CN108273963B - Casting method for preventing shrinkage porosity defect at thick and large wall of casting - Google Patents
Casting method for preventing shrinkage porosity defect at thick and large wall of casting Download PDFInfo
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- CN108273963B CN108273963B CN201810062987.8A CN201810062987A CN108273963B CN 108273963 B CN108273963 B CN 108273963B CN 201810062987 A CN201810062987 A CN 201810062987A CN 108273963 B CN108273963 B CN 108273963B
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- casting
- thick
- lost foam
- chilling
- large wall
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
- B22C9/046—Use of patterns which are eliminated by the liquid metal in the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
Abstract
The invention provides a casting method for preventing a casting from generating shrinkage porosity defect at a thick and large wall, which adopts a lost foam casting process, adopts a vacuum negative pressure molding method in a molding process, places a chilling block made of light chilling material at a corresponding position of a lost foam pattern according to the requirement of a casting process before carrying out vacuum negative pressure molding on the lost foam, and bonds the chilling block and the lost foam pattern together. The invention overcomes the problems that the chilling block used in the existing molding method can not be fixed, the chilling block can not be fed to the thick and large wall of the casting due to easy movement and displacement in the molding compaction process, and the chilling block used in the existing molding method is heavier and can easily cause damage and deformation to the mold, and provides a casting method for preventing the shrinkage porosity defect at the thick and large wall of the casting.
Description
Technical Field
The invention relates to the technical field of vacuum negative pressure lost foam casting, in particular to a casting method for preventing a thick large wall of a casting from generating shrinkage porosity defects.
Background
The lost foam casting is a casting method that uses a foam plastic mould to replace a casting mould for casting, a metal liquid is directly poured without taking out a mould sample, and the metal liquid burns out the mould sample to obtain an ideal casting. The casting technology uses low-density lost foam material, such as EPS/STMMA, as raw material, and surface coating paint is used for building strength and then sand filling molding is carried out.
The vacuum negative pressure molding method is a green casting method which uses dry sand to be buried in a box for molding, and uses sealed vacuum to ensure that the dry sand builds strength around a mold and then is cast for molding. The pattern surface of this casting method cannot place moving process information such as chills, risers, etc. Firstly, a negative pressure lost foam casting method is dry sand modeling, a sand mold is in a collapsing state before pouring, a chill, a riser and the like cannot be guaranteed to be completely attached to a pattern, and dry sand is filled between the sand mold and the pattern; and secondly, the negative pressure lost foam casting method is that dry sand is compacted by using a compaction platform, and a chilling block, a riser and the like can shift in the compaction process, so that chilling and feeding effects of the chilling block and the riser are inconsistent with the process design, finally, the casting quality cannot be guaranteed, and the defects of looseness, shrinkage porosity and the like can occur.
Disclosure of Invention
The invention overcomes the problems that the chilling block used in the existing molding method can not be fixed, the chilling block can not be fed to the thick and large wall of the casting due to easy movement and displacement in the molding compaction process, and the chilling block used in the existing molding method is heavier and can easily cause damage and deformation to the mold, and provides a casting method for preventing the shrinkage porosity defect at the thick and large wall of the casting.
The technical scheme of the invention is as follows: a casting method for preventing the shrinkage porosity defect at the thick wall of a casting adopts a lost foam casting process, a vacuum negative pressure molding method is adopted in a molding process, before the lost foam is subjected to vacuum negative pressure molding, a chilling block made of light chilling materials is placed at a corresponding position of a lost foam pattern according to the requirement of a casting process, and the chilling block and the lost foam pattern are bonded together.
Further, when the thick and large wall of the casting is of a special-shaped structure, the chilling block made of the light chilling material is designed into a structure matched with the special-shaped structure along with the shape, after the chilling block made of the light chilling material and the corresponding special-shaped structure of the lost foam pattern are assembled, a hot melt adhesive is used for bonding a gap at the contact part of the chilling block and the lost foam pattern, and after the hot melt adhesive is hardened, the lost foam pattern is sequentially coated, dried and molded. The treatment can avoid the situation that the graphite chilling block cannot be completely attached to the lost foam pattern after the complex shapes are applied, and the chilling effect is influenced. The special-shaped structure is a nonstandard structure such as a jaw, a nonstandard hole, a groove and the like.
Further, when the thick and large wall of the casting is in a plane structure, designing the chilling block made of the light chilling material into a rectangular block structure, sequentially coating and drying the lost foam pattern, placing the rectangular block chilling block on the plane structure of the thick and large wall of the lost foam pattern according to the casting process requirement, bonding the chilling block and the lost foam pattern by using a sand mold adhesive, and molding after the sand mold adhesive is hardened.
Further, the light chilling material is graphite.
The light chilling material has the characteristics of light weight, large heat capacity ratio, low cost, easy forming and the like, and the materials meeting the requirements comprise a chromium ore sand mixture, a metal powder and resin sand mixture, graphite and the like, but the graphite is the most preferable. The physical properties of the graphite chiller and the cast iron chiller are compared, the essence of the graphite chiller is the physical properties of graphite and metal iron, and the detailed table 1 shows that the density of the graphite chiller is only 1/4 of the cast iron chiller, the heat conduction and heat storage capacity of the graphite chiller is 3-4 times of that of the cast iron chiller, the melting point of the graphite chiller is far higher than that of iron, and the graphite chiller and the cast iron chiller are small in thermal expansion, so that the graphite chiller and the cast iron chiller have different performances in the aspects of modeling, core making process, casting cooling result and the like.
TABLE 1 comparison of the physical Properties of cast iron chill and graphite chill
| Index (I) | Cast iron chill | Graphite chill |
| Density/(g/cm)3) | 7.5 | 1.65～1.85 |
| Thermal conductivity/(/ m.degree. C.) | 48 | 115～129 |
| Specific heat capacity/(J/kg. ℃ C.) | 444 | 710～1510 |
| Melting Point/. degree.C | 1535 | 3850 |
| Coefficient of thermal expansion/(10E-6/. degree. C.) | 10 | ＜6 |
The technical effect of the technical scheme is as follows: the graphite is selected as the chilling block, so that the characteristics of light weight, large heat capacity ratio, low cost, easy forming and the like can be achieved; the process method of 'light chilling material + cold iron assembled in advance' is adopted, and the problems of looseness and shrinkage of the thick-wall part in the casting process are effectively solved.
Drawings
FIG. 1 is a schematic view of a jaw configuration at a thick large wall of a casting according to an embodiment;
FIG. 2 is a graphite chill configuration for jaw assembly in an exemplary embodiment;
FIG. 3 is a schematic diagram of the assembly of the jaw graphite chiller according to an embodiment;
FIG. 4 is a schematic view of the casting structure with the thick bulkheads of the casting in a planar configuration according to an exemplary embodiment;
FIG. 5 is a schematic structural diagram of a graphite chiller used in the embodiment when the thick large wall of the casting is a planar structure;
FIG. 6 is a schematic structural diagram of the graphite chill bonded to the lost foam pattern when the thick and large walls of the casting are planar in the embodiment.
In the figure, 1-jaw structure, 2-jaw graphite chill, 3-hot melt adhesive, 4-plane structure, 5-rectangular graphite chill and 6-sand mold adhesive.
Detailed Description
For further explanation of the present invention, the present invention will be explained in detail with reference to examples.
Example one
As shown in figures 1 to 3, the casting method for preventing the shrinkage porosity defect at the thick and large wall of the casting adopts a lost foam casting process, the molding process adopts a vacuum negative pressure molding method, before the lost foam is subjected to vacuum negative pressure molding, a chilling block made of light chilling materials is placed at the corresponding position of a lost foam pattern according to the requirement of a casting process, and is bonded with the lost foam pattern, and the light chilling materials are graphite.
When the thick and large wall of the casting is provided with a jaw structure 1, selecting graphite as a light chilling material, designing the light chilling material into a jaw graphite chiller 2 structure matched with the jaw structure 1 along with the shape, after assembling the jaw graphite chiller 2 with the jaw structure 1 of the corresponding lost foam pattern, adhering a gap at the contact part of the jaw graphite chiller 2 and the lost foam pattern by using a hot melt adhesive 3, and after hardening the hot melt adhesive 3, sequentially coating, drying and molding the lost foam pattern.
Example two
As shown in fig. 4 to 6, when the thick and large wall of the casting is a plane structure 4, selecting graphite as a light chilling material, designing the light chilling material into a rectangular graphite chill 5 structure, sequentially coating and drying the lost foam pattern, placing the rectangular graphite chill 5 on the plane structure 4 of the thick and large wall of the lost foam pattern according to the casting process requirement, bonding the chill and the lost foam pattern by using a sand mold adhesive 6, and molding after the sand mold adhesive 6 is hardened.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill 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.
Claims (3)
1. A casting method for preventing shrinkage porosity defect at the thick and large wall of a casting adopts a lost foam casting process, and a vacuum negative pressure molding method is adopted in a molding process.
