阅读说明：本技术 火电球铁低压内缸的铸造工艺 (Casting process of thermal power ductile iron low-pressure inner cylinder ) 是由 郑永杰 孙福俊 薛吉庆 钱红武 裴志勇 刘广升 杨继伟 于 2020-07-11 设计创作，主要内容包括：本发明火电球铁低压内缸的铸造工艺,涉及球铁铸造技术领域,尤其涉及火电球铁低压内缸的铸造工艺。本发明火电球铁低压内缸的铸造工艺的浇注方式为底注式；铸造用的火电球铁低压内缸型芯结构分为上半型芯和下半型芯,两个型芯经底注式浇注后分别铸造出上半和下半两个半型内缸,两半内缸经加工后装配在一起,组成一个整体的低压内缸结构。本发明的技术方案解决了现有技术中的稳定性差,废品率高,铸造难度极大,制造成本高,适用范围小,无法实现量产等问题。(The invention discloses a casting process of a thermal power ductile iron low-pressure inner cylinder, relates to the technical field of ductile iron casting, and particularly relates to a casting process of a thermal power ductile iron low-pressure inner cylinder. The casting process of the thermal power ductile iron low-pressure inner cylinder adopts a bottom pouring mode; the core structure of the thermal power ductile iron low-pressure inner cylinder for casting is divided into an upper half core and a lower half core, the upper half and the lower half of the two cores are respectively cast after bottom pouring, and the two half inner cylinders are assembled together after being processed to form an integral low-pressure inner cylinder structure. The technical scheme of the invention solves the problems of poor stability, high rejection rate, great casting difficulty, high manufacturing cost, small application range, incapability of realizing mass production and the like in the prior art.)

1. A casting process of a thermal power ductile iron low-pressure inner cylinder; the method is characterized in that the casting mode of the casting process of the thermal power ductile iron low-pressure inner cylinder is a bottom pouring mode; the core structure of the thermal power ductile iron low-pressure inner cylinder for casting is divided into an upper half core and a lower half core, the two cores are respectively cast into an upper half inner cylinder and a lower half inner cylinder after bottom pouring, and the two half inner cylinders are assembled together after being processed to form an integral low-pressure inner cylinder structure;

the upper half core comprises: the upper half upper die (1), the upper half middle-sized assembly (6), the upper half lower die (9), the upper half flaky core assembly (4), the upper half volute core (5), the upper half air inlet pipe outer core (10), the upper half air inlet pipe inner core (11), a chill (7) and a riser (3); the upper half-middle-sized component (6) is arranged on the upper part of the upper half-lower mould (9); the upper half air inlet pipe inner core (11) is arranged in the middle of the upper half middle-sized component (6) and embedded in a core print on the upper end surface of the upper half lower mold (9); two upper half air inlet pipe outer cores (10) are symmetrically arranged on two sides of the outer part of the upper half air inlet pipe inner core (11); the upper half volute core (5) is arranged at the upper part of the upper half air inlet pipe inner core (11), and two groups of upper half sheet-shaped core components (4) are symmetrically arranged outside the upper half volute core; the upper half upper die (1) is arranged at the upper part of the upper half middle-sized assembly (6), and the upper half flaky core assembly (4), the upper half volute core (5), the upper half air inlet pipe inner core (11) and the upper half air inlet pipe outer core (10) are packaged inside the upper half middle-sized assembly (6) and the upper half lower die (9); three groups of straight runners (2) and inner runners (8) are arranged inside the upper half upper mould (1), the upper half middle-sized component (6) and the upper half lower mould; the upper half upper mold (1) is provided with at least 6 risers (3); a plurality of chills (7) are arranged at the lower pouring cavity of the upper half volute core (5) and the upper half sheet-shaped core component (4);

the lower half core comprises: a lower half upper mold (13), a lower half middle-sized assembly (16), a lower half lower mold (17), a lower half sheet-shaped core assembly (14), a lower half volute core (15), a lower half air inlet pipe core assembly (18), a chill (7) and a riser (3); the lower half-middle-sized component (16) is arranged at the upper part of the lower half lower mould (17); the lower half air inlet pipe core-shaped component (18) is arranged in the middle of the lower half middle-sized component (16) and embedded in a core print on the upper end surface of the lower half lower-shaped component (17); the lower half volute core (15) is arranged in the middle of the lower half middle-sized component (16) and positioned at the upper part of the lower half air inlet pipe core-shaped component (18), and two groups of lower half sheet-shaped core components (14) are symmetrically arranged outside the lower half volute core; the lower half upper mold (13) is arranged at the upper part of the lower half middle-sized component (16), and a lower half volute core (15), a lower half sheet-shaped core component (14) and a lower half air inlet pipe core component (18) are packaged inside the lower half middle-sized component (16) and the lower half lower mold (17); 2-4 groups of straight pouring channel straight pouring channels (2) and 2-4 groups of ingates (8) are arranged in the lower half lower die (17), the lower half middle-sized component (16) and the lower half lower die; the lower half lower mould (17) is provided with at least 6 risers (3), and a plurality of chills (7) are arranged at the lower pouring cavity of the lower half volute core (15) and the lower plate sheet core component.

2. A casting process of a thermal power ductile iron low-pressure inner cylinder according to claim 1, wherein the upper half middle assembly (6) comprises: a top half-middle a (63), a top half-middle B (62), and a top half-middle C (61); the upper part of the upper half lower mould (9) is sequentially arranged from bottom to top to form an integral core structure, and the shape of the inner surface of the integral core structure is the same as that of the integral outer surfaces of the upper half flaky core assembly (4) and the upper half air inlet pipe outer core (10).

3. The casting process of the thermal power ductile iron low-pressure inner cylinder as claimed in claim 1, wherein the upper semi-sheet core assembly (4) consists of three pairs of semi-arc upper semi-sheet cores A (43), upper semi-sheet cores B (42) and upper semi-sheet cores C (41); three pairs of upper half flaky cores A (43), upper half flaky cores B (42) and upper half flaky cores C (41) are symmetrically arranged on two sides of the upper half volute core (5) from inside to outside in sequence; the inner shape formed by combining the pair of upper half sheet-shaped cores A (43) is the same as the outer shape of the upper half volute core (5); gaps of 2mm are reserved among the adjacent upper half flaky cores A (43), the upper half flaky cores B (42) and the upper half flaky cores C (41) to prevent scratching during core loading; and a 60mm gap is reserved between the upper half sheet-shaped core C (41) on the outermost side and the upper half medium-sized component (6), and the gap is filled with resin sand after the upper core is finished so as to prevent the sand core from moving outwards when molten iron is poured.

4. A casting process of a thermal power ductile iron low pressure inner cylinder according to claim 1, wherein said lower semi-intermediate assembly (16) comprises: a lower half-middle a (162) and a lower plate middle B (161); the lower half core assembly is sequentially arranged on the upper part of a lower half lower die (17) from bottom to top to form an integral core structure, and the shape of the inner surface of the integral core structure is the same as that of the integral outer surfaces of the lower half flaky core assembly (14) and the lower half air inlet pipe core assembly (18).

5. The casting process of the thermal power ductile iron low-pressure inner cylinder as claimed in claim 1, wherein the lower half flaky core assembly (14) consists of three half-and-half arc-shaped lower half flaky cores A (143), a lower flaky core B (142) and a lower flaky core C (141); three pairs of lower half flaky cores A (143), lower flaky cores B (142) and lower flaky cores C (141) are symmetrically arranged at two sides of the lower half volute core (15) from inside to outside in sequence; the inner shape formed by combining the pair of lower half sheet cores A (143) is the same as the outer shape of the lower half volute core (15); gaps of 2mm are reserved among the adjacent lower half flaky core A (143), the lower flaky core B (142) and the lower flaky core C (141) to prevent scratching during core descending; a60 mm gap is reserved between the lower flaky core C (141) at the outermost side and the lower half-middle-sized component (16), and the gap is filled with resin sand after core setting is finished so as to prevent the sand core from moving outwards when molten iron is poured.

6. The casting process of the thermal power ductile iron low-pressure inner cylinder as claimed in claim 1, wherein the lower half air inlet pipe core assembly (18) comprises a lower half air inlet pipe core A (181) and a lower half air inlet pipe core B (182) which are oppositely arranged, and the middle parts of the lower half air inlet pipe core A and the lower half air inlet pipe core B are combined to form an embedded positioning core head of a lower half volute core (15).

7. A pouring system for a casting process of a thermal power ductile iron low-pressure inner cylinder; the method is characterized in that: the gating system comprises: the upper half type casting system and the lower half type casting system;

first type gating system design have 3 sprue (2) and 3 groups ingate (8), every sprue (2) is alone for respective ingate (8) molten iron that supplies with, the choked flow cross-section is the sprue, each cross-section ratio is the sprue: a horizontal pouring channel: the inner pouring gate is 1: 1.2-1.5: 3.0-5.0; wherein 1 group of ingates (8) are designed on the end face of the air inlet pipe at the bottommost part of the cylinder, the other 2 groups of ingates (8) are designed on the bottom of the air passage at the outermost side of the electric regulation end at the secondary bottom, molten iron rises to a median plane through the bottom of a casting, turbulence and backflow are not generated when three parts of molten iron are converged, staggered pouring is needed during pouring, molten iron in a pouring box of the air inlet pipe is poured for 10-20 seconds first, and then the other 2 pouring boxes start pouring;

the whole designs of ingate (8) of the lower half type gating system are on the end face of the outlet pipe, molten iron rises to the median plane through the bottom of the casting, 2-4 straight runners (2) and 2-4 groups of ingates (8) are designed according to the molten iron amount condition, the outlet pipe of the lower half type is usually on the same plane, or the height difference of the plane is small, turbulence and backflow are generated, the influence on the molten iron can be ignored, and staggered pouring can be avoided.

Technical Field

The invention discloses a casting process of a thermal power ductile iron low-pressure inner cylinder, relates to the technical field of ductile iron casting, and particularly relates to a casting process of a thermal power ductile iron low-pressure inner cylinder.

Background

At present, most of low-pressure inner cylinders used in thermal power generating units at home and abroad are steel structural members, the steel structural members cannot manufacture volute streamline structures theoretically required by the low-pressure inner cylinders and only can manufacture structures similar to theoretical curves, so that the generating efficiency of the units is influenced, meanwhile, the steel structural members are unstable, the phenomena of deformation and air leakage can occur in the using process, and the generating efficiency of the thermal power generating units is reduced.

In order to solve the defects of the steel structural member, foreign production enterprises design the ductile iron low-pressure inner cylinder and realize application, the ductile iron low-pressure inner cylinder casts a volute streamline structure required by theoretical calculation, the power generation efficiency is obviously improved, the structure is stable, and the phenomenon of deformation and air leakage is avoided in the using process.

However, the ductile iron low-pressure inner cylinder has a complex structure, poor stability of casting process, high rejection rate, great casting difficulty and high manufacturing cost, and can only be used in individual units, and mass production cannot be realized, so that the manufacturing bottleneck hinders the wide application of the ductile iron low-pressure inner cylinder.

Aiming at the problems in the prior art, the novel casting process of the thermal power ductile iron low-pressure inner cylinder is researched and designed, so that the problem in the prior art is very necessary to be overcome.

Disclosure of Invention

According to the technical problems that the stability is poor, the rejection rate is high, the casting difficulty is extremely high, the manufacturing cost is high, the application range is small, mass production cannot be achieved, and the like, the casting process of the thermal power ductile iron low-pressure inner cylinder is provided. The low-pressure inner cylinder is divided into the upper half part and the lower half part to be cast separately and assembled together after being processed, so that the effects of high process stability, low manufacturing cost, relative simple operation and mass production can be achieved.

The technical means adopted by the invention are as follows:

the pouring mode of the casting process of the thermal power ductile iron low-pressure inner cylinder is a bottom pouring mode; the core structure of the thermal power ductile iron low-pressure inner cylinder for casting is divided into an upper half core and a lower half core, the two cores are respectively cast into an upper half inner cylinder and a lower half inner cylinder after bottom pouring, and the two half inner cylinders are assembled together after being processed to form an integral low-pressure inner cylinder structure;

further, the upper half core comprises: the upper half upper die, the upper half middle-sized assembly, the upper half lower die, the upper half sheet-shaped core assembly, the upper half volute core, the upper half air inlet pipe outer core, the upper half air inlet pipe inner core, the chill and the riser; the upper half middle-sized component is arranged on the upper part of the upper half lower mould; the inner core of the upper half air inlet pipe is arranged in the middle of the upper half medium-sized component and is embedded in the core print on the upper end face of the upper half lower mould; two upper half air inlet pipe outer cores are symmetrically arranged on two sides of the outer part of the upper half air inlet pipe inner core; the upper half volute core is arranged at the upper part of the inner core of the upper half air inlet pipe, and two groups of upper half sheet-shaped core components are symmetrically arranged outside the upper half volute core; the upper half upper mould is arranged at the upper part of the upper half middle-sized assembly, and the upper half flaky core assembly, the upper half volute core, the upper half air inlet pipe inner core and the upper half air inlet pipe outer core are packaged in the upper half middle-sized assembly and the upper half lower mould; three groups of straight runners and inner runners are arranged inside the upper half upper mold, the upper half middle-sized component and the upper half lower mold; at least 6 risers are arranged on the upper half upper mould; a plurality of chills are arranged at the lower pouring cavity of the upper half volute core and the upper half sheet-shaped core component;

further, the lower core half comprises: the lower half upper die, the lower half middle die assembly, the lower half lower die, the lower half sheet-shaped core assembly, the lower half volute core, the lower half air inlet pipe core assembly, the chill and the riser; the lower half middle-sized component is arranged at the upper part of the lower half lower mold; the lower half air inlet pipe core assembly is arranged in the middle of the lower half middle-sized assembly and embedded in a core print on the upper end surface of the lower half lower mold; the lower half volute core is arranged in the middle of the lower half middle-sized component and positioned at the upper part of the lower half air inlet pipe core-type component, and two groups of lower half sheet-shaped core components are symmetrically arranged outside the lower half volute core; the lower half upper mold is arranged at the upper part of the lower half middle-sized component, and the lower half volute core, the lower half sheet-shaped core component and the lower half air inlet pipe core component are packaged in the lower half middle-sized component and the lower half lower mold; 2-4 groups of straight pouring channel straight pouring channels and 2-4 groups of ingates are arranged in the lower half lower die, the lower half middle-sized component and the lower half lower die; the lower half lower mold is provided with at least 6 risers, and a plurality of chills are arranged at the lower pouring cavity of the lower half volute core and the lower plate core component.

Further, the upper half-middle assembly includes: a middle-upper half a, a middle-upper half B and a middle-upper half C; the core is sequentially arranged on the upper part of the upper half lower mould from bottom to top to form an integral core structure, and the shape of the inner surface of the core is the same as that of the integral outer surface of the upper half sheet-shaped core assembly and the upper half air inlet pipe outer core.

Furthermore, the upper half sheet-shaped core assembly consists of three half-arc upper half sheet-shaped cores A, an upper half sheet-shaped core B and an upper half sheet-shaped core C; the three pairs of upper half flaky cores A, B and C are symmetrically arranged on two sides of the upper half volute core from inside to outside in sequence; the inner shape formed by combining the pair of upper half flaky cores A is the same as the outer shape of the upper half volute core; gaps of 2mm are reserved among the adjacent upper half flaky cores A, the adjacent upper half flaky cores B and the adjacent upper half flaky cores C so as to prevent rubbing during upper core setting; and a 60mm gap is reserved between the upper half flaky core C and the upper half middle-sized component on the outermost side, and the gap is filled with resin sand after the upper core is finished so as to prevent the sand core from shifting outwards when molten iron is poured.

Further, the lower semi-mesoscale assembly includes: a lower half medium a and a lower plate medium B; and the lower half core assembly and the lower half air inlet pipe core assembly are sequentially arranged on the upper part of the lower half lower mold from bottom to top to form an integral core structure, and the shape of the inner surface of the integral core structure is the same as that of the integral outer surface of the lower half flaky core assembly and the lower half air inlet pipe core assembly.

Further, the lower half sheet-shaped core assembly consists of three half-and-half arc-shaped lower half sheet-shaped cores A, a lower sheet-shaped core B and a lower sheet-shaped core C; the three pairs of lower half flaky cores A, lower part flaky cores B and lower part flaky cores C are symmetrically arranged at two sides of the lower half volute core from inside to outside in sequence; the inner shape formed by combining the pair of lower half flaky cores A is the same as the outer shape of the lower half volute core; gaps of 2mm are reserved among the adjacent lower half flaky cores A, the lower flaky cores B and the lower flaky cores C to prevent rubbing during core descending; and a 60mm gap is reserved between the lower flaky core C at the outermost side and the lower half-middle-sized component, and the gap is filled with resin sand after core setting is finished so as to prevent the sand core from shifting outwards when molten iron is poured.

Furthermore, the lower half air inlet pipe core type assembly comprises a lower half air inlet pipe core A and a lower half air inlet pipe core B which are oppositely arranged, and the middle parts of the lower half air inlet pipe core A and the lower half air inlet pipe core B form an embedded positioning core head of a lower half volute core after combination.

Further, a pouring system for a casting process of the thermal power ductile iron low-pressure inner cylinder; the method is characterized in that: the gating system comprises: the upper half type casting system and the lower half type casting system;

further, first half type gating system design has 3 runners and 3 groups of ingates, and every runner is alone for respective ingate molten iron supply, and the choked flow cross section is the runner, and each cross section ratio is the runner: a horizontal pouring channel: the inner pouring gate is 1: 1.2-1.5: 3.0-5.0; wherein 1 group of ingates are designed on the end surface of the air inlet pipe at the bottommost part of the air cylinder, the other 2 groups of ingates are designed on the bottom of the air passage at the outermost side of the electric regulation end at the secondary bottom, molten iron rises to a bisection surface through the bottom of a casting, turbulence and backflow phenomena are not generated when three parts of molten iron are converged, staggered pouring is needed during pouring, molten iron in pouring boxes of the air inlet pipe is poured for 10-20 seconds first, and then the other 2 pouring boxes start pouring;

further, the ingate of the lower half type gating system is designed on the end face of the outlet pipe, molten iron rises to the median plane through the bottom of the casting, 2-4 straight runners and 2-4 groups of ingates are designed according to the iron water quantity condition, the outlet pipe of the lower half type is usually on the same plane or the height difference of the planes is small, the turbulence and backflow phenomena are generated to be light, the influence on the molten iron can be ignored, and the staggered pouring can be avoided.

The design idea of the invention is as follows:

firstly, designing a pouring direction:

the wall thickness of the low-pressure cylinder is mainly the thickness of a large wall (100-350 mm) of a median plane and the thickness of a thin wall (40-60 mm) of a blank surface, the low-pressure cylinder can be solidified simultaneously when molten iron at the thin-wall position is solidified, the modulus of the thick-wall position is large (more than or equal to 3cm), self-feeding can be realized through graphite expansion during solidification, and therefore the influence of the pouring direction on the shrinkage porosity defect of the cylinder is small.

In other aspects, when the mid-plane is poured downwards, the ingate needs to be arranged on the end faces of the mid-planes at two sides, molten iron enters the cavity from the end faces of the mid-planes at two sides and finally collects at the top of the blank, oxidizing slag at the front end of the molten iron is dispersed on the outer surface of the blank, the appearance and the magnetic powder inspection requirements can be met only by polishing and eliminating defects, and a large amount of labor polishing cost can be consumed. Meanwhile, the sand core is assembled firstly when the box is closed, the sand mould is assembled after the sand core is assembled, and if the wall thickness among the sand cores is deviated after the sand core is assembled, the wall thickness is difficult to adjust, so that the wall thickness uniformity of the sand core is difficult to control. In addition, when molten iron is poured, the sand core floats upwards due to the buoyancy of the molten iron, the sand core and the sand mold handle are required to be welded together to prevent the sand core and the sand mold handle from floating upwards, the handling and welding workload is large, and the box closing operation process is complex.

When the split surface is poured upwards, the ingate enters the cavity from the air inlet (outlet) pipe and the electric adjusting end arc surfaces at two sides, the oxidizing slag at the front end of the molten iron is dispersed on the surfaces of the gantry barrier and the split surface, the surfaces are all processing surfaces, the oxidizing slag can be processed and removed in the processing process, and extra manual polishing and defect eliminating work are not needed. Meanwhile, when the mold is closed, the sand mold is assembled firstly, then the sand core is assembled, when the wall thickness is deviated, the core head gap can be adjusted to ensure the wall thickness dimension, and the uniformity of the wall thickness among the cores can be well controlled. And the sand core can be compacted by depending on the upper box sand mould, and can be effectively prevented from floating upwards during pouring without being welded with the sand mould handle, and the operation process of box combination is simple.

Through comparative analysis of the two casting directions, the casting direction of the low-pressure air cylinder is selected as that the middle division surface is upwards cast.

Secondly, core structure design:

the inner cavity structure of cylinder is more complicated, separates by the baffle between every air flue, and the baffle is nonparallel and has the contained angle with the axis, so can't realize the whole core making mode of making the core of whole system cores of ideal inner cavity, and need make the core alone with the psammitolite of every air flue, assemble together one by one with it when the mould assembling.

The existing mold core structural design, the structure outside the inner cavity air flue is designed into 3 integral cores, the sand core structural design of the inner cavity air flue is annular, and after the 3 integral cores are combined and completed, the annular cores are assembled on the integral cores. The requirement of the annular air passage core on the size precision and the structural strength of the core frame is high, the manufacturing difficulty of the core frame is high, the manufacturing cost is high, the strength inspection difficulty of the core frame is high, when the strength is slightly insufficient, cracks can appear on the surface of the annular core in the sand core assembling process, the larger cracks cannot be repaired, molten iron can enter crack gaps in the pouring process to cause sand hole defects, and when the strength is serious, the annular core deforms to cause the condition of insufficient wall thickness of a casting.

The core of the cylinder cavity is designed into a laminated shape, the traditional integral core design is cancelled, each cavity air passage and the outer side structure part of the cavity air passage are independently discharged, the width of the laminated core is equivalent to the width of the air passage, the integral structure is in a cantilever shape, the core head is designed on a split surface, the height of the core head is 500mm, a core bone is preset in the core head, and the laminated core is positioned at a preset position by means of positioning and supporting of the core head. Assembling a sand mould firstly when the mould is closed, then assembling the lamellar cores in the sand mould one by one, wherein the assembly sequence of the lamellar cores is that the most middle volute core is assembled firstly, then assembling the lamellar cores at two sides of the volute core one by one according to the sequence from inside to outside, a gap of 2mm is reserved between the lamellar cores to prevent rubbing when the cores are placed, a gap of 60mm is reserved between the outermost core and the shape, and the gap is filled with resin sand after the cores are placed so as to prevent the sand cores from shifting outwards when molten iron is poured.

The laminated core has low requirements on the structure and strength of the core iron, does not need special core iron with high dimensional precision and high structural strength, and has lower cost. Meanwhile, in the core assembling process, the wall thickness between the cores can be conveniently measured, and when the wall thickness is inappropriate, the wall thickness size can be controlled by adjusting the core head gap so as to ensure the uniformity of the wall thickness of the casting. In addition, extra core floating prevention measures are not needed, the core can be completely compacted by utilizing the pressure applied to the core head by the upper mold, the sand core and the sand mold are not needed to be welded, and the uncertainty in the operation process is reduced.

