CN109226677B - Sand casting mold and method for preparing bucket tooth holder by using same - Google Patents

Sand casting mold and method for preparing bucket tooth holder by using same Download PDF

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Publication number
CN109226677B
CN109226677B CN201811157877.6A CN201811157877A CN109226677B CN 109226677 B CN109226677 B CN 109226677B CN 201811157877 A CN201811157877 A CN 201811157877A CN 109226677 B CN109226677 B CN 109226677B
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sand casting
casting mold
sand
portions
modification
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CN109226677A (en
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钱嘉镕新
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NINGBO JIADA PRECISION CASTING CO Ltd
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NINGBO JIADA PRECISION CASTING CO Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/22—Moulds for peculiarly-shaped castings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/28—Small metalwork for digging elements, e.g. teeth scraper bits
    • E02F9/2808—Teeth

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Mold Materials And Core Materials (AREA)

Abstract

The invention relates to a sand casting die and a method for preparing a bucket tooth base by using the same, belonging to the technical field of machinery2O3. The sand casting mold can provide molten metal with good fluidity and reduce the defects of the surface layer of a casting, and the mechanical property of the bucket tooth holder of the casting mold can be effectively improved.

Description

Sand casting mold and method for preparing bucket tooth holder by using same
Technical Field
The invention belongs to the technical field of machinery, and relates to a sand casting mold and a method for preparing a bucket tooth holder by using the sand casting mold.
Background
The excavator bucket tooth is an important consumable part on an excavator, is similar to a human tooth, and is a combined bucket tooth consisting of a tooth holder and a tooth tip, and the tooth holder and the tooth tip are connected through a pin shaft. The bucket teeth of the excavator are directly contacted with rock soil, ore and the like in the process of mine excavation, geological exploration and infrastructure construction, and not only bear the friction wear of the rock soil, the ore and the like, but also bear certain impact load, so that the bucket teeth become the most easily worn parts of the excavator, and a large amount of bucket teeth accessories are consumed by each excavator every year. The bucket tooth holder is an important part in the excavator and is an important component for connecting the bucket tooth and the bucket, the bucket tooth holder is arranged on a bottom plate of the excavator bucket, and the bucket tooth holder can reduce damage to the bottom plate by using the bucket tooth holder, so that most of abrasion in excavation is concentrated on the bucket tooth, and the loss cost of the excavator is reduced. The tooth holder is required to have higher toughness and hardness, and good weldability is required to ensure the strength of a welded junction and the welding reliability. The prior art toothholder has short service life and is easy to break or crack because the toothholder has poor weldability and wear resistance and low impact toughness and tensile strength.
The tooth holder is generally made of cast iron or alloy steel, and in order to ensure the toughness and hardness of the tooth holder, the cast iron is required to have higher carbon content and alloy content, but the higher carbon content and alloy content cannot ensure better welding performance, and simultaneously can cause the reduction of the fluidity of molten iron in the casting process, and the casting is easy to generate shrinkage porosity defects, so that a product with high density, complete appearance and good mechanical property cannot be obtained easily. In actual production, in order to improve the fluidity of molten iron, a method of raising the temperature is often adopted, however, when pouring is carried out at an excessively high temperature, the sand mold is expanded, the rejection rate of castings is greatly improved, and the manufacturing cost is also increased.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a sand casting mold which has good air permeability, can provide molten metal with good fluidity and reduce defects on the surface layer of a casting.
The purpose of the invention can be realized by the following technical scheme:
the sand casting mold consists of a base body and a modification layer coated on the inner surface of the base body, wherein the modification layer comprises α -Al with the particle size distribution of 20nm-50nm2O3。