2. The casting method for preventing the shrinkage porosity defect at the thick and large wall of the casting according to claim 1, wherein when the thick and large wall of the casting is in a plane structure, the chilling block of the light chilling material is designed into a rectangular block structure, after the lost foam pattern is sequentially coated and dried, the rectangular block chilling block is placed on the plane structure of the thick and large wall of the lost foam pattern according to the casting process requirement, the chilling block and the lost foam pattern are bonded by using a sand mold adhesive, and the casting is carried out after the sand mold adhesive is hardened.
3. The casting method for preventing the shrinkage porosity defect at the thick large wall of the casting according to claim 1, wherein the light chilling material is graphite.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810062987.8A CN108273963B (en) | 2018-01-23 | 2018-01-23 | Casting method for preventing shrinkage porosity defect at thick and large wall of casting |
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| CN201810062987.8A CN108273963B (en) | 2018-01-23 | 2018-01-23 | Casting method for preventing shrinkage porosity defect at thick and large wall of casting |
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| CN108273963A CN108273963A (en) | 2018-07-13 |
| CN108273963B true CN108273963B (en) | 2020-03-10 |
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| CN110625066B (en) * | 2019-10-29 | 2021-12-21 | 湖北星源科技有限公司 | Preparation method of balance shaft bracket casting |
| CN113042686A (en) * | 2019-12-27 | 2021-06-29 | 南通虹冈铸钢有限公司 | Processing method for preventing defects of guide post hole of automobile stamping die and direct chill |
| CN113333673A (en) * | 2021-05-21 | 2021-09-03 | 中国航发哈尔滨东安发动机有限公司 | Quick preparation method of resin sand casting mold |
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| JPH0230360A (en) * | 1988-07-16 | 1990-01-31 | Nippon Piston Ring Co Ltd | Production of cast iron product |
| CN201922016U (en) * | 2010-12-10 | 2011-08-10 | 四川简阳海特有限公司 | Natural-shape graphite chilling block |
| CN103506576A (en) * | 2013-09-18 | 2014-01-15 | 宁夏共享集团有限责任公司 | Production method for preventing evaporative pattern casting deformation |
| CN103691885A (en) * | 2013-12-05 | 2014-04-02 | 山东省源通机械股份有限公司 | Method for installing chilling block or sand coating iron mould |
| CN105537522A (en) * | 2016-02-22 | 2016-05-04 | 江苏钜源机械有限公司 | Technological method of using internal chill for expendable pattern negative pressure casting |
| CN205270819U (en) * | 2015-12-10 | 2016-06-01 | 宁夏共享能源有限公司 | Graphite chill for casting process |
| CN205834117U (en) * | 2016-06-30 | 2016-12-28 | 天津虹冈铸钢有限公司 | A kind of die reducing casting shrinking hole |
| CN107297486A (en) * | 2017-06-30 | 2017-10-27 | 共享装备股份有限公司 | A kind of set-up mode every sand cooling iron |
| CN107570669A (en) * | 2017-08-30 | 2018-01-12 | 信阳同合车轮有限公司 | Railway cast steel wheel evaporative pattern graphite Quench gravity foundry technology |
-
2018
- 2018-01-23 CN CN201810062987.8A patent/CN108273963B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0230360A (en) * | 1988-07-16 | 1990-01-31 | Nippon Piston Ring Co Ltd | Production of cast iron product |
| CN201922016U (en) * | 2010-12-10 | 2011-08-10 | 四川简阳海特有限公司 | Natural-shape graphite chilling block |
| CN103506576A (en) * | 2013-09-18 | 2014-01-15 | 宁夏共享集团有限责任公司 | Production method for preventing evaporative pattern casting deformation |
| CN103691885A (en) * | 2013-12-05 | 2014-04-02 | 山东省源通机械股份有限公司 | Method for installing chilling block or sand coating iron mould |
| CN205270819U (en) * | 2015-12-10 | 2016-06-01 | 宁夏共享能源有限公司 | Graphite chill for casting process |
| CN105537522A (en) * | 2016-02-22 | 2016-05-04 | 江苏钜源机械有限公司 | Technological method of using internal chill for expendable pattern negative pressure casting |
| CN205834117U (en) * | 2016-06-30 | 2016-12-28 | 天津虹冈铸钢有限公司 | A kind of die reducing casting shrinking hole |
| CN107297486A (en) * | 2017-06-30 | 2017-10-27 | 共享装备股份有限公司 | A kind of set-up mode every sand cooling iron |
| CN107570669A (en) * | 2017-08-30 | 2018-01-12 | 信阳同合车轮有限公司 | Railway cast steel wheel evaporative pattern graphite Quench gravity foundry technology |
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