阅读说明：本技术 一种耐热钢连接管壳体熔模铸造工艺 (Investment casting process for heat-resistant steel connecting pipe shell ) 是由 董晟全 高云鹏 王睿仪 何子博 梁艳峰 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种耐热钢连接管壳体熔模铸造工艺,包括以下步骤：S1、石蜡注射成型即得蜡型,电烙铁焊粘组装成蜡模；S2、以硅溶胶为粘接剂,掺入锆粉填料、防裂剂、润湿剂、消泡剂,制得浆料,将蜡模浸入浆料中进行挂浆,撒锆英石耐火材料,形成型壳,硬化后反复操作4次即得模壳；S3、将模壳置于脱蜡炉中,通蒸汽,至石蜡完全流出,置于造型机中填砂,焙烧即得高强度模壳；S4、将耐热钢连接管原材料放入熔炼炉,保温,即得金属液；S5、成分检测；S6、浇注；S7、热处理；S8、铸件检验,即完成耐热钢连接管壳体熔模铸造工艺。本发明提出的熔模铸造工艺,可生产高质量铸件,铸件合格率高,不易出现夹杂、冷隔的现象。(The invention discloses a heat-resistant steel connecting pipe shell investment casting process, which comprises the following steps: s1, paraffin is injected and molded to obtain a wax pattern, and the wax pattern is assembled by welding and bonding an electric soldering iron; s2, taking silica sol as a bonding agent, doping zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent to prepare slurry, immersing a wax mould into the slurry for slurry hanging, spreading a zircon refractory material to form a shell, and repeatedly operating for 4 times after hardening to obtain the mould shell; s3, placing the formwork in a dewaxing furnace, introducing steam until paraffin completely flows out, placing the formwork in a molding machine for sand filling, and roasting to obtain a high-strength formwork; s4, putting the raw material of the heat-resistant steel connecting pipe into a smelting furnace, and preserving heat to obtain molten metal; s5, detecting components; s6, pouring; s7, heat treatment; and S8, inspecting the casting, namely completing the investment casting process of the heat-resistant steel connecting pipe shell. The investment casting process provided by the invention can produce high-quality castings, the casting yield is high, and the phenomena of inclusion and cold shut are not easy to occur.)

1. The investment casting process of the heat-resistant steel connecting pipe shell is characterized by comprising the following steps of:

s1, manufacturing a wax mould: selecting semi-solid paraffin as a wax mould material, injecting the semi-solid paraffin into a wax mould by using a paraffin injection machine, then forming to obtain a wax pattern, carrying out piece-by-piece hot welding on the wax pattern by using a flat-head electric soldering iron in a manual mode, and welding, adhering and assembling the wax pattern into a wax mould;

s2, preparing a formwork: taking silica sol as a bonding agent, adding zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent, stirring for 8-10 hours to prepare slurry, immersing the wax mold prepared in the step S1 into the slurry for slurry coating, then scattering zircon refractory material to form a shell, coating a layer of hardened shell outside the wax mold after the shell is hardened, and repeatedly coating 4 layers of hardened shells outside the wax mold to obtain the mold shell;

s3, dewaxing and roasting: placing the formwork prepared in the step S2 in a dewaxing furnace, introducing steam with the temperature of 145-155 ℃ into the dewaxing furnace until paraffin in the formwork is melted and completely flows out, cleaning an inner cavity of the formwork with hot water at 50-60 ℃, simultaneously washing off a wax film adhered to the outer wall of the formwork, drying, placing the formwork in a molding machine for sand filling, then heating to 1000 ℃, roasting at 1000 ℃ for 25-35 min, and cooling to obtain a high-strength formwork;

s4, smelting: presetting the furnace temperature of a smelting furnace to be 1555-1565 ℃, starting heating, monitoring the furnace temperature once every 30min, putting the raw material of the heat-resistant steel connecting pipe into the smelting furnace after the furnace temperature of the smelting furnace reaches the preset temperature, and preserving the heat for 40-60 min to obtain molten metal;

s5, component detection: taking the molten metal by using a small ladle, pouring the molten metal into a metal mold for manufacturing a spectrum detection sample, cooling to obtain the sample, turning the cross section of the sample flat by using a lathe, detecting components by using a direct-reading spectrometer, performing the next step if the detection result meets the casting requirement of the heat-resistant steel connecting pipe, and adjusting the components of the molten metal in the step S4 according to the detection result if the detection result does not meet the casting requirement of the heat-resistant steel connecting pipe until the component detection result meets the casting requirement of the heat-resistant steel connecting pipe;

s6, pouring: keeping the temperature of the molten metal meeting the casting requirement of the heat-resistant steel connecting pipe according to the component detection result in the step S5 at 1555-1565 ℃ for 10min, standing, removing floating slag by using a slag removing spoon after impurities are completely precipitated, and then pouring the molten metal into the high-strength formwork prepared in the step S3, wherein the speed is in the principle of slow first and fast second, and the pouring time is 25S, so that a casting is obtained;

s7, heat treatment: placing the casting obtained in the step S6 into a cage, wherein the preset annealing furnace temperature is 1055-1065 ℃, starting to heat up an annealing furnace, placing the casting and the cage into the annealing furnace when the annealing furnace temperature is raised to the preset temperature, keeping the temperature at 1055-1065 ℃ for 40-60 min, taking out the material, and naturally cooling the material to room temperature by contacting with air to obtain the heat-resistant steel connecting pipe shell;

s8, casting inspection: and (5) flaw detection is carried out on the heat-resistant steel connecting pipe shell obtained in the step S7 by using X-ray, no defect is found, and the size of the casting meets the requirement, so that the investment casting process of the heat-resistant steel connecting pipe shell is completed.

