CN115921791A - Diesel engine body sand core integration combined casting method - Google Patents

Abstract

The integrated combined casting method for the sand core of the diesel engine body is provided, the integral core rod with the deformation prevention function is designed, the oil-water channel double-pipe integral sand core with the long and thin oil channel and the water channel is integrally manufactured at one time, the size deviation caused by the independent casting of two holes is avoided, the internal skin seam formed by casting a plurality of sand cores is avoided, and the leakage and oil-water pollution caused by the deformation, bending, seam and the like of a cast steel pipe are avoided; by combining and coating different coating processes on the surface of the oil-water channel double-pipe integral sand core, the cleanliness of the inner wall of the long and thin high-temperature cavity pipeline is improved, and the production efficiency in a cleaning stage is improved; the internal size and the surface quality of the air cavity are improved by manufacturing the integral sand core of the air cavity; by integrating the cylinder hole, the crankshaft cavity and the base plate, the internal and external shapes of the cylinder hole, the crankshaft cavity, the base plate and the like are formed by one-time core making, the number of sand cores is reduced, the internal and external dimensional precision and the surface quality of the machine body are ensured, and the efficiency is improved.

Description

Diesel engine body sand core integration combined casting method

Technical Field

The invention belongs to the technical field of diesel engine casting, and particularly relates to a method for casting a sand core of a diesel engine body in an integrated combination manner.

Background

The diesel engine invented by German people for over one hundred years, and in China, the diesel engine has more than seventy years of production and use history. The design and manufacture frontier technology of the diesel engine is always dominated by Europe and America, china always adopts a patent introduction mode to produce and manufacture the diesel engine for many years, but the introduction, digestion and absorption of the diesel engine and the original design, process research and development work of China are always carried out persistently, in recent years, a plurality of original diesel engines with independent property rights are successfully developed and put into use in China, the economic benefit is greatly improved, and the situation that the power of the diesel engine is restricted by Europe and America is greatly improved.

The engine body is a matrix of the diesel engine, all parts of the diesel engine are supported by the engine body, and the strength, rigidity, shock resistance and other properties of the engine body play a decisive role in the normal operation of the whole diesel engine. The machine body has complex structure, high requirement on size precision and great difficulty in casting technology. The large diesel engine casting body is generally produced by two materials of high-strength gray cast iron and ductile cast iron with higher strength and toughness. After more than sixty years of development of nodular cast iron in China, the manufacturing technology is mature, and the manufacturing cost of the nodular cast iron is basically close to that of high-strength gray cast iron.

The lubrication of the kinematic pairs such as a crankshaft, a connecting rod, a camshaft and the like of the diesel engine is realized by lubricating oil provided by an oil duct of the engine body, and the size and the quality of the oil duct play an important role in the operation of the whole diesel engine. In addition, if a large amount of heat generated by the diesel engine cannot be transferred out of a working position in time, the diesel engine cannot work normally, and the medium for transferring out the heat generated by the diesel engine is realized by water with a certain flow rate provided by a water channel of the diesel engine. If the pressure and flow of the circulating water are insufficient due to various reasons, the temperature of working parts of the diesel engine is high, and the diesel engine cannot normally operate. Therefore, the quality of the oil passage and the water passage of the diesel engine body is very important for the whole diesel engine.

The large diesel engine body casting sand core produced in China for a long time has the disadvantages of serious fragmentation degree, large quantity of sand cores, complex operation, poor quality of the inner and outer surfaces of a casting and low size precision.

The defects of the prior art are as follows:

the main oil passage and the water passage of the large diesel engine body generally have three forming modes, namely pipe expanding, steel pipe casting and sand casting.

The tube expansion is realized in the machining stage by embedding steel tubes between all the gears in a plastic deformation mode to form a main oil duct and a water duct after the machine body is machined.

Both the cast-in steel tube and the sand casting are performed at the blank casting stage. Both methods are practiced in production practice. Generally, many oil passages are cast into steel pipes, many water pipes are cast by sand, and oil passages and water passages are rarely cast into steel pipes or sand at the same time.

The cast-in steel pipe is a cast hole forming method in which seamless steel pipes with certain sizes are respectively placed at the positions of an oil passage or a water passage of a machine body, and the steel pipes are coated by molten iron to form a whole during casting.

