CN111604475A

CN111604475A - Short-flow V-method modeling process

Info

Publication number: CN111604475A
Application number: CN202010506037.7A
Authority: CN
Inventors: 王振升; 孙瑞霞
Original assignee: Individual
Current assignee: Wang Zenghui
Priority date: 2020-06-05
Filing date: 2020-06-05
Publication date: 2020-09-01
Anticipated expiration: 2040-06-05
Also published as: CN111604475B

Abstract

The invention discloses a short-process V-method modeling process, which comprises the steps of firstly, manufacturing a model, and placing the model on a flat plate with a reserved air suction hole with an opening facing downwards; sleeving a high-pressure polyethylene film sleeve with the thickness of 0.02mm on the model; starting a vacuum pump to vacuumize the model so that the outer sleeve is tightly attached to the outer surface of the model; spraying high-temperature resistant paint; putting the opening of the manufactured model into a sand box filled with dry sand upwards, and sealing the surface of the sand box by using a sealing film; pumping out air in dry sand in the sand box by using a vacuum pump, reserving a riser, and automatically attaching the sealing film to the peripheral high-pressure polyethylene film; and taking out the mold to obtain a cavity meeting the requirements. The invention creatively adopts the high-pressure polyethylene film with the thickness of 0.02mm to replace the conventionally used EVA negative pressure casting film, thereby reducing the use cost of the film and saving the working procedures of sealing a dead head and the edge of a sand box; during pouring, the casting does not have air holes or has low porosity, the surface of the casting is not blackened, and the yield of the casting is improved.

Description

Short-flow V-method modeling process

Technical Field

The invention relates to a manufacturing process of a pouring model, in particular to a short-process V-method molding process.

Background

The V-method casting is a vacuum seal molding casting process, also called vacuum seal molding method, and is called V method (vacuum molding) for short. The casting method is characterized in that dry sand without a binder is used as a molding material, a special sand box is sealed by a plastic film, air in a mold is pumped out by a vacuum pump, the pressure difference between the inside and the outside of the mold is caused, the dry sand is compacted, and a required cavity is formed to carry out molten metal pouring to obtain a casting.

The V-process molding process originated in japan and has been rapidly developed worldwide. China is a technology introduced in the early 80 s of the 20 th century, and a part of clay sand molding process is rapidly replaced due to low investment, high efficiency and high casting surface quality; meanwhile, the method replaces the production of resin sand and sodium silicate sand in a certain range due to the superiority of the method in the aspect of economic benefit. With the intensive research on the method by scientific and technological workers, cast products such as steel castings, ball-milling iron castings, aluminum alloy products and the like are produced by utilizing V-shaped forming.

The V-method molding process adopted at present roughly comprises the following steps: firstly, prefabricating a model according to a design size, and putting the completed model on a negative pressure box with an opening facing downwards; the film supporting vehicle sends the casting film to a film baking device frame, the casting film is softened through heating, and the softened casting film falls onto a prefabricated model; starting a vacuum pump, and pumping air in the model through a negative pressure box to enable the casting film to be attached to the surface of the model; spraying high-temperature resistant paint outside the casting film; putting the opening of the model with the casting film and the high-temperature-resistant coating upwards into a sand box filled with dry sand, and sealing the surface of the sand box by adopting a film after the dry sand is vibrated and leveled; and (3) pumping out air in dry sand in the sand box by adopting a vacuum pump, reserving a riser, and sealing the riser and the edge of the sand box by using an adhesive tape to obtain a cavity meeting the requirements.

Because of the superiority of V-process casting, it was introduced in the refractory industry in about 2010 for producing the lining of glass furnaces, i.e. the fused cast refractory. The casting film used in the current casting process is an EVA negative pressure casting film (such as those produced by Wuhan Hengde technology Co., Ltd., Yongshengyoujia packaging material Co., Ltd., Beijing) with a thickness of about 0.1-0.3 mm (the thickness of more than or equal to 0.3mm is super-thick, and the thickness of less than or equal to 0.1mm is super-thin). In principle, the thinner the casting film used for casting the refractory material is, the better the casting film is, but the temperature of the ultrathin casting film for heating and softening is not easy to control, the coating property is not good when the casting film is thick, the casting film is easy to rot when the casting film is thin, the upper surface of the coating film after heating and softening keeps the original thickness, the casting film on the side surface can be downwards stretched to thin the thickness, the corner position at the bottom is easy to tear when the casting is vacuumized, and the problems that the quality of the casting is influenced by more air holes at the bottom of the casting, blackening of the surface and the like can occur even if the casting is not rott; the black smoke emitted during casting can not be collected and treated, and can only be directly discharged in the atmosphere, thereby causing environmental pollution. This has become a long-standing and pending technical problem for those skilled in the art.

Disclosure of Invention

The invention aims to provide a short-flow V-method modeling process aiming at the defects in the prior art, and well solves the technical problems of black smoke emission, more casting pores and blackened surface.

In order to achieve the purpose, the invention can adopt the following technical scheme:

the short-flow V-method modeling process comprises the following specific steps of:

firstly, manufacturing a model according to the size of a drawing, placing the model on a flat plate with an opening facing downwards, and reserving a through hole at the center of the flat plate and connecting the through hole with an exhaust pipe of a vacuum pump;

secondly, manufacturing an outer sleeve by adopting a high-pressure polyethylene film with the thickness of 0.02mm according to the outline of the model placed on the flat plate, sleeving the outer sleeve on the model, and extending the bottom edge to the position below the flat plate;

thirdly, starting a vacuum pump to vacuumize the model so that the outer sleeve is tightly attached to the outer surface of the model; spraying high-temperature resistant paint;

fourthly, putting the opening of the model manufactured in the third step upwards into a sand box filled with dry sand, and sealing the surface of the sand box by using a sealing film after the dry sand is vibrated and leveled;

fifthly, pumping out air in dry sand in the sand box by using a vacuum pump, reserving a riser, and automatically attaching a sealing film to a peripheral high-pressure polyethylene film;

and sixthly, taking out the mold to obtain a cavity meeting the requirements.

Film absorbing holes are formed in the side edges of the model manufactured in the first step; in order to avoid the inward collapse and deformation of the model during vacuum pumping, a supporting plate is arranged in the vacuum pump, and air holes are formed in the supporting plate; compared with a finished product casting, the manufactured model increases the reduced size by 1% and the processing amount by 2-3 mm.

The sealing film used in the fourth step is a PE film with the thickness of 0.004-0.006 mm, and a common polyethylene agricultural micro-mulching film can be adopted.

The invention has the advantages that the high-pressure polyethylene film (high-pressure polyethylene is also called low-density polyethylene, called LDPE for short) with the thickness of 0.02mm is creatively adopted to replace the conventionally used EVA negative pressure casting film, the use cost of the film is reduced (the EVA negative pressure casting film is 28000-38000 yuan/ton, and the high-pressure polyethylene film is only 20000-25000 yuan/ton), the flexibility and the sticking property of the thinner high-pressure polyethylene film are better, the high-pressure polyethylene film can be directly used without heating, and the equipment such as a film supporting vehicle, a film baking device, a negative pressure box and the like required by the traditional modeling are saved; the sealing film is an ultra-thin PE film (8-9 yuan/kg) with lower price, and is directly adsorbed with a high-pressure polyethylene film at a riser when in use, so that the process of sealing the riser and the edge of a sand box by using an adhesive tape is omitted; during pouring, the casting does not have air holes or has low porosity, and the high-pressure polyethylene film does not generate black smoke after combustion, so that the environment is protected, the surface of the casting is not blackened, and the yield of the casting is improved.

Drawings

Fig. 1, 2 and 3 are schematic views showing a cavity formed by the molding method of the present invention.

Detailed Description

The present invention is described in more detail below with reference to specific examples to facilitate understanding by those skilled in the art.

The high-pressure polyethylene film with the thickness of 0.02mm used in the invention and the PE film (polyethylene agricultural micro-mulching film) with the thickness of 0.005mm used for sealing are all commercial products.

