CN109396336B - Casting method of main bearing cap of medium-speed and high-speed high-power diesel engine - Google Patents

Casting method of main bearing cap of medium-speed and high-speed high-power diesel engine Download PDF

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CN109396336B
CN109396336B CN201811318457.1A CN201811318457A CN109396336B CN 109396336 B CN109396336 B CN 109396336B CN 201811318457 A CN201811318457 A CN 201811318457A CN 109396336 B CN109396336 B CN 109396336B
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main bearing
casting
pouring
bearing cap
riser
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CN109396336A (en
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裴泽辉
李光辉
刘志
曹德水
张帅强
杨永辉
陈冬玲
吴红光
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Henan Diesel Engine Industry Co Ltd
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Henan Diesel Engine Industry Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/20—Stack moulds, i.e. arrangement of multiple moulds or flasks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/08—Features with respect to supply of molten metal, e.g. ingates, circular gates, skim gates
    • B22C9/082—Sprues, pouring cups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/08—Features with respect to supply of molten metal, e.g. ingates, circular gates, skim gates
    • B22C9/088—Feeder heads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/22—Moulds for peculiarly-shaped castings

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Abstract

A casting method for the main bearing cover of medium-speed and high-power diesel engine features that according to the solidification characteristics of nodular iron, the casting position with downward tile mouth is used to ensure the compactness of main bearing cover and prevent the generation of shrinkage cavity (looseness) casting defect, and the molten metal is introduced from the riser at top of casting.

Description

Casting method of main bearing cap of medium-speed and high-speed high-power diesel engine
Technical Field
The invention relates to the technical field of casting, in particular to a casting method of a main bearing cap of a medium-speed and high-speed high-power diesel engine.
Background
The main bearing cap is known as one of important parts in diesel engine parts, is made of nodular cast iron (hereinafter referred to as nodular cast iron), is matched with an engine body, needs to bear larger alternating impact load, has higher quality requirement, does not allow welding repair, does not allow casting defects such as shrinkage cavities (looseness), air holes, slag inclusion, cracks and the like, and the like.
The applicant carries out technical novelty search and search at home and abroad on the casting technology of the main bearing cap of the diesel engine and finds that:
1. related literature '280 diesel engine main bearing cap process improvement' (papers published date 2013, written popliteal wins, published journal cold and hot processing processes 2013, 5, page numbers 13-14) introduces 280 diesel engine main bearing cap process improvement, and a bottom pouring vertical pouring measure with a tile opening facing upwards is adopted after improvement. This configuration is not conducive to ensuring quality of the tile mouth face and to controlling temperature gradients, etc.
2. Related literature "process optimization of high-horsepower main bearing cap based on MAGM software" (papers published by 2013, written casting periodicals 2013, 62 (4) published by Li Chang, Wangzhou and Huang Youyu, page number 296-300) introduces the process optimization of the high-horsepower main bearing cap based on the MAGM software, a spherical dead head is placed in the middle of the top after the optimization introduced by the literature, an inner sprue is arranged at the position of a riser neck, and a slender sand core is adopted at the hot spot at two ends of a casting to reduce the hot spot at the thick part and the large part of the casting. The slender sand core cannot smoothly discharge gas generated in the cavity in the casting process, and is very easy to deform, break and chemically stick sand, so that products are scrapped and the like.
3. Related literature VHP type main bearing cap casting process development (papers published in 2017, modern cast iron periodicals 2017 and 5 published by Tsuki pine and Tsuwood, page numbers 77-79)) introduces casting process development of the VHP type main bearing cap, and the literature discloses that horizontal pouring is adopted at a pouring position of the bearing cap, and defects such as inclusion, air holes and the like are easy to occur on the upper plane of the pouring position to cause casting scrap.
4. Chinese patent, patent name: a casting method of a main shaft cover of a nodular cast iron gasoline engine and a casting mold applying the method are disclosed in the specification: CN102489667A, published: 2012.06.13, this patent adopts the iron mold precoated sand casting process (a special casting technique, the casting mold has high rigidity, cooling is fast, especially suitable for the production of nodular cast iron, can utilize the graphitization expansion of nodular cast iron to self-feeding the casting when producing nodular cast iron — realize the little, no riser casting of nodular cast iron, get the high quality casting, this method iron mold has large capital investment, need the core shooting machine of the hot box when the iron mold is coated with sand).
5. Chinese patent, patent name: the diesel engine owner bears the group type molding of lid, publication number: CN202105983U, published: 2012.01.11, the main bearing cap of this patent is used in horizontal casting; the special iron box, the bottom plate, the iron frame, the adjusting iron block, the locking iron, the triangular iron sheet and other tools need to be designed and manufactured in the group.
In summary, through search, further exploration and research on the casting method of the main bearing cap of the medium-speed and high-power diesel engine are urgently needed at present.
Disclosure of Invention
In order to overcome the defects in the background technology, the invention provides a casting method of a main bearing cap of a medium-speed high-power diesel engine, which is characterized in that according to the solidification characteristics of ductile iron, the structure and the quality requirements of the main bearing cap are considered, and in order to ensure the density of the main bearing cap and prevent the generation of shrinkage cavity (loose) casting defects during the design of a casting process, a top pouring rain pouring mode that molten metal is introduced from a dead head arranged at the top of a casting by adopting a pouring position with a tile mouth facing downwards is adopted, and the molten metal is dispersedly introduced to ensure the uniformity, the small impact force and the continuous filling of a cavity.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a casting method of a main bearing cap of a medium-speed high-power diesel engine specifically comprises the following steps:
the first step is casting process design:
in order to ensure the quality of the tile opening surface, the pouring position of the main bearing cover is determined to ensure that the tile opening surface faces downwards, the center line of the side surface of the main bearing cover is used as a vertical pouring parting surface for left and right parting, and the casting parameter design comprises the following contents:
A. designing a riser modulus and a riser neck modulus:
firstly, calculating a thermal node modulus MC of a main bearing cover, a modulus MR of a riser and a modulus MN of a riser neck, wherein MC: MR: MN = 1: (0.9-1.1): (0.25-0.4), the thermal node modulus MC of the main bearing cover is one half of the maximum thickness of the main bearing cover, so the total thickness of the riser is 0.9-1.1 times of the maximum thickness of the main bearing cover, the total thickness of the riser neck is 0.25-0.4 times of the maximum thickness of the main bearing cover, and the height HR = (0.5-0.7) HC, wherein HC is the height of the main bearing cover;
B. designing the pouring weight of the main bearing cap:
and estimating the weight of the pouring system according to the weight of the main bearing cap and the weight of the required riser, and calculating the pouring weight G of the main bearing cap as follows: the weight of the main bearing cover, the weight of a riser and the weight of a pouring system;
C. a conventional casting process is adopted, and a top surface rain pouring mode is designed:
designing a pouring system, and selecting a top-shower pouring system according to the characteristics of the main bearing cover, the solidification characteristic of the ductile iron and the quality requirement, wherein the proportion of the pouring system is firstly opened and then closed, and the proportion of the pouring system is ∑ FStraight bar:∑FHorizontal bar:∑FInner partThe ratio of the casting time to the casting time is 1.0:2.0, (1.2-1.5), and the formula is as follows:
Figure 196804DEST_PATH_DEST_PATH_IMAGE001
g is the pouring weight, S is the coefficient related to the wall thickness of the main bearing cap, the value of S is reasonably adjusted, the gas in the casting mold can be discharged conveniently, the casting mold is not damaged, and then the average pressure head h is calculatedpCalculating the sectional areas and the sizes of the sprue, the cross sprue and the ingate;
step two, manufacturing a left half die and a right half die:
the production method comprises the following steps of manufacturing a left half mould and a right half mould according to the casting process and the drawing of the main bearing cover, wherein the production mode adopts a core assembly mode, the left half mould and the right half mould are in a frame type for facilitating drawing, and the periphery of the left half mould and the right half mould is in a falling type;
the third step: manufacturing a left half sand core and a right half sand core:
filling configured molding sand into the manufactured left half die and the right half die respectively, tamping and scraping, after the molding sand in the left half die and the right half die is hardened, lifting the molding sand in the left half die out of the left half die to form a left half sand core, and lifting the molding sand in the right half die out of the right half die to form a right half sand core;
the fourth step: closing the box and enclosing the box:
the right half sand core and the left half sand core are combined to form a casting mold, at least one group of casting molds are matched and arranged according to the casting weight requirement, then a sleeve box is used for sheathing the arranged casting molds, the prepared molding sand is filled between the casting molds and the sleeve box and is tamped, and a sprue seat is placed at a sprue gate when a group of main bearing covers are cast;
the fifth step: smelting and pouring:
smelting molten metal by using an induction furnace, wherein the tapping temperature of the molten metal is 1470-1490 ℃, the pouring temperature is 1350-1360 ℃, and the pouring time is 12-15S;
and a sixth step: cleaning a blank:
carrying out shakeout, riser cutting, artificial aging, body performance sample extraction according to batches, shot blasting and polishing on the cast main bearing cap;
the seventh step: and (4) checking:
and (5) inspecting the body performance, the hardness and the appearance of the body of the main bearing cap according to the pouring batch.
According to the casting method of the main bearing cap of the medium and high speed high power diesel engine, in the first step, the heat joint is a thick and large part, and the heat joint modulus of the main bearing cap is half of the maximum thickness of the main bearing cap.
According to the casting method of the main bearing cap of the medium-speed and high-power diesel engine, the value of S in the first step is 2.5-3.5.
In the casting method of the main bearing cap of the medium and high speed high power diesel engine, the material of the left half mould and the right half mould in the second step is wood, resin or metal.
According to the casting method of the main bearing cover of the medium-speed high-power diesel engine, in the fourth step, a main bearing cover casting mold is formed after the middle-right half sand core and the left half sand core are spliced, a main bearing cover cavity is arranged in the main bearing cover casting mold, a sprue seat is arranged at the top end of the main bearing cover casting mold, a sprue arranged in the main bearing cover casting mold is connected to the bottom of the sprue seat, the bottom of the sprue is communicated with a runner, the bottom of the runner is provided with a plurality of ingates, the bottom of the ingates is communicated with risers, the bottom of the risers is communicated with a riser neck, the bottom of the riser neck is communicated with the main bearing cover cavity, the main bearing cover casting mold is arranged into at least one group, a sleeve box is arranged on the periphery of one or more groups of main bearing cover casting molds, and molding sand.
According to the casting method of the main bearing cap of the medium and high speed high power diesel engine, the bottom of the sprue seat is provided with the filter disc.
According to the casting method of the main bearing cap of the medium-speed and high-power diesel engine, an air outlet is formed in one side of the riser.
According to the casting method of the main bearing cap of the medium-speed and high-power diesel engine, the molding sand is furan resin sand or suitable molding sand which is easily obtained in a production field.
By adopting the technical scheme, the invention has the following advantages:
according to the solidification characteristics of ductile iron, the structure and quality requirements of the main bearing cap are considered, and in order to ensure the density of the main bearing cap and prevent the generation of shrinkage cavity (loose) casting defects, a top pouring shower pouring mode that molten metal is introduced from a riser arranged at the top of a casting at a pouring position with a downward tile opening is adopted during the design of a casting process, and the molten metal is dispersedly introduced to ensure the uniformity of the molten metal, small impact force and continuous filling of a cavity.
Drawings
FIG. 1 is a schematic view of the structure of a left half sand core or a right half sand core in the present invention;
FIG. 2 is a schematic cross-sectional structural view of the present invention;
in the figure: 1. a cross gate; 2. an inner gate; 3. a riser; 4. a riser neck; 5. a main bearing cap; 6. an air outlet; 7. a sprue seat; 8. a filter disc; 9. a right half sand core; 10. molding sand; 11. a left half sand core; 12. sleeving a box; 13. a sprue.
Detailed Description
The present invention will be explained in more detail by the following examples, which are not intended to limit the invention;
when the sand core positioning device is specifically implemented, the right half sand core 9 and the left half sand core 11 are respectively provided with a positioning pin and a positioning hole.
When the molten metal pouring device is specifically applied, molten metal sequentially passes through a sprue seat 7, a filter plate 8, a sprue 13, a cross runner 1, an inner sprue 2, a riser 3 and a riser neck 4 and then enters a main bearing cover cavity, wherein the number of the inner sprue 2 is 10-12 small round sprues which are similar to a rain pattern, so that the impact force on the main bearing cover cavity is small, the hot molten metal flow continuously washes the rising liquid level, and molten slag is not easy to adhere to the wall of the main bearing cover cavity; the temperature of the top of the molten metal is always kept higher than that of the bottom of the molten metal in the pouring process, a feeding channel from bottom to top is formed, the temperature of the upper part of the molten metal is higher than that of the bottom of the molten metal after filling, sequential solidification of castings from bottom to top and feeding of a riser are facilitated, and the purpose of controlling the temperature gradient is achieved; the gas outlet 6 arranged at the top of the riser 3 can smoothly discharge gas and the like generated in the cavity in the casting process.
Furthermore, the invention calculates the casting thermal section, a riser feeding is arranged at the top of the casting, in order to ensure the quality of the tile opening, the pouring position of the main bearing cover casting is determined to be that the tile opening faces downwards, the riser designed at the top plays a role in feeding and slag collection, and a cavity gas outlet 6 is arranged at the top of the riser 3 far away from the end of the sprue 13, so that the purpose of discharging gas in the cavity in the pouring process is achieved.
Furthermore, the invention has simple and convenient operation, obviously reduces the labor intensity of operators, does not need special tools, occupies less production field, is convenient for production organization, has high production efficiency and high and stable yield.
