RU2015799C1 - Method for painting of working surfaces of microcellular mold with system of gas cooling and casting ejection - Google Patents

Abstract

FIELD: foundry. SUBSTANCE: method includes isolation of mold working surfaces from atmosphere, evacuation of air from mold working surfaces to its nonworking side. Sucking of heat-resistant paint into isolated part of mold to obtain the desired thickness of coating. Paint is sucked into working hollow of mold assembled for filling through gate by communicating it with system of foamed paint. In this case, specific volume of heat-resistant filler in unit of volume of foamed paint should be less than ratio of total volume of (formed) coating to total volume of hollow of painted mold. Evacuation of air and suction of paint are carried out concurrently, and rarefaction in mold is maintained up to completion of its pouring. EFFECT: reduced cycle, increased uniformity and simplified painting process. 1 dwg

Description

 The invention relates to foundry, and in particular to a method for coloring permanent microporous molds.

 A known method of painting foundry molds.

 The disadvantage of this method is that it is acceptable only for painting individual half-molds, which are located when painting the work surfaces down. When painting assembled (closed, spray-filled molds as a result of gravitational forces and aerosol paint separation), more heat-resistant dye will be deposited on the working surfaces of the lower half-mold than on the upper half-mold. This will cause uneven coloring of them, since a special (sealing) device is required (cap), and also increases the production cycle.

 The purpose of the invention is to shorten the cycle, increase uniformity and simplify the process of coloring the form.

 The goal is achieved by the fact that with the method of painting the working surfaces of cast microporous molds with a gas cooling system and ejecting castings, which includes isolation of the working surfaces of the mold from the atmosphere, air suction from the working surfaces of the molds to its non-working side, suction into the insulated cavity of the mold of heat-resistant paint until the desired the thickness of the coating, characterized in that the paint is sucked into the mold assembled for pouring through the sprue channel, by communicating it with the foam paint system, while the volume of filler in a unit volume of foamy paint should be less than the ratio of the total coating volume to the total volume of the cavity of the mold to be painted, air suction and suction are carried out simultaneously with an infinitely small vacuum in the mold working cavity, the vacuum in the mold cavity is maintained until it is filled.

 The drawing shows a permanent microporous mold with a gas cooling system and pushing the castings in assembled form.

 The mold consists of the lower 5 and upper 8 half-molds, sealed on the outside and through the connector outside the working cavity by the gasket 17. The upper and lower half-molds have a gas cooling system for castings 3 and 12 with valves 4 and 11.

 In both half-molds there is a vacuum system 1 and 9 with valves 2 and 10, as well as pressure control valves 6 and 7.

The working surface of the form is painted as follows. Valves 14 and 15, informed runner passage 16 with coloring system 13. Then, the valves 2 and 10 and the vacuum system sucking portion of the foamed ink into the working cavity 18 of the assembled mold preheated to a temperature of 100 ° ^C under vacuum in an infinitesimal shape to foam ink is not sprayed . The suction of foamy paint is continued until the required coating thickness is formed on all working surfaces of the mold within 0.1-0.2 mm. Then close valve 14, valve 15 open the gate channel 16, under the influence of rarefaction, the mold cavity is ventilated (purged) with air to release it from the foam and the mold is ready for filling. After filling with valves 2 and 10, close the vacuum system. As it enters the mold cavity, the foam along the path of movement is filtered through the working surfaces, air and vapors are removed through the pores of the mold, and powder dye particles are deposited on its working surfaces and are held until the mold is finally poured under vacuum in the mold pores. In this case, the dye particles are larger than the pores of the form, deposited on the working surface, they overlap the pores, reducing the gas permeability of the surfaces, preventing the gas and sediment from precipitating the dye on already painted surfaces. This ensures that the foam moves deeper into the mold and fills it, eliminating the possibility of forming too thick or uneven coating layers, since the gas permeability of the surfaces depends on the thickness of the coating. The optimal shape porosity is assumed to be 10 μm.

 In this case, the specific volume of the filler per unit volume of foamed paint should be less than the ratio of the total volume of the coating to the total volume of the cavity of the mold to be painted. This is ensured by the composition of the paint, in which the DS-RAS surfactant (surfactant) can be used as a foaming agent, graphite powder, soot, talc, molybdenum disulfate and other heat-resistant fillers as a dye (filler). Due to the high stability of the state and composition of the foam due to the surfactant, it is less susceptible to separation of the heat-resistant component (filler) under the influence of gravitational forces and separation compared to aerosols.

 As a result, uniform coloring of the mold is ensured regardless of the location of the half-molds and the configuration of its working cavity.

 Maintaining a vacuum in the mold vapor until the filling is completed helps to keep the powder dye on the working surfaces of the mold, which allows the use of paint without a fastener. This coloring is characterized by increased lubricity, does not clog the pores of the mold, high-temperature drying of the coating is not required, it allows to reduce the force of gas ejection of the casting, to avoid warping of the castings during gas ejection.

 When filling the mold with foam under the action of rarefaction, the mold temperature should be lower than the boiling point of the liquid component of the paint (water) to prevent spraying of the foam.

 To obtain castings from cast iron, steel, and copper alloys in microporous chills with a gas cooling system and pushing out castings, a paint containing up to 15% silver graphite powder with an average particle size of 11.1 μm, up to 1% DS-RAS foam blower can be used , the rest is water. Foamed paint with a foaming coefficient of more than 15 is sucked into a heated mold.

 When the dye content is up to 15% by volume of liquid paint and its foaming coefficient is more than 15, the specific volume of the filler per unit volume of foamed paint will be less than the ratio of the total coating volume to the total volume of the cavity of the paintable form (with a coating thickness of 0.1-0.2 mm and thickness walls of the casting more than 3 mm), which will make it possible to obtain a coating of small thickness.

Mold Mode
Form temperature up to 100 ^о С
Form vacuum at
suction foam and
ventilation forms infinitesimal
Painting and ventilation time
forms 5-10 s
Paint layer thickness 0.1-0.2 mm
Pore Vacuum Depth
forms up to 0.05 MPa
The mold is painted before each casting to increase its durability, reduce warpage of castings during ejection, and reduce the force of gas ejection.

 The method is most suitable for producing shaped castings of small sizes from cast iron and copper alloys in all sectors of mass and large-scale engineering.

Claims (1)

 METHOD FOR PAINTING WORKING SURFACES OF CASTING MICROPOROUS FORMS WITH GAS COOLING SYSTEM AND PUSHING OF CASTINGS, including isolation of the working surfaces of the molds from the atmosphere, creating a vacuum in the form, sucking air from the working surfaces of the mold to its non-working side, forming the floor to form into the mold coatings, characterized in that, in order to shorten the cycle, increase uniformity and simplify the process of painting the mold, the paint is sucked into the cavity of the cutting its sprue channel by communicating it with the paint foaming system, while the specific volume of the heat-resistant paint filler per unit volume of foamy paint should be less than the ratio of the total volume of the formed coating to the total volume of the cavity of the painted form, the air is sucked and the paint is sucked in simultaneously form support until the end of its filling.

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