CN102699277B - Casting process method for gray cast iron lost foam - Google Patents

Casting process method for gray cast iron lost foam Download PDF

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CN102699277B
CN102699277B CN201210142421.9A CN201210142421A CN102699277B CN 102699277 B CN102699277 B CN 102699277B CN 201210142421 A CN201210142421 A CN 201210142421A CN 102699277 B CN102699277 B CN 102699277B
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lost foam
sectional area
ingate
casting
control
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CN102699277A (en
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杨玉光
廖希亮
董利
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杨玉光
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Abstract

The invention discloses a casting process method for a gray cast iron lost foam, which comprises the steps of design of a pouring system, control of the pouring temperature, control of a pouring negative pressure degree and control of the normal temperature air permeability of a coating. By selecting suitable control parameters and adopting a comprehensive control process, the conditions of totally gasifying a styrofoam pattern in the casting process of the lost foam are totally met, so that the defect of dirt inclusion of the lost foam is eliminated and the casting quality of the lost foam is improved. By the actual production inspection, the rejection rate caused by the dirt inclusion is reduced to 1 percent to 3 percent from the original rejection rate of 5 percent to 10 percent. The process has the characteristics of reliable design, good field operability and easiness for implementing. According to the process control methods provided by the invention, the defect of dirt inclusion of a lost foam gray cast iron can be basically eliminated and the finished product rate of castings is improved. The process method is suitable for the lost foam gray cast irons with different marks.

Description

A kind of grey cast-iron lost foam casting process method
Technical field
The invention belongs to casting engineering technical field, particularly grey cast-iron lost foam casting process category.
Background technology
In China, grey cast-iron lost foam casting is the advanced manufacturing technology of the casting field closely grown up during the last ten years, low with its cost, technique is advanced, environmental protection and the advantage such as casting quality is high, obtains attention and the application of more foundry enterprise.But, because its Foam Pattern making evaporative pattern mainly adopts the polystyrene of carbon containing about 92% to be that raw material makes, distinctive casting flaw under conventional casting technique causes foundry goods to produce this technology---folder ash, presss from both sides the percent defective of ash generally 5 ~ 10% in production.And folder ash often produces under the epidermis of foundry goods, and naked eyes are difficult to observe, and only just can be found when machining, to producing the waste causing greatly manpower and the energy.Owing to pressing from both sides the existence of grey phenomenon, the environmental protection advantage of lost foam casting is made to can not get sufficient embodiment.Found by research: the main Crack cause of folder ash is that in casting pouring process, the gasification of expanded polystyrene pattern sample is bad, and the residuals of generation is rolled into caused by liquid cast-iron.For this reason, the present inventor, according to the formation mechenism of folder ash, proposes and a kind ofly substantially can eliminate the process that lost foam cast iron part presss from both sides grey defect.
Summary of the invention
Goal of the invention of the present invention presss from both sides grey defect to overcome lost foam cast iron part, thus the object improving whole grey cast-iron lost foam casting quality puts forward.Namely a kind of grey cast-iron lost foam casting process method is provided.
Technical solution of the present invention is achieved in that by controlling closely-related technological parameter, and comprise running gate system and control, pouring temperature controls, and cast vacuum degree controls, and coating normal temperature gas permeability controls, and waits the technical process control of four aspects.It is characterized in that the design of running gate system comprises the ratio of sectional area of ingate, cross gate, sprue, the zone of reasonableness value of pouring temperature controls, suitable vacuum degree scope, and the gas permeability of coating controls.The specific design of grey cast-iron lost foam casting process method is as follows:
One, the pouring temperature of evaporative pattern grey casting controls between 1400 ~ 1500 DEG C, and preferred temperature controlling range is between 1420 ~ 1450 DEG C.As foundry goods average wall thickness δ≤2cm, get pouring temperature higher limit, as δ > 2cm, get pouring temperature lower limit.
Two, the vacuum degree of the casting system of lost foam casting when pouring into a mould controls within 0.035 ~ 0.050MP scope.As foundry goods gross mass G≤50Kg, get vacuum degree at 0.035 ~ 0.040Mp, as G > 50Kg, get vacuum degree at 0.04 ~ 0.050Mp.
Three, the gas permeability of the coating of the evaporative pattern extexine of evaporative pattern grey cast-iron casting utilizes STZ direct-reading molding sand permeability apparatus to record, and its normal temperature gas permeability should control at 40 ~ 60cm 2/ KPamin, preferred normal temperature gas permeability should control at 45 ~ 55cm 2/ KPamin.As foundry goods gross mass G < 50Kg, get the lower limit of gas permeability, as G >=50Kg, get the higher limit of gas permeability.
Four, the sprue of running gate system, cross gate and ingate cross-sectional area ratio are:
Sprue total sectional area: cross gate total sectional area: ingate total sectional area=(0.9 ~ 1.1): (0.8 ~ 0.9): 1.
Be formulated: s directly: ∑ s horizontal: ∑ s in=(0.9 ~ 1.1): (0.8 ~ 0.9): 1.
Wherein:
In formula, S represents each running channel cross-sectional area.S is straight=sprue cross-sectional area; S horizontal stroke=cross gate cross-sectional area; In S=ingate cross-sectional area.
G in formula---be casting quality, comprise running gate system quality, unit K g.
μ---Flow coefficient of gating system, value standard is according to following table requirement.
κ---casting section thickness coefficient, value standard is according to following table requirement
δ---foundry goods average wall thickness, unit cm.
H p---average static pressure head, determined by pouring type, size is that the height of sprue deducts 0 ~ 0.5 times of foundry goods height, unit cm.Concrete calculating is according to the requirement of following table.
Pouring type in upper table is determined primarily of the height of foundry goods.Casting way selection is according to the requirement of following table.
Be described as follows: ∑ S inthe total sectional area of ingate, unit: cm 2; G is the gross mass of foundry goods and running channel, unit: Kg; μ is Flow coefficient of gating system, number range: 0.3 ~ 0.65; κ is casting section thickness coefficient, number range: 0.4 ~ 0.6; δ is foundry goods average wall thickness, unit cm; Hp is casting average static pressure head, span: the height of sprue deducts 0 ~ 0.5 times of foundry goods height, unit: cm.
Useful technique effect of the present invention is: by selecting suitable controling parameters, adopting Comprehensive Control technique, meet the condition that in lost foam casting, expanded polystyrene pattern sample is gasified totally completely, thus elimination evaporative pattern foundry goods presss from both sides grey defect, improves lost foam casting quality.Through production inspection, the percent defective produced owing to pressing from both sides ash drops to 1% ~ 3% by original 5% ~ 10%.This technique has reliable design, the feature of good, the easy realization of site operative.
Accompanying drawing explanation
Accompanying drawing 1 is one of grey cast-iron lost foam casting part, is an end cover part.
Accompanying drawing 2 is end cap part apperances with running gate system of accompanying drawing 1, can clearly be seen that sprue, cross gate and ingate from figure.
Accompanying drawing 3 is grey cast-iron lost foam casting parts two, is a box parts.
Accompanying drawing 4 is box parts apperances with running channel of accompanying drawing 3.
Accompanying drawing 5 is grey cast-iron lost foam casting parts three, is a shell part.
Accompanying drawing 6 is apperances with running channel of the housing part of accompanying drawing 5.
Detailed description of the invention
Provide specific embodiments of the invention below, the present invention is described in detail.Data in embodiment are not limitation of the present invention and constraint, the fit applications just in order to various process is described.Due to lost foam casting, general casting pig cast member is all adopted to the design of single sprue, except non-specifically is complicated and oversized cast member, then the sprue more than 1 can be set.Therefore in an embodiment, the design of a sprue is only discussed, and its reason of multiple sprue is consistent with the design of single sprue with calculating, both the cross-sectional area of N number of sprue was the 1/N of single sprue.