The main problem of the cast steel pipe is that the cast steel pipe and the machine body are made of different materials, and the melting point, shrinkage rate and other properties of the cast steel pipe and the machine body have large differences, so that the steel pipe and the machine body are difficult to fuse well, and a certain gap a is often formed between the machine body and the steel pipe, as shown in fig. 9 and 10. In addition, when the camshaft and the Qu Zhouzhi oil duct are machined subsequently, due to the action of drilling pressure, the gap between the steel pipe and the main body in the main oil duct is increased, so that lubricating oil exists between the steel pipe and the main body of the engine body during the operation of the engine body and migrates, metal chips generated during machining can be reserved in the gaps, the metal foreign bodies often cause abnormal abrasion of a cylinder pulling and a friction pair of the engine body due to unknown reasons, and the service life and the safe operation of the diesel engine are greatly adversely affected. In addition, the cast-in steel pipe may be deformed b or bent due to insufficient strength and rigidity, so that the wall thickness around the oil passage or water passage may be locally thinned, and the dimensions of the oil passage or water passage may not meet the requirements, as shown in fig. 11. The measures generally taken to reduce the deformation of the steel pipe are to fix the steel pipe by using a certain number of core supports, but oil or water can seep out along the core supports and gaps between the steel pipe and the body, so that the diesel engine often leaks as a result, and the oil leakage and the water leakage of the diesel engine are fatal and stubborn diseases in the diesel engine industry in China and are one of main bottlenecks restricting the development of the diesel engine in China.

The sand casting method is that sand cores are arranged at corresponding positions of the oil duct or the water duct of the engine body, sand in the oil duct and the water duct of the engine body is cleaned after molten iron is poured, and finally the oil duct or the water duct of the engine body is formed.

As for the method for forming the oil duct and the water duct of the diesel engine body by using the sand core, the oil duct and the water duct of the large diesel engine body are long and thin ducts, the long diameter is large (the length/the diameter are generally more than 20), the rigidity of the sand core is poor, and the sand core can deform due to continuous change of gravity and buoyancy at different time intervals in the pouring process. The common method for solving the problem is to divide the sand core of the oil duct and the water duct into a plurality of sections, and each section is fixed by using a chaplet. However, as a result of the method, a plurality of sand core butt joint skin seams are formed inside the oil and water pipelines, and the inner size of the pipelines is small (generally less than 100 mm), so that the pipeline is difficult to observe and clean, and the cleaning tool is limited by space, so that the cleaning of the inner skin seams of the pipelines is very difficult; in addition, the core support often leaks oil and water through the core support, so that the water pressure and the oil pressure are reduced, and the diesel engine cannot work normally.

Because the manufacturing means of the mold is lagged behind, the practical situation of operation of workers is considered, the sand cores of the large diesel engine body are various in types and quantity, and the general body sand cores comprise cylinder hole sand cores, camshaft sand cores, air cavity sand cores, crankshaft cavity sand cores, sand cores on two side surfaces of the body, baseboard sand cores and the like, as shown in figure 12. The size control deviation is large in the box matching process, skin seams on the inner surface and the outer surface of a casting are more, interweaving exists in different directions, the cleaning difficulty of the casting is large, the quality of the inner surface and the outer surface of the casting is affected by the skin seam residues after cleaning, and the size uniformity and the stability of a finished product machine body are poor. In addition, a large number of skin seams consume excessive molten iron, and the cost of the machine body is increased. There is therefore a need for improvements.

Disclosure of Invention

The technical problems solved by the invention are as follows: the invention provides an integrated combined casting method for a sand core of a diesel engine body, which integrally manufactures an oil-water channel double-pipe integral sand core with a long and thin oil channel and a water channel at one time by designing an integral core rod with a deformation prevention function, thereby avoiding the size deviation caused by independent casting of two holes, avoiding the internal skin seams formed by casting a plurality of sand cores, and avoiding the leakage and oil-water pollution caused by the deformation, bending, gaps and the like of cast steel pipes; by combining and coating different coating processes on the surface of the oil-water channel double-pipe integral sand core, the cleanliness of the inner wall of the long and thin high-temperature cavity pipeline is improved, and the production efficiency in a cleaning stage is improved; the internal size and the surface quality of the air cavity are improved by manufacturing the integral sand core of the air cavity; by integrating the cylinder hole, the crankshaft cavity and the base plate, the internal and external shapes of the cylinder hole, the crankshaft cavity, the base plate and the like are formed by one-time core making, the number of sand cores is reduced, the internal and external dimensional precision and the surface quality of the machine body are ensured, and the efficiency is improved.

