WO2017114066A1

WO2017114066A1 - Environmentally friendly method for preparing automobile engine shell

Info

Publication number: WO2017114066A1
Application number: PCT/CN2016/107864
Authority: WO
Inventors: 张建勋; 侯晓翠
Original assignee: 张建勋
Priority date: 2015-12-29
Filing date: 2016-11-30
Publication date: 2017-07-06
Also published as: CN105618676A

Abstract

An environmentally friendly method for preparing an automobile engine shell, comprising the steps of preparing a mould shell, preparing an alloy material, smelting and pouring, cooling, and post-treatment; a TiAl-based titanium aluminium compound is used as the shell material, able to work continuously for a long duration under a high temperature, improving performance and service life; fine sawdust and crop straw fibre are used as shell-making materials, reducing the amount of fire-resistant materials used and being environmentally friendly, and a reasonable proportion being used; breathability is increased whilst ensuring moulding cast strength, and using porous attapulgite is beneficial for ventilation, reducing shell pore defects, increasing the yield of finished products, and reducing the weight of the mould shell.

Description

Environment-friendly preparation method for automobile engine casing

Technical field

The invention belongs to the technical field of metal investment precision casting, and in particular relates to an environmentally friendly preparation method of an automobile engine casing.

Background technique

Mold precision casting is an advanced casting forming process, which is used to realize complex, thin-walled and precision shell forming. It has great advantages in precision jewelry, aero-engines and other precision molded parts. The traditional investment casting process is A fusible model (such as a melt mold) is made of a fusible material (such as a wax), and a number of special refractory coatings are applied thereon, dried and hardened to form an integral module, and then melted from the module. A method of obtaining a casing by melting the mold to obtain a hollow mold shell, then subjecting the mold shell to high temperature sintering, and finally casting molten metal therein. At present, ceramic sand is often used in the production process of investment casting. The mold shell broken after casting is difficult to recover from sand and has great environmental pollution. Therefore, it is very necessary to find a high-performance and environmentally-friendly mold preparation method. Is necessary.

Global vehicle production continues to grow, and demand for low-energy, high-performance engines is increasing due to lower fuel consumption and improved urban air quality. Turbochargers can significantly increase engine power, improve emissions, and reduce fuel consumption. The use of a small engine with a turbocharger instead of a naturally aspirated engine is a fundamental trend in the modern automotive industry. Since the turbine casing is subjected to high temperature and high pressure exhaust of the engine, the exhaust gas temperature of the passenger car diesel engine is up to approximately 850 °C. The gasoline engine can reach 1050 °C, and it can work continuously at high speed under the harsh working environment, so the material and performance requirements are very high.

Summary of the invention

Based on the above technical problems, the present invention discloses a preparation method of an environmentally-friendly precision casting mold shell, which can efficiently obtain a casting mold shell, and adopts environmentally friendly materials to protect the environment and resources.

The complete technical solution of the present invention includes:

An environmentally friendly preparation method for an automobile engine casing, characterized in that the method comprises the following steps:

(1) preparing a mold shell, comprising: a. preparing a corresponding wax mold, a casting system, a riser according to the shape of the shell to be obtained, and bonding to a wax module; b. using a suitable ratio of zircon powder, silicon Sol, fine wood chips, n-octanol, aluminate Cobalt mixing and mixing to obtain the surface coating, after coating the wax module, the surface sand is coated with alumina sand and fine wood chips, c. using appropriate proportion of attapulgite powder, mullite powder, crop straw fiber, The backing coating is prepared by mixing and stirring the ethyl silicate hydrolyzate. After the wax module is applied, the back sand is hung, and the sand is repeatedly suspended for several times, and then the slurry is dried. d. Dewaxing and roasting to obtain a mold shell.

(2) alloying ingredients, wherein the alloy contains, by atomic percentage, chemical composition: Al: 44.0 to 47.0 at%, V: 0.5 to 1.2 at%, Cr: 0.4 to 1.6 at%, and Nb: 2.0 to 7.0 at%. B: 0.2 to 0.8 at%, C: 1.0 to 1.3 at%, N: 0.3 to 0.5%, and the balance being Ti.

(3) smelting casting, adding the alloy component described in step (2) to the crucible of the induction melting furnace, evacuating to 10 ^-4 Pa, blowing in argon gas protection, loading power to 350-400 KW, heating 20- After 25 minutes, the temperature reached 1600-1800 ° C, the alloy material was completely melted and then kept for 10 minutes, then the crucible was turned over, the crucible was turned in a vacuum induction melting furnace, and the alloy liquid was poured into the mold shell obtained in the step (1).

(4) After cooling to room temperature, the vacuum is broken, and the mold case is broken to obtain an engine casing.

(5) heat treatment of the shell, surface blast cleaning and other processes;

(6) coating the shell, the coating containing B: 14.0 at%, C: 43.5 at%, V: 12.0 at%, Cr: 12.0 at%, Nb: 5.5 at a chemical composition of atomic percent. %, H: 13.0 at%.

Compared with the prior art, the invention adopts fine wood chips and crop straw fiber as the shell material, reduces the use amount of the refractory material, is beneficial to environmental protection, and adopts a reasonable ratio, and increases the ventilation under the premise of ensuring the strength of the shell. The attapulgite in the back coat is porous, which is good for exhausting, reduces the porosity of the shell, increases the yield, reduces the weight of the shell, and the raw material is easy to obtain. Reasonable, with greatly improved lubricity and heat resistance.

detailed description

The present invention will be further described below in conjunction with specific embodiments.

