CN103418746A - Technique for casting gray cast iron thin-wall pipe fitting evanescent die - Google Patents
Technique for casting gray cast iron thin-wall pipe fitting evanescent die Download PDFInfo
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- CN103418746A CN103418746A CN2013103725253A CN201310372525A CN103418746A CN 103418746 A CN103418746 A CN 103418746A CN 2013103725253 A CN2013103725253 A CN 2013103725253A CN 201310372525 A CN201310372525 A CN 201310372525A CN 103418746 A CN103418746 A CN 103418746A
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Abstract
The invention relates to the field of casting evanescent dies, in particular to the technique for casting a gray cast iron thin-wall pipe fitting evanescent die. The purpose that the technique for casting the evanescent die is applied to the field of gray cast iron thin-wall pipe fitting production is achieved. The technique for casting the gray cast iron thin-wall pipe fitting evanescent die comprises the steps of bead pre-foaming, die manufacturing and forming, white die drying and bonding, coating, drying, encasing, vacuum-assist pouring and out-casing and grinding. The die manufacturing and forming comprises that the steps of operating a make-up machine to close the die, filling a model of the make-up machine with EPS beads obtained in the step of bead pre-foaming, filling the model of the make-up machine with steam, cured EPS beads and the formed white die, filling the model of the make-up machine with cooling water to be cooled and operating the make-up machine to open the die and taking out the white die. The technique is improved reasonably, the defect of caliber of a gray cast iron thin-wall pipe fitting can be effectively avoided, the quality of the gray cast iron thin-wall pipe fitting is improved, and the technique is suitable for being used for manufacturing a high-precision and high-quality gray cast iron thin-wall pipe fitting.
Description
Technical field
The present invention relates to the lost foam casting field, specifically a kind of casting pig thin-wall pipe lost foam casting process.
Background technology
The production of the many employings of casting pig thin-wall pipe in the market (wall thickness 3-4mm) sand mould casting method.Produce thin-wall pipe with sand mould casting method and have following technical problem: 1, the more complicated thin-wall pipe for structure, the coremaking difficulty is large, and after casting, arbor takes out difficulty, can only interrupt and scrap, and regeneration is produced needs constantly to make arbor; 2, locate inaccuracy in casting process, produce in casting process and easily form core lift, cause tube wall thickness inhomogeneous; 3, for the pipe fitting product than long type, as the long straight curved thin-wall pipe product of 1.5 meters double spigot mouth thin-wall pipes and both sides, larger with clay-bonded sand green casting difficulty, need to adopt clay-bonded sand dry sand casting technique, arbor needs drying, and the clay-bonded sand dry sand casting, environmental pollution is serious, workman's operating environment is severe, the core-baking over that the clay-bonded sand dry sand casting is used wastes energy again, and clay-bonded sand dry sand casting technique has been that Ministry of Industry and Information's foundry enterprise access system and Ministry of Industry and Information [2010] eliminate the backward technique that will eliminate in part chemical product technique catalogue.
Divided by sand mould casting method, produce outside the casting pig thin-wall pipe, resin sand and V method casting technique also can be produced, but, because production cost is higher, essentially no enterprise adopts.
Lost foam casting is called again dry sand full mold negative pressure casting, is a kind of technique of founding process of nearly clean type, and the green casting technique of 21 century is cast boundary both at home and abroad and is called in not only energy-conservation but also environmental protection.This casting technique is, after the bubbles model consistent with the casting dimension shape brushed to fireproof coating oven dry, to be embedded in vibration molding in dry quartz sand, under negative pressure, pours into a mould, and makes the model gasification, and liquid metals occupies modal position, solidifies cooling rear formation foundry goods.Its technological process roughly is divided into: bead prefoam, molding moulding, Bai Mo dry and bond, coat, oven dry, vanning, vacuum-assist pouring, outlet cleaning polish and obtain product.And current lost foam casting process is mainly used in the production of casting pig thick-walled casting, for thick-walled casting, even there are some density irregularities the white mould part of its foundry goods, on the impact of casting quality, can ignore.And be only the thin-section casting of 3-4mm for wall thickness, the density irregularity of the white mould of foundry goods directly causes the strength and stiffness of Bai Mo corresponding position also very inhomogeneous, while causing sticking to mould, white mould circularity is wayward, be easy to cause the bore defect (oval or not round) of pipe fitting, not only give sticking to mould, coat, dry and the subsequent technique such as the moulding of case in proofread and correct its bore and bring great difficulty, the difficult assurance of product quality; But also serious waste EPS bead raw material, this may be exactly the domestic reason that seldom has producer to adopt lost foam casting process production thin-wall pipe.In addition, produce with lost foam casting process " coating foaming " that also there is a very important white mould of problem-pipe fitting in the casting pig thin-wall pipe, after being white mould applying of refractory material coating, when drying, coating surface occurs that some are not of uniform size, random coating protrusion distributes, finger is tattered once pressing gently, forms empty phenomenon between coating and Bai Mo; This phenomenon directly affects product surface quality.