The technical scheme adopted by the invention is as follows: a method for integrally and compositely casting a sand core of a diesel engine body comprises the following steps:

the method comprises the following steps: firstly, respectively manufacturing an oil-water channel double-pipe integral sand core, an air cavity integral sand core, a cylinder hole crankshaft cavity base plate integral sand core, a camshaft sand core, an air cavity side sand core, a free end sand core and an output end sand core;

step two: assembling each sand core manufactured in the step one in a diesel engine body casting mould,

1) Placing the integral sand core of the air cavity into a casting mold, enabling core heads at two ends of the integral sand core of the air cavity to be flush with the plane of the casting mold, and locking the integral sand core of the air cavity and the casting mold at two locking platforms at the lower middle part;

2) Respectively placing a camshaft sand core and a gas cavity side sand core at two sides of a diesel engine body casting mold;

3) Respectively placing the end supporting sand cores of the free end sand core and the output end sand core into the lower parts of two end surfaces of a diesel engine body casting mold;

4) Placing the oil-water channel double-pipe integral sand core on the free end sand core and the end support sand core of the output end sand core, and keeping the oil-water channel double-pipe integral sand core level with the end support sand core;

5) Placing the cylinder hole crankshaft cavity base plate integrated sand core on the camshaft sand core and the air cavity side sand core, wherein the length direction is positioned by the camshaft sand core and the side core head of the air cavity side sand core, and the width is positioned by the free end sand core and the lower core head of the output end sand core;

6) Respectively placing upper sand cores at two ends of the free end sand core and the output end sand core on the oil-water channel double-pipe integral sand core; completing the assembly of the sand core;

step three: and pouring the prepared molten iron into a diesel engine body casting mold, and cooling the molten iron to form a diesel engine body casting.

Further limiting the technical scheme, the manufacturing method of the oil-water channel double-pipe integral sand core comprises the following steps: the core-sand core comprises an integral core, wherein a core strengthening layer for preventing the deformation of the integral core and a sand core is arranged in the middle of the inner cavity of the integral core, and a plurality of taper holes for better combining the core and the resin sand are uniformly formed in the wall of the integral core; the integral core bar is placed in a mould, so that the core bar and the edge of the mould are ensured to have uniform sand consumption, and the minimum sand consumption is more than 20mm; filling resin sand I into the mould and compacting, wherein the strength of the resin sand I is more than 1.3MPa; after the resin sand I is hardened for 24 hours, stripping, checking and finishing the surface of the sand core; coating an anti-cracking coating on the surface of the sand core, wherein the thickness is 0.3mm-0.4mm; 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 0.2mm-0.3mm; after 2 hours, brushing a heat-resistant coating on the surface of the sand core twice, wherein the first time of baume degree is 60-65Be, the second time of baume degree is 40-45Be, the interval time of the two times is 30 minutes, and the thickness of the coating is 0.3-0.5 mm; and after 1 hour, painting an antioxidant coating on the surface of the sand core twice, wherein the baume degrees of the two times are both 30-35Be, the interval time is 30 minutes, and the thickness of the coating is 0.3-0.5 mm.

The technical scheme is further limited, the diameter of the taper holes is phi 10, the taper holes are uniformly distributed in the circumferential direction of the whole core bone at 120 degrees, and the distance in the length direction is 150mm; the anti-cracking coating is formed by mixing a repairing agent and a binder according to a certain proportion; the anti-cracking cloth is a compact asbestos product; the heat-resistant coating is prepared by adopting alcohol-based zircon powder and chromite powder according to a certain proportion; the oxidation-resistant coating is prepared by mixing alcohol-based graphite powder according to a certain proportion.

Further limiting the technical scheme, the manufacturing method of the integral sand core of the air cavity comprises the following steps: placing two lock core rings and accessories in the middle of a mould in advance, placing resin sand II with the thickness of 100mm and compacting, and placing two core rods I with certain length and distance; resin sand II with the thickness of 150mm is placed, and two core rods I with certain length and interval are placed; an air outlet fuse is arranged between the two core rods I; putting resin sand II with the thickness of 100mm, compacting, and putting a core rod II with a certain length; filling resin sand II into all the spaces and compacting; drawing a die after hardening for 24 hours, finishing the surface of the sand core, and brushing three times of alcohol-based silicon dioxide coating at intervals of 20 minutes, wherein the Baume degrees are 60-65Be, 40-45Be and 30-35Be in sequence; the gas outlet fuse is ignited.

Further limiting the technical scheme, the manufacturing method of the integrated sand core of the bottom plate of the cylinder bore crankshaft cavity comprises the following steps: and optimizing and integrating the cylinder hole sand core, the crankshaft cavity sand core and the base plate sand core by using three-dimensional software, so that the cylinder hole part, the inner part and the outer part of the crankshaft cavity, the upper part and the lower part of the base plates on two sides and the side surfaces form the cylinder hole, the crankshaft cavity and the base plate integrated sand core.

Compared with the prior art, the invention has the advantages that:

1. according to the scheme, the integral core rod with the deformation prevention function is designed, the oil-water channel double-pipe integral sand core with the long and thin oil channel and the water channel is accurately formed through one-time integral manufacturing, the size deviation caused by independent casting of two holes is avoided, the size precision of the relative positions of the two pipelines is improved, the internal skin seams formed by casting of a plurality of sand cores are avoided, and the cleaning efficiency is greatly improved; the leakage and oil-water pollution caused by the deformation, bending, gaps and the like of the cast steel pipe are avoided, and the safety and reliability of the diesel engine are improved;

2. according to the scheme, different combined use processes of anti-cracking, high-temperature-resistant and anti-oxidation coatings are combined and coated on the surface of the oil-water channel double-pipe integral sand core, so that the high-temperature tolerance and high-temperature strength of the sand core are improved, the sand core is cleaned more conveniently, the cleanliness of the inner wall of the long and thin high-temperature cavity channel pipeline is improved, the production efficiency of a cleaning stage is improved, sand sticking caused by high-temperature sintering is avoided, and the inner surfaces of an oil channel and a water channel are smoother and cleaner;

3. according to the scheme, the whole sand core of the air cavity is manufactured, and the whole air cavity with sealed multiple surfaces is formed at one time in a reverse locking mode, so that the conventional mode of fixing a plurality of sand cores and chaplets is changed, the leakage phenomenon caused by using the chaplets is avoided, the internal size of the air cavity is improved, and the compactness of a machine body is improved; the air cavity sand core is integrally cast, so that skin seams formed by casting a plurality of sand cores are avoided, the production efficiency is improved, and the surface quality inside the air cavity is improved;

4. according to the scheme, the cylinder hole, the crankshaft cavity and the base plate element are integrated, so that the integrated sand core of the cylinder hole, the crankshaft cavity and the base plate of the crankshaft cavity is formed by one-time core making of the inner shapes and the outer shapes of the cylinder hole, the crankshaft cavity, the base plate and the like, the number of sand cores is reduced by 2/3 compared with the number of the sand cores in the past, the efficiency is improved, and the dimensional accuracy and the surface quality of the inner side and the outer side of a machine body are guaranteed;

5. because the cylinder hole, the crankshaft cavity and the base plate are integrally cast by one sand core, the influence of human factors is avoided, and the size precision of the engine body is greatly improved; the skin seam between the sand cores is avoided, the surface quality of the casting is greatly improved, the manpower and material resources consumed by the core making, skin seam cleaning and other processes are reduced, and the production cost is greatly reduced;

6. according to the scheme, the sand cores are combined to form a casting mold, chemical components and casting temperature are controlled through reasonable proportioning, reasonable spheroidizing inoculation is carried out, molten iron is poured into the casting mold, and various performances of a machine body are finally guaranteed through controlling the temperature rising and falling speed, the heat preservation temperature and the heat preservation time of heat treatment.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a left side view of FIG. 1 of the present invention;

FIG. 3 isbase:Sub>A sectional view taken along line A-A of FIG. 1 according to the present invention;

FIG. 4 is a sectional view taken along line B-B of FIG. 1 according to the present invention;

FIG. 5 is a front view of the structure of the oil-water channel double-barreled integral sand core of the present invention;

FIG. 6 is a left side view of the structure of the oil-water channel double-barreled integral sand core of the present invention;

FIG. 7 is a schematic structural view of the air cavity integral sand core of the present invention;

FIG. 8 is a schematic structural diagram of an integrated sand core of a bottom foot plate of a cylinder bore crankshaft cavity in the present invention;

FIG. 9 is a schematic view of the structure of the cracking of the steel pipe and the machine body in the prior art;

FIG. 10 is an enlarged view of the section I in FIG. 9;

FIG. 11 is a schematic view showing a configuration of a prior art deformation of a cast-in steel pipe in a machine body;

fig. 12 is a schematic view of an assembly structure of a sand core of a machine body in the prior art.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation. The use of the verb "to comprise a" does not exclude the presence of other, identical elements in a process, method, article or apparatus that comprises a stated element.

Referring to fig. 1-8, embodiments of the present invention are described in detail.

The manufacturing of the engine body of the 6-cylinder L-shaped diesel engine is taken as an example for explanation.

The method specifically comprises the following steps:

the method comprises the following steps: firstly, respectively manufacturing an oil-water channel double-pipe integral sand core 1, an air cavity integral sand core 2, a cylinder hole crankshaft cavity base plate integral sand core 3, a camshaft sand core 4, an air cavity side surface sand core 5, a free end sand core 6 and an output end sand core 7;

the manufacturing method of the oil-water channel double-pipe integral sand core 1 is shown in figures 5 and 6:

firstly, designing and manufacturing an integral core 1-1 with enough strength and rigidity, and in order to ensure that the sand core outside the core has enough sand eating amount, the middle part of the inner cavity of the integral core 1-1 is provided with a core strengthening layer 1-2 for preventing the integral core 1-1 and the sand core from deforming. In order to enable the core bone and the resin sand to have better bonding force and avoid the sand core from cracking, a plurality of taper holes 1-3 enabling the core bone and the resin sand to be better bonded are uniformly arranged on the wall of the integral core bone 1-1, the diameter of each taper hole 1-3 is phi 10, the taper holes 1-3 are uniformly distributed in the circumferential direction of the integral core bone 1-1 at 120 degrees, and the distance in the length direction is 150mm.

The integral core rod 1-1 is placed in a mould, so that the core rod and the edge of the mould are ensured to have uniform sand eating amount, and the minimum sand eating amount is more than 20mm; filling and compacting resin sand I1-4 into the mould, wherein the strength of the resin sand I1-4 is required to be more than 1.3MPa; after the resin sand I is hardened for 24 hours 1-4, stripping, checking and finishing the surface of the sand core; coating 1-5 of anti-cracking coating with the thickness of 0.3-0.4 mm on the surface of the sand core; after 1 hour, continuously and uniformly winding 1-6 layers of anti-cracking cloth on the surface of the sand core, wherein the thickness is 0.2-0.3 mm; after 2 hours, coating a heat-resistant coating on the surface of the sand core for 1-7 times, wherein the baume degree of the first time is 60-65Be, the baume degree of the second time is 40-45Be, the interval time of the two times is 30 minutes, and the thickness of the coating is 0.3-0.5 mm; and after 1 hour, the surface of the sand core is coated with the antioxidant coating for 1 to 8 times, wherein the baume degrees of the two times are both 30 to 35Be, the interval time is 30 minutes, and the thickness of the coating is 0.3 to 0.5mm.

The anti-cracking coatings 1-5 are formed by mixing a repairing agent and an adhesive in a certain ratio, and the repairing agent and the adhesive are prepared in a ratio of 8:2; the anti-cracking cloth 1-6 is a compact asbestos product and can be purchased in the market; the heat-resistant coatings 1-7 are coatings prepared by alcohol-based zircon powder and chromite powder according to a certain proportion, wherein the zircon powder and the chromite powder are uniformly mixed according to a proportion of 3:7; the oxidation resistant coating 1-8 is prepared by mixing alcohol-based graphite powder according to 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 after being uniformly mixed in a dry state, 30-35% ethanol is added and uniformly stirred.

The manufacturing method of the integral sand core 2 of the air cavity is shown in fig. 7:

placing two lock core rings and accessories 2-1 in the middle of a mold in advance, placing resin sand II 2-3 with the thickness of 100mm and compacting, placing two core frames I2-2 with the length phi of 45 multiplied by 3500, and enabling the distance between the core frames to be 110mm; resin sand II 2-3 with the thickness of 150mm is placed, two mandrels I2-2 with the length phi of 45 multiplied by 3500 are placed, and the distance between the mandrels I2-2 is 110mm; 2-5 of an air outlet blasting fuse is arranged between the two core rods I2-2; putting 2-3 of resin sand II with the thickness of 100mm, compacting, and putting 2-4 of core bones II with the length of phi 45 multiplied by 3100; filling resin sand II 2-3 into all the spaces and compacting; drawing a die after hardening for 24 hours, finishing the surface of the sand core, and brushing alcohol-based silicon dioxide paint for three times at intervals of 20 minutes for 2-6 times, wherein the Baume degrees are 60-65Be, 40-45Be and 30-35Be in sequence; igniting the gas outlet fuse 2-5.

The manufacturing method of the cylinder bore crankshaft cavity base plate integrated sand core 3 is as shown in FIG. 8:

the cylinder hole sand core, the crankshaft cavity sand core and the base plate sand core are optimized and integrated by utilizing three-dimensional software, so that the cylinder hole position, the inside and outside of the crankshaft cavity, the base plates on the two sides, the upper part and the lower part of the base plates on the two sides and the side surface form the cylinder hole and crankshaft cavity base plate integrated sand core 3, the number of the combined machine body mud cores is reduced by two thirds, the production efficiency is greatly improved, the size precision of a machine body is ensured, and the cost is reduced.

Step two: assembling each sand core manufactured in the first step in a diesel engine body casting mould, specifically,

1) Placing the integral sand core 2 of the air cavity into a casting mold, enabling core heads at two ends of the integral sand core 2 of the air cavity to be flush with the plane of the casting mold, and locking the integral sand core 2 of the air cavity and the casting mold at two locking platforms at the lower middle part;

2) Respectively placing a camshaft sand core 4 and an air cavity side sand core 5 on two sides of a diesel engine body casting mold;

3) Respectively placing the end supporting sand cores of the free end sand core 6 and the output end sand core 7 into the lower parts of two end surfaces of a diesel engine body casting mold;

4) Placing the oil-water channel double-pipe integral sand core 1 on the end support sand core of the free end sand core 6 and the output end sand core 7, and keeping the oil-water channel double-pipe integral sand core 1 and the end support sand core flush;

5) Placing the cylinder hole crankshaft cavity base plate integrated sand core 3 above the camshaft sand core 4 and the air cavity side sand core 5, wherein the length direction is positioned by the side core heads of the camshaft sand core 4 and the air cavity side sand core 5, and the width is positioned by the lower core heads of the free end sand core 6 and the output end sand core 7;

6) Respectively placing upper sand cores at two ends of a free end sand core 6 and an output end sand core 7 on the oil-water channel double-pipe integral sand core 1; completing the assembly of the sand core;

step three: pouring the engine body after the engine body is assembled in the casting mold, pouring the prepared molten iron with certain chemical vehicle components and temperature into the diesel engine body casting mold, and cooling the molten iron to form a diesel engine body casting.

The casting molding of the method comprises the processes of molten iron melting, component control, high-temperature standing treatment, molten iron spheroidizing treatment, molten iron inoculation treatment, molten iron purification treatment and casting, and the casting process is the prior art. The specific method comprises the following steps: smelting 60-70% of Q10 pig iron, 20% of scrap steel, 10-20% of scrap returns and the like in an intermediate frequency furnace, raising the temperature to 1430-1460 ℃, scooping iron liquid 80-150mm below the liquid level by a sample spoon, and respectively pouring a spectrum sample and a chemical sample for chemical component analysis. Standing for 10-15 minutes at 1500-1530 ℃, carrying out spheroidization and primary inoculation at 1480-1510 ℃ in a dam-type spheroidizing ladle, controlling a spheroidizing agent to be 1.0-1.5 percent of the weight of molten iron, controlling a primary inoculant to be 0.4-0.5 percent of the total amount of the molten iron, carrying out stream-following secondary inoculation when the molten iron is discharged at 2/3-3/4, controlling the secondary inoculant to be 0.3-0.6 percent of the total amount of the molten iron, pouring the molten iron into a pouring cup containing an instantaneous inoculant for carrying out tertiary inoculation, controlling a gate of the molten iron to be 0.1-0.4 percent of the amount of the molten iron, starting a molten iron control gate when the temperature of the molten iron in the pouring cup is 1350-1390 ℃, and forming a casting after the molten iron enters a casting mold to be solidified.

The casting molding process of the method can adopt the following modes:

the method should be kept stand for 10-20 minutes at 1480-1520 ℃ before the furnace is taken out.

The pouring ladle of the method adopts a dam type pouring ladle and a sandwich type ladle packing method. The nodulizer layer, the inoculant layer, the carburant, the scrap iron layer and the steel plate are arranged from bottom to top in sequence. Wherein the thickness of the scrap iron layer is 30-40mm, and the thickness of the steel plate is 10-20mm.

