CN111558693A - Method for preventing shell manufacturing and cracking of thick and large part surface of part - Google Patents
Method for preventing shell manufacturing and cracking of thick and large part surface of part Download PDFInfo
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- CN111558693A CN111558693A CN202010551376.7A CN202010551376A CN111558693A CN 111558693 A CN111558693 A CN 111558693A CN 202010551376 A CN202010551376 A CN 202010551376A CN 111558693 A CN111558693 A CN 111558693A
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- wax
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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
- B22C9/043—Removing the consumable pattern
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Abstract
The invention provides a method for avoiding cracking of a shell-making layer on the surface of a thick and large part of a part, which can avoid the problem of cracking of the shell-making layer caused by inconsistent wall thickness of a wax mould, is simple and low in cost, and can greatly improve the yield and production efficiency of products. In the technical scheme of the invention, the wax overflow grooves are formed on the parts to be processed, the thickness of which exceeds the thick-wall threshold value, so that the wall thicknesses of the wax molds tend to be the same; when the wax mould provided with the wax overflowing groove is heated and expanded, redundant wax moulds can flow to the wax overflowing groove, so that the wax mould has a more melting space, the mould shell cannot be expanded, and the cracking phenomenon of the inner surface layer or the transition layer of the mould shell caused by melting of the wax mould is avoided.
Description
Technical Field
The invention relates to the technical field of investment casting technology, in particular to a method for avoiding shell-making cracking of the surfaces of thick and large parts of a part.
Background
Investment casting is a production mode with a complex process and a long period, and the final product is produced by a wax mould. The wax mould is an important link in the process, and parts of some complex products have different wall thicknesses, and sometimes the thickness can be suspended by dozens of millimeters. When the wax patterns with uneven wall thickness are dewaxed by steam after shell making is finished, the thin parts can be melted firstly and the thick parts can be melted later due to temperature change. In actual production, the wax melted first often cannot be discharged first, but expands all the time inside the wax mold, and when the wax expands to a certain extent, the wax will adhere to the surface of the part, and affect the shell-making layer, such as: internal penetrating micro-cracks can be formed on the surface layer or the transition layer; in the pouring process, when molten steel impacts the area, a surface layer or a transition layer can generate mold leakage and burrs, so that the surface of an investment casting is damaged, the cleaning difficulty in the subsequent process is increased, and the production efficiency is finally influenced.
Disclosure of Invention
In order to solve the problem that a shell making layer is cracked due to inconsistent melting speed when wax molds of parts with different wall thicknesses in complex products are dewaxed after shell making, the invention provides a method for avoiding shell making cracks on the surfaces of thick parts and large parts, which can avoid the problem of cracking of the shell making layer due to inconsistent wall thicknesses of the wax molds, and has the advantages of simple method, low cost and capability of greatly improving the yield and the production efficiency of products.
The technical scheme of the invention is as follows: a method for avoiding cracking of a shell on the surface of a thick large part is characterized by comprising the following steps:
s1: presetting a thick-wall threshold and a thin-wall threshold;
the thick wall threshold value represents the problem that the wax mould is not uniformly melted when dewaxing is carried out after shell manufacturing after the wall thickness of the wax mould is larger than the threshold value;
the thin-wall threshold value indicates that the problem of part falling in the wax mould welding process can occur after the wall thickness of the wax mould is smaller than the threshold value;
in the mold design procedure, all parts exceeding the wall thickness threshold are found and recorded as parts to be processed;
s2: according to the type of the part to be processed, forming different types of wax overflow grooves on the part to be processed;
the wax overflow groove is distinguished according to the closure, and comprises: only one weight-reducing groove with an opening and more than one hollow-out groove with an opening are arranged;
s3: confirming the wall thickness of the wax mould after the wax overflow groove is formed;
after the parts to be processed are provided with the wax overflow grooves, the wall thickness of the thinnest part of the wax mould is more than or equal to the thin-wall threshold value;
s4: designing subsequent procedures for the wax overflow groove;
the weight reduction grooves and the hollow grooves are welded through a sealing process or a module welding process with wax molds of other parts before a shell manufacturing process, so that the insides of the grooves are vacuumized.
It is further characterized in that:
the thick wall threshold is set at 10 mm;
the thin wall threshold is set to 5 mm;
in step S2, when the to-be-processed component is an inner gate, selecting the hollow groove;
when the part to be processed is a non-gate position in the module, selecting the weight reduction groove;
and when the part to be processed is a single part, the weight-reducing groove is formed in the part.