The specific embodiment of the invention is as follows:
EXAMPLE 1 TBD620 Main bearing Cap of high speed Diesel Engine
The first step is as follows: and (3) casting process design:
A. designing a riser modulus and a riser neck modulus:
calculating a hot spot modulus MC of a TBD620 main bearing cap 5, wherein the hot spot modulus of the main bearing cap is one half of the maximum thickness of the main bearing cap, the thickness of the TBD620 main bearing cap is 68mm, the thickness of a riser 3 is selected according to 0.9 in the coefficient relation of (0.9-1.1), the thickness of the riser 3 is calculated to be 61.2 mm, and 62mm is taken; the thickness of the riser neck 4 is selected according to 0.3 in the coefficient relation of (0.25-0.4), the thickness of the riser neck 4 is calculated to be 20.4mm, and 21mm is taken; selecting the height HR of the riser 3 according to 0.5 in the coefficient relation of (0.5-0.7), and designing the height of the riser 3 to be 100 mm;
B. designing the pouring weight of the casting:
the main bearing caps 5 weighed 25kg, the risers 3 weighed 13 kg based on volume and density, the gating system weight was estimated to be 6kg, two pieces were poured in one set, so the pouring weight was (25 +13+ 6) × 2-88 kg;
C. a conventional casting process is adopted, and a top surface rain pouring mode is designed:
designing a pouring system, and selecting a top-shower pouring system according to the characteristics of the main bearing cover 5, the solidification characteristics of the ductile iron and the quality requirements, wherein the proportion of the pouring system is ∑ FStraight bar:∑FHorizontal bar:∑FInner part＝1.0:2.0: 1.2：
1. The pouring time calculation formula is as follows: t = (2.5 to 3.5)
Figure 700753DEST_PATH_IMAGE002
G- -the casting weight, 88 kg; the coefficient is 3.0;
Figure 344224DEST_PATH_IMAGE003
2. calculating the average head hp:
hp=
Figure 741707DEST_PATH_IMAGE004
In the formula: h, the sum of the height of the sprue and the height of the sprue seat ring is 200 mm;
K1、K2the effective section ratios of the straight pouring channel and the horizontal pouring channel and the straight pouring channel and the inner pouring channel are respectively;
K1=
Figure 470629DEST_PATH_IMAGE005
，μ1、μ2flow coefficients of a straight pouring channel and a horizontal pouring channel are respectively set;
K2=
Figure 549443DEST_PATH_IMAGE006
，μ1、μ3flow coefficients of a straight pouring channel and an inner pouring channel are respectively set;
μ1=0.50～0.65，μ2=0.50～0.65，μ3= 0.45-0.60; get
μ1=0.55，μ2=0.55，μ3= 0.50. Calculated, K1、K2Respectively as follows: 0.5 and 0.917.
Average head hp=
Figure 860470DEST_PATH_IMAGE007
=80 mm=8 cm；
3. Calculating minimum cross-sectional area of pouring system
The minimum section of the gating system is a cross gate;
Figure 632117DEST_PATH_IMAGE008
4. calculating gating system dimensions
4.1, calculating the diameter of the sprue
A straight-hole ceramic filter plate is placed at the sprue, and when the straight-hole ceramic filter plate is used for the ductile iron, the filtering area is larger than the flow choking area of 4-8 times, and the filtering area is 4 times;
∑Ffor treating=4∑FStraight bar=62.4cm2Design phi after calculationFor treating=88 mm；
4.2 calculating the size of the horizontal runner
∑FStraight bar:∑FHorizontal bar＝1.0:2.0，∑FHorizontal bar＝31.2 cm2. This case is a set of 2 pieces, and thus the cross-sectional area of the runner for each bearing cap is 15.6 cm2The cross section area of the horizontal runner is designed to be 32/38 × 45 mm;
4.3 calculating the size of the inner pouring gate
∑FStraight bar:∑FInner part＝1.0: 1.2，∑FInner part＝18.72 cm2. This case is a set of 2 pieces, so that the sectional area of the ingate for each bearing cap is 9.36 cm2Each bearing cover is provided with 12 rain inner gates, and the size of each inner gate is calculated to be phi 10 mm;
step two, manufacturing a left half die and a right half die:
manufacturing a left half die and a right half die according to a designed TBD620 main bearing cap casting process and a main bearing cap drawing, wherein the materials are wood, the production mode adopts a core assembly mode, in order to facilitate stripping, the main bodies of the left half die and the right half die adopt a frame type, and the periphery of the left half die and the right half die adopts a falling type;
the third step: manufacturing a left half sand core 11 and a right half sand core 9:
filling the prepared furan resin sand into the manufactured left half die and the right half die respectively, tamping and scraping, lifting the furan resin sand in the left half die out of the left half die to form a left half sand core 11 after the furan resin sand in the left half die and the right half die is hardened, and lifting the furan resin sand in the right half die out of the right half die to form a right half sand core 9;
the fourth step: closing the box and enclosing the box:
forming a casting mold after the right half sand core 9 and the left half sand core 11 are combined, matching and arranging the casting mold according to the casting weight requirement, then sheathing the arranged casting mold by using a suitable sleeve 12 on site, filling the prepared furan resin sand between the casting mold and the sleeve 12, tamping, and placing a 100X 20mm straight-hole ceramic filter sheet 8 and a sprue seat 7 at a sprue 13 when a group of bearing covers are cast;
the fifth step: smelting and pouring:
smelting molten metal by using an induction furnace, wherein the components of the molten metal are determined and selected according to actual use requirements, the tapping temperature of the molten metal is 1470-1490 ℃, the pouring temperature is 1350-1360 ℃, and the pouring time is 12-15S;
and a sixth step: cleaning a blank:
carrying out cleaning work on the cast main bearing cap, such as shakeout, riser cutting, artificial aging, body performance sample extraction according to batches, shot blasting, polishing and the like;
the seventh step: and (4) checking:
and (4) testing the performance of the body according to the casting batch, testing the hardness of the body, performing appearance test and the like.
