A method for forming the main lubricating oil channel of a ductile iron diesel engine body and its application

Abstract

The present invention belongs to the technical field of cast iron casting, and discloses a method and application for forming the main lubricating oil channel of a ductile iron diesel engine body. A bottom-pouring open pouring system with a filtering device is used to purify molten iron, and a shrinkage feed riser is set at the hot node of the main lubricating oil channel and a chiller is used in combination to balance the temperature field of ductile iron. The chemical composition before the furnace is determined according to the principles of high carbon equivalent and high carbon and low silicon, reasonable packaging, multi-stage inoculation, controlled time, good spheroidization, thorough slag removal, and rapid pouring parameters to achieve internal densification of thick and large hot nodes and eliminate shrinkage and slag inclusions in the main lubricating oil channel of the engine body. The present invention is conducive to achieving basic balance of the temperature field of ductile iron. The present invention ensures that the molten iron has high quality, achieves internal densification of thick and large hot nodes, eliminates the quality risk of shrinkage and slag inclusion defects in the main lubricating oil channel of the engine body, and solves the shrinkage casting defects of the main lubricating oil channel of a complex ductile iron engine body.

Description

Technical Field

[0001] The invention belongs to the technical field of cast iron casting, and in particular relates to a method for forming a main lubricating oil channel of a ductile iron diesel engine body and application thereof. Background Art

[0002] At present, the engine body of 8DK20 diesel engine is a complex ductile iron casting made of QT400-15. The main lubricating oil channel in the length direction of the engine body runs from the gear end to the flywheel end and passes through the lower part of the camshaft cavity. The main lubricating oil channel in the width direction of the engine body is located at the upper part of the gear box end and passes from the camshaft side to the air cavity side. The main lubricating oil channels in two directions (cylindrical clasps with a diameter of about φ90) cross-connect at the lower part of the camshaft cavity at the gear end of the engine body, and the entire main lubricating oil channel of the engine body is in a "T shape".

[0003] The main lubricating oil channel has a large difference in wall thickness compared to the surrounding wall thickness (15), which is prone to casting defects such as shrinkage and slag inclusion, leading to quality problems such as leakage. Drilling a φ45 main lubricating oil channel in the center of the cylindrical saddle to achieve a dense interior of the slender cavity poses a risk.

[0004] Through the above analysis, the problems and defects of the prior art are as follows:

[0005] (1) The existing technology is prone to secondary oxidation slag inclusions in the molding process. In addition, no shrinkage feeder is set at the hot node of the main lubricating oil channel and no chiller is used in combination, so the basic balance of the temperature field of ductile iron cannot be achieved.

[0006] (2) In terms of melting process: the chemical composition before furnace was determined according to the principle of high carbon equivalent and high carbon and low silicon, and the packaging was not reasonable, multi-stage inoculation was not carried out, the duration was controlled, the spheroidization was good, and the slag was removed thoroughly. The self-compensation caused by the graphitization expansion of ductile iron was not fully utilized, resulting in the failure to achieve internal densification of thick and large hot nodes and the failure to eliminate the risk of shrinkage and slag inclusion defects in the main lubricating oil channel of the engine body. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a method and application for forming the main lubricating oil channel of a ductile iron diesel engine body. Specifically, it relates to a method for forming the main lubricating oil channel of a complex ductile iron diesel engine body "T-shaped" ductile iron diesel engine body. This is achieved by controlling the pouring position, pouring system, process parameters, chemical composition, multi-stage inoculation and the like.

[0008] The present invention is achieved in that a method for forming a main lubricating oil channel of a ductile iron diesel engine body comprises:

[0009] A bottom-pouring open pouring system with a filter device is used to purify the molten iron. Feeding risers are set at the hot joints of the main lubricating oil channel and used in conjunction with chillers to balance the temperature field of ductile iron.

[0010] And according to the principle of high carbon equivalent and high carbon and low silicon, the chemical composition before the furnace, reasonable packaging, multi-stage inoculation, controlled duration, good spheroidization, thorough slag removal and rapid pouring parameters are determined to carry out internal densification of thick and large hot nodes and eliminate shrinkage and slag inclusion inside the main lubricating oil channel of the machine body.

[0011] Furthermore, the method for forming the main lubricating oil channel of the graphite cast iron diesel engine body further comprises:

[0012] The first step: determine the pouring position, and place the important part of the main lubricating oil channel in the length direction of the machine body at the lower part of the pouring position of the machine body; avoid the accumulation of slag and floating sand in the lubricating oil channel in the main length direction of the machine body, and also facilitate the formation of sequential shrinkage conditions in the lubricating oil channel in the width direction of the machine body.

[0013] Step 2: The design of the pouring system adopts a bottom-pouring open pouring system. Each endogate is introduced into the mold from the lowest surface of the mold with a large flow rate and low flow rate. It has the characteristics of small scouring force and stable filling, which keeps the liquid level rising steadily, avoids the formation of secondary oxidation slag, and improves the quality of the filling molten iron. In order to avoid the primary slag entering the mold cavity with the molten iron, the air bubbles, ash-containing oxides and various impurities in the molten iron are effectively removed, and the molten iron filter is set on the overlapping surface of the cross runner and pressed after the box is closed.

[0014] 1. Casting system size:

[0015] The gross weight of the 8DK-20 fuselage casting is 5160 Kg.