Thirdly, designing a pouring system:

the pouring mode all designs for the end pouring formula, and for guaranteeing that the temperature in the die cavity is even, reduces the molten iron pouring in-process and appears turbulent flow and refluence phenomenon, first half designs 3 sprue and 3 groups ingates, and every sprue is alone for respective ingate supply molten iron, and the choked flow cross-section is the sprue, and each cross-section ratio is the sprue: a horizontal pouring channel: the inner pouring gate is 1: 1.2-1.5: 3.0-5.0. Wherein 1 group's ingate design is at the intake pipe terminal surface of cylinder bottommost, and 2 group's ingates designs in addition are in the electricity of inferior bottom and hold outside air flue bottom, and the molten iron rises to the bisection face through the foundry goods bottom, and when meeting for realizing the triplex molten iron, do not produce turbulent flow and refluence phenomenon, need the pouring in time of staggering during the pouring, intake pipe pouring box molten iron pour into a mould earlier 10 ~ 20 seconds after, 2 pouring boxes begin to pour into a mould in addition.

The whole designs of runner in the second half rise to the bisection face through the foundry goods bottom at the outlet duct terminal surface, and the molten iron designs 2 ~ 4 sprue and 2 ~ 4 group's ingate according to the molten iron volume condition, and the outlet duct of the second half is usually in the coplanar, or plane difference in height is less, and it is lighter to produce turbulent flow and refluence phenomenon, can ignore the influence of molten iron, can not need the pouring of staggering time.

Fourthly, designing a cold iron:

the wall thickness of the thin wall position of the cylinder is thin, the cylinder can be quickly crusted in the solidification process, the simultaneous solidification is realized, and chilling by cold iron can be omitted. The wall thickness of the middle parting surface is more than 100mm, the modulus is more than 3cm, and the simultaneous solidification can not be realized, but under the condition that the carbon equivalent of the molten iron is more than 4.5 and the compressive strength of the molding sand is more than 3MPa, the shrinkage porosity can not be realized by means of the graphitization expansion of the molten iron and the rigidity guarantee of the sand mold. The processing surface of the gantry block at the position of the air passage of the inner cavity cannot realize simultaneous solidification because the graphitization expansion is not enough to offset the shrinkage of molten iron, so that a chilling block needs to be designed. The chilling blocks are made of graphite, the thickness of the chilling blocks is 0.8-1.2 times of the thickness of the chilling blocks, gaps among the chilling blocks are 30-40 mm, molding sand among the chilling blocks needs to be compacted by using wood boards during molding, and otherwise shrinkage porosity defects can occur among the chilling block seams.

Fifthly, design of a riser:

the ductile iron cylinder does not need feeding of a riser, but liquid state shrinkage can be generated in the process of molten iron solidification, molten iron can enter between mold core gaps, and about 2.5% of the total amount of the molten iron needs to be stored in the riser to supplement the liquid state shrinkage and the mold core gaps. The riser is designed on a split surface, 6-10 risers are designed according to different quantities of molten iron, the riser is connected with a casting through a thin-sheet riser plate, the thickness of the position where the plate-shaped riser is connected with the casting is not more than 40mm, so that the plate-shaped riser is rapidly solidified after liquid state shrinkage of molten iron is finished, the thick part where the split surface is located cannot expand into the riser during graphitization expansion, and the self-feeding effect of the molten iron is weakened. Meanwhile, when the plate riser is used for pouring molten iron, the function of exhausting gas in the cavity can be achieved.

Sixthly, designing chemical components:

smelting molten iron in an intermediate frequency furnace, turning the molten iron into a spheroidizing ladle after the components in front of the furnace are qualified, spheroidizing and performing primary inoculation in the ladle turning process, then turning the molten iron into a quantitative pouring box from the pouring ladle, realizing secondary inoculation in the ladle turning process, standing the molten iron in the pouring box for 2 minutes, and starting pouring after oxidizing slag completely floats to the surface, wherein the pouring temperature is controlled between 1340 and 1360 ℃, the pouring time is controlled between 120 and 300 seconds, the pouring time exceeds 300 seconds, and the surface of a casting can have cold shut defects, and the components in front of the furnace and a finished product are designed as follows:

composition (I)

C

Si

Mn

S

P

Mg

In front of furnace

3.5～3.7

1.4～1.8

≤0.2

≤0.02

≤0.04

/

Finished product

3.6～3.8

2.2～2.4

≤0.2

≤0.02

≤0.04

0.035～0.050

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

1. according to the casting process of the thermal power ductile iron low-pressure inner cylinder, the casting process has simple requirements on the operation of the modeling mould, the operation process can be measured and controlled, and the stability of the casting quality of a casting can be effectively realized;

2. according to the casting process of the thermal power ductile iron low-pressure inner cylinder, the casting process does not need feeding of a dead head and chilling of a large amount of cold iron, and low-cost casting can be realized on the premise of ensuring the strength of molding sand;

3. according to the casting process of the thermal power ductile iron low-pressure inner cylinder, scum on the surface of molten iron is dispersed on a processing surface by the casting process, the scum is processed and removed in the rough processing process, the manual polishing and defect eliminating process is cancelled, and the manufacturing period is shortened.