Example 2 high speed Diesel TBD234 Main bearing Cap
The first step is as follows: casting process design
A. Design of riser modulus and riser neck modulus
Calculating a hot spot module MC of the TBD234 main bearing cap, wherein the hot spot module of the main bearing cap is one half of the maximum thickness of the main bearing cap, the thickness of the TBD234 main bearing cap 5 is 40mm, the size of a top riser 3 of the TBD234 main bearing cap 5 is selected according to 1.1 in the coefficient relation of (0.9-1.1), and the thickness of the riser 3 is designed to be 44 mm; selecting the riser neck 4 according to 0.4 in the coefficient relation of (0.25-0.4), calculating the thickness of the riser neck 4 to be 17.6 mm, and taking the thickness to be 18 mm; the height HR of the riser 3 is selected according to 0.7 in the coefficient relation of (0.5-0.7), and the height of the riser is designed to be 100 mm;
B. design of casting pouring weight
The TBD234 main bearing cap weighed 11kg, the riser 3 weighed 5kg based on volume and density, the gating system weight was estimated to be 4kg, and a set of 4 castings was poured, so the poured weight was (11 +5+ 4) × 4-80 kg;
C. adopts conventional casting process and designs top surface shower pouring mode
Designing a pouring system, and selecting the pouring system with top rain according to the characteristics of the main bearing cover, the solidification characteristics of the ductile iron and the quality requirementsThe gating system proportion is selected as open-then-closed gating system, and the gating system proportion is selected as ∑ FStraight bar:∑FHorizontal bar:∑FInner part＝1.0:2.0: 1.5；
1 the pouring time calculation formula is as follows: t = (2.5 to 3.5)
Figure 645073DEST_PATH_IMAGE009
G- -the casting weight, is 80 kg; the coefficient is 3.0;
Figure 527578DEST_PATH_IMAGE010
2 calculate average head hp:
hp=
Figure 880062DEST_PATH_IMAGE011
In the formula: h-the sum of the sprue height and the gate seat height, in this case 180 mm;
K1、K2the effective section ratios of the straight pouring channel and the horizontal pouring channel and the straight pouring channel and the inner pouring channel are respectively;
K1=
Figure 638589DEST_PATH_IMAGE012
，μ1、μ2flow coefficients of a straight pouring channel and a horizontal pouring channel are respectively set;
K2=
Figure 76524DEST_PATH_IMAGE013
，μ1、μ3flow coefficients of a straight pouring channel and an inner pouring channel are respectively set;
μ1=0.50～0.65，μ2=0.50～0.65，μ3= 0.45-0.60; get
μ1=0.55，μ2=0.55，μ3= 0.50. Calculated, K1、K2Respectively as follows: 0.5 and 0.73.