The invention forms a layer of nano α -Al on the surface of quartz sand2O3And control the nano α -Al2O3Size due to nano α -Al2O3The surface of the sand mold has specific surface performance due to specific structure and property, the surface tension of the mold surface can be effectively reduced, when molten metal is contacted with the mold surface, the interfacial tension of the molten metal and the mold surface can be reduced due to the large surface tension difference between the molten metal surface layer and the mold surface, so that the fluidity of the molten metal in a sand mold cavity is improved, the time for forming a film after the molten metal is contacted with the sand mold is reduced, bubbles formed under the molten metal surface layer have time to be more easily separated out due to the surface tension difference, the generation of subcutaneous air holes of a casting is reduced, and the mechanical property of the casting can be improved.
Preferably, the modification layer is formed by coating modification liquid on the inner surface of the sand casting mold and then heating the sand casting mold through laser scanning.
Preferably, the preparation method of the modification liquid comprises the following steps of preparing raw materials in percentage by weight:
Al(NO3)31.5％-3.8％、
2.3 to 4.0 percent of water-based acrylic emulsion,
7.6 to 9.5 percent of polyacrylate,
The balance of water,
mixing the raw materials, adding NaOH solution to adjust the pH value to 7.5-8.0, and stirring to obtain the modification solution.
Preferably, the raw material of the modification liquid also comprises 2.0-5.0% by mass of kaolin.
According to the invention, a proper amount of kaolin is added into the modification liquid, and due to the large specific surface area, low surface energy and large shrinkage rate, the modification layer can be promoted to form tiny pore channels, and the situation that only α -Al is contained is avoided2O3The modification layer which is too compact is easy to form, and the air hole channel of the mould is easy to block, so that the air permeability of the mould is reduced.
Preferably, the scanning power of the laser scanning is 1.5kw-2.0kw, the scanning speed is 150mm/min-200mm/min, and the spot size is 5.0mm × 4.5.5 mm.
The invention is on Al (NO)3)3Adding NaOH solution to the solution to generate Al (OH)3，Al(OH)3Al is generated under the high-temperature action of the laser scanning surface2O3。
Al (NO) in solution3)3The concentration of (3) affects the formation of Al (OH)3Size, in turn, affects Al formation2O3The size of (c). The scanning power, scanning speed and spot size of the laser scanning surface influence Al2O3The important factors of the generation quality, namely the over-low laser scanning power or the over-high scanning speed, can cause the local insufficient heat and insufficient generation of α -Al2O3The excessive laser scanning power or the insufficient scanning speed can locally generate excessive heat, so that the modification layer is excessively burnt, the burning loss is large, the surface of the die is rough, and the flowing of molten metal is influenced. The scanning power, scanning speed and spot size can also directly affect Al2O3By controlling the growth rate, size and other properties of Al (NO)3)3Content in slurry and laser scanningParameter, α -Al will be generated2O3The size of the nano-particles is controlled between 20nm and 50 nm.
Preferably, the sand casting mold matrix is prepared from the following raw materials in parts by weight:
Figure GDA0002414299400000031
according to the invention, a proper amount of wollastonite is added into the conventional sand mold raw material, and the wollastonite can form fine and stable pores with quartz sand in a sand mold casting mold by utilizing special plate column, beam or radial structures and the like, so that the air permeability of the mold is increased. And also can improve the strength and toughness of the die and the heat resistance, corrosion resistance and weather resistance of the die. On the other hand, the thermal expansion shrinkage rate of the die can be effectively reduced, the moisture absorption expansibility of the die is reduced, and the influence on the performance of the casting caused by the cracking of the die due to the high temperature of the molten metal in the using process is prevented.
Another object of the present invention is to provide a method for preparing a tooth holder of a tooth of a bucket tooth using the sand casting mold described above, the method comprising the steps of:
heating and melting component raw materials of alloy steel into molten metal, pouring the molten metal into the sand casting mould, standing to form a green body, and carrying out heat treatment on the green body to obtain the bucket tooth holder.
Preferably, the temperature for heating and melting the component raw materials of the alloy steel into molten metal is 1430-1460 ℃.
Preferably, the temperature for pouring the molten metal is 1310-1340 ℃,
preferably, the heat treatment is that the prepared green body is rapidly cooled to 920-960 ℃ at the speed of 8-12 ℃/min and is kept for 2-3 h, then is slowly cooled to 490-530 ℃ at the speed of 5-6 ℃/min and is kept for 3-5 h, and finally is cooled to 250-300 ℃ and is kept for 3-4 h.
The invention is characterized in that the temperature is quickly reduced to a high temperature area for heat preservation, then is slowly reduced to a medium temperature area for heat preservation, and finally is subjected to heat preservation treatment at a low temperature, thereby being beneficial to the refinement of crystal grains in the alloy steel, particularly the refinement of carbide, avoiding the influence on the toughness of a final product due to overlarge crystal grain size, simultaneously being beneficial to the full generation of crystals and the release of stress, reducing the internal stress of the alloy steel and further reducing the deformation.
Compared with the prior art, the invention has the following beneficial effects: the surface of the sand casting mold can provide molten metal with better flowing property and good gas escape effect of the surface layer of the molten metal, so that the bucket tooth holder prepared by using the sand casting mold reduces casting defects and improves mechanical property.
Detailed Description
The following are specific examples of the present invention and further describe the technical solutions of the present invention, but the present invention is not limited to these examples.
Examples 1-3 are examples of sand casting mold finishes.
Example 1
The preparation method of the sand casting mold modification layer in the embodiment comprises the following steps:
(1) 1.5% Al (NO) by weight3)3Uniformly mixing 2.0% of kaolin, 2.3% of water-based acrylic emulsion, 7.6% of polyacrylate and 86.60% of water, adding NaOH solution to adjust the pH value to 7.5, and stirring for 30min to obtain a modification solution;
(2) coating the modifying liquid on the inner surface of a sand casting mould, and carrying out laser scanning heating on the inner surface of the mould to form a modifying layer, wherein the scanning power of laser scanning is 1.5kw, the scanning speed is 150mm/min, the light spot size is 5.0mm × 4.5.5 mm, and α -Al with the particle size distribution of 38nm-50nm is formed in the modifying layer2O3。
Example 2
The preparation method of the sand casting mold modification layer in the embodiment comprises the following steps:
(1) by weight percent, 2.6% Al (NO)3)3Uniformly mixing 3.7% of kaolin, 3.0% of water-based acrylic emulsion, 8.3% of polyacrylate and 78.90% of water, adding a NaOH solution to adjust the pH value to 7.8, and stirring for 30min to obtain a modification solution;
(2) coating the decorative liquidCovering the inner surface of a sand casting mould, carrying out laser scanning heating on the inner surface of the mould to form a modification layer, wherein the scanning power of the laser scanning is 1.8kw, the scanning speed is 170mm/min, the spot size is 5.0mm × 4.5.5 mm, and α -Al with the particle size distribution of 33nm-43nm is formed in the modification layer2O3。
Example 3
The preparation method of the sand casting mold modification layer in the embodiment comprises the following steps:
(1) by weight percent, 3.8% Al (NO)3)3Uniformly mixing 5.0% of kaolin, 4.0% of water-based acrylic emulsion, 9.5% of polyacrylate and water, adding NaOH solution to adjust the pH value to 8.0, and stirring for 30min to obtain a modification solution;
(2) coating the modification liquid on the inner surface of a sand casting mould, and carrying out laser scanning heating on the inner surface of the mould to form a modification layer, wherein the scanning power of laser scanning is 2.0kw, the scanning speed is 200mm/min, the spot size is 5.0mm × 4.5.5 mm, and α -Al with the particle size distribution of 20nm-35nm is formed in the modification layer2O3。
Examples 4-6 are examples of sand casting mold bases.
In examples 4-6, the sand casting mold matrix was made from the following raw materials in parts by weight as shown in table 1:
table 1: EXAMPLES 4-6 formulation of Sand casting mold base
Example 4 Example 5 Example 6
Quartz sand 100 portions of 100 portions of 100 portions of
Wollastonite 12 portions of 20 portions of 30 portions of
Calcium bentonite 4 portions of 5 portions of 6 portions of
Pulverized coal 1 part of 2 portions of 4 portions of
Water (W) 6 portions of 7 portions of 9 portions of
The sand casting mold substrates of examples 4-6 were prepared using a conventional sand casting mold process.
Examples 7-9 examples of methods for preparing tooth holders for bucket teeth
Example 7
The method for preparing the bucket tooth holder in the embodiment comprises the following steps of:
(1) preparing raw materials according to the following alloy steel components: 0.25% of C, 1.6% of Si, 0.7% of Mn, 1.3% of Ni, 0.2% of Mo, 0.1% of Ti, 0.03% of RE, and the balance of Fe and inevitable impurities;
(2) melting the raw materials of the components of the alloy steel into molten metal at the temperature of 1430 ℃, pouring the molten metal into a sand casting mould with the modification layer of the embodiment 2 and the matrix of the embodiment 5 at the temperature of 1310 ℃, and standing to form a green body;
(3) and (3) rapidly cooling the prepared green body to 920 ℃ at the speed of 8 ℃/min, preserving heat for 3h, then slowly cooling to 490 ℃ at the speed of 5 ℃/min, preserving heat for 5h, finally cooling to 250 ℃, preserving heat for 4h, and then air cooling to room temperature to obtain the bucket tooth holder.
Example 8
The method for preparing the bucket tooth holder in the embodiment comprises the following steps of:
(1) preparing raw materials according to the following alloy steel components: 0.25% of C, 1.6% of Si, 0.7% of Mn, 1.3% of Ni, 0.2% of Mo, 0.1% of Ti, 0.03% of RE, and the balance of Fe and inevitable impurities;
(2) melting the component raw materials of the alloy steel into molten metal at 1440 ℃, pouring the molten metal into a sand casting mold with the modification layer of the embodiment 2 and the base body of the embodiment 5 at 1330 ℃, and standing to form a green body;
(3) and (3) rapidly cooling the prepared green body to 950 ℃ at the speed of 10 ℃/min, preserving heat for 2.5h, then slowly cooling to 500 ℃ at the speed of 5.5 ℃/min, preserving heat for 4h, finally cooling to 280 ℃ and preserving heat for 3.5h, and then air cooling to room temperature to obtain the bucket tooth holder.
Example 9
The method for preparing the bucket tooth holder in the embodiment comprises the following steps of:
(1) preparing raw materials according to the following alloy steel components: 0.25% of C, 1.6% of Si, 0.7% of Mn, 1.3% of Ni, 0.2% of Mo, 0.1% of Ti, 0.03% of RE, and the balance of Fe and inevitable impurities;
(2) melting the raw materials of the components of the alloy steel into molten metal at 1460 ℃, pouring the molten metal into a sand casting mold with the modification layer in the embodiment 2 and the matrix in the embodiment 5 at 1340 ℃, and standing to form a green body;
(3) and (3) rapidly cooling the prepared green body to 960 ℃ at the speed of 12 ℃/min, preserving heat for 2h, then slowly cooling to 530 ℃ at the speed of 6 ℃/min, preserving heat for 3h, finally cooling to 300 ℃, preserving heat for 3h, and then air-cooling to room temperature to obtain the bucket tooth holder.
Example 10
The sand casting mold used for casting had the finish layer of example 1 and the base of example 4, and the other steps were the same as in example 8.
Example 11
The sand casting mold used for casting had the finish of example 3 and the base of example 6, and the rest was the same as in example 8.
Comparative example 1
The sand casting mold used for casting was the same as in example 8 except that no modification layer was provided.
Comparative example 2
In the modifying liquid, Al (NO)3)3The weight percentage of (B) was 4.0%, and the rest was the same as in example 8.
Comparative example 3
The modification solution contained no kaolin, and the other steps were the same as in example 8.
Comparative example 4
The laser scanning power of the modified layer was 1.5kw, and the rest was the same as in example 8.
The properties of the tooth holders of the teeth of the bucket teeth manufactured in examples 7 to 11 according to the present invention and comparative examples 1 to 4 were compared, and the results are shown in table 2 below.
Table 2: comparison of casting Properties after Heat treatment in examples 7 to 11 and comparative examples 1 to 4
Figure GDA0002414299400000081
In conclusion, the invention improves the molding sand casting mould used for preparing the bucket tooth seat, arranges a layer of modification layer on the inner surface of the mould, reasonably matches the formula of the modification layer, effectively improves the fluidity of molten metal in the casting process, reduces the defects of the surface layer of a casting, further improves the mechanical property and the air permeability of the mould matrix by reasonably matching the formula of the mould matrix, ensures that the mould is more durable, and simultaneously improves the mechanical property of the bucket tooth seat,
the specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims (5)

1. The sand casting mold is characterized by comprising a base body and a modification layer coated on the inner surface of the base body, wherein the modification layer comprises α -Al with the particle size distribution of 20nm-50nm2O3；
The modification layer is formed by coating modification liquid on the inner surface of the sand casting mould and then heating the sand casting mould by laser scanning,
the preparation method of the modification liquid comprises the following steps of:
Al(NO3)31.5%-3.8%、
2.3 to 4.0 percent of water-based acrylic emulsion,
7.6 to 9.5 percent of polyacrylate,
The balance of water,
mixing the raw materials, adding NaOH solution to adjust the pH value to 7.5-8.0, and stirring to obtain the modification solution.
2. The sand casting mold according to claim 1, wherein the modifying liquid further comprises kaolin clay in a mass percentage of 2.0-5.0%.
3. A sand casting mould according to claim 1, wherein the laser scanning has a scanning power of 1.5kw-2.0kw, a scanning speed of 150mm/min-200mm/min and a spot size of 5.0mm × 4.5.5 mm.
4. A sand casting mold according to claim 1,
the sand casting mould is prepared from the following raw materials in parts by weight:
100 portions of quartz sand,
12 to 30 portions of wollastonite,
4 to 6 portions of calcium bentonite,
1 to 4 portions of coal powder,
6-9 parts of water.
5. A method of making a tooth holder for a tooth using a sand casting mold according to any of claims 1 to 4, the method comprising the steps of:
heating and melting component raw materials of alloy steel into molten metal, pouring the molten metal into the sand casting mould, standing to form a green body, and carrying out heat treatment on the green body to obtain the bucket tooth holder.
CN201811157877.6A 2018-09-30 2018-09-30 Sand casting mold and method for preparing bucket tooth holder by using same Expired - Fee Related CN109226677B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5091523A (en) * 1973-12-15 1975-07-22
JPH04178235A (en) * 1990-11-09 1992-06-25 Sanyo Chem Ind Ltd Resin composition for wear resistant pattern for sand mold casting
KR20070111738A (en) * 2006-05-19 2007-11-22 현대자동차주식회사 Sand type core manufacturing method for high pressure casting
CN103272993A (en) * 2013-04-16 2013-09-04 繁昌县恒鑫汽车零部件有限公司 Molding sand manufactured from quartz sand as main material and manufacturing method thereof
KR20180017400A (en) * 2016-08-09 2018-02-21 창원대학교 산학협력단 Method for preparing casting mold with high strength using ternary inorganic binder

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5091523A (en) * 1973-12-15 1975-07-22
JPH04178235A (en) * 1990-11-09 1992-06-25 Sanyo Chem Ind Ltd Resin composition for wear resistant pattern for sand mold casting
KR20070111738A (en) * 2006-05-19 2007-11-22 현대자동차주식회사 Sand type core manufacturing method for high pressure casting
CN103272993A (en) * 2013-04-16 2013-09-04 繁昌县恒鑫汽车零部件有限公司 Molding sand manufactured from quartz sand as main material and manufacturing method thereof
KR20180017400A (en) * 2016-08-09 2018-02-21 창원대학교 산학협력단 Method for preparing casting mold with high strength using ternary inorganic binder

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