In conclusion, the technical scheme of the invention solves the problems of poor stability, high rejection rate, great casting difficulty, high manufacturing cost, small application range, incapability of realizing mass production and the like in the prior art.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a top plan view of the upper core half of the present invention;

FIG. 2 is an AB-AB view of FIG. 1;

FIG. 3 is a view of AA-AA of FIG. 1;

FIG. 4 is a top view of the casting process of the upper half structure of the present invention;

FIG. 5 is an AF-AF view of FIG. 4;

FIG. 6 is a view of the AG-AG of FIG. 4;

FIG. 7 is a top view of the lower core half of the present invention;

FIG. 8 is a view B-B of FIG. 7;

FIG. 9 is a view A-A of FIG. 7;

FIG. 10 is a top view of the casting process of the lower half-structure of the present invention;

FIG. 11 is a view C-C of FIG. 10;

fig. 12 is a view from D-D of fig. 10.

In the figure: 1. the structure comprises an upper half upper die 2, a sprue 3, a riser 4, an upper half sheet-shaped core assembly 41, an upper half sheet-shaped core C42, an upper half sheet-shaped core B43, an upper half sheet-shaped core A5, an upper half volute core 6, an upper half middle assembly 61, an upper half middle C62, an upper half middle B63, an upper half middle A7, a chiller 8, an ingate 9, an upper half lower die 10, an upper half air inlet pipe outer core 11, an upper half air inlet pipe inner core 12, a pouring cavity 13, a lower half upper die 14, a lower half sheet-shaped core assembly 141, a lower sheet-shaped core C142, a lower sheet-shaped core B143, a lower half sheet-shaped core A15, a lower half volute core 16, a lower half middle assembly 161, a lower plate middle B162, a lower half middle A17, a lower half lower die 18, a lower half sheet-shaped core assembly 181, a lower half air inlet pipe.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the absence of any contrary indication, these directional terms are not intended to indicate and imply that the device or element so referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be considered as limiting the scope of the present invention: the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

As shown in the figure, the pouring mode of the casting process of the thermal power ductile iron low-pressure inner cylinder is a bottom pouring mode; the core structure of the thermal power ductile iron low-pressure inner cylinder for casting is divided into an upper half core and a lower half core, the two cores are respectively cast into an upper half inner cylinder and a lower half inner cylinder after bottom pouring, and the two half inner cylinders are assembled together after being processed to form an integral low-pressure inner cylinder structure;

the upper core half includes: the device comprises an upper half upper mold 1, an upper half middle-sized assembly 6, an upper half lower mold 9, an upper half flaky core assembly 4, an upper half volute core 5, an upper half air inlet pipe outer core 10, an upper half air inlet pipe inner core 11, a chill 7 and a riser 3; the upper half-middle-sized component 6 is arranged at the upper part of the upper half lower mould 9; the upper half air inlet pipe inner core 11 is arranged in the middle of the upper half middle-sized component 6 and is embedded in a core print on the upper end face of the upper half lower mold 9; two upper half air inlet pipe outer cores 10 are symmetrically arranged on two sides of the outer part of the upper half air inlet pipe inner core 11; the upper half volute core 5 is arranged at the upper part of the inner core of the upper half air inlet pipe, and two groups of upper half sheet-shaped core components 4 are symmetrically arranged outside the upper half volute core; the upper half upper die 1 is arranged at the upper part of the upper half middle-sized assembly 6, and the upper half flaky core assembly 4, the upper half volute core 5, the upper half air inlet pipe inner core 11 and the upper half air inlet pipe outer core 10 are packaged inside the upper half middle-sized assembly 6 and the upper half lower die 9; three groups of communicated straight pouring channels 2 and inner pouring channels 8 are arranged inside the upper half upper mould 1, the upper half middle-sized component 6 and the upper half lower mould; at least 6 risers 3 are arranged on the upper half mould 1, and the risers 3 are communicated with a casting cavity 12 in the upper half mould core; a plurality of chills 7 are arranged at the lower pouring cavity of the upper half volute core 5 and the upper half sheet-shaped core component 4;

the lower core half comprises: a lower half upper mold 13, a lower half middle-sized assembly 16, a lower half lower mold 17, a lower half sheet-shaped core assembly 14, a lower half volute core 15, a lower half air inlet pipe core assembly 18, a chill 7 and a riser 3; the lower half-middle module 16 is arranged at the upper part of the lower half lower mould 17; the lower half air inlet pipe core assembly 18 is arranged in the middle of the lower half middle assembly 16 and is embedded in a core print on the upper end surface of the lower half lower mold 17; the lower half volute core 15 is arranged in the middle of the lower half middle-sized component 16 and positioned at the upper part of the lower half air inlet pipe core component 18, and two groups of lower half sheet-shaped core components 14 are symmetrically arranged outside the lower half volute core; the lower half upper mold 13 is arranged at the upper part of the lower half middle-sized component 16, and a lower half volute core 15, a lower half sheet-shaped core component 14 and a lower half air inlet pipe core component 18 are packaged inside the lower half middle-sized component 16 and a lower half lower mold 17; 2-4 groups of straight pouring channel straight pouring channels 2 and 2-4 groups of ingates 8 are arranged in the lower half lower die 17, the lower half middle-sized component 16 and the lower half lower die; the lower half lower mould 17 is provided with at least 6 risers 3, and a plurality of chills 7 are arranged at the lower pouring cavity of the lower half volute core 15 and the lower plate sheet core component.

