CN107931525B - Method for controlling solidification of investment casting - Google Patents
Method for controlling solidification of investment casting Download PDFInfo
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- CN107931525B CN107931525B CN201711167851.5A CN201711167851A CN107931525B CN 107931525 B CN107931525 B CN 107931525B CN 201711167851 A CN201711167851 A CN 201711167851A CN 107931525 B CN107931525 B CN 107931525B
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- casting
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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
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Abstract
The invention discloses a method for controlling solidification of an investment casting, which comprises the following steps: determining parameters for soaking and cooling the cast formwork; manufacturing wax molds and combining the wax molds into a module; coating a coating on the module to manufacture a shell, reinforcing the outer surface of the module when the number of the shell manufacturing layers is 50% -70%, and continuing the coating and shell manufacturing process; dewaxing and roasting the shell to form a finished mould shell; and (4) casting, wherein after casting, the parts of the mold shell needing to be cooled are subjected to soaking cooling treatment according to the water inlet cooling requirement. The method for controlling the solidification of the investment casting ensures that the mold shell does not crack in the water cooling process by properly reinforcing the mold shell, improves the cooling process and the part of the mold shell after pouring by utilizing the casting process simulation analysis technology, achieves the aim of controlling the solidification of the casting in the investment casting process, accelerates the local solidification cooling speed of the casting, avoids the defects of shrinkage cavity and looseness of the casting, and further improves the yield and the finished product rate of the casting.
Description
Technical Field
The invention belongs to the technical field of precision casting, and particularly relates to a method for controlling solidification of an investment casting.
Background
Precision castings cast by adopting an investment mold are complex in general structure and more in heat conservation, and the traditional casting method is low in yield and low in efficiency due to the fact that a pouring channel is used for feeding or a riser is arranged for feeding; meanwhile, the other part is used for realizing casting feeding, and the solidification time of a feeding channel is delayed by adopting a local heat preservation mode so as to obtain a casting without shrinkage cavity and looseness; particularly, due to the structural particularity of part of castings, after the process design, the bottom of the castings still has large isolated thermal junctions, so that feeding is difficult, and defects are generated.
The Chinese patent (application No. 201510690405.7, application No. 2015.10.22, publication No. 105364002, published No. 2016.03.02) named as an investment casting process for accelerating the solidification and cooling of castings provides an investment casting process for accelerating the solidification and cooling of castings, which comprises the following steps of manufacturing a wax mold and a wax mold group synthesis module according to a normal process; coating materials on a wax mould according to a normal process to manufacture a shell, inserting battens into an inner cavity of a mould shell when 60% of shell manufacturing is finished, preparing cold iron bars with the same number as the battens, manufacturing the shell according to the normal process, dewaxing and roasting to form the finished mould shell; breaking the formwork at the exposed part of the batten by using a small hammer; and (3) inserting the prepared cold iron bars into a formwork cavity formed after the wood bars are burnt out, and finishing casting and subsequent treatment operation according to a normal process. The method has the advantages that the battens are inserted into the inner cavity of the formwork in the manufacturing process of the formwork, the burnt battens are replaced by the iron bars and inserted into the hollow cavity of the formwork after the formwork is roasted, the heat in the pipeline or the inner cavity is quickly discharged by utilizing the good heat conductivity of the iron bars after casting, the solidification cooling speed of the casting is accelerated, and the defects of shrinkage cavity and looseness of the casting are avoided. A method for precisely casting the investment pattern of casting includes such steps as changing the number of local layers of casting shell, coating a layer of paint on the fusible pattern, coating sand, sticking wax on the position to be thinned, and making the layer number of local layer less than that of other position.
Disclosure of Invention
The invention aims to provide a method for controlling solidification of an investment casting, which simplifies the operation process and solves the casting quality problems that the part of the casting with a complex structure is easy to shrink due to poor heat dissipation, and the like in the production process of the investment casting.
The technical scheme adopted by the invention is as follows: a method for controlling solidification of investment casting castings comprising the steps of:
confirming casting parameters of investment casting, and determining parameters for soaking and cooling a cast formwork;
secondly, manufacturing wax molds according to the casting requirement, and combining the wax molds into a module;
coating the coating on the module to prepare a shell, reinforcing the outer surface of the module when the number of the shell preparation layers is 50% -70%, and continuing the coating and shell preparation process;
dewaxing and roasting the shell to form a finished formwork;
and step five, casting the formwork according to the process requirements, and soaking and cooling the part of the formwork needing to be cooled according to the water inlet cooling requirements after casting, so as to finish the solidification of the casting.
The present invention is also characterized in that,
the concrete mode of reinforcing the outer surface of the module in the third step is as follows: and reinforcing the outer surface of the module in a net shape by using metal wires.
The interval between two adjacent metal wires is 10-50 mm.