Summary of the invention
The present invention, in order to realize the application of lost foam casting process in casting pig thin-wall pipe production field, avoids the bore defect of casting pig thin-wall pipe, guarantees the product quality of casting pig thin-wall pipe, and a kind of casting pig thin-wall pipe lost foam casting process is provided.
The present invention adopts following technical scheme to realize: casting pig thin-wall pipe lost foam casting process, its technological process comprises: bead prefoam, molding moulding, Bai Mo dry and bond, coat, oven dry, vanning, vacuum-assist pouring, outlet polish, wherein, the molding forming step is as follows: operation forming machine mould matching (making dynamic model and the cover half closure of forming machine)---and to being filled with the EPS bead obtained through bead prefoam step in the model of forming machine, (filling while expecting the gas that enters forming machine model and die cavity is discharged by discharge duct, as shown in Figure 1)---be filled with steam in the model of forming machine, slaking EPS bead, the white mould of moulding---is filled with water quench---in the model of forming machine, and the die sinking of operation forming machine is taken out white mould (during die sinking, cooling water is discharged, enter compressed air in die cavity, loosening white mould is in order to take out).
In prior art, domestic manufacturer is when adopting lost foam casting process processing casting pig heavier walled fitting,---lifting mould (raising dynamic model 3-5mm)---filled the EPS bead and (discharged when filling gas that when material enter model and die cavity and being lifted by dynamic model and in the gap that forms of cover half generally to adopt following molding forming process: matched moulds, as shown in Figure 2)---entering the white mould of steam slaking EPS bead moulding---enters water quench-die sinking and takes out white mould (during die sinking, cooling water is discharged, enter compressed air in die cavity, loosening white mould is in order to take out); Taked to lift modulo operation when filling material, made to enter a large amount of compressed air of die cavity and discharge by lifting die slot gap (no longer by the discharge duct at the fixed half and moving half back side).There is the irregular problem of local density in the white mould obtained with this molding forming process, and for thick-walled casting, the irregular impact on casting quality of Bai Mo local density can be ignored.And be only the thin-section casting of 3-4mm for wall thickness, the density irregularity of the white mould of foundry goods directly causes the strength and stiffness of Bai Mo corresponding position also very inhomogeneous, while causing sticking to mould, white mould circularity is wayward, be easy to cause the bore defect (oval or not round) of pipe fitting, not only give sticking to mould, coat, dry and the subsequent technique such as the moulding of case in proofread and correct its bore and bring great difficulty, the difficult assurance of product quality; Therefore above-mentioned molding forming process is not suitable for the lost foam casting process of thin-wall pipe.
Compared with prior art, during the molding moulding of casting technique of the present invention, directly under the forming machine mould matching state, filled material, the discharge duct that the high-speed gas entered in die cavity is caused on forming machine dynamic model and cover half is discharged; Rather than rely on to lift when material is filled in the mould discharge and enter the high-speed gas in die cavity.Like this, can guarantee that the white density of modes of foundry goods of moulding is even, make white mould bulk strength and rigidity even, during sticking to mould, can fabulously must control white mould circularity, can not cause the bore defect (oval or not round) of pipe fitting, and then guarantee the product quality of casting pig thin-wall pipe.Also simplify the molding moulding process, can also save EPS bead raw material, reduced production costs, to enterprise, brought considerable economic benefit, as adopted by domestic evaporative pattern manufacturer, will, saving on EPS bead raw material, realize larger social benefit.
For " coating foaming " phenomenon that affects the thin-wall pipe product surface quality, technique of the present invention adopts following formulation for coating material coating in step: comprise silica flour, bauxite, bentonite, CMC, Ludox and fire clay, wherein, the weight ratio of silica flour and bauxite is 3:1, and the content of bentonite, CMC, Ludox, fire clay accounts for respectively 2%, 2.5%, 3%, 1.5% of silica flour and bauxite gross weight; During use, the coating of above-mentioned formula is poured in agitator, added water and fully stir, coating density is controlled at 1.6～1.9g/cm
3, stand-by; White mould after drying is carried out to 2～3 dip-coatings in the coating be stirred to be got final product.Facts have proved, after adopting the coating of above-mentioned formula, the defect of coating foaming is resolved really, and the pipe fitting product surface is smooth, has effectively guaranteed the surface quality of casting pig thin-wall pipe product.
The inventive method is improved rationally, can effectively avoid the bore defect of casting pig thin-wall pipe, stands on the product quality that improves the casting pig thin-wall pipe, is applicable to machining high-precision, high-quality casting pig thin-wall pipe.
The accompanying drawing explanation
Fig. 1 is forming machine mould matching state diagram in molding moulding of the present invention;
Fig. 2 be in prior art in the molding moulding forming machine lift the state diagram after mould;
In figure: the 1-dynamic model; The 2-cover half; The direction of arrow is for filling the material discharge directions.
The specific embodiment
Casting pig thin-wall pipe lost foam casting process, its technological process comprises: bead prefoam, molding moulding, Bai Mo dry and bond, coat, oven dry, vanning, vacuum-assist pouring, outlet polish;
A, bead prefoam
At first select GP-45 standard level polystyrene bead to add in foaming machine and carry out prefoam, steam pressure is 0.1～0.15kg/cm
2, the temperature of foaming staving is 98～100oC, air pressure is 0.05～0.1kg/cm
2, an inventory is 0.7～1kg, after bead foaming discharging in the Bed heated-air drying, baking temperature 20～25oC, the feed bin slaking of packing into can be used after two hours, in 24 hours, was finished.After the prefoam of casting pig thin-wall pipe bead, bead diameter is evenly ￠ 1mm, and it is 26～28 grams/cm that density is controlled
3, so that the white mould of making has certain strength and stiffness;
B, molding moulding
The operation forming machine mould matching, be filled with moulding in the model of forming machine by the EPS bead that foam through pressure pan, and conveying prefoam bead pressure pan use air pressure is 0.05～0.1kg/cm
2To charged pressure in the model of forming machine, be 0.8～1.2kg/cm
2Steam, slaking EPS bead 12～16 seconds, the white mould of moulding, be filled with cooling water in the model of forming machine, be cooled to 30～35oC, white mould is taken out in operation forming machine die sinking;
C, Bai Mo are dried and bonding
The white mould that makes is dry more than 48 hours under indoor temperature, or in the drying box of 40～60oC dry two hours, the moisture brought while removing molding, after drying, bonding forms the white mould of pipe fitting;
D, coat
At first coating is poured in agitator and added water and fully stir, coating density is controlled at 1.6～1.9g/cm
3, stand-by; Then the white mould of pipe fitting is carried out to 2～3 dip-coatings.The formula of described coating is: comprise silica flour, bauxite, bentonite, CMC, Ludox and fire clay, wherein, the weight ratio of silica flour and bauxite is 3:1, and the content of bentonite, CMC, Ludox, fire clay accounts for respectively 2%, 2.5%, 3%, 1.5% of silica flour and bauxite gross weight;
E, oven dry
The product that each dip-coating is good is dried, the product introduction baking room, the first two hour temperature is controlled at 40～50 oC, and humidity is controlled at 20～25%, after two hours, temperature is controlled at 45～60 oC, humidity is controlled at 10～15%, continues 12 hours, and the assembling product cluster of finally drying is mended to coating, then putting into baking room dries, temperature is controlled at 45～55oC, and humidity is controlled at 10～15%, and the time is not less than 6 hours;
F, vanning
At first will put into the bed load of certain altitude in sandbox, the pipe fitting model of having dried is put into to sandbox, dry sand jolt ramming is filled in gradation, then covers polyethylene film, to be cast;
G, vacuum-assist pouring
Lay cup, be communicated with negative pressure, negative pressure control, built in the 0.03MP left and right, is poured into a mould, and pouring temperature is controlled at 1450～1500oC, according to each running channel of cast skill of slow speed, in 20～30 seconds, completes cast, treats outlet;
H, outlet polishing
The product of having poured into a mould is carried out to the mould turnover knockout, and molding sand is sent into after sand preparing system is processed and is recycled; Product is sent into the cleaning worker-house cleaning of polishing, and obtains the finished product of casting pig thin-wall pipe.
During concrete enforcement, for under the forming machine mould matching state, the a large amount of compressed air that enter in die cavity can be discharged fully when filling material, to guarantee charging density, make the thick and even density of the white die wall of moulding, can be to the discharge duct overstriking at the forming machine fixed half and moving half back side, strengthen row of conduits tolerance, also can utilize water inlet on the forming machine fixed half and moving half, advance steam or compressed air and discharge water or compressed-air actuated all pipelines are auxiliary realizes exhaust.As for how realizing auxiliary exhaust, how improving gas exhaust piping for a person skilled in the art, be easy to realize.
Claims (2)
1. a casting pig thin-wall pipe lost foam casting process, its technological process comprises: bead prefoam, molding moulding, Bai Mo dry and bond, coat, oven dry, vanning, vacuum-assist pouring, outlet polish; It is characterized in that: wherein, the molding forming step is as follows: the operation forming machine mould matching---is filled with the EPS bead obtained through bead prefoam step and---to being filled with steam, slaking EPS bead, the white mould of moulding in the model of forming machine,---in the model of forming machine, being filled with water quench---white mould is taken out in the die sinking of operation forming machine in the model of forming machine.
2. casting pig thin-wall pipe lost foam casting process according to claim 1, it is characterized in that: coat in step and adopt following formulation for coating material: comprise silica flour, bauxite, bentonite, CMC, Ludox and fire clay, wherein, the weight ratio of silica flour and bauxite is 3:1, and the content of bentonite, CMC, Ludox, fire clay accounts for respectively 2%, 2.5%, 3%, 1.5% of silica flour and bauxite gross weight.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103909218A (en) * | 2014-04-04 | 2014-07-09 | 含山县恒翔机械制造有限公司 | Casting method of clutch shell mold |
| CN104874734A (en) * | 2015-05-06 | 2015-09-02 | 柳州科尔特锻造机械有限公司 | Full mold casting method |
| CN105499504A (en) * | 2015-12-29 | 2016-04-20 | 马鞍山市三峰机械制造有限公司 | Lost foam casting technology for scraping knife or side blade or middle blade wear-resistant parts |
| CN105665639A (en) * | 2016-02-23 | 2016-06-15 | 重庆市大足区通达铁路车辆配件制造有限公司 | Manufacturing method for movable device of cast steel curved support |
| CN105728651A (en) * | 2016-02-22 | 2016-07-06 | 江苏钜源机械有限公司 | Preset inner core integral forming method for evanescent mold for complex workpiece |
| CN108655337A (en) * | 2018-05-15 | 2018-10-16 | 芜湖新兴新材料产业园有限公司 | A kind of foamed model of baffle ring and baffle ring lost foam casting process |
| CN109093073A (en) * | 2018-09-01 | 2018-12-28 | 台州进亿成再生资源回收有限公司 | A kind of cast shaping process based on evaporative pattern |
| CN109773121A (en) * | 2019-02-15 | 2019-05-21 | 刘娜 | A kind of Agricultural Machinery Equipment traveling wheel lost foam casting process |
| CN112605337A (en) * | 2020-11-15 | 2021-04-06 | 浙大城市学院 | Forming method of tensile sample EPS foam model |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103909218A (en) * | 2014-04-04 | 2014-07-09 | 含山县恒翔机械制造有限公司 | Casting method of clutch shell mold |
| CN104874734A (en) * | 2015-05-06 | 2015-09-02 | 柳州科尔特锻造机械有限公司 | Full mold casting method |
| CN105499504A (en) * | 2015-12-29 | 2016-04-20 | 马鞍山市三峰机械制造有限公司 | Lost foam casting technology for scraping knife or side blade or middle blade wear-resistant parts |
| CN107096887A (en) * | 2015-12-29 | 2017-08-29 | 马鞍山市三峰机械制造有限公司 | A kind of method that lost foam process casts Leaf wearing piece |
| CN105728651A (en) * | 2016-02-22 | 2016-07-06 | 江苏钜源机械有限公司 | Preset inner core integral forming method for evanescent mold for complex workpiece |
| CN105665639A (en) * | 2016-02-23 | 2016-06-15 | 重庆市大足区通达铁路车辆配件制造有限公司 | Manufacturing method for movable device of cast steel curved support |
| CN105665639B (en) * | 2016-02-23 | 2018-02-02 | 重庆市大足区通达铁路车辆配件制造有限公司 | Cast steel curve support head preparation method |
| CN108655337A (en) * | 2018-05-15 | 2018-10-16 | 芜湖新兴新材料产业园有限公司 | A kind of foamed model of baffle ring and baffle ring lost foam casting process |
| CN108655337B (en) * | 2018-05-15 | 2023-11-07 | 芜湖新兴新材料产业园有限公司 | Baffle ring foam plastic model and baffle ring lost foam casting process |
| CN109093073A (en) * | 2018-09-01 | 2018-12-28 | 台州进亿成再生资源回收有限公司 | A kind of cast shaping process based on evaporative pattern |
| CN109773121A (en) * | 2019-02-15 | 2019-05-21 | 刘娜 | A kind of Agricultural Machinery Equipment traveling wheel lost foam casting process |
| CN112605337A (en) * | 2020-11-15 | 2021-04-06 | 浙大城市学院 | Forming method of tensile sample EPS foam model |
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Application publication date: 20131204 |