According to the method for preventing the surface of the thick part from cracking during shell manufacturing, the wax overflow groove is formed in the part to be processed, the thickness of which exceeds the thick-wall threshold value, so that the wall thickness of the wax mould tends to be the same; when the wax mould provided with the wax overflowing groove is heated and expanded, redundant wax moulds can flow to the wax overflowing groove, so that the wax mould has a more melting space, the mould shell cannot be expanded, and the cracking phenomenon of the inner surface layer or the transition layer of the mould shell caused by melting of the wax mould is avoided.
Drawings
FIG. 1 is a schematic structural diagram of a part provided with weight-reducing slots according to a first embodiment;
FIG. 2 is a schematic structural diagram of a part in a vacuum state in a lightening groove after a sealing process in the first embodiment;
FIG. 3 is a schematic structural diagram of a non-gate position of a module with weight-reducing slots according to a second embodiment;
fig. 4 is a schematic structural view of a gate position of a module provided with a hollow groove according to a third embodiment;
fig. 5 is a schematic structural view illustrating a structure of the mold gate in a vacuum state after the welding process in the third embodiment.
Detailed Description
The invention discloses a method for avoiding cracking of a shell on the surface of a thick large part, which comprises the following steps.
S1: presetting a thick-wall threshold and a thin-wall threshold;
the thick-wall threshold value represents the problem that the wax mould is unevenly melted when dewaxing occurs after shell manufacturing after the wax mould is made to have a wall thickness larger than the threshold value;
the thin-wall threshold value indicates that the problem of part falling in the wax mould welding process can occur after the wall thickness of the wax mould is smaller than the threshold value;
in the present embodiment, the thick wall threshold is set to 10 mm; the thin wall threshold is set to 5 mm;
in the mold design process, all parts exceeding the wall thickness threshold are found and recorded as the parts to be processed.
S2: according to the type of the parts to be processed, different types of wax overflow grooves are formed in the parts to be processed;
the wax overflow groove is distinguished according to the closure, and comprises: only one weight-reducing groove with an opening and more than one hollow-out groove with an opening.
S3: confirming the wall thickness of the wax mould after the wax overflow groove is formed;
after the parts to be processed are provided with the wax overflow grooves, the wall thickness of the thinnest part of the wax mould is more than or equal to the thin-wall threshold value; if the wall of the wax mould is too thin, the loose welding of the wax mould can cause the problem of mould assembly falling in the welding process; this problem is prevented by the setting of the thin-wall threshold.
S4: designing a subsequent process for the wax overflowing groove;
no matter the weight reduction groove or the hollow groove is formed before the shell manufacturing process, the welding process is carried out through a sealing process or a wax mold through module welding process with other parts, so that the inside of the groove is vacuumized.
When the parts to be processed are single parts, lightening slots are formed in the parts; as shown in FIG. 1, for a single part 1 to be processed, FIG. 1 shows a structure after a lightening groove 2 is formed in the part 1, and FIG. 2 shows a structure that in a subsequent process, the lightening groove 2 is blocked by a closing part 3 (such as an inner sprue on a die set) based on a closing process, and the lightening groove 2 in the part 1 is in a vacuum state.
When the part to be processed is a non-gate position in the module, selecting a weight reduction groove; as shown in FIG. 3, a pouring gate 4 of the die set is provided, and in this embodiment, a lightening groove 5 with a diameter of 10mm is formed in the pouring gate 4.
When the part to be processed is the inner sprue 6, selecting a hollow groove; as shown in fig. 4, an open hollow groove 8 is opened at the gate position 7; as shown in fig. 5, the gate 6 having the hollow-out groove 8 formed therein is welded to another member 9 in a die set welding process, and a vacuum state is formed inside the gate 6.
The technical scheme of the invention is simple and easy to popularize, reduces the weight consumption of the wax mould and the mould set, improves the product quality and does not increase the labor intensity of staff.
