CN112427603A

CN112427603A - Large-size pipe fitting and lost foam casting method thereof

Info

Publication number: CN112427603A
Application number: CN202011104313.3A
Authority: CN
Inventors: 龙枚青; 莫正田; 汤迪文; 徐浩; 贾伟峰; 吴超; 刘湘资
Original assignee: Taojiang Xinxing Fittings Co ltd
Current assignee: Taojiang Xinxing Fittings Co ltd
Priority date: 2020-10-15
Filing date: 2020-10-15
Publication date: 2021-03-02
Anticipated expiration: 2040-10-15
Also published as: CN112427603B

Abstract

The invention discloses a large-size pipe fitting and a lost foam casting method thereof, wherein the large-size pipe fitting lost foam casting method comprises the processes of foam molding model manufacturing, model coating, vibration molding, pouring replacement and cooling cleaning, after the model coating is finished, a supporting ring is sleeved outside a bell and spigot flange of the model in a matching manner, the model sleeved with the supporting ring is shaped in a sand box, and the supporting ring is dip-coated with an anti-sticking coating with the thickness of 1-1.2mm in advance before being assembled with the model. The pipe fitting prepared by the scheme can ensure the surface quality and improve the roundness of the pipe fitting.

Description

Large-size pipe fitting and lost foam casting method thereof

Technical Field

The invention belongs to the technical field of pipe casting, and particularly relates to a large-size pipe and a lost foam casting method thereof.

Background

Lost foam casting (also called solid casting) is a novel casting method which comprises the steps of bonding foam models with similar sizes and shapes to form a model cluster, brushing refractory paint, drying, burying in dry quartz sand for vibration molding, pouring under negative pressure to gasify the model, enabling liquid metal to occupy the position of the model, solidifying and cooling to form the casting. When the existing large-size pipe fitting (the diameter is generally more than or equal to 300mm) is produced by a vacuum lost foam, because the model is made of EPS, the model coated with the coating is baked and then embedded into sand, and during the molding process, the bell and spigot flange of the model is easy to deform, so that the roundness of the finally produced pipe fitting does not meet the requirement.

In conclusion, the existing large-size pipe fitting lost foam casting process needs to be improved.

Disclosure of Invention

The invention mainly aims to provide a large-size pipe fitting and a lost foam casting method thereof, aiming at improving the roundness of the pipe fitting while ensuring the surface quality of the pipe fitting.

In order to solve the technical problem, the following technical scheme is adopted in the application:

a large-size pipe fitting lost foam casting method comprises the processes of foam molding model manufacturing, model coating, vibration molding, pouring replacement and cooling cleaning, wherein after the model coating is finished, a support ring is sleeved outside a bell and spigot flange of a model in a matching mode, and the model sleeved with the support ring is shaped in a sand box; wherein;

before the support substrate is assembled with the model, an anti-sticking coating with the thickness of 1-1.2mm is dip-coated in advance, and the anti-sticking coating comprises the following substances in percentage by weight: 90-100 parts of water glass, 110-125 parts of high-alumina powder, 0.8-1.2 parts of wetting agent JFC and 0.1-0.2 part of alkynediol.

Specifically, the preparation process of the anti-sticking coating comprises the following steps: weighing water glass, high-alumina powder, a wetting agent and alkynediol according to the formula, then adding the high-alumina powder, the wetting agent and the alkynediol into the water glass under the stirring state of a stirrer, and stirring for 6-10 hours at a stirring speed of 22-50 r/min.

Specifically, the dip-coating curing time is 10-15 minutes, and the curing temperature is 40-60 ℃.

Specifically, EPS beads with the pre-foaming density of 18-20 g/L are used for manufacturing a module, and the module is assembled into a foam plastic model by glue.

Specifically, the mold is adhered to a pouring system, the mold is molded in a sand box, the mold is vacuumized, the high-temperature molten iron with the temperature of 1480-1500 is poured, and the box is turned over and the casting is lifted out after 4 to 16 hours.

Specifically, the high-alumina powder is GAL-85 high-alumina powder, and the mesh number is 280-340.

Specifically, the support substrate is made of a3 steel.

A large-size pipe fitting is prepared by adopting the lost foam casting method for the large-size pipe fitting.

Specifically, the diameter of the large-size pipe fitting is more than or equal to 300 mm.

The principle and the advantages are as follows:

the support ring is sleeved on the weak part of the bell and spigot flange of the pipe fitting foam molding model, and the support ring is positioned and fixedly placed in the sand box for molding through a tool, so that the model can be prevented from deforming, and the roundness of the prepared pipe fitting is ensured; the anti-sticking coating with special components is coated on the supporting ring, the supporting ring is effectively isolated from molten iron by the anti-sticking coating in the pouring process, the supporting ring is prevented from being wholly or partially melted in the molten iron, the problem of adhesion of the pipe and the supporting ring is solved, and the surface quality of the pipe is improved;

in addition, because the coating has good thermal insulation and isolation protection effects, the support ring is heated to expand and is solidified on the surface layer of the casting mold metal liquid in a delayed manner, the phenomenon that the casting surface is sunken due to the fact that the support ring is locally deformed and inlaid in molten iron can not occur, and the casting quality is high.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic view of the installation of a foam model and a support substrate according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1, the large-size pipe lost foam casting method comprises the processes of foam molding model manufacturing, model coating, vibration molding, pouring replacement and cooling cleaning, after the model 1 is coated, a supporting ring 2 is sleeved outside a bell and spigot flange of the model 1 in a matching manner, and the model sleeved with the supporting ring 2 is shaped in a sand box; wherein; before being assembled with a model, the support ring 2 is dip-coated with a layer of anti-sticking coating in advance, wherein the anti-sticking coating comprises the following substances in percentage by weight: 100 parts of water glass, 110 parts of high-alumina powder, 0.9 part of wetting agent JFC and 0.1 part of acetylene glycol, and the viscosity of the coating is 20 s. The thickness of the coating layer of the primary dip coating is 1mm, the dip coating curing time is 10 minutes, the curing temperature is 40 ℃, and the coating layer is uniform and has strength.

The casting that adopts this embodiment to obtain does not take place oval problem, and the circularity satisfies the design requirement, and support circle does not have adhesion and can peel off from the casting easily moreover, and support circle position is level and smooth on the casting does not have long-pending tumour, and surface quality is high, and the antiseized coating of this component can satisfy the requirement of once dip-coating hanging in addition, has convenient operation, and is practical reliable, advantage that production efficiency is high.

In addition, the inventor finds that the coating is added with high-alumina powder, so that the coating has good heat insulation and isolation effects, the support ring expands due to heat and solidifies on the surface layer of the casting metal liquid, the phenomenon that the surface of a casting is sunken due to the fact that the support ring is locally deformed and inserted into molten iron does not occur, and the casting quality is high.

In practical application, a water glass supplier is Hunan Pontan chemical industry Co., Ltd, the modulus of the water glass is 3.0-3.4, and the density is 1.27-1.29(g/m 3); the supplier of the high-alumina powder is Zhengzhou Xiangyu casting material company, the high-alumina powder is GAL-85 high-alumina powder, the mesh number is 280, and the supplier of the wetting agent JFC and the alkynediol is Wuhanji industry promotion chemical company. The material of the support ring is A3 steel, but of course, other metal materials can be used.

Specifically, EPS beads with the pre-foaming density of 18-20 g/L are used for manufacturing a module, the module is assembled into a foam mold by glue, the mold is adhered to a casting system and molded in a sand box, the mold is vacuumized, the vacuum degree in the sand box is ensured to be-0.04-0.06 MPa, high-temperature molten iron with the temperature of 1480-1500 is used for casting, and the box is turned over and the casting is lifted out after 4-16 hours.

Example 2

Different from the embodiment 1, the weight percentage of each substance in the anti-sticking coating in the embodiment is as follows: 90 parts of water glass, 125 parts of high-alumina powder, 1.1 parts of wetting agent JFC and 0.2 part of alkynediol, and the viscosity of the coating is 22 s. The thickness of the coating layer of the primary dip coating is 1.2mm, the dip coating curing time is 15 minutes, the curing temperature is 60 ℃, and the coating layer is uniform and has strength.

The casting obtained by the embodiment also has no ellipse problem, the roundness meets the design requirement, the support ring is not adhered and can be easily peeled off from the casting, the position of the support ring on the casting is smooth and has no accumulated tumors, and the surface quality is high.

The application also provides a large-size pipe fitting prepared by the method in the embodiment 1 and the embodiment 2, wherein the diameter of the large-size pipe fitting is more than or equal to 300 mm.

Comparative example 1

Different from the embodiment 1, in the embodiment, the support ring is not arranged outside the socket flange of the foam plastic model, so that the obtained casting is seriously deformed, and the roundness cannot meet the design requirement.

Comparative example 2

Different from the embodiment 1, in the embodiment, the support ring is not coated with the anti-sticking coating, and although the casting obtained is not seriously changed, the support ring is inserted into molten metal surface layer molten iron due to local deformation caused by thermal expansion before the casting molten metal surface layer is not solidified, so that the casting surface is sunken.

Comparative example 3

Different from the embodiment 1, the weight percentage of each substance in the anti-sticking coating in the embodiment is as follows: 100 parts of water glass, 80 parts of high-alumina powder, 0.9 part of wetting agent JFC and 0.1 part of alkynediol, the content of the high-alumina powder in the anti-sticking coating is reduced, the viscosity of the coating is 16s, the coating performance is reduced, the thickness of the coating in one-time dip coating is 0.6mm, the coating is uniform and has strength, and finally, the casting and the support ring are adhered due to insufficient thickness of the anti-sticking coating, so that the aim of preventing the support ring from being adhered can be fulfilled only by multiple dip coating, and the preparation cost is increased.

Comparative example 4

Different from the embodiment 1, the weight percentage of each substance in the anti-sticking coating in the embodiment is as follows: 100 parts of water glass, 110 parts of high-alumina powder, 0.5 part of wetting agent JFC and 0.1 part of alkynediol, wherein the viscosity of the coating is 21 s; the coating thickness of the primary dip coating is 1.1mm, the support ring local coating is not adhered to the support ring due to the reduction of the JFC wetting agent, the coating is not uniform, the support ring local coating is thin, and the casting and the support ring are locally adhered and difficult to peel, so that the production quality requirement cannot be met.

Comparative example 5

Different from the embodiment 1, the weight percentage of each substance in the anti-sticking coating in the embodiment is as follows: 100 parts of water glass, 110 parts of high-alumina powder, 0.5 part of wetting agent JFC and 0.05 part of alkynediol, wherein the viscosity of the coating is 20 s; the thickness of the coating layer of one-time dip coating is 1.2mm, the coating layer is uniform and has strength, and the casting and the lining ring are not adhered and can be easily peeled. However, because the alkynediol is reduced, the coating on the support substrate is provided with a plurality of cavities formed after the bubbles penetrate, and a plurality of iron beans are generated on the corresponding casting, so that the surface quality of the casting is influenced, and the polishing workload is increased, and the production quality requirement cannot be met.

Comparative example 6

Different from the embodiment 1, the weight percentage of each substance in the anti-sticking coating in the embodiment is as follows: 100 parts of water glass, 150 parts of high-alumina powder, 0.9 part of wetting agent JFC and 0.1 part of alkynediol, because the content of the high-alumina powder in the anti-sticking coating is reduced, the viscosity of the coating is 28s, the thickness of the coating in one-time dip coating is 2.2mm, the coating is uniform and has strength, the final casting is not adhered to a lining ring and can be easily peeled off, the position of the lining ring on the casting is smooth and has no accumulated tumor, but because the thickness of the coating on the supporting lining ring is increased, the coating cost is increased, the inner diameter size is also reduced, the diameter of a pipe fitting is also reduced, and the processing workload is increased.

The above examples are merely illustrative for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Nor is it intended to be exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.

Claims

1. The lost foam casting method for the large-size pipe fitting comprises the processes of foam plastic model manufacturing, model coating, vibration modeling, pouring replacement and cooling cleaning, and is characterized in that: after the model coating is finished, a supporting ring is sleeved outside a bell and spigot flange of the model in a matching mode, and the model sleeved with the supporting ring is molded in a sand box; wherein;

2. The lost foam casting method for the large-size pipe fitting according to claim 1, wherein the anti-sticking coating is prepared by the following steps: weighing water glass, high-alumina powder, a wetting agent and alkynediol according to the formula, then adding the high-alumina powder, the wetting agent and the alkynediol into the water glass under the stirring state of a stirrer, and stirring for 6-10 hours at a stirring speed of 22-50 r/min.

3. The lost foam casting method of large-size pipes according to claim 1, wherein: the curing time of dip coating is 10-15 minutes, and the curing temperature is 40-60 ℃.

4. The lost foam casting method of large-size pipes according to claim 1, wherein: the EPS beads with the pre-foaming density of 18-20 g/l are used for manufacturing a module, and the module is assembled into a foam plastic model by glue.

5. The lost foam casting method of large-size pipes according to claim 1, wherein: adhering the mold to a pouring system, molding in a sand box, vacuumizing, pouring high-temperature molten iron at the temperature of 1480 and 1500 ℃, turning over the box after 4-16 hours and hanging out the casting.

6. The lost foam casting method of large-size pipes according to claim 1, wherein: the high-alumina powder is GAL-85 high-alumina powder, and the mesh number is 280-340.

7. The lost foam casting method of large-size pipes according to claim 1, wherein: the material of support circle is A3 steel.

8. A large-size pipe fitting is characterized in that: the large-size pipe fitting is prepared by the lost foam casting method of any one of claims 1 to 7.

9. The large size pipe of claim 8, wherein: the diameter of the large-size pipe fitting is more than or equal to 300 mm.