The nodulizer in the method is an ADLLOY6RE type rare earth magnesium alloy nodulizer with the granularity of 10-30 mm; 1. the secondary inoculant is a mixture of 75SiFe and Incollin380 in half proportion, the granularity is 3-8 mm and 15-35 mm respectively, the primary inoculant is arranged in a spheroidizing ladle, and the secondary inoculant is used for stream inoculation when molten iron is discharged by 3/4; the tertiary inoculant is Incollin380 with the granularity of 0.5-1.5 mm, and is put in a pouring cup for instantaneous inoculation during pouring. The total amount of the inoculant is controlled to be 0.8-1.5% of the weight of the molten iron.

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

The blasting fuse, the ADLLOY6RE rare earth magnesium alloy nodulizer, the 75SiFe and the Incollin380 inoculant used in the method can be purchased in the market.

The following is a test and verification example of the method for manufacturing the diesel engine body with 6 cylinders and L shape.

The material used in the practice is nodular cast iron with the grade QT400-15A, and the smelting ingredients are controlled as shown in Table 1. The control of the main chemical components in the smelting process in the inventive example is shown in Table 2. The control of the parameters of pouring temperature, time and the like in the invention examples is shown in Table 3.

The comparison of the detection result and the standard parameters of the main assessment indexes of the invention can be known as follows: QT400-15A of the above different components all meet the performance index requirements of the machine body of the diesel engine. Meanwhile, the cast machine body has no leakage in a water channel and an oil channel after a hydrostatic test of 1.5MPa for 30 minutes. The size and shape of the body meet the requirements after inspection and processing verification. Therefore, the diesel engine body is feasible by adopting modeling, smelting and casting processes.

Table 1: smelting burden control

Table 2: smelting chemical composition

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

Table 3: pouring parameter control

According to the invention, by designing the integral core rod with the deformation prevention function and integrally manufacturing the oil-water channel double-pipe integral sand core with the slender oil channel and the water channel at one time, the size deviation caused by independent casting of two holes is avoided, the internal skin seam formed by casting of a plurality of sand cores is avoided, and the leakage and oil-water pollution caused by deformation, bending, seam and the like of the cast steel pipe are avoided; by combining and coating different coating processes on the surface of the oil-water pipeline double-pipe integral sand core, the cleanliness of the inner wall of the slender high-temperature cavity pipeline is improved, and the production efficiency in a cleaning stage is improved; the internal size and the surface quality of the air cavity are improved by manufacturing the integral sand core of the air cavity; by integrating the cylinder hole, the crankshaft cavity and the base plate, the internal and external shapes of the cylinder hole, the crankshaft cavity, the base plate and the like are formed by one-time core making, the number of sand cores is reduced, the internal and external dimensional precision and the surface quality of the machine body are ensured, and the efficiency is improved.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention 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. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (5)

1. A diesel engine body sand core integration combined casting method is characterized in that: the method comprises the following steps:

the method comprises the following steps: firstly, respectively manufacturing an oil-water channel double-pipe integral sand core (1), an air cavity integral sand core (2), a cylinder hole crankshaft cavity base plate integral sand core (3), a camshaft sand core (4), an air cavity side surface sand core (5), a free end sand core (6) and an output end sand core (7);

step two: assembling each sand core manufactured in the first step in a diesel engine body casting mould, specifically,

1) Putting the integral sand core (2) of the air cavity into a casting mold, enabling core heads at two ends of the integral sand core (2) of the air cavity to be flush with the plane of the casting mold, and locking the integral sand core (2) of the air cavity and the casting mold at two locking platforms at the lower middle part;

2) Respectively placing a camshaft sand core (4) and an air cavity side sand core (5) at two sides of a diesel engine body casting mold;

3) Respectively placing the lower end supporting sand cores of the free end sand core (6) and the output end sand core (7) into the lower parts of two end surfaces of the diesel engine body casting mold;

4) Placing the oil-water channel double-pipe integral sand core (1) on the lower end supporting sand cores of the free end sand core (6) and the output end sand core (7), and keeping the oil-water channel double-pipe integral sand core (1) flush with the lower end supporting sand core;

5) Placing the integrated sand core (3) of the crank chamber and the base plate of the cylinder hole on the camshaft sand core (4) and the side sand core (5) of the air chamber, positioning the sand core (3) by the side core heads of the camshaft sand core (4) and the side sand core (5) of the air chamber in the length direction, and positioning the sand core (3) by the lower core heads of the free end sand core (6) and the output end sand core (7) in the width direction;

6) Respectively placing upper sand cores at two ends of a free end sand core (6) and an output end sand core (7) on the oil-water channel double-pipe integral sand core (1); completing the assembly of the sand core;

step three: and pouring the prepared molten iron into a diesel engine body casting mold, and cooling the molten iron to form a diesel engine body casting.