[0016] 1. Calculation of pouring system

[0017] 1) Liquid weight: G = casting weight × (100 + pouring system weight)%

[0018] The process yield is calculated as 80%, liquid weight G = 5160 × (100 + 25)% = 5160 × 125% = 6450 kg

[0019] 2) Pouring time: t=S1

[0020] G—Total weight of molten iron in the mold, including the weight of the pouring system (Kg)

[0021] t—pouring time (s)

[0022] δ—Wall thickness of main part of casting (mm)

[0023] S1—coefficient 1.7~1.9, take S1=1.3

[0024] t=S1 =1.3× =60 s

[0025] 3) Static pressure head: H P = HO-0.5H C

[0026] H O —Distance from the bottom plane of the mold to the top surface of the gate

[0027] H C —Mold height

[0028] H C =1350+450(mm)

[0029] Ho=1800(mm)

[0030] h p = Ho - 0.5 H C =1800-950 / 2=1323(mm)= 132.3cm

[0031] 4) Total area of ​​flow resistance section: A resistance = G / 0.31μt (cm 2 )

[0032] G—Total weight of molten iron in the mold, including the weight of the pouring system (Kg)

[0033] μ—Flow loss coefficient, the value range is 0.41~0.60, take μ=0.60,

[0034] t—pouring time (s)

[0035] Substituting the above known numbers into the total area formula of the flow resistance cross section Fresistance =, we get:

[0036] A resistance = =50.24cm 2

[0037] The pouring system adopts bottom pouring open type, and is selected according to the ratio of thick-walled cast iron parts: vertical: horizontal: internal = 1: (1.2-2.0): (1.2-2.0), the straight runner diameter is φ80, and the cross-sectional area is 5024mm 2 , runner trapezoid: 70 / 80×80, cross-sectional area 6000 mm 2 , Number of entrapments: 10 per type, entrapment diameter φ30, cross-sectional area 7065 mm 2 , the actual vertical:horizontal:inner = 1:1.2:1.4.

[0038] 2. Design and verification of pouring system:

[0039] 1) Liquid level rising speed in the mold:

[0040] V rise = height Hc of each part of the mold filled with molten iron / pouring time t, generally V rise is 10-20mm / s.

[0041] V rise—rising speed of liquid level in mold (cm / s)

[0042] Hc—Height of each part of the liquid-filled mold (cm)

[0043] t—pouring time (s)

[0044] V rise = 950 / 60 = 15.8 mm / s. This meets the range requirements for the rising speed of the molten iron in the mold.

[0045] 2) Minimum residual pressure head height: hM ≥ L tanα

[0046] hM—minimum residual pressure head height (mm)

[0047] L—Metal liquid flow (mm)

[0048] α—pressure angle (°)

[0049] When the wall thickness of the casting is 15-20, the metal liquid flow L is 1200-1400, the pressure angle is between 7-8°, and α=8° is taken for calculation.

[0050] h M = 1275 tan8°=179, actual h M =450, pressure calculation meets h M ≥L tanα requirement.

[0051] 2. Liquid iron filter

[0052] The molten iron filter is installed on the lap surface of the runner and is pressed after the box is closed. It effectively removes bubbles, ash oxides, and various impurities in the molten iron, greatly improving the yield strength of the casting and improving the internal and external quality of the casting.

[0053] Cross-sectional area F of casting filter to pouring system 过 =F 原 / a×b

[0054] —a: The porosity of the filter is generally 50-60%.

[0055] —b: The filtration efficiency of the filter is generally 60-80%.

[0056] Therefore, the area of ​​the pouring system where the filter is placed is generally 2 to 4 times the area of ​​the part without the filter. The size should be about 20 to 30 mm larger than the pouring area.

[0057] F 内过 =F 内原 / a×b=760.5×4=2826 mm 2 A 100×100 straight hole filter is set on the upper part of the ingates to filter the molten iron. One is set on the upper part of each ingates and one at each end, for a total of 10.

[0058] Step 3: Combine the riser and chiller to design the main lubricating oil passages in the length direction and the width direction; set chillers around the main lubricating oil passages in the length direction of the machine body to balance the hot spots in the thick parts, and set chillers in the middle and lower parts of the main lubricating oil passages in the width direction of the machine body to speed up the cooling rate of the hot spots of the casting, increase the temperature gradient between the surface and the center of the casting, strengthen the conditions for directional (sequential) solidification of the parts, and improve the effective shrinkage compensation of the insulation riser.

[0059] 1. Main lubrication oil channel position in length direction:

[0060] The main lubricating oil channel in the longitudinal direction of the machine body is a cylinder with a diameter of φ85. The calculation process of the chiller thickness dimension T around it is as follows:

[0061] T=tT 热节

[0062] T-chill iron thickness

[0063] t-thickness coefficient, the value range is 0.3≤t≤1.0, and the actual value is 0.5

[0064] T 热节 -Thickness of the cast lubrication oil channel along the length of the engine body.

[0065] Specific calculation: T = tT 热节 =0.5×85=42.5, rounded to 45

[0066] According to the specific shape of the main lubricating oil channel in the length direction, the chiller is arranged specifically:

[0067] 1) Conformal chiller 1: area 60×80, quantity 16 pieces, placed on the side of the main lubricating oil channel outside the camshaft of the engine body;

[0068] 2) Conformal chiller 2: area 70×50, quantity 16 pieces, placed on the side of the main lubricating oil channel inside the camshaft of the engine body;

[0069] 3) Conformal chiller 3: area 90×70, quantity 16 pieces, placed on the side of the main lubricating oil channel inside the crankshaft cavity of the engine body;

[0070] 4) Flat chiller 4: area 70×70, quantity 1 piece, placed at the end of the main lubricating oil channel inside the output end cavity of the machine body.

[0071] 2. Chilled iron in the main lubricating oil channel in the width direction:

[0072] The main lubricating oil channel in the width direction of the machine body is a cylinder with a diameter of φ90. The calculation process of the chiller thickness dimension T around it is as follows:

[0073] T=tT 热节

[0074] T-chill iron thickness

[0075] t-thickness coefficient, the value range is 0.3≤t≤1.0, and the actual value is 0.55

[0076] T 热节 -Thickness of the cast lubrication oil channel along the length of the engine body.