2. The investment casting process of a heat resistant steel connecting pipe shell as claimed in claim 1, wherein the injection pressure is 15kg/cm in step S1²The temperature is 58-62 ℃.

3. The investment casting process for the heat-resistant steel connecting pipe shell according to claim 1, wherein in the step S2, the mass ratio of the silica sol, the zirconium powder filler, the anti-cracking agent, the wetting agent and the defoaming agent is 5: 16-20.01-0.02: 8-10: 8-12.

4. The investment casting process of a heat-resistant steel connecting pipe shell as claimed in claim 1 or 3, wherein the anti-cracking agent is one of N-phenyl-2-naphthylamine, N-diphenyl-p-phenylenediamine, N-p-phenylmethyl-2-naphthylamine, N-isopropyl-N-phenyl-p-phenylenediamine; the wetting agent is a compound of heptadecyl imidazoline, polyoxyethylene fatty alcohol ether and propylene glycol, and the mass ratio of the heptadecyl imidazoline to the polyoxyethylene fatty alcohol ether to the propylene glycol is 10: 6-8: 3-5; the defoaming agent is fatty acid glyceride or polydimethylsiloxane.

5. The investment casting process of a heat-resistant steel connecting pipe shell as claimed in claim 1, wherein in step S2, the hardening temperature is 20-25 ℃, the relative humidity is 55-65%, and the hardening time is 1-2 h.

6. The investment casting process of a heat-resistant steel connecting pipe shell as claimed in claim 1, wherein in step S5, the metal mold is preheated to 195-205 ℃ in a heat treatment furnace in advance.

7. The investment casting process for connecting tube shells of heat-resistant steel as claimed in claim 1, wherein in step S7, the temperature of the annealing furnace is monitored every 1h during the temperature rise of the annealing furnace, the temperature of the annealing furnace is monitored every 5min after the casting is placed in the annealing furnace, and the temperature of the annealing furnace is monitored every 10min during the cooling process.

Technical Field

The invention relates to the technical field of investment casting, in particular to an investment casting process for a heat-resistant steel connecting pipe shell.

Background

The heat-resistant steel has higher strength and chemical stability under high temperature conditions, and is widely applied to parts working under high temperature conditions such as power machinery, boilers, steam turbines and the like. In addition to high temperatures, high strength and resistance to high-temperature oxidation corrosion, these components also require, depending on the application, adequate toughness, good workability and weldability, and a certain structural stability. Therefore, the heat-resistant steel is one of the common materials for castings, but because some castings with structures have more complex structures, thin-wall connecting pipe castings have higher quality requirements, and if the traditional casting process is used, the produced connecting pipe castings are easy to have the phenomena of inclusion, cold shut and the like, and the quality cannot meet the requirements. Based on the defects in the prior art, the invention provides a fired mold casting process for a shell of a heat-resistant steel connecting pipe.

Disclosure of Invention

The invention aims to solve the problems that the phenomena of inclusion and cold shut are easy to occur in the production process of the existing connecting pipe casting, and the quality of the produced casting is not ideal, and provides a heat-resistant steel connecting pipe shell investment casting process.

A heat-resistant steel connecting pipe shell investment casting process comprises the following steps:

s1, manufacturing a wax mould: selecting semi-solid paraffin as a wax mould material, injecting the semi-solid paraffin into a wax mould by using a paraffin injection machine, then forming to obtain a wax pattern, carrying out piece-by-piece hot welding on the wax pattern by using a flat-head electric soldering iron in a manual mode, and welding, adhering and assembling the wax pattern into a wax mould;

s2, preparing a formwork: taking silica sol as a bonding agent, adding zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent, stirring for 8-10 hours to prepare slurry, immersing the wax mold prepared in the step S1 into the slurry for slurry coating, then scattering zircon refractory material to form a shell, coating a layer of hardened shell outside the wax mold after the shell is hardened, and repeatedly coating 4 layers of hardened shells outside the wax mold to obtain the mold shell;

s3, dewaxing and roasting: placing the formwork prepared in the step S2 in a dewaxing furnace, introducing steam with the temperature of 145-155 ℃ into the dewaxing furnace until paraffin in the formwork is melted and completely flows out, cleaning an inner cavity of the formwork with hot water at 50-60 ℃, simultaneously washing off a wax film adhered to the outer wall of the formwork, drying, placing the formwork in a molding machine for sand filling, then heating to 1000 ℃, roasting at 1000 ℃ for 25-35 min, and cooling to obtain a high-strength formwork;