The medium-sized module 6 includes: a mid-half a63, a mid-half B62, and a mid-half C61; and the core is sequentially arranged on the upper part of the upper half lower mold 9 from bottom to top to form an integral core structure, and the shape of the inner surface of the core is the same as that of the integral outer surfaces of the upper half sheet-shaped core assembly 4 and the upper half air inlet pipe outer core 10.

The upper half sheet-shaped core component 4 consists of three half-arc upper half sheet-shaped cores A43, an upper half sheet-shaped core B42 and an upper half sheet-shaped core C41; three pairs of upper half flaky cores A43, B42 and C41 are symmetrically arranged on two sides of the upper half volute core 5 from inside to outside; the inner shape formed by combining the pair of upper half sheet cores A43 is the same as the outer shape of the upper half volute core 5; 2mm gaps are reserved among the adjacent upper half flaky core A43, the upper half flaky core B42 and the upper half flaky core C41 to prevent scratching during upper core; a60 mm gap is reserved between the upper half flaky core C41 on the outermost side and the upper half medium-sized component 6, and the gap is filled with resin sand after the upper core is finished so as to prevent the sand core from moving outwards when molten iron is poured.

The lower semi-mesoscale component 16 includes: a lower half medium a162 and a lower plate medium B161; and the lower half core assembly is sequentially arranged on the upper part of the lower half lower die 17 from bottom to top to form an integral core structure, and the shape of the inner surface of the integral core structure is the same as that of the integral outer surfaces of the lower half flaky core assembly 14 and the lower half air inlet pipe core assembly 18.

The lower half sheet-like core assembly 14 is composed of three half-arc lower half sheet-like cores a143, a lower sheet-like core B142 and a lower sheet-like core C141; the three pairs of the lower half flaky cores A143, the lower flaky cores B142 and the lower flaky cores C141 are symmetrically arranged at two sides of the lower half volute core 15 from inside to outside in sequence; the inner shape formed by combining the pair of lower half chip cores A143 is the same as the outer shape of the lower half volute core 15; gaps of 2mm are reserved among the adjacent lower half flaky cores A143, the lower flaky cores B142 and the lower flaky cores C141 to prevent scratches during core descending; a60 mm gap is reserved between the lower flaky core C141 at the outermost side and the lower half-middle-sized component 16, and the gap is filled with resin sand after core setting is finished so as to prevent the sand core from shifting outwards when molten iron is poured.

The lower half air inlet pipe core assembly 18 comprises a lower half air inlet pipe core A181 and a lower half air inlet pipe core B182 which are oppositely arranged, and the middle parts of the lower half air inlet pipe core A181 and the lower half air inlet pipe core B182 are combined to form an embedded positioning core head of the lower half volute core 15.

A pouring system for a casting process of the thermal power ductile iron low-pressure inner cylinder; the method is characterized in that: the gating system comprises: the upper half type casting system and the lower half type casting system;

first type gating system design have 3 sprue 2 and 3 groups ingate 8, every sprue 2 alone gives respective ingate 8 and supplies with the molten iron, the choked flow cross section is the sprue, each cross section ratio is the sprue: a horizontal pouring channel: the inner pouring gate is 1: 1.2-1.5: 3.0-5.0; wherein 1 group of ingates 8 are designed on the end face of the air inlet pipe at the bottommost part of the cylinder, the other 2 groups of ingates 8 are designed on the bottom of the air passage at the outermost side of the electric regulation end at the secondary bottom, molten iron rises to a bisection plane through the bottom of a casting, turbulence and backflow phenomena are not generated when three parts of molten iron are converged, staggered pouring is needed during pouring, molten iron in pouring boxes of the air inlet pipe is poured for 10-20 seconds first, and then the other 2 pouring boxes start pouring;

the whole designs of ingate 8 of half type gating system down in the outlet duct terminal surface, the molten iron rises to the bisection face through the foundry goods bottom, according to the molten iron volume condition design 2 ~ 4 sprue 2 and 2 ~ 4 group ingate 8, the outlet duct of half type down is in the coplanar usually, or the plane difference in height is less, it is lighter to produce turbulent flow and refluence phenomenon, can ignore the influence of molten iron, can not need the pouring of staggering time.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.