[0077] Specific calculation: T = tT 热节 =0.55×90=49.5, rounded to 50

[0078] According to the specific shape of the main lubricating oil channel in the width direction, the chiller is arranged specifically:

[0079] 1) Flat chiller 5: area 90×90, quantity 2, placed on the side of the main lubricating oil passage of the length and width of the gear end of the machine body;

[0080] 2) Conformal chiller 6: area 110×80, quantity 4, placed on the side of the main lubricating oil passage in the width direction of the crankshaft cavity of the engine body;

[0081] 3) Conformal chiller 7: area 110×70, quantity 3, placed on the side of the main lubricating oil passage in the width direction of the gear end of the machine body;

[0082] Larger chillers are used on the sides of the main lubricating oil passages in the width direction of the machine body. The chillers are arranged from sparse to dense from top to bottom, which accelerates the cooling rate of the hot spots of the casting and increases the temperature gradient between the surface and the center of the casting, which is beneficial to improving the utilization of graphitization expansion and improving the shrinkage compensation effect of the riser. Chilled iron acceleration areas are set on the sides and bottom of the main lubricating oil passages in the width direction of the machine body to increase the cooling rate, strengthen the conditions for directional (sequential) solidification of the parts, and improve the effective shrinkage compensation of the thermal insulation riser for the main lubricating oil passages in the width direction of the machine body.

[0083] 3. Riser of the main lubricating oil channel in the width direction:

[0084] A thermal insulation riser made of pearlite powder material with a small heat storage coefficient and a thermal insulation function is arranged on the top of the hot node of the wide main lubricating oil channel.

[0085] According to the diameter of the hot spot of the cylindrical main lubricating oil channel and height And the jamming theory, the modulus of the hot spot of the cylindrical main lubricating oil channel is obtained for:

[0086]

[0087]

[0088] Inner diameter of insulation riser for:

[0089] From this we can get:

[0090] - casting modulus,

[0091] - Insulation riser modulus,

[0092] -Increase coefficient, the value range is: 1.0≤ ≤1.9,

[0093] -Insulation riser inner diameter

[0094] The diameter of the circular riser neck of the insulation riser The calculation process is as follows:

[0095]

[0096]

[0097] From this we can get:

[0098] -Insulation riser neck modulus,

[0099] - Reduction factor of the insulating riser neck, The value range is: 0.5≤ ≤0.9,

[0100] -Insulation riser round riser neck diameter

[0101] Cylindrical diameter and height , =90mm, =810mm, here, Take 1.9, according to the inner diameter of the insulation riser , after rounding, we get =130mm;

[0102] Insulation riser neck diameter In the calculation of Take 0.9, then according to the formula , after calculation, round off to get the insulation riser neck diameter =40mm.

[0103] Step 4: Chemical composition control. Determine the chemical composition before the furnace according to the principles of high carbon equivalent, high carbon and low silicon, low sulfur, low phosphorus, and large inoculation amount; select high carbon equivalent, high carbon and low silicon to promote graphitization. The hypoeutectic composition with carbon equivalent close to the eutectic composition promotes the solidification of molten iron according to the stable eutectic, which can not only improve the fluidity of molten iron, but also improve the self-shrinkage caused by graphitization expansion during solidification of molten iron. The carbon content is controlled between 3.8-3.9 and the carbon equivalent is controlled between 4.5-4.8, which is conducive to casting, shrinkage, small shrinkage holes, and less shrinkage. The silicon content has the effect of refining the eutectic group and improving the roundness of graphite, but silicon increases the toughness-brittleness transition temperature of cast iron, which is generally controlled at 1.4-3.0. After selecting the carbon equivalent, the lower limit of silicon is based on the principle of no free cementite.

[0104] Controlling the sulfur content is an important condition for producing ductile iron. The range of sulfur control is as follows: S is an anti-spheroidizing element. It has a strong affinity with spheroidizing elements such as magnesium and rare earth. It will consume a large amount of spheroidizing elements in the molten iron to form magnesium and rare earth sulfides, causing casting defects such as slag inclusions and pores; the heterogeneous crystal nuclei on which graphite crystallization is attached are also composed of sulfides and oxides. In order to ensure the normal spheroidization of graphite, sulfur is an indispensable element in ductile iron. For ferritic ductile iron, it is more appropriate to control S in the range of 0.008-0.015%. Phosphorus is a harmful element that is very easy to segregate at the boundary of eutectic groups to form binary, ternary or composite phosphorus eutectics, reducing the toughness of cast iron. Control should be less than 0.05%.

[0105] The fifth step: pretreatment of molten iron. The pretreatment agent has the functions of deoxidation, siliconization, purification of molten iron and inoculation. It can increase the number of graphite balls, make graphite more round and fine, enhance the nucleation ability and increase the graphite core during smelting, and effectively solve the casting defects such as pores, shrinkage, white spots, slag inclusions, etc. The general addition amount is 3.2-3.3%.

[0106] The pretreatment agent 0.4% Jurong Yafeng YFYY-2 and 0.2% FeSi75 were loaded into the non-spheroidizing pit.

[0107] Step 6: Selection of spheroidizer. Use a dam-type spheroidizing ladle. The ratio of the height and diameter of the ladle is determined to be 2:1, which is conducive to improving the absorption rate of the spheroidizer and increasing the spheroidizing effect. The spheroidizer uses rare earth magnesium ferrosilicon spheroidizer, which combines the advantages of rare earth and magnesium. The alloy has a high silicon content, which can significantly reduce the intensity of the reaction during magnesium treatment. At the same time, it also has some inoculation effect due to the increase of silicon. The amount of spheroidizer added should be determined based on factors such as the composition of the molten iron, the wall thickness of the casting, the composition of the spheroidizer, and the absorption rate of the spheroidizing process. The general addition amount is 1.6-2.0%, and the spheroidizing temperature is 1420-1450. The spheroidizer is installed on one side of the bottom of the ladle, and ferrosilicon alloy is added on it. It is slightly tightened. In order to delay the spheroidizing reaction time and enhance the spheroidizing and inoculation effects, a layer of rust-free ductile iron pins should be covered on it, and a steel plate should be covered on it.

[0108] Step 7: Multi-stage delayed inoculation. The purpose of multi-stage inoculation is to increase the temperature fluctuation, concentration fluctuation and structure fluctuation of the molten iron, and increase the core of heterogeneous nucleation in the molten iron at a smaller degree of supercooling. The fundamental way to improve the inoculated cast iron is to increase the carbon and silicon content of the molten iron, make it close to the eutectic composition, improve the fluidity and shrinkage compensation capacity of the molten iron, and reduce the casting stress. It is very important. The multi-stage inoculation method of ladle inoculation, front-furnace rush (delayed inoculation), pouring cup instant (stream inoculation) is adopted, and the inoculant containing bismuth is used to strongly increase the number of graphite balls.

[0109] 1. Incubation in the package:

[0110] 1) Non-spheroidizing pit: The non-spheroidizing pit is filled with pretreatment agent 0.4% Jurong Yafeng YFYY-2, 0.2% FeSi75;

[0111] 2) Spheroidizing pit: 1.2% Jurong Yafeng YFQ-7A and 0.3% FeSi75 are added into the spheroidizing pit in turn, and then covered with 0.3% ductile iron chips.

[0112] 2. Furnace front flushing: When the iron output reaches 2 / 3 of the total molten iron, the spheroidizer and molten iron are fully reacted, the inoculant body is introduced into the iron tank, and the remaining 1 / 3 of the molten iron is flushed into the ladle for inoculation. The inoculant is Jurong Yafeng 0.2% YFYY-2.

[0113] 3. In-stream inoculation: The instantaneous inoculant is Jurong Yafeng YFY-380, with a particle size of 0.2-0.5mm, and the inoculation is carried out using an instantaneous inoculation device.

[0114] Step 8: Loading control, dry the ladle thoroughly, add 0.4% Jurong Yafeng YFYY-2 and 0.2% FeSi75 as pretreatment agent, and put it into the non-spheroidizing pit. Add spheroidizing agent 1.2% YFQ-7A and 0.3% FeSi75 in the spheroidizing pit, tighten it slightly, cover it with 0.3% rust-free ductile iron chips, cover it with 10mm thick steel plate, and finally press 2-4 pieces of pig iron.

[0115] Step 9: Control of discharge from the furnace. High temperature standing is conducive to the floating of slag and gas in the molten iron, purification of the molten iron, refinement of graphite and matrix structure, formation of a large number of heterogeneous crystal nuclei, and improvement of cast iron strength. Before discharge from the furnace, the temperature is raised to 1500-1510℃ and stood for 10-15 minutes; before the molten iron is discharged from the furnace, the slag in the furnace is first scraped clean, and the molten iron temperature is measured to meet the process requirements before discharge from the furnace. When the amount of iron discharged reaches 2 / 3 of the total liquid weight, the furnace body stops introducing molten iron into the ladle. When the spheroidization reaction is about to end, the furnace body is started to introduce the remaining 1 / 3 of the molten iron into the ladle. The inoculant 0.2% Jurong Yafeng YFYY-2 is flushed into the front of the iron trough furnace with the molten iron for delayed inoculation. After the weight of the molten iron in the ladle meets the requirements, the furnace is closed, and the slag aggregation agent is sprinkled on the surface of the ladle to thoroughly remove the slag.

[0116] Step 10: Pouring: Before pouring, measure the pouring temperature as required and remove the slag in the ladle. When pouring, pull out the plug when the pouring cup temperature is controlled at 1350-1360℃. The instantaneous inoculant uses the silicon-bismuth inoculant Jurong Yafeng YFY-380, which strongly increases the number of graphite balls, with a particle size of 0.2-0.5mm. Use the instantaneous inoculation device for inoculation. After the spheroidization of the molten iron is completed, the pouring should be completed within 15 minutes without spheroidization decay.

[0117] The entire melting and pouring process is controlled and organized according to the principles of reasonable packaging, multi-stage inoculation, controlled duration, good spheroidization, thorough slag removal, and rapid pouring.

[0118] Step 11: Production verification.

[0119] Furthermore, the first step places an important part of the main lubricating oil channel in the length direction of the machine body at the lower part of the casting position of the machine body, which is used to reduce the accumulation of floating sand and slag in this part to form casting defects, and is also used to form shrinkage compensation for the thick part of the main lubricating oil channel to reduce the occurrence of shrinkage defects.

[0120] Furthermore, in the second step, a 100×100 straight hole filter is set at the inner runner to filter the molten iron. The pouring system size is: one straight runner φ80, and the cross runner section is ×80mm, inner runner φ30, one for each level, 10 runs in total.

[0121] Furthermore, the design method of the main lubricating oil channel in the length direction of the third step includes: arranging a length-direction chilled iron quenching equilibrium temperature field with a thickness of 1 / 2 around the main lubricating oil channel, and the length-direction chilled iron quenching equilibrium temperature field includes: a conformal chilled iron 1 with a thickness of 45, 60×80, a conformal chilled iron 2 with a thickness of 70×50, a conformal chilled iron 3 with a thickness of 90×70, and a flat chilled iron 4 with a thickness of 70×70.

[0122] Furthermore, the design method of the main lubricating oil channel in the width direction of the third step includes:

[0123] 1) A chilled iron quenching equilibrium temperature field with a thickness of 1 / 2 of the main lubricating oil channel is arranged around the main lubricating oil channel. The chilled iron quenching equilibrium temperature field with a thickness of 1 / 2 of the main lubricating oil channel includes: a flat chilled iron 5 with a thickness of 50, 90×90, a conformal chilled iron 6 with a thickness of 110×80, and a conformal chilled iron 7 with a thickness of 110×70.

[0124] 2) An insulating riser is set at the top of the hot node of the width main lubricating oil channel, and a larger chiller is used on the side of the main lubricating oil channel in the width direction of the machine body. The chillers are arranged from sparse to dense from top to bottom to accelerate the cooling rate of the hot node of the casting and increase the temperature gradient between the surface and the center of the casting, which is beneficial to improve the utilization of graphitization expansion and improve the shrinkage compensation effect of the riser. Chilled iron acceleration areas are set on the side and bottom of the main lubricating oil channel in the width direction of the machine body to increase the cooling rate, strengthen the conditions for directional (sequential) solidification of the parts, and improve the effective shrinkage compensation of the insulating riser for the main lubricating oil channel in the width direction of the machine body.

[0125] Furthermore, the chemical composition of the fourth step is: C: 3.8-3.9, Si: 1.5-1.7, Mn: 0.15-0.25, P≤0.04, S≤0.015.

[0126] Further, the fifth step of melting and pouring control specifically includes:

[0127] (1) Packaging: pretreatment agent 0.4% Jurong Yafeng YFYY-2, 0.2% FeSi75, loaded into the non-spheroidizing pit; spheroidizing agent 1.2% Jurong Yafeng YFQ-7A, 0.3% FeSi75 were added to the spheroidizing pit in turn, and then covered with 0.3% ductile iron filings, and then covered with spheroidizing steel plates after layer by layer compaction, and finally pressed 2-4 pieces of pig iron;

[0128] (2) Unloading: Before unloading, heat to 1500-1510℃ and let stand for 10-15 minutes; before unloading, scrape off the slag in the furnace and measure the temperature of the molten iron to see if it meets the process requirements before unloading; when the amount of unloaded iron reaches 2 / 3, add 0.2% Jurong Yafeng YFYY-2, a secondary inoculant;

[0129] (3) Pouring: Before pouring, measure the pouring temperature as required and scrape off the slag in the bag. During pouring, use the instantaneous inoculant Jurong Yafeng YFY-380 with a particle size of 0.2-0.5mm and inoculate with an instantaneous inoculation device.

[0130] Another object of the present invention is to provide a main lubricating oil passage manufactured by using the method for forming the main lubricating oil passage of a graphite cast iron diesel engine body.

[0131] Another object of the present invention is to provide a complex ductile iron diesel engine block manufactured using the main lubricating oil gallery.

[0132] Combined with all the above technical solutions, the advantages and positive effects of the present invention are as follows: In terms of molding process, the present invention: by placing the main lubricating oil channel in the length direction at the lower part of the pouring position, setting the main lubricating oil channel in the width direction with a shrinkage feed riser and using a chiller to ensure the internal quality, the basic balance of the temperature field of ductile iron is achieved. The use of a bottom-pouring open pouring system with a filtering device can improve the purification of molten iron and avoid the generation of secondary oxidation slag inclusions. Shrinkage feed risers are set in the hot section of the main lubricating oil channel and chillers are used to achieve the basic balance of the temperature field of ductile iron. In terms of melting process: the chemical composition before the furnace is determined according to the principles of high carbon equivalent, high carbon and low silicon, low sulfur, low phosphorus, and large inoculation amount, reasonable packaging, multi-stage inoculation, control of time, good spheroidization, and thorough slag removal, and full use of the self-shrinkage brought by the graphitization expansion of ductile iron. The internal density of the thick and large hot section is achieved, and the risk of shrinkage and slag inclusion defects inside the main lubricating oil channel of the machine body is eliminated.

[0133] The method of the present invention effectively solves the shrinkage casting defects of the main lubricating oil channel of the complex ductile iron body, and realizes the mass production of the body. The present invention adopts a bottom-pouring open pouring system with a filtering device to improve the purification degree of molten iron, and sets a shrinkage feed riser at the hot node of the main lubricating oil channel and uses a chiller in combination, which is conducive to achieving the basic balance of the ductile iron temperature field. The chemical composition before the furnace is determined according to the principle of high carbon equivalent and high carbon and low silicon. Reasonable packaging, multi-stage inoculation, controlled time, good spheroidization, thorough slag removal, and rapid pouring ensure that the molten iron has high quality, achieves internal density of thick and large hot nodes, and eliminates the quality risks of shrinkage and slag inclusion defects inside the main lubricating oil channel of the body.

[0134] Compared with the prior art, the present invention has the following advantages:

[0135] (1) The present invention places the important part of the main lubricating oil channel in the longitudinal direction of the machine body at the lower part of the casting position of the machine body, so as to avoid the accumulation of slag and floating sand in the lubricating oil channel in the longitudinal direction of the machine body, and is also beneficial to the formation sequence compensation of the lubricating oil channel in the width direction of the machine body.

[0136] (2) In the design of the pouring system, the present invention adopts a bottom pouring open pouring system. Each level of the inner runner is introduced into the mold from the lowest surface of the mold with a large flow rate and a low flow rate. It has the characteristics of small flushing force and stable filling, which keeps the liquid level rising steadily, avoids the formation of secondary oxidation slag, and improves the quality of the filled iron liquid. In order to prevent the primary slag from entering the mold cavity with the iron liquid and effectively remove the bubbles, ash-containing oxides and various impurities in the iron liquid, the iron liquid filter is set on the overlapping surface of the cross runner and pressed tightly after the box is closed.

[0137] (3) The present invention arranges chillers around the main lubricating oil passage in the length direction of the machine body to balance the hot spots in the thick and large parts. A chiller with a larger size is used in the middle and lower part of the main lubricating oil passage in the width direction to accelerate the cooling rate of the hot spots of the casting and increase the temperature gradient between the surface and the center of the casting, which is beneficial to improving the utilization of graphitization expansion and improving the shrinkage compensation effect of the riser. A chiller acceleration area is arranged at the bottom of the main lubricating oil passage to strengthen the conditions for directional (sequential) solidification of the parts and improve the effective shrinkage compensation of the insulation riser.

[0138] (4) The chemical composition control of the present invention determines the chemical composition before the furnace according to the principles of high carbon equivalent, high carbon and low silicon, low sulfur, low phosphorus, and large inoculation amount; high carbon equivalent, high carbon and low silicon are selected to promote graphitization, and the sub-eutectic composition with carbon equivalent close to the eutectic composition promotes the solidification of the molten iron according to the stable system eutectic, which can not only improve the fluidity of the molten iron, but also improve the self-compensation caused by the graphitization expansion during the solidification of the molten iron. In order to ensure the normal spheroidization of graphite, sulfur is an indispensable element in ductile iron. For ferritic ductile iron, it is more appropriate to control S in the range of 0.008-0.015%.