Embodiment 1
Attachedly Figure 1 shows that an end cap part, material is HT200, and quality is 54Kg, and end cap diameter dimension H is 520mm, and foundry goods average wall thickness δ is 30mm.
(1) Design of Runner System: pouring position is upright casting, foundry goods height between 300 ~ 600mm, therefore adopts bottom filling, and every case two pieces cast, shown in accompanying drawing 2.Because the structure of this end cover part is relatively simple, so, Flow coefficient of gating system μ=0.30 or 0.35 or 0.40 can be got respectively, casting section thickness coefficient gets κ=0.5, usually, in lost foam casting, get the distance that cup rim of a cup leaves the peak place of foundry goods is 30cm, then single sprue height H 0=30+52=82cm,
G=2 × 54+54X2 × 20% (running gate system quality will ask for 20% of cast member quality according to lost foam casting basic technology)=129.6 (Kg),
H p=H 0-H/2=82-52/2=56 (cm), δ=3cm, then:
When discharge coefficient μ=0.30, wall thickness coefficient get κ=0.5, then have:
Get: ∑ S directly: ∑ S horizontal: ∑ S in=1.1: 0.9: 1, then: S directly=20.80 (cm 2), ∑ S horizontal=17.02 (cm 2).
When discharge coefficient μ=0.35, wall thickness coefficient get κ=0.5, then have:
Get: ∑ S directly: ∑ S horizontal: ∑ S in=1.0: 0.85: 1, then: S directly=1 6.2 1 (cm 2), ∑ S horizontal=13.77 (cm 2).
When discharge coefficient μ=0.4, wall thickness coefficient get κ=0.5, then have:
Get: s directly: ∑ s horizontal: ∑ s in=0.9: 0.8: 1, then: S directly=1 2.76cm 2, ∑ S horizontal=11.34cm 2.
During actual cast, according to cross gate and the ingate quantity of actual design, according to above-mentioned result of calculation, the cross sectional dimensions of mean allocation cross gate and ingate.Such as, according to the total cross-sectional area of ingate: 14.18cm 2, adopt 4 ingates, the square-section size of each rectangle ingate is about 1.0 × 3.5=3.5 (cm 2), the square-section size of rectangle cross gate is about 3 × 4=12 (cm 2), the circular section diameter of cylindrical straight running channel is about 4cm.
(2) pouring temperature is taken as 1400 DEG C ~ 1500 DEG C.
(3) pour into a mould vacuum degree and be taken as 0.040 ~ 0.050MPa
(4) the normal temperature gas permeability of coating controls at 40 ~ 60cm 2/ KPamin.
Embodiment 2
Attachedly Figure 3 shows that a casing, material is HT250, and quality is 198Kg, and foundry goods height dimension is 810mm, foundry goods average wall thickness 20mm.
(1) Design of Runner System: pouring position is upright casting, and foundry goods height is greater than 600mm, therefore adopt side note staged, 3 ingates, single-piece is poured into a mould, shown in accompanying drawing 4.Because this foundry goods is relatively complicated, highly higher, get Flow coefficient of gating system μ=0.41 or 0.50 or 0.60, casting section thickness coefficient gets κ=0.5, single sprue height H 0=81+30=111cm,
G=198+198 × 20% (running gate system quality will ask for 20% of cast member quality according to lost foam casting basic technology)=237.6 (Kg),
H p=H 0-H/10=111-84/10=102.6 (cm), δ=2.0cm, then:
When flow system flow coefficient μ=0.41, casting section thickness coefficient get κ=0.5, have:
Get: ∑ S directly: ∑ S horizontal: ∑ S in=1.1: 0.8: 1, then: S directly=18.65 (cm 2), ∑ S horizontal=13.56 (cm 2).
When flow system flow coefficient μ=0.50, casting section thickness coefficient get κ=0.5, have
Get: ∑ S directly: ∑ S horizontal: ∑ S in=0.9: 0.85: 1, then: S directly=12.51 (cm 2), ∑ S horizontal=11.82 (cm 2).
When flow system flow coefficient μ=0.60, casting section thickness coefficient get κ=0.5, have
Get s directly: ∑ s horizontal: ∑ s in=1: 0.9: 1, then: S directly=11.58cm 2, ∑ S horizontal=10.42cm 2.
Because the present embodiment does not design cross gate, so the numerical value of the above-mentioned cross gate of the present embodiment is only the result of calculating, reality is not adopted.
During actual cast, according to cross gate and the ingate quantity of actual design, according to above-mentioned result of calculation, the cross sectional dimensions of mean allocation cross gate and ingate.Such as, according to the total cross-sectional area of ingate: 11.58cm 2, adopt 3 ingates, the square-section of each rectangle ingate is of a size of 1.0 × 3.9=3.9 (cm 2), the circular section diameter of cylindrical straight running channel is 3.85cm.
(2) pouring temperature is taken as 1420 DEG C ~ 1450 DEG C.
(3) pour into a mould vacuum degree and be taken as 0.040 ~ 0.050MPa
(4) the normal temperature gas permeability of coating controls at 50 ~ 55 cm 2/ KPamin.
Embodiment 3
Attachedly Figure 5 shows that housing, material is HT250, and quality is 71Kg, and foundry goods height dimension is 610mm, foundry goods average wall thickness 15mm.
(1) Design of Runner System: pouring position is upright casting, and foundry goods height is greater than 600mm, therefore adopt side note staged, 2 ingate mouths, do not establish cross gate, and single-piece is poured into a mould, shown in accompanying drawing 6.Due to this foundry goods housing more complicated, get Flow coefficient of gating system μ=0.5 1 or 0.60 or 0.65, casting section thickness coefficient gets κ=0.4 respectively, single sprue height H 0=61+30=91cm,
G=71+71 × 15% (running gate system quality will ask for 20% of cast member quality according to lost foam casting basic technology)=81.65 (Kg),
H p=H 0-H/10=91-61/8=83.38 (cm), δ=1.5cm, then:
When flow system flow coefficient μ=0.51, casting section thickness coefficient get κ=0.4, have:
Get: ∑ S directly: ∑ S horizontal: ∑ S in=1.0: 0.8: 1, then: S directly=1 2.79 (cm 2), ∑ S horizontal=10.23 (cm 2).
When flow system flow coefficient μ=0.65, casting section thickness coefficient get κ=0.4, have
Get: ∑ S directly: ∑ S horizontal: ∑ S in=0.9: 0.85: 1, then: S directly=9.03 (cm 2), ∑ S horizontal=8.53 (cm 2).
When flow system flow coefficient μ=0.60, casting section thickness coefficient get κ=0.4, have
Get s directly: ∑ s horizontal: ∑ s in=1.1: 0.9: 1, then: S directly=11.96 (cm 2), ∑ S horizontal=9.78 (cm 2)
Because the present embodiment does not design cross gate, so the numerical value of the above-mentioned cross gate of the present embodiment is only the result of calculating, reality is not adopted.
During actual cast, according to the ingate quantity of actual design, according to above-mentioned result of calculation, the cross sectional dimensions of mean allocation ingate.Such as, according to the total cross-sectional area of ingate: 10.87 (cm 2), adopt 2 ingates, the square-section of each ingate is of a size of 1 × 5.4=5.4 (cm 2), the circular section diameter of cylindrical straight running channel is about 4cm.
(2) pouring temperature is taken as 1440 DEG C ~ 1500 DEG C.
(3) pour into a mould vacuum degree and be taken as 0.040 ~ 0.050MPa
(4) the normal temperature gas permeability of coating controls at 45 ~ 55cm 2/ KPamin.