2. The integrated combined casting method for the sand core of the diesel engine body according to claim 1, which is characterized in that: the manufacturing method of the oil-water channel double-pipe integral sand core (1) comprises the following steps: the core-sand composite sand core comprises an integral core (1-1), wherein a core strengthening layer (1-2) for preventing the integral core (1-1) and a sand core from deforming is arranged in the middle of the inner cavity of the integral core (1-1), and a plurality of taper holes (1-3) for better combining the core and resin sand are uniformly formed in the wall of the integral core (1-1); the integral core rod (1-1) is placed in a mould, so that the core rod and the edge of the mould are ensured to have uniform sand eating amount, and the minimum sand eating amount is more than 20mm; filling resin sand I (1-4) into the mould and compacting, wherein the strength of the resin sand I (1-4) is more than 1.3MPa; after the resin sand I (1-4) is hardened for 24 hours, stripping, checking and finishing the surface of the sand core; coating an anti-cracking coating (1-5) with the thickness of 0.3-0.4 mm on the surface of the sand core; after 1 hour, two layers of anti-cracking cloth (1-6) are continuously and uniformly wound on the surface of the sand core, and the thickness is 0.2mm-0.3mm; after 2 hours, brushing a heat-resistant coating (1-7) on the surface of the sand core twice, wherein the first time of Baume degree is 60-65Be, the second time of Baume degree is 40-45Be, the interval time of the two times is 30 minutes, and the thickness of the coating is 0.3-0.5 mm; and after 1 hour, painting an antioxidant coating (1-8) twice on the surface of the sand core, wherein the baume degrees of the two times are both 30-35Be, the interval time is 30 minutes, and the thickness of the coating is 0.3-0.5 mm.

3. The integrated combined casting method for the sand core of the diesel engine body according to claim 2, which is characterized in that: the diameter of the taper holes (1-3) is phi 10, the taper holes (1-3) are uniformly distributed at 120 degrees in the circumferential direction of the integral core rod (1-1), and the distance between the taper holes in the length direction is 150mm; the anti-cracking coating (1-5) is formed by mixing a repairing agent and a bonding agent according to a certain proportion; the anti-cracking cloth (1-6) is a compact asbestos product; the heat-resistant coating (1-7) is prepared by coating alcohol-based zircon powder and chromite powder according to a certain proportion; the oxidation resistant coating (1-8) is prepared by mixing alcohol-based graphite powder according to a certain proportion.

4. The method for integrally and compositely casting the sand core of the diesel engine body as claimed in claim 1, wherein: the manufacturing method of the air cavity integral sand core (2) comprises the following steps: putting two lock core rings and accessories (2-1) in the middle of a mould in advance, putting resin sand II (2-3) with the thickness of 100mm, compacting, and putting two core rods I (2-2) with certain length and spacing; resin sand II (2-3) with the thickness of 150mm is placed, and two core rods I (2-2) with certain length and certain distance are placed; an air outlet fuse (2-5) is arranged between the two core rods I (2-2); then resin sand II (2-3) with the thickness of 100mm is put in and compacted, and then a core rod II (2-4) with a certain length is put in; then filling resin sand II (2-3) into all the spaces and compacting; drawing a die after hardening for 24 hours, finishing the surface of the sand core, and brushing three times of alcohol-based silicon dioxide coatings (2-6) at intervals of 20 minutes, wherein the Baume degrees are 60-65Be, 40-45Be and 30-35Be in sequence; igniting the gas outlet fuse (2-5).

5. The integrated combined casting method for the sand core of the diesel engine body according to claim 1, which is characterized in that: the manufacturing method of the cylinder hole crankshaft cavity base plate integrated sand core (3) comprises the following steps: and optimizing and integrating the inner and outer shape structures of the cylinder hole sand core, the crankshaft cavity sand core and the bottom plate sand core by using three-dimensional software, so that the cylinder hole position, the inner and outer parts of the crankshaft cavity, the upper and lower sides of the bottom plates at two sides and the side surface form a cylinder hole and crankshaft cavity bottom plate integrated sand core (3).

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