[0139] (5) The pretreatment agent of the present invention has the functions of deoxidation, silicon addition, purification and inoculation of molten iron. It can increase the number of graphite nodules during smelting, make graphite more round and fine, enhance the nucleation ability and increase the graphite core, and effectively solve the problems of casting defects such as pores, shrinkage, white spots and slag inclusions.

[0140] (6) The present invention uses a dam-type spheroidizing ladle, and the ratio of the height and diameter of the ladle is determined to be 2:1, which is conducive to improving the absorption rate of the spheroidizing agent and increasing the spheroidizing effect. The spheroidizing agent uses rare earth magnesium ferrosilicon spheroidizing agent, which combines the advantages of rare earth and magnesium. The alloy has a high silicon content, which can significantly reduce the intensity of the reaction during magnesium treatment. At the same time, it also has some inoculation effect due to the increase in silicon. The amount of spheroidizing agent added should be determined based on factors such as the composition of the molten iron, the wall thickness of the casting, the composition of the spheroidizing agent, and the absorption rate of the spheroidizing process.

[0141] (7) The purpose of the multi-stage delayed inoculation of the present invention is to increase the temperature fluctuation, concentration fluctuation and structure fluctuation of the molten iron, and to increase the core of heterogeneous nucleation in the molten iron at a relatively small degree of supercooling. The fundamental way to improve the inoculated cast iron is to increase the carbon and silicon content of the molten iron to make it close to the eutectic composition, improve the fluidity and shrinkage compensation capacity of the molten iron, and reduce the casting stress. The multi-stage inoculation method of inoculation in the ladle, front-of-furnace flushing (delayed inoculation) and instantaneous pouring cup (stream inoculation) is adopted, and the inoculant containing bismuth is used to strongly increase the number of graphite nodules.

[0142] (8) The present invention solves the problem of liquid shrinkage compensation of thick and large isolated hot nodes in the main lubrication channel of a complex ductile iron engine body during casting, eliminates casting defects such as shrinkage and slag inclusion, and realizes mass production of the engine body. BRIEF DESCRIPTION OF THE DRAWINGS

[0143] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0144] Figure 1 It is a flow chart of a method for forming a main lubricating oil passage of a graphite cast iron diesel engine body provided by an embodiment of the present invention.

[0145] Figure 2 It is a schematic diagram of a main lubricating oil channel of an aircraft body provided in an embodiment of the present invention.

[0146] Figure 3 It is a schematic diagram of the main lubricating oil passage at the gear end of the machine body provided by an embodiment of the present invention.

[0147] Figure 4 It is a schematic diagram of the main lubricating oil passage on the camshaft side of the engine body provided by an embodiment of the present invention.

[0148] Figure 5 It is a rendering of the main lubricating oil channel of the 19-011# 6DK20 engine body provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0149] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0150] In terms of molding process, the prior art is prone to secondary oxidation slag inclusions. Moreover, no shrinkage feed riser is set in the hot node of the main lubricating oil channel and no cold iron is used in combination, so the basic balance of the temperature field of ductile iron cannot be achieved. In terms of melting process: the chemical composition before the furnace is determined according to the principle of high carbon equivalent, high carbon and low silicon, reasonable packaging, multi-stage inoculation, controlled duration, good spheroidization, and thorough slag removal are not carried out, and the self-shrinkage brought about by the graphitization expansion of ductile iron is not fully utilized, resulting in the inability to achieve internal density of thick and large hot nodes, and the inability to eliminate the risks of shrinkage and slag inclusion defects in the main lubricating oil channel of the engine body. In view of the problems existing in the prior art, the present invention provides a method and application for molding the main lubricating oil channel of a ductile iron diesel engine body, and the present invention is described in detail below in conjunction with the accompanying drawings.

[0151] The method for forming the main lubricating oil channel of a ductile iron diesel engine body provided by the present invention comprises: using a bottom-pouring open-type pouring system with a filtering device to purify molten iron, setting a shrinkage feed riser at a hot node of the main lubricating oil channel and using a chiller in cooperation to balance the temperature field of the ductile iron; and determining the chemical composition before the furnace, reasonable packaging, multi-stage inoculation, controlled time, good spheroidization, thorough slag removal, and rapid pouring parameters according to the principles of high carbon equivalent and high carbon and low silicon, to make the inside of the thick and large hot node part dense, and eliminate shrinkage and slag inclusion inside the main lubricating oil channel of the engine body.

[0152] The method for forming the main lubricating oil channel of a graphite cast iron diesel engine body provided by the present invention comprises the following steps:

[0153] S101: Determine the pouring position, and place the important part of the main lubricating oil channel in the length direction of the machine body at the lower part of the pouring position of the machine body.

[0154] S102: The pouring system is designed with a bottom pouring open pouring system. Each endogate is introduced into the mold from the lowest surface of the mold with a large flow rate and low flow rate to keep the liquid level rising steadily and avoid the formation of secondary oxidation slag.

[0155] S103: The riser and the chill are combined to design the main lubricating oil passages in the length direction and the main lubricating oil passages in the width direction.

[0156] S104: Chemical composition control, determine the chemical composition before the furnace according to the principle of high carbon equivalent, high carbon and low silicon.

[0157] S105: Melting and pouring control is carried out according to the principles of reasonable packaging, multi-stage inoculation, controlled time, good spheroidization, thorough slag removal and rapid pouring.

[0158] S106: Production verification.

[0159] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0160] The present invention provides a method for forming a main lubricating oil channel of a ductile iron diesel engine body, comprising:

[0161] Step 1: Determination of pouring position

[0162] Placing the important part of the main lubricating oil channel in the length direction of the engine body at the lower part of the casting position of the engine body can, on the one hand, reduce the accumulation of floating sand and slag in this part to form casting defects. On the other hand, it is conducive to forming shrinkage compensation for the thick part of the main lubricating oil channel and reducing the occurrence of shrinkage defects.

[0163] Step 2: Design of pouring system

[0164] The bottom pouring open pouring system is adopted. Each entrant is introduced into the mold from the lowest surface of the mold (the rib on the top of the camshaft) with a large flow rate and low flow rate to keep the liquid level rising steadily and avoid the generation of secondary oxidation slag. A 100×100 straight hole filter is set at the entrant to filter the molten iron and improve the purity of the molten iron. Casting system size: one straight runner φ80, and the cross runner section is ×80mm, inner runner φ30, one for each level, 10 runs in total.

[0165] Step 3: Design a solution combining riser and chill

[0166] 1. Main lubrication oil channel in length direction

[0167] The main lubricating oil channel is shaped like a circle with a diameter of φ85, and a chiller with a thickness of 1 / 2 is arranged around it to form a balanced temperature field, that is, 16 pieces of 60×80 conformal chillers 1 with a thickness of 45, 16 pieces of 70×50 conformal chillers 2 with a thickness of 90×70 conformal chillers 3 with a thickness of 16. There is one piece of 70×70, 40 thick plane chiller 4, and one piece of 90×90, 50 thick plane chiller 5 with a thickness of 50.

[0168] 2. Main lubrication oil channel in width direction

[0169] 1) Cold Iron

[0170] The main lubricating oil channel is shaped like a circle with a diameter of φ90, and a chiller with a thickness of 1 / 2 of the thickness is arranged around it to form a balanced temperature field, that is, 4 pieces of 110×80 conformal chillers 6 with a thickness of 50, 3 pieces of 110×70 conformal chillers 7, and 1 piece of 90×90, 50 thick flat chiller 5.

[0171] 2) Insulation riser

[0172] An insulating riser is set at the top of the hot section of the width main lubricating oil channel, and the chill iron is arranged from sparse to dense from top to bottom to maintain the continuity of the riser shrinkage compensation. The cooling rate of the hot section of the casting is accelerated, the temperature gradient between the surface and the center of the casting is increased, the conditions for directional (sequential) solidification of the part are strengthened, and the insulation riser is improved. Effective shrinkage compensation for the main lubricating oil channel in the width direction of the body.

[0173] The width of the main lubricating oil channel is similar to a cylinder with a diameter of φ90 and a height of 810. Its modulus Ms=DH / (2D+4H)=2.1, the modulus of the riser body: MT=0.9Ms=1.89, and the modulus of the riser neck M=0.8MT=1.51. Cylindrical riser body: MT=d / 4, d=4MT=7.56, taking the increase coefficient f2=1.8, the riser body diameter D=1.8×7.56=13.6, and the actual use of the insulation riser with an inner diameter of φ130. The circular riser neck M=d / 4, d = 4M =6.04, taking the reduction coefficient f3=0.85, the square riser neck diameter is 6.04×0.85=5.13cm, and the actual riser neck diameter size is φ40mm.

[0174] Step 4: Chemical composition control

[0175] The chemical composition before the furnace is determined according to the principle of high carbon equivalent, high carbon and low silicon, C: 3.8-3.9, Si: 1.5-1.7, Mn: 0.15-0.25, P≤0.04, S≤0.015.

[0176] Step 5: Melting and pouring control

[0177] The organization and control are carried out according to the principles of reasonable packaging, multi-stage inoculation, controlled duration, good spheroidization, thorough slag removal and rapid pouring to ensure the high quality of molten iron.

[0178] 1. Packaging process: pretreatment agent 0.4% Jurong Yafeng YFYY-2, 0.2% FeSi75, loaded into the non-spheroidizing pit. Spheroidizing agent 1.2% Jurong Yafeng YFQ-7A, 0.3% FeSi75 (cover) are added to the spheroidizing pit in turn, and then covered with 0.3% ductile iron filings, and then covered with spheroidizing steel plates after appropriate compaction layer by layer, and finally pressed 2-4 pieces of pig iron.

[0179] 2. Furnace-out process: before being discharged from the furnace, the temperature is raised to 1500-1510℃ and allowed to stand for 10-15 minutes. Before the molten iron is discharged from the furnace, the slag in the furnace should be scraped clean and the molten iron temperature should be measured to meet the process requirements before it can be discharged from the furnace. When the amount of iron discharged is 2 / 3, the reaction starts to pause for a while and then 0.2% Jurong Yafeng YFYY-2, a secondary inoculant, can be added.

[0180] 3. Pouring process: Before pouring, measure the pouring temperature as required and scrape off the slag in the bag. During pouring, use the instantaneous inoculant Jurong Yafeng YFY-380 with a particle size of 0.2-0.5mm to inoculate.

[0181] Step 5: Production Verification

[0182] After production verification, it can be confirmed that the shrinkage and slag inclusion quality problems of the main lubricating oil channel of the complex ductile iron body have been solved. After drilling, the interior of the main lubricating oil channel is dense, and the water pressure test is passed without leakage.

[0183] like Figure 2-Figure 5 As shown, the 19-011# 6DK20 engine body is the main lubricating oil passage effect diagram provided by the embodiment of the present invention; the engine body 19-011# 6DK20 produced by the method of the present invention has passed the inspection and has entered the diesel engine assembly stage. The 6DK20 engine body is the main lubricating oil passage test requirements provided by the embodiment of the present invention; the water test pressure of the lubricating oil cavity is 0.75MPa (7.5Kg / cm 2 ), water test pressure is maintained for 15 minutes. 19-011# 6DK20 engine body is the main lubricating oil channel test process record provided by the embodiment of the present invention; 19-011# 6DK20 engine body main lubricating oil channel test process record, indicating that the lubricating oil cavity water test pressure is 0.75MPa (7.5Kg / cm 2 ), water test pressure maintained for 15 minutes without leakage, meeting the requirements.