Average head hp
Figure 559458DEST_PATH_IMAGE014
；
3 calculating minimum cross-sectional area of pouring system
The minimum section of the gating system is a cross gate;
Figure 32027DEST_PATH_IMAGE015
4 calculating the size of the gating system
4.1 calculate sprue diameter
A straight-hole ceramic filter plate is placed at the sprue, and when the straight-hole ceramic filter plate is used for the ductile iron, the filtering area is larger than the flow choking area of 4-8 times, and the filtering area is 4 times;
∑Ffor treating=4∑FStraight bar=68.4cm2Design phi after calculationFor treating=92 mm；
4.2 calculate Cross Runner size
∑FStraight bar:∑FHorizontal bar＝1.0:2.0，∑FHorizontal bar＝34.2cm2(ii) a This case is a set of 4 pieces, and thus the cross-sectional area of the runner for each bearing cap is 8.55cm2The cross section area of the cross gate is designed to be 24/30 × 32 mm;
4.3 calculate the ingate size
∑FStraight bar:∑FInner part＝1.0: 1.5，∑FInner part＝25.65cm2. This case is a set of 4 pieces, and thus the sectional area of the ingate for each bearing cap is 6.41cm2Each bearing cover is provided with 10 rain inner gates, and the size of each inner gate is calculated to be phi 9 mm;
step two, manufacturing a left half die and a right half die:
manufacturing a left half die and a right half die according to a designed TBD234 main bearing cap casting process and a drawing of a main bearing cap 5, wherein the materials are selected from metals such as cast aluminum, cast iron and the like, the production mode adopts a core assembly mode, the left half die and the right half die are in a frame mode for facilitating die drawing, and the periphery of the left half die and the right half die are in a falling mode;
the third step: manufacturing a left half sand core 11 and a right half sand core 9:
respectively filling the prepared furan resin sand into the manufactured left half mould and the right half mould, tamping and scraping, after the furan resin sand in the left half mould and the right half mould is hardened, lifting the furan resin sand in the left half mould out of the left half mould to form a left half sand core 11, and lifting the furan resin sand in the right half mould out of the right half mould to form a right half sand core 9;
the fourth step: closing the box and enclosing the box:
forming a casting mold after the right half sand core 9 and the left half sand core 11 are combined, matching and arranging the casting mold according to the casting weight requirement, then sheathing the arranged casting mold by a sleeve 12, filling the prepared furan resin sand between the casting mold and the sleeve 12, tamping, and placing a 100 multiplied by 20mm straight hole ceramic filter sheet 8 and a sprue seat 7 at a sprue 13 when a group of bearing covers are cast;
the fifth step: smelting and pouring:
smelting molten metal by using an induction furnace, wherein the tapping temperature of the molten metal is 1470-1490 ℃, the pouring temperature is 1350-1360 ℃, and the pouring time is 12-15S;
and a sixth step: cleaning a blank:
carrying out cleaning work on the cast main bearing cap, such as shakeout, riser cutting, artificial aging, body performance sample extraction according to batches, shot blasting, polishing and the like;
the seventh step: and (4) checking:
and (4) testing the performance of the body according to the casting batch, testing the hardness of the body, performing appearance test and the like.
Example 3 medium speed machine MAN 21/31 main bearing cap:
the first step is as follows: and (3) casting process design:
A. designing a riser modulus and a riser neck modulus:
calculating a hot joint modulus MC of a main bearing cover of the medium-speed machine MAN 21/31, wherein the hot joint modulus of the main bearing cover is one half of the maximum thickness of the main bearing cover, the thickness of a casting of the main bearing cover of the medium-speed machine MAN 21/31 is 90mm, the thickness of a riser 3 on the top surface of the casting is selected according to 0.9 in the coefficient relation of (0.9-1.1), and the thickness of the riser 3 is calculated to be 81 mm; the thickness of the riser neck 4 is selected according to 0.33 in the coefficient relation of (0.25-0.4), the thickness of the riser neck 4 is calculated to be 29.7mm, and 30 mm is taken; the height HR of the riser 3 is selected according to 0.5 in the coefficient relation of (0.5-0.7), and the height of the riser 3 is designed to be 140 mm;
B. designing the pouring weight of the casting:
the weight of the casting is 65kg, the weight of the riser is 20 kg according to the volume and the density, the weight of the pouring system is estimated to be 8kg, and 1 piece is poured in a group, so that the pouring weight is 65+20+8 which is 93 kg;
C. a conventional casting process is adopted, and a top surface rain pouring mode is designed:
designing a pouring system, and selecting the pouring system with top rain according to the characteristics of the main bearing cover, the solidification characteristic of the ductile iron and the quality requirement, wherein the proportion of the pouring system is selected to be firstly opened and then closed, and the proportion of the pouring system is selected to be ∑ FStraight bar：∑FHorizontal bar：∑FInner part＝1.0:2.0:1.2；
1. The pouring time calculation formula is as follows: t = (2.5 to 3.5)
Figure 145477DEST_PATH_IMAGE016
G- -the casting weight is 93 kg; the coefficient is 3.0;
t=
Figure 883757DEST_PATH_IMAGE017
2. calculating the average head hp:
hp=
Figure 108065DEST_PATH_IMAGE018
In the formula: h-the sum of the sprue height and the gate seat height, in this case 200 mm;
K1、K2the effective section ratios of the straight pouring channel and the horizontal pouring channel and the straight pouring channel and the inner pouring channel are respectively;
K1=
Figure 169562DEST_PATH_IMAGE019
，μ1、μ2flow coefficients of a straight pouring channel and a horizontal pouring channel are respectively set;
K2=
Figure 516229DEST_PATH_IMAGE020
，μ1、μ3flow coefficients of a straight pouring channel and an inner pouring channel are respectively set;
μ1=0.50～0.65，μ2=0.50～0.65，μ3= 0.45-0.60; get
μ1=0.55，μ2=0.55，μ3= 0.50. Calculated, K1、K2Respectively as follows: 0.5 and 0.917.
Average head hp=
Figure 928756DEST_PATH_IMAGE021
；
3. Calculating minimum cross-sectional area of pouring system
The minimum section of the gating system is a cross gate;
Figure 769804DEST_PATH_IMAGE022
4. calculating gating system dimensions
4.1 calculate sprue diameter
A straight-hole ceramic filter plate is placed at the sprue, and when the straight-hole ceramic filter plate is used for the ductile iron, the filtering area is larger than the flow choking area of 4-8 times, and the filtering area is 4 times;
∑Ffor treating=4∑FStraight bar=60.57cm2Design phi after calculationFor treating=88 mm；
4.2 calculate Cross Runner size
∑FStraight bar:∑FHorizontal bar＝1.0:2.0，∑FHorizontal bar＝30.3cm2(ii) a This case is a set of 1 piece, and thus the cross-sectional area of the runner for each bearing cap is 30.3 cm2The cross section area of the horizontal runner is designed to be 58/62 × 50 mm;
4.3 calculate the ingate size
∑FStraight bar:∑FInner part＝1.0: 1.2，∑FInner part＝18.18cm2. This case is a set of 1-piece parts, so that each bearing cap is used internallyThe cross-sectional area of the gate is 18.18cm2Each bearing cover is provided with 12 deluge inner gates, and the size of the inner gate is calculated to be phi 14 mm;
step two, manufacturing a left half die and a right half die:
manufacturing a left half die and a right half die according to a designed MAN 21/31 main bearing cap casting process and a drawing of a main bearing cap 5, wherein the materials are selected from resin, the production mode adopts a core assembly mode, the left half die and the right half die are in a frame type for facilitating die stripping, and the periphery of the left half die and the right half die are in a falling type;
the third step: manufacturing a left half sand core 11 and a right half sand core 9:
filling configured molding sand 10 into the manufactured left half mold and the right half mold respectively, tamping and scraping, after the molding sand 10 in the left half mold and the right half mold is hardened, lifting the molding sand 10 in the left half mold out of the left half mold to form a left half sand core 11, and lifting the molding sand 10 in the right half mold out of the right half mold to form a right half sand core 9;
the fourth step: closing the box and enclosing the box:
forming a casting mold after the right half sand core 9 and the left half sand core 11 are combined, matching and arranging the casting mold according to the casting weight requirement, then sheathing the arranged casting mold by using a sleeve 12, filling the prepared molding sand 10 between the casting mold and the sleeve 12, tamping, and placing a 100 multiplied by 20mm straight hole ceramic filter sheet 8 and a sprue seat 7 at a straight pouring gate 13 when a group of bearing covers are poured;
the fifth step: smelting and pouring:
smelting molten metal by using an induction furnace, wherein the tapping temperature of the molten metal is 1470-1490 ℃, the pouring temperature is 1350-1360 ℃, and the pouring time is 12-15S;
and a sixth step: cleaning a blank:
carrying out cleaning work on the cast main bearing cap, such as shakeout, riser cutting, artificial aging, body performance sample extraction according to batches, shot blasting, polishing and the like;
the seventh step: and (4) checking:
and (4) testing the performance of the body according to the casting batch, testing the hardness of the body, performing appearance test and the like.
The present invention is not described in detail in the prior art.
The embodiments selected for the purpose of disclosing the invention are presently considered to be suitable, however, it should be understood that the invention is intended to cover all variations and modifications of the embodiments falling within the spirit and scope of the present inventive concept.