And in the first step, simulation analysis is carried out by using ProCAST software to obtain the parameters of soaking and cooling.
The soaking cooling parameters comprise soaking depth and soaking time.
And step five, carrying out soaking cooling treatment on the cast formwork in a cooling water tank.
The method for controlling the solidification of the investment casting ensures that the mold shell does not crack in the water cooling process by properly reinforcing the mold shell, improves the cooling process and the part of the mold shell after pouring by utilizing the casting process simulation analysis technology, achieves the aim of controlling the solidification of the casting in the investment casting process, accelerates the local solidification cooling speed of the casting, avoids the defects of shrinkage cavity and looseness of the casting, and further improves the yield and the yield of the casting.
Drawings
FIG. 1 is a schematic structural view of a type II grommet casting according to example 1 of the present invention;
FIG. 2 is a cross-sectional view of FIG. 1;
FIG. 3 is a perspective view of a casting scheme of a type II grommet casting according to example 1 of the present invention;
FIG. 4 is a side view of FIG. 3;
FIG. 5 is a schematic view of the structure of a casing casting according to embodiment 2 of the present invention;
fig. 6 is a perspective view of a casting scheme of a housing casting according to embodiment 2 of the present invention.
In the figure, 1 is a casting, 2 is a sprue, 3 is a cross runner, 4 is a riser and 5 is an ingate.
Detailed Description
The invention provides a method for controlling solidification of investment casting, which comprises the following steps:
confirming casting parameters of investment casting, and determining parameters for soaking and cooling a cast formwork; in an exemplary manner, the parameters of the immersion cooling are obtained by simulation analysis using ProCAST software. And the soaking cooling parameters comprise soaking depth and soaking time.
Secondly, manufacturing wax molds according to the casting requirement, and combining the wax molds into a module;
coating on the module to form a shell, reinforcing the outer surface of the module when the number of the shell forming layers is 50% -70%, and continuing the coating shell forming process; preferably, the outer surface of the module is reinforced in a net shape by using metal wires. And the interval between two adjacent metal wires is 10-50 mm.
Dewaxing and roasting the shell to form a finished formwork;
and step five, casting the mold shell according to the process requirement, and performing forced cooling treatment on the part, needing to be cooled, of the mold shell by soaking according to the water inlet cooling requirement after casting, so as to finish the solidification of the casting. For example, the cast formwork can be immersed in a cooling water tank for cooling.
The invention is described in detail below with reference to the figures and specific embodiments.
Example 1
When the casting 1 of a certain II-type protective ring is in an annular structure (shown in figure 1), the cross section of the casting is in an I-shaped structure (shown in figure 2), and the process design is carried out, the lower triangular area always has a thermal node which is difficult to completely eliminate, and finally, the defects of shrinkage cavity and shrinkage porosity are generated at the part. According to the invention, the process scheme shown in figures 3 and 4 is adopted, a sprue 2 and a runner 3, a riser 4 and an ingate 5 are respectively arranged and the positions of the sprue 2 and the runner 3, the riser 4 and the ingate 5 are determined according to the shape and the process requirements of a casting 1 of a II-type retaining ring, firstly, ProCAST software is used for carrying out simulation analysis to obtain soaking process parameters of 30mm of soaking depth and 10 seconds of soaking time; after the wax pattern is manufactured and the wax pattern assembly is completed, coating the wax pattern according to the process to make a shell, and when the coating finishes the 4 th layer, using
The unfinished formwork is reinforced by the iron wires, the iron wires are separated by about 40mm and are reinforced in a net shape, and the distance between the metal wires such as the iron wires can be set to be 10mm, 30mm or even 50mm according to the reinforcement requirements according to different casting structures and process requirements. Then, finishing the shell making process of the following 3 layers of coatings; after dewaxing and roasting, pouring stainless steel water into the formwork, vertically immersing the formwork with the poured molten steel into a frame hopper with the water depth of 30mm in a special water tank within 8 seconds after pouring for 10 seconds, taking out the incompletely cooled formwork, and subsequently placing the formwork into a special sand hopper for continuous cooling. Through X-ray detection, the triangular area at the lower part of the casting has no defects of shrinkage cavity and shrinkage porosity, and the internal quality of the casting meets the requirements of a drawing and a technical protocol.
Example 2:
as shown in figure 5, the weight of a certain shell casting 1 reaches 13Kg, a top riser horizontal process is adopted in process design, shrinkage cavity or shrinkage porosity defects frequently occur at the bottoms of flanges at two sides in actual pouring, and by applying the method for controlling solidification of investment casting, after simulation of casting process simulation software, soaking technological parameters are obtained, namely the soaking depth is 50mm, and the soaking time is not less than 35 seconds. In actual production, when the coating is used for preparing the 7 th layer according to the process
The shuttering is reinforced by the iron wires, the iron wires are reinforced in a net shape at intervals of about 50mm, and then the shell making process of the following 3 layers of coatings is completed; then pouring stainless steel water into the finished mould shell after dewaxing and roasting, vertically immersing the mould shell poured with the molten steel into a frame bucket with the water depth of 50mm in a special water tank within 15 seconds after pouring for 35 seconds, and then placing the mould shell which is not completely cooled into a special sand bucket for continuous cooling. Through the confirmation of the dissection of the casting, the shrinkage cavity or shrinkage porosity defects at the bottoms of the flanges at the two sides of the casting are thoroughly eliminated.
Claims (2)
1. A method for controlling solidification of investment casting castings comprising the steps of:
confirming casting parameters of investment casting, determining parameters for carrying out immersion cooling on a cast formwork, and carrying out simulation analysis by using ProCAST software to obtain the parameters for immersion cooling, wherein the parameters for immersion cooling comprise immersion depth and immersion time;
secondly, manufacturing wax molds according to the casting requirement, and combining the wax molds into a module;
coating the die set with a coating to form a shell, reinforcing the outer surface of the die set in a net shape by using metal wires when the number of the shell-making layers is 50-70%, wherein the interval between every two adjacent metal wires is 10-50mm, and then continuing the coating and shell-making process;
dewaxing and roasting the shell to form a finished formwork;
and step five, casting the formwork according to the process requirements, and carrying out soaking cooling treatment on the part of the formwork needing to be cooled according to the soaking cooling requirements after casting, namely completing the solidification of the casting.
2. The method of claim 1 for controlling solidification of investment casting castings, wherein in step five the as-cast form is subjected to a water immersion cooling process in a cooling water bath.
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| CN201711167851.5A CN107931525B (en) | 2017-11-21 | 2017-11-21 | Method for controlling solidification of investment casting |
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| CN110711842A (en) * | 2018-07-12 | 2020-01-21 | 无锡市东明冠特种金属制造有限公司 | Directional solidification casting method of radiation finned tube |
| CN109570444A (en) * | 2018-09-30 | 2019-04-05 | 鹰普航空零部件（无锡）有限公司 | A kind of manufacturing process of complex-shaped surface mould stainless cast steel part |
| CN109396345A (en) * | 2018-12-10 | 2019-03-01 | 中国船舶重工集团公司第十二研究所 | A method of for investment casting formwork part Quench |
| CN109482818A (en) * | 2018-12-14 | 2019-03-19 | 山西天海泵业有限公司 | Model casting locally dips in water-cooling method |
| CN110938731B (en) * | 2019-12-24 | 2021-10-15 | 陕西宏远航空锻造有限责任公司 | Method for improving rust resistance of investment casting austenitic stainless steel |
| CN111957890B (en) * | 2020-06-30 | 2022-05-06 | 中国航发南方工业有限公司 | Preparation method of formwork with controllable heat dissipation conditions |
| CN112756554B (en) * | 2020-12-24 | 2024-03-05 | 南通海泰科特精密材料有限公司 | Shell making process method for preventing dewaxing, cracking and wax seepage of fused quartz mould shell |
| CN114951586A (en) * | 2022-05-30 | 2022-08-30 | 阿诺诗(广东)精密金属科技有限公司 | Cold and hot paste application structure of precision casting and application method thereof |
| CN116274869A (en) * | 2022-12-30 | 2023-06-23 | 哈尔滨工业大学 | Aluminum alloy investment casting device and casting method using device |
Citations (1)
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| CN105364002A (en) * | 2015-10-22 | 2016-03-02 | 贵州安吉航空精密铸造有限责任公司 | Investment casting process accelerating solidification and cooling of casting |
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| JPH07214236A (en) * | 1994-01-31 | 1995-08-15 | Mitsubishi Materials Corp | Production of casting mold |
| CN102554125B (en) * | 2011-12-28 | 2013-11-06 | 西安西工大超晶科技发展有限责任公司 | Precision casting method of aluminum gearbox |
| CN103464683B (en) * | 2013-09-05 | 2015-07-22 | 贵州安吉航空精密铸造有限责任公司 | Investment casting method |
| CN104493090A (en) * | 2014-12-11 | 2015-04-08 | 贵州红林机械有限公司 | Investment casting pouring method of thin-wall aluminum alloy casting |
| CN106734886A (en) * | 2017-01-23 | 2017-05-31 | 江苏永瀚特种合金技术有限公司 | A kind of method for preventing the formwork cracking during shell processed |
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| CN105364002A (en) * | 2015-10-22 | 2016-03-02 | 贵州安吉航空精密铸造有限责任公司 | Investment casting process accelerating solidification and cooling of casting |
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| 熔模精密铸造型壳局部淬水工艺探讨;包玉秋等;《特种铸造及有色合金》;20121231;第32卷(第10期);第928-931页 * |
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