[0184] The method of the present invention effectively solves the shrinkage casting defect of the main lubricating oil channel of the complex ductile iron engine body, and realizes the mass production of the engine body.

[0185] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for forming a main lubricating oil channel of a ductile iron diesel engine body, characterized in that: The method for forming the main lubricating oil channel of a ductile iron diesel engine body adopts a bottom-pouring open-type pouring system with a filtering device to purify molten iron, sets a shrinkage feeder at the hot section of the main lubricating oil channel and uses a chiller to balance the temperature field of the ductile iron; determines the chemical composition before the furnace, reasonable packaging, multi-stage inoculation, controlled time, good spheroidization, thorough slag removal, and fast pouring parameters according to the principles of high carbon equivalent and high carbon and low silicon, and makes the internal of the thick and large hot section dense, and eliminates shrinkage and slag inclusion inside the main lubricating oil channel of the engine body; The method for forming the main lubricating oil channel of a ductile iron diesel engine body comprises: The first step is to determine the pouring position, and place the important part of the main lubricating oil channel in the length direction of the machine body below the pouring position of the machine body; The second step is to design the pouring system, using a bottom pouring open pouring system, where each endogate is introduced into the mold from the lowest surface of the mold with a large flow rate and low flow rate; The third step is to combine the riser and the chiller to design the main lubricating oil passage in the length direction and the main lubricating oil passage in the width direction; The fourth step is chemical composition control, which determines the chemical composition before the furnace according to the principles of high carbon equivalent, high carbon and low silicon, low sulfur, low phosphorus and large inoculation amount; The fifth step is melting and pouring control, which is carried out according to the principles of reasonable packaging, multi-stage inoculation, controlled duration, good spheroidization, thorough slag removal, and rapid pouring; Step 6: Production verification.

2. The method for forming the main lubricating oil channel of a ductile iron diesel engine body according to claim 1, characterized in that: The first step places the important part of the main lubricating oil channel in the length direction of the machine body at the lower part of the casting position of the machine body, which is used to reduce the accumulation of floating sand and slag in this part to form casting defects, and is also used to form shrinkage compensation for the thick part of the main lubricating oil channel.

3. The method for forming the main lubricating oil channel of a ductile iron diesel engine body according to claim 1, characterized in that: The second step is to set a 100×100 straight hole filter at the ingrate to filter the molten iron. The pouring system size is: one straight sprue with a cross section of φ80, one cross sprue with a cross section of ×80mm, and an ingrate with a cross section of φ30, one for each level, for a total of 10.

4. The method for forming the main lubricating oil passage of a graphite cast iron diesel engine body according to claim 1, characterized in that: The design method of the main lubricating oil channel in the length direction of the third step includes: arranging a length-direction chiller quenching equilibrium temperature field with a thickness of 1 / 2 around the main lubricating oil channel in the length direction of the machine body, and the length-direction chiller quenching equilibrium temperature field includes: a conformal chiller 1 with a thickness of 45, 60×80, a conformal chiller 2 with a thickness of 70×50, a conformal chiller 3 with a thickness of 90×70, a flat chiller 4 with a thickness of 70×70, and a flat chiller 5 with a thickness of 50, 90×90.

5. The method for forming the main lubricating oil passage of a ductile iron diesel engine body according to claim 1, characterized in that: The design method of the main lubricating oil passage in the width direction in the third step includes: (1) A width-direction chilling equilibrium temperature field with a thickness of 1 / 2 of the main lubricating oil passage in the width direction of the machine body is arranged, wherein the width-direction chilling equilibrium temperature field includes: a plane chilling iron 5 with a thickness of 50, 90×90, a conformal chilling iron 6 with a thickness of 110×80, a conformal chilling iron 7 with a thickness of 110×70, and a chilling iron 5 with a thickness of 90×90 and 50; (2) An insulating riser is set at the top of the hot section of the wide main lubricating oil channel, and the chill is arranged from sparse to dense from top to bottom to maintain the continuity of the riser shrinkage compensation; accelerate the cooling rate of the hot section of the casting, increase the temperature gradient between the surface and the center of the casting, strengthen the conditions for directional solidification of the part, and improve the effective shrinkage compensation of the insulating riser.

6. The method for forming the main lubricating oil passage of a ductile iron diesel engine body according to claim 1, characterized in that: The chemical composition of the fourth step is: C: 3.8-3.9, Si: 1.5-1.7, Mn: 0.15-0.25, P≤0.04, S≤0.

015.

7. The method for forming the main lubricating oil passage of a ductile iron diesel engine body according to claim 1, characterized in that: The fifth step of melting and pouring control specifically includes: (1) Packaging: pretreatment agent 0.4% Jurong Yafeng YFYY-2, 0.2% FeSi75, loaded into the non-spheroidizing pit; spheroidizing agent 1.2% Jurong Yafeng YFQ-7A, 0.3% FeSi75 were added to the spheroidizing pit in turn, and then covered with 0.3% ductile iron filings, and then covered with spheroidizing steel plates after layer by layer compaction, and finally pressed 2-4 pieces of pig iron; (2) Unloading: Before unloading, heat to 1500-1510℃ and let stand for 10-15 minutes; before unloading, scrape off the slag in the furnace and measure the temperature of the molten iron to see if it meets the process requirements before unloading; when the amount of unloaded iron reaches 2 / 3, add 0.2% Jurong Yafeng YFYY-2, a secondary inoculant; (3) Pouring: Before pouring, measure the pouring temperature as required and remove the slag in the ladle. During pouring, use the instantaneous inoculant Jurong Yafeng YFY-380 with a particle size of 0.2-0.5 mm and use an instantaneous inoculation device for inoculation.

8. A main lubricating oil passage manufactured by the method for forming a main lubricating oil passage of a ductile iron diesel engine body according to any one of claims 1 to 7.

9. A ductile iron diesel engine body manufactured using the main lubricating oil passage according to claim 8.

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