(1) preparing a mold shell, comprising: a. preparing a corresponding wax mold, a casting system, a riser according to the shape of the shell to be obtained, and bonding to a wax module; b. using a suitable ratio of zircon powder, silicon The sol, fine wood chips, n-octanol, and cobalt aluminate are mixed and stirred to obtain a surface coating, and after coating the wax module, the surface sand is coated, the surface sand component is alumina sand and fine wood chips, c. using a suitable ratio of attapulgite Mixing and stirring of soil powder, mullite powder, crop straw fiber and ethyl silicate hydrolyzate The back layer coating is prepared, the back sand is hung after the wax module is applied, the sand is repeatedly suspended after several times, and d. dewaxing and roasting to obtain a mold shell.

(5) heat treatment of the shell, surface blast cleaning and other processes;

In addition, specifically, the specific preparation process of the mold shell is:

(1) preparing a wax mold, preparing a corresponding wax mold, a pouring system, a riser according to the shape of the shell to be obtained, and bonding into a wax module;

(2) Preparation of the top layer coating, the surface coating is prepared by mixing zircon powder, silica sol, fine wood chips, n-octanol and cobalt aluminate. The zircon powder has a particle size of 300 mesh and the fine wood chip size is 240. The weight ratio of the above coating components is: zircon powder: silica sol: fine wood chips: n-octanol: cobalt aluminate = (1800-2000): (140-160): (100-200): (1 -2): (2-5);

(3) noodles sand: the wax module is immersed in the surface coating pool, and then taken out, and the surface is blown to make it evenly coated under rotating conditions, the blowing time is 30s-60s, preferably 40s; Subsequently, the surface sand is sprinkled under the rotating condition, and the surface sand is made of alumina sand and fine wood chips, and the weight ratio is alumina sand: fine wood chips = (10-15): 1, oxidation The aluminum sand has a particle size of 80-100 mesh, and the fine wood chip has a particle size of 160-200 mesh; the wax module coated with the facial sand is dried for 12-18 h, preferably 15 h;

(4) preparation of back layer coating, mixing attapulgite powder, mullite powder, crop straw fiber, ethyl silicate hydrolyzate to obtain a back layer coating, the attapulgite powder particle size is 240 mesh, Molai The stone particle size is 240 mesh, the straw fiber diameter of the crop is 2-3 mm, and the silica content of the ethyl silicate hydrolyzate is 20%. The weight ratio is: attapulgite powder: mullite powder: crop straw fiber: ethyl silicate hydrolyzate = (350-500): (1800-2000): (50-120): (2-4);

(5) Hanging the sand, immersing the dried wax module in step (3) into the back coating tank, and then taking it out, blowing it to the surface under rotation to make it evenly coated, the blowing time is 40s -80s, preferably 60s; then sprinkle back sand on the surface under rotating conditions, the back sand component is mullite coarse powder and crop straw fiber, and the weight ratio is mullite coarse powder: crop straw fiber =(10-15):1, the particle size of the mullite coarse powder is 40-60 mesh, the diameter of the crop straw fiber is 4-6 mm; the wax module coated with the back sand is dried for 12-18 h, preferably 15 h;

(6) repeating step (4) and step (5) 2-4 times until the thickness of the mold shell reaches 6-10 mm, preferably 8 mm, and is dried after sealing;

(7) The mold shell after step (6) is dried by steam dewaxing, the dewaxing pressure is 0.4 MPa to 0.8 MPa, the dewaxing time is 6 min to 8 min, and sent to a high temperature resistance furnace at 2-4 ° C. The heating rate of /min is raised to 300-450 ° C, and kept for 1.5 h, then heated to 750-800 ° C at a heating rate of 6-10 ° C / min, held for 1.5 h, and then heated at a heating rate of 2-4 ° C / min. To 1100-1250 ° C, heat preservation for 4h, with the furnace cooling, get environmentally friendly casting mold shell.

Claims

An environmentally friendly preparation method for an automobile engine casing, characterized in that the method comprises the following steps:

(1) preparing a mold shell, comprising: a. preparing a corresponding wax mold, a casting system, a riser according to the shape of the shell to be obtained, and bonding to a wax module; b. using a suitable ratio of zircon powder, silicon The sol, fine wood chips, n-octanol, and cobalt aluminate are mixed and stirred to obtain a surface coating, and after coating the wax module, the surface sand is coated, the surface sand component is alumina sand and fine wood chips, c. using a suitable ratio of attapulgite The back layer coating is prepared by mixing the soil powder, the mullite powder, the crop straw fiber and the ethyl silicate hydrolyzate, and the backing sand is applied after the wax module is applied, and the sand is repeatedly suspended after several times of sealing, d. dewaxing Calcination gives a mold shell.

(2) alloying ingredients, wherein the alloy contains, by atomic percentage, chemical composition: Al: 44.0 to 47.0 at%, V: 0.5 to 1.2 at%, Cr: 0.4 to 1.6 at%, and Nb: 2.0 to 7.0 at%. B: 0.2 to 0.8 at%, C: 1.0 to 1.3 at%, N: 0.3 to 0.5%, and the balance being Ti.

(3) smelting casting, adding the alloy component described in step (2) to the crucible of the induction melting furnace, evacuating to 10 -4 Pa, blowing in argon gas protection, loading power to 350-400 KW, heating 20- After 25 minutes, the temperature reached 1600-1800 ° C, the alloy material was completely melted and then kept for 10 minutes, then the crucible was turned over, the crucible was turned in a vacuum induction melting furnace, and the alloy liquid was poured into the mold shell obtained in the step (1).

(4) After cooling to room temperature, the vacuum is broken, and the mold case is broken to obtain an engine casing.

(5) heat treatment of the shell, surface blast cleaning and other processes;

(6) coating the shell, the coating containing B: 14.0 at%, C: 43.5 at%, V: 12.0 at%, Cr: 12.0 at%, Nb: 5.5 at a chemical composition of atomic percent. %, H: 13.0 at%.