Claims (6)
1. A method for avoiding cracking of a shell on the surface of a thick large part is characterized by comprising the following steps:
s1: presetting a thick-wall threshold and a thin-wall threshold;
the thick wall threshold value represents the problem that the wax mould is not uniformly melted when dewaxing is carried out after shell manufacturing after the wall thickness of the wax mould is larger than the threshold value;
the thin-wall threshold value indicates that the problem of part falling in the wax mould welding process can occur after the wall thickness of the wax mould is smaller than the threshold value;
in the mold design procedure, all parts exceeding the wall thickness threshold are found and recorded as parts to be processed;
s2: according to the type of the part to be processed, forming different types of wax overflow grooves on the part to be processed;
the wax overflow groove is distinguished according to the closure, and comprises: only one weight-reducing groove with an opening and more than one hollow-out groove with an opening are arranged;
s3: confirming the wall thickness of the wax mould after the wax overflow groove is formed;
after the parts to be processed are provided with the wax overflow grooves, the wall thickness of the thinnest part of the wax mould is more than or equal to the thin-wall threshold value;
s4: designing subsequent procedures for the wax overflow groove;
the weight reduction grooves and the hollow grooves are welded through a sealing process or a module welding process with wax molds of other parts before a shell manufacturing process, so that the insides of the grooves are vacuumized.
2. The method for avoiding cracking of the surface of the thick large part of the part in the crust according to claim 1, wherein: the thick wall threshold is set at 10 mm.
3. The method for avoiding cracking of the surface of the thick large part of the part in the crust according to claim 1, wherein: the thin wall threshold is set to 5 mm.
4. The method for avoiding cracking of the surface of the thick large part of the part in the crust according to claim 1, wherein: in step S2, when the component to be processed is an inner gate, the hollow groove is selected.
5. The method for avoiding cracking of the surface of the thick large part of the part in the crust according to claim 1, wherein: and when the part to be processed is a non-gate position in the module, selecting the weight-reducing groove.
6. The method for avoiding cracking of the surface of the thick large part of the part in the crust according to claim 1, wherein: and when the part to be processed is a single part, the weight-reducing groove is formed in the part.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010551376.7A CN111558693A (en) | 2020-06-17 | 2020-06-17 | Method for preventing shell manufacturing and cracking of thick and large part surface of part |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010551376.7A CN111558693A (en) | 2020-06-17 | 2020-06-17 | Method for preventing shell manufacturing and cracking of thick and large part surface of part |
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| CN111558693A true CN111558693A (en) | 2020-08-21 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010551376.7A Pending CN111558693A (en) | 2020-06-17 | 2020-06-17 | Method for preventing shell manufacturing and cracking of thick and large part surface of part |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2435170Y (en) * | 2000-07-07 | 2001-06-20 | 苏章仁 | Runner moulded inner tube for lost pattern casting |
| CN105458180A (en) * | 2015-11-20 | 2016-04-06 | 沈阳黎明航空发动机(集团)有限责任公司 | Forming pouring gate with dewaxing opening and preparing and blocking method of forming pouring gate |
| CN107812884A (en) * | 2017-11-06 | 2018-03-20 | 东方电气集团东方汽轮机有限公司 | Investment pattern precision casting auxiliary dewaxing mouth moulding process |
| CN208004740U (en) * | 2018-01-02 | 2018-10-26 | 上海华培动力科技股份有限公司 | A kind of dewaxing structure |
| CN108746496A (en) * | 2018-06-01 | 2018-11-06 | 中国航发北京航空材料研究院 | A kind of moltening mold castings shell preparation method |
| CN109014038A (en) * | 2018-10-16 | 2018-12-18 | 北京星航机电装备有限公司 | A method of reducing shell spalling in precision-investment casting dewaxing process |
-
2020
- 2020-06-17 CN CN202010551376.7A patent/CN111558693A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2435170Y (en) * | 2000-07-07 | 2001-06-20 | 苏章仁 | Runner moulded inner tube for lost pattern casting |
| CN105458180A (en) * | 2015-11-20 | 2016-04-06 | 沈阳黎明航空发动机(集团)有限责任公司 | Forming pouring gate with dewaxing opening and preparing and blocking method of forming pouring gate |
| CN107812884A (en) * | 2017-11-06 | 2018-03-20 | 东方电气集团东方汽轮机有限公司 | Investment pattern precision casting auxiliary dewaxing mouth moulding process |
| CN208004740U (en) * | 2018-01-02 | 2018-10-26 | 上海华培动力科技股份有限公司 | A kind of dewaxing structure |
| CN108746496A (en) * | 2018-06-01 | 2018-11-06 | 中国航发北京航空材料研究院 | A kind of moltening mold castings shell preparation method |
| CN109014038A (en) * | 2018-10-16 | 2018-12-18 | 北京星航机电装备有限公司 | A method of reducing shell spalling in precision-investment casting dewaxing process |
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Application publication date: 20200821 |
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