Claims (3)

1. a grey cast-iron lost foam casting process method, the method mainly comprises the control of the sprue of running gate system, cross gate and ingate cross-sectional area, and pouring temperature controls, and cast vacuum degree controls, the normal temperature gas permeability of coating controls the control of four process aspects
One, cast temperature controls at 1400 ~ 1500 DEG C;
Two, vacuum degree of casting controls at 0.035 ~ 0.050MP a;
Three, evaporative pattern rustproof lacquer normal temperature gas permeability controls at 40 ~ 60cm 2/ KP amin;
Four, the sprue of running gate system, cross gate and ingate cross-sectional area control be: sprue total sectional area: cross gate total sectional area: ingate total sectional area=(0.9 ~ 1.1): (0.8 ~ 0.9): 1;
It is characterized in that ingate total cross sectional area controls by the technical conditions of formulae discovery below:
Wherein: ∑ S inthe total sectional area of ingate, unit: cm 2; G is the gross mass of foundry goods and running channel, unit: Kg; μ is Flow coefficient of gating system; κ is casting section thickness coefficient; δ is foundry goods average wall thickness, unit cm; Hp is casting average static pressure head, unit cm.
2., according to a kind of grey cast-iron lost foam casting process method according to claim 1, it is characterized in that the ingate total cross sectional area formula of said running gate system
In the span of parameter μ: 0.3 ~ 0.65; The span of parameter κ: 0.4 ~ 0.6; The span of Hp: the height of sprue deducts 0 ~ 0.5 times of foundry goods height, unit: cm.
3., according to a kind of grey cast-iron lost foam casting process method according to claim 2, it is characterized in that the said cast temperature meeting the requirement of ingate total cross sectional area formula should control at 1420 ~ 1450 DEG C.
CN201210142421.9A 2012-05-10 2012-05-10 Casting process method for gray cast iron lost foam Expired - Fee Related CN102699277B (en)

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CN105344940B (en) * 2015-12-07 2017-12-05 兴化市雅兰机械制造有限公司 Motor casing lost foam casting process

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101736206A (en) * 2009-12-15 2010-06-16 山西百一机械设备制造有限公司 Coking cart heat-resisting and wear-resisting lining plate and manufacturing method thereof
CN101954458A (en) * 2010-04-22 2011-01-26 广西钟山长城矿山机械厂 Method for manufacturing crushing wall or rolling mortar wall pouring system of cone crusher during sand-coated casting of inner/outer metal molds
JP2011110577A (en) * 2009-11-26 2011-06-09 Honda Motor Co Ltd Lost foam pattern casting method
CN102294434A (en) * 2011-08-05 2011-12-28 谌征 Composite molding casting process

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011110577A (en) * 2009-11-26 2011-06-09 Honda Motor Co Ltd Lost foam pattern casting method
CN101736206A (en) * 2009-12-15 2010-06-16 山西百一机械设备制造有限公司 Coking cart heat-resisting and wear-resisting lining plate and manufacturing method thereof
CN101954458A (en) * 2010-04-22 2011-01-26 广西钟山长城矿山机械厂 Method for manufacturing crushing wall or rolling mortar wall pouring system of cone crusher during sand-coated casting of inner/outer metal molds
CN102294434A (en) * 2011-08-05 2011-12-28 谌征 Composite molding casting process

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