Claims (3)

1. A casting method of a main bearing cap of a medium-speed and high-speed high-power diesel engine is characterized by comprising the following steps: the casting method specifically comprises the following steps:
the first step is casting process design:
in order to ensure the quality of the bearing opening surface, the pouring position of the main bearing cover (5) is determined to ensure that the bearing opening surface faces downwards, the center line of the side surface of the main bearing cover (5) is used as a vertical pouring parting surface for left and right parting, and the casting parameter design comprises the following contents:
A. designing a riser modulus and a riser neck modulus:
firstly, calculating a thermal section modulus MC of a main bearing cover (5), a modulus MR of a riser (3) and a modulus MN of a riser neck (4), wherein MC: MR: MN = 1: (0.9-1.1): (0.25-0.4), the total thickness of the riser (3) is 0.9-1.1 times of the maximum thickness of the main bearing cover (5), the total thickness of the riser neck (4) is 0.25-0.4 times of the maximum thickness of the main bearing cover (5), and the height HR = (0.5-0.7) HC of the riser (3), wherein HC is the height of the main bearing cover (5);
B. designing the pouring weight of the main bearing cap (5):
and then estimating the weight of the pouring system according to the weight of the main bearing cap (5) and the weight of the required riser (3), and calculating the pouring weight G of the main bearing cap (5) as follows: the weight of the main bearing cap (5), the weight of the riser (3) and the weight of a pouring system;
C. a conventional casting process is adopted, and a top surface rain pouring mode is designed:
designing a pouring system, selecting a top-shower pouring system according to the characteristics of the main bearing cover (5), the solidification characteristic of the ductile iron and the quality requirement, wherein the pouring system is selected to be an open-first closed pouring system, and the proportion of the pouring system is selected to be ∑ FStraight bar:∑FHorizontal bar:∑FInner part1.0:2.0 (1.2-1.5), and pouring timeThe calculation formula is as follows: t = S
Figure 75362DEST_PATH_IMAGE001
G is the pouring weight, S is a coefficient related to the wall thickness of the main bearing cover (5), the value of S is 2.5-3.5, the value of S is reasonably adjusted, the gas in the casting mold can be discharged conveniently, the casting mold is not damaged, and then the average pressure head h is calculatedpCalculating the sectional areas and the sizes of the straight pouring channel (13), the horizontal pouring channel (1) and the inner pouring gate (2);
step two, manufacturing a left half die and a right half die:
the production method comprises the following steps of manufacturing a left half mould and a right half mould according to the casting process and the drawing of the main bearing cover (5), wherein the production mode adopts a core assembly mode, the left half mould and the right half mould adopt a frame type for facilitating stripping, and the periphery of the left half mould and the right half mould adopts a drop type;
the third step: manufacturing a left half sand core (11) and a right half sand core (9):
filling configured molding sand (10) into the manufactured left half mould and the right half mould respectively, tamping and scraping, after the molding sand (10) in the left half mould and the right half mould is hardened, taking out the molding sand (10) in the left half mould from the left half mould to form a left half sand core (11), and taking out the molding sand (10) in the right half mould from the right half mould to form a right half sand core (9);
the fourth step: closing the box and enclosing the box:
the method comprises the following steps of forming casting molds after a right half sand core (9) and a left half sand core (11) are combined, matching and arranging at least one group of casting molds according to the casting weight requirement, then sheathing the arranged casting molds by using a sleeve box (12), filling prepared molding sand (10) between the casting molds and the sleeve box (12), tamping, placing a sprue seat (7) at a sprue (13) when a group of main bearing caps (5) are cast, arranging a filter sheet (8) at the bottom of the sprue seat (7), forming a main bearing cap casting mold after the right half sand core (9) and the left half sand core (11) are combined, arranging a main bearing cap cavity in the main bearing cap casting mold, arranging the sprue seat (7) at the top end of the main bearing cap casting mold, connecting the sprue (13) arranged in the main bearing cap casting mold with the bottom of the sprue seat (7), and communicating the bottom of the sprue (13) with a cross runner (1), the casting mould is characterized in that a plurality of inner gates (2) are arranged at the bottom of the cross runner (1), the bottoms of the inner gates (2) are communicated with risers (3), gas outlets (6) are formed in one sides of the risers (3), the bottoms of the risers (3) are communicated with riser necks (4), the bottoms of the riser necks (4) are communicated with main bearing cover mould cavities, at least one group of main bearing cover casting moulds are arranged, sleeve boxes (12) are arranged on the peripheries of one or more groups of main bearing cover casting moulds, and molding sand (10) is arranged between the inner cavities of the sleeve boxes (12) and the main bearing cover casting moulds;
the fifth step: smelting and pouring:
smelting molten metal by using an induction furnace, wherein the tapping temperature of the molten metal is 1470-1490 ℃, the pouring temperature is 1350-1360 ℃, and the pouring time is 12-15 s;
and a sixth step: cleaning a blank:
carrying out shakeout, riser cutting, artificial aging, body performance sample extraction according to batches, shot blasting and polishing on the cast main bearing cap (5);
the seventh step: and (4) checking:
and (5) inspecting the body performance, the body hardness and the appearance of the main bearing cap (5) according to the pouring batch.
2. The method for casting the main bearing cap of the medium-high speed and high-power diesel engine according to claim 1, wherein the method comprises the following steps: and in the second step, the left half die and the right half die are made of wood, resin or metal.
3. The method for casting the main bearing cap of the medium-high speed and high-power diesel engine according to claim 1, wherein the method comprises the following steps: the molding sand (10) is furan resin sand.
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