft sand core (4) and the air cavity side sand core (5), position it in the length direction by the side cores of the camshaft sand core (4) and the air cavity side sand core (5), and position it in the width direction by the lower cores of the free end sand core (6) and the output end sand core (7); 6) place the upper sand cores of the two end cores of the free end sand core (6) and the output end sand core (7) on the oil-water channel double-pipe integral sand core (1); the sand core assembly is completed; Step three: pour the prepared molten iron into the diesel engine body casting mold, and form the diesel engine body casting after the molten iron is cooled.

2. A method of integrated group casting of diesel engine blocks according to claim 1, characterized in that: The method for making the oil-water channel double-pipe integral sand core (1) comprises an integral core bone (1-1), a core bone reinforcing layer (1-2) is arranged in the middle of the inner cavity of the integral core bone (1-1) to prevent the integral core bone (1-1) and the sand core from deforming, and a plurality of tapered holes (1-3) are uniformly arranged on the wall of the integral core bone (1-1) to better combine the core bone and the resin sand; the integral core bone (1-1) is placed in a mold to ensure that the core bone and the mold edge eat sand uniformly, and the minimum sand eating amount is greater than 20 mm; resin sand I (1-4) is filled into the mold and compacted, and the strength of the resin sand I (1-4) must be greater than 1.3 MPa; the mold is removed after the resin sand I (1-4) is hardened for 24 hours, the surface of the sand core is checked and finished; an anti-cracking coating (1-5) is brushed on the surface of the sand core, and the thickness is 0.3-0.4 mm; two layers of crack-resistant cloth (1-6) are continuously and uniformly wound on the surface of the sand core after 1 hour, and the thickness is 0.2-0.3 mm; heat-resistant coating (1-7) is brushed on the surface of the sand core for two times after 2 hours, the first time is 60-65 Be, and the second time is 40-45 Be, the interval time between the two times is 30 minutes, and the coating thickness is 0.3-0.5 mm; antioxidant coating (1-8) is brushed on the surface of the sand core for two times after 1 hour, the two times are both 30-35 Be, the interval time is 30 minutes, and the coating thickness is 0.3-0.5 mm.

3. A method of integrated group casting of diesel engine blocks according to claim 2, wherein: The diameter of the taper hole (1-3) is φ10, the taper hole (1-3) is uniformly distributed in the circumferential direction of the whole core bone (1-1) by 120°, and the length direction interval is 150mm; the anti-cracking coating (1-5) is mixed by a certain proportion of repair agent and adhesive; the anti-cracking cloth (1-6) is a dense asbestos product; the heat-resistant coating (1-7) is a coating prepared by mixing alcohol-based zirconium powder and chromite powder in a certain proportion; and the antioxidant coating (1-8) is mixed by alcohol-based graphite powder in a certain proportion.

4. A method of integrated group casting of diesel engine blocks as claimed in claim 1 wherein: The production method of the air cavity integral sand core (2) is as follows: two lock core rings and accessories (2-1) are placed in the middle of the mold, resin sand II (2-3) with a thickness of 100mm is placed and compacted, two core bones I (2-2) with a certain length and interval are placed, resin sand II (2-3) with a thickness of 150mm is placed, two core bones I (2-2) with a certain length and interval are placed, an air outlet fuse (2-5) is placed between the two core bones I (2-2), resin sand II (2-3) with a thickness of 100mm is placed and compacted, and one core bone II (2-4) with a certain length is placed; resin sand II (2-3) is filled into all spaces and compacted; after hardening for 24 hours, the mold is removed, the surface of the sand core is finished, and alcohol-based silicon dioxide paint (2-6) is brushed three times, with an interval of 20 minutes each time, and the Baume degrees are 60-65Be, 40-45Be and 30-35Be in turn; the air outlet fuse (2-5) is ignited.

5. A method of integrated group casting of diesel engine blocks as claimed in claim 1 wherein: The production method of the cylinder hole-crankshaft cavity foot plate integrated sand core (3) is as follows: the inner and outer shape structures of the cylinder hole sand core, the crankshaft cavity sand core and the foot plate sand core are optimized and integrated by using three-dimensional software, so that the cylinder hole part, the inner and outer parts of the crankshaft cavity, the upper and lower parts of the two side foot plates and the side surfaces form the cylinder hole-crankshaft cavity foot plate integrated sand core (3).

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