The short-process V-method modeling process comprises the following specific steps of:

firstly, a model 1 is manufactured according to the product size (300 mm multiplied by 400 mm multiplied by 800 mm), the model 1 manufactured by adding a reduced scale and the processing amount is 300mm multiplied by 408 mm multiplied by 812mm, the interior of the model is of a grid ventilation structure, the periphery is provided with a film suction hole 2, and the product is directly manufactured into a combined model with a riser when in manufacturing due to simple structure, as shown in figure 1; placing the model 1 with an opening downward on a flat plate 3, wherein the shape of the flat plate 3 is the same as that of the opening edge of the model 1, a through hole is reserved in the center of the flat plate 3, a connecting pipe 4 is arranged at the through hole in a penetrating manner, and the connecting pipe 4 is connected with an exhaust pipe of an external vacuum pump;

secondly, manufacturing an outer sleeve 5 by adopting a high-pressure polyethylene film with the thickness of 0.02mm according to the outer contour of the model 1, sleeving the outer sleeve 5 on the model 1, and extending the bottom edge to be below the flat plate 3 and be longer than the flat plate 3, as shown in figure 1;

thirdly, starting a vacuum pump to vacuumize the interior of the model 1, so that the outer sleeve is tightly attached to the outer surface of the model 1, and ensuring that the high-pressure polyethylene film is flatly attached to the exterior of the model 1 due to the fact that the outer sleeve is consistent with the outer contour of the model 1; the film is not required to be heated during film pasting, the film cannot droop and stretch, the lower edge cannot be damaged, the film with the thickness of 0.02mm is thinner (compared with the conventional ultrathin EVA negative pressure casting film with the thickness of 0.15 mm), air can be discharged in time during casting, and air holes cannot be generated in the casting (the air holes generated in the original casting are caused by the fact that the film thickness around the cavity is inconsistent, and the air in the casting cannot overflow from the thicker film in time); then spraying high-temperature resistant paint according to a conventional method;

fourthly, putting the opening of the model manufactured in the third step upwards into a sand box 7 filled with dry sand 6 (according to a conventional method, filling dry sand with a certain thickness at the bottom of the sand box, and continuously adding the dry sand in the sand box at the periphery of the model after the model is put in), and vibrating and flattening the dry sand 6 and sealing the surface of the sand box by using a sealing film 8 as shown in figure 2; in order to reduce the production cost, the sealing film 8 can adopt a high-pressure polyethylene film made of the same material, and can also adopt a PE film with a lower price and a thickness of 0.004-0.006 mm, such as a common polyethylene agricultural micro-mulching film, so that the use requirement can be met, more importantly, the film has an ultrathin thickness and can be better attached to a casting head, and the process of adhering the film and the casting head by using an adhesive tape at the joint is omitted in the subsequent operation;

fifthly, pumping out air in dry sand in the sand box 7 by using a vacuum pump (a connecting pipe 9 is arranged at an opening of the sand box 7 and is used for being connected with an air pumping pipe of the vacuum pump), and reserving a riser (a sealing film 8 at the riser is cut off), wherein the sealing film is very thin, so that the sealing film is automatically attached to the peripheral high-pressure polyethylene film without being connected by using an adhesive tape;

sixthly, taking out the mold 1 to obtain a cavity 9 meeting the requirements, as shown in fig. 3; and (4) pouring according to a conventional method. Finally, cutting off a dead head to obtain the finished refractory brick with the quality meeting the requirements.

The high-pressure polyethylene film has no black smoke when burning during pouring, solves the defect of local blackening of the product, and simultaneously protects the environment.

In view of the characteristic of simple shape of the casting refractory brick, the casting refractory brick can be connected with a film manufacturer to directly produce film bags with different specifications and shapes, and is more convenient to use.

From the aspect of film cost, the film is purchased according to weight, and consumed according to area when in use, and only the high-pressure polyethylene film with the thickness of 0.02mm and the PE film with the thickness of 0.004-0.006 mm are adopted, so that the cost can be saved by 50 percent compared with the EVA negative pressure casting film with the thickness of 0.15mm which is conventionally used; in addition, auxiliary equipment such as a film supporting vehicle, a film baking device, a negative pressure box and the like is also omitted.

Claims

1. A short-process V-method modeling process is characterized in that: the method comprises the following specific steps:

and sixthly, taking out the mold to obtain a cavity meeting the requirements.

2. The short-flow V-process modeling process of claim 1, characterized in that: film absorbing holes are formed in the side edges of the model manufactured in the first step; a support plate is arranged in the air inlet pipe, and air holes are formed in the support plate; compared with a finished product casting, the manufactured model increases the reduced size by 1% and the processing amount by 2-3 mm.

3. The short-flow V-process modeling process of claim 1, characterized in that: the sealing film used in the fourth step is a PE film with the thickness of 0.004-0.006 mm.