s4, smelting: presetting the furnace temperature of a smelting furnace to be 1555-1565 ℃, starting heating, monitoring the furnace temperature once every 30min, putting the raw material of the heat-resistant steel connecting pipe into the smelting furnace after the furnace temperature of the smelting furnace reaches the preset temperature, and preserving the heat for 40-60 min to obtain molten metal;

s5, component detection: taking the molten metal by using a small ladle, pouring the molten metal into a metal mold for manufacturing a spectrum detection sample, cooling to obtain the sample, turning the cross section of the sample flat by using a lathe, detecting components by using a direct-reading spectrometer, performing the next step if the detection result meets the casting requirement of the heat-resistant steel connecting pipe, and adjusting the components of the molten metal in the step S4 according to the detection result if the detection result does not meet the casting requirement of the heat-resistant steel connecting pipe until the component detection result meets the casting requirement of the heat-resistant steel connecting pipe;

s6, pouring: keeping the temperature of the molten metal meeting the casting requirement of the heat-resistant steel connecting pipe according to the component detection result in the step S5 at 1555-1565 ℃ for 10min, standing, removing floating slag by using a slag removing spoon after impurities are completely precipitated, and then pouring the molten metal into the high-strength formwork prepared in the step S3, wherein the speed is in the principle of slow first and fast second, and the pouring time is 25S, so that a casting is obtained;

s7, heat treatment: placing the casting obtained in the step S6 into a cage, wherein the preset annealing furnace temperature is 1055-1065 ℃, starting to heat up an annealing furnace, placing the casting and the cage into the annealing furnace when the annealing furnace temperature is raised to the preset temperature, keeping the temperature at 1055-1065 ℃ for 40-60 min, taking out the material, and naturally cooling the material to room temperature by contacting with air to obtain the heat-resistant steel connecting pipe shell;

s8, casting inspection: and (5) flaw detection is carried out on the heat-resistant steel connecting pipe shell obtained in the step S7 by using X-ray, no defect is found, and the size of the casting meets the requirement, so that the investment casting process of the heat-resistant steel connecting pipe shell is completed.

Preferably, in step S1, the injection pressure is 15kg/cm²The temperature is 58-62 ℃.

Preferably, in step S2, the mass ratio of the silica sol to the zirconium powder filler to the anti-cracking agent to the wetting agent to the defoaming agent is 5: 16 to 20: 0.01 to 0.02: 8 to 10: 8 to 12, and more preferably, the mass ratio of the silica sol to the zirconium powder filler to the anti-cracking agent to the wetting agent to the defoaming agent is 5: 18: 0.015: 9: 10.

Preferably, the anti-cracking agent is one of N-phenyl-2-naphthylamine, N-diphenyl-p-phenylenediamine, N-p-phenylmethyl-2-naphthylamine and N-isopropyl-N-phenyl-p-phenylenediamine; the wetting agent is a compound of heptadecyl imidazoline, polyoxyethylene fatty alcohol ether and propylene glycol, and the mass ratio of the heptadecyl imidazoline to the polyoxyethylene fatty alcohol ether to the propylene glycol is 10: 6-8: 3-5; the defoaming agent is fatty acid glyceride or polydimethylsiloxane.

Preferably, in step S2, the curing temperature is 20 to 25 ℃, the relative humidity is 55 to 65%, and the curing time is 1 to 2 hours, and more preferably, the curing temperature is 23 ℃, the relative humidity is 60%, and the curing time is 1.5 hours.

Preferably, in step S5, the metal mold is preheated to 195 to 205 ℃ in advance in a heat treatment furnace.

Preferably, in step S7, the temperature of the annealing furnace is monitored every 1 hour during the temperature rise, the temperature of the casting is monitored every 5 minutes after the casting is placed in the annealing furnace, and the temperature of the annealing furnace is monitored every 10 minutes during the cooling process.

Compared with the prior art, the invention has the beneficial effects that:

1. the investment casting process provided by the invention has the advantages that the process is complete, the content is detailed, the whole process of investment casting is formed by wax pattern manufacturing, formwork preparation, dewaxing roasting, smelting, component detection, pouring, heat treatment and casting inspection, the thin-wall part heat-resistant steel connecting pipe shell with complex casting structure and high quality requirement can be manufactured by the investment casting process provided by the invention, and the problems that the phenomena of inclusion and cold shut are easy to occur in the production process of the connecting pipe shell and the quality of the produced casting is not ideal can be effectively solved;

2. the shell of the connecting pipe manufactured by the investment casting process has high precision, high quality, good quality and excellent heat resistance, and the phenomena of inclusion and cold shut are not easy to occur, so that the comprehensive performance of the shell of the connecting pipe is good;

3. when the formwork is prepared, the silica sol is used as the adhesive, and the zirconium powder filler, the anti-cracking agent, the wetting agent and the defoaming agent are added in a reasonable proportion, so that the integral precision and the product percent of pass of the casting are improved, compared with the casting produced by using the traditional formwork, the percent of pass is improved by 10.6-13.2%, the production cost of the casting can be effectively reduced, the economic benefit is good, and the formwork is worthy of popularization.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples.