RU2754730C1 - Method for producing a heat insulation insert - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method for producing a heat insulation insert of a chill mould includes vacuum moulding said insert from a fibrous material and a binder. A heat insulation insert is made, containing a flanged part with a recess for installation of the siphon of the casting bowl in the process of casting metal from the casting bowl into the chill mould and a circular heat insulation part, with an outer diameter of 45 to 790 mm, an inner diameter of 30 to 730 mm, and a height of 50 to 500 mm. A mould is assembled, containing a body and an inner part, placed over the inner surface whereof is a mesh frame. A hydromass is made, containing, wt.%: mullite silica fibre - 1.5 to 3.0, binder - 0.1 to 0.25, hardener - 0.25 to 0.7, water the rest. The hydromass is sent to a moulding tank whereto the mould is submerged, and vacuum moulding is performed, distributing the hydromass over the mesh frame, the mould is removed and dried at 80 to 140°C for 8 to 24 hours.

EFFECT: splashing of molten metal is prevented due to the secure fixation of the insert in the chill mould and the tightness of casting.

1 cl, 2 dwg, 5 ex

Description

The claimed invention relates to metallurgy, and in particular to methods of manufacturing isothermal insulating inserts for gating systems.

Known analogue insert in the description of the invention to the inventor's certificate No. 389878, IPC B22D 7/10, on application No. 1629809 / 22-2 dated 02.III.1971, publ. in bul. No. 30 of 11.VII.1973, made in the form of a mold wall or a profitable extension, where a step is made in the lower part of the insert, which forms a gap between the mold wall and the insert, while the height of the step is 75-150 mm, and its width is 8-15 mm.

Disadvantages: it does not sufficiently ensure reliable fixation of the product in the chill mold, therefore, it does not exclude the liner displacement from its place during casting, which entails additional ingot trimming, does not ensure the tightness of the casting and does not completely exclude the splashing of molten metal.

Known closest analogue insulation insert in the description of the invention to the copyright certificate No. 1472174, IPC B22D7 / 10, on application No. 4217602 from 25.03.87, publ. in bul. No. 14 dated 04/15/89. predominantly of refractory fibers on a thermoplastic bond, the shape of which corresponds to a cylindrical mold and forms a gap in the lower part with the mold wall, the lower part of the insert is made in the form of a truncated cone, the height of which is 0.3-0.5 of the insert height, the lower part of the insert is inclined relative to mold walls at an angle of 10-15 degrees.

Disadvantages: it does not sufficiently ensure reliable fixation of the product in the chill mold, therefore, it does not exclude the liner displacement from its place during casting, which entails additional ingot trimming, does not ensure the tightness of the casting and does not completely exclude the splashing of molten metal.

EFFECT: creation of a product from a heat-insulating material, the geometric parameters of which ensure reliable fixation of the product in the chill mold, which excludes additional ingot trimming, casting tightness and completely prevents splashing of molten metal.

The technical result in a method for manufacturing an insulating chill insert containing a flange part with a recess for installing a pouring bowl siphon during pouring metal from a pouring bowl into a chill mold and a round heat-insulating part, with an outer diameter of 45-790 mm, an inner diameter of 30-730 mm and a height of 50 -500 mm, including its molding from a fibrous material and a binder, is achieved due to the fact that vacuum molding is carried out, in front of which a mold is assembled containing a body and an inner part that repeats the contour and dimensions of an insulating insert, on the inner surface of which a mesh frame is placed with a hole diameter equal to at least 0.1 mm, and a hydromass is produced containing mullite-silica fiber, a binder, a hardener and water in the following ratio of ingredients, wt%:

mullite-silica fiber 1.5-3.0 binder 0.1-0.25 hardener 0.25-0.7 water rest

the produced hydromass is sent to the molding container, into which the mold is immersed and vacuum molding is carried out with uniform distribution of the hydromass over the mesh frame, the mold is removed from the molding container and drying is carried out at a temperature of 80-140 ° C for 8-24 hours.

The technical result is achieved due to an optimal and balanced set of ingredients and an optimal volumetric content of ingredients, due to the optimal value of time and temperature. A deviation in any direction from the indicated values of the ingredients leads to a decrease in the technical result.

The insert obtained by the claimed method consists of a flange part, which helps to securely hold the product in the chill mold and at the same time plays the role of a heat-insulating gasket between the pouring bowl and the chill mold, a recess for the pouring siphon on the bowl, which protects against splashing of molten metal, a round thermal insulation located in the chill mold and insulating profitable part of the ingot. The flange part helps to keep the product in the chill mold and at the same time acts as a heat-insulating gasket between the pouring cup and the chill mold, eliminates spatter, metal losses, maintaining the melt temperature, which will lead to the preservation of the physical and mechanical properties of the ingot. The flange part eliminates the displacement of the insulation insert during metal casting, maintaining the minimum size of the finished ingot trim.

It has an outer diameter of 45-790 mm, an inner diameter of 30-730 mm, a height of 50-500 mm, an application temperature of 1200 ° C -1600 ° C.

The flange part helps to hold the product in the chill mold, and also serves as a gasket between the chill mold and the casting bowl.

The shape of the recess corresponds to the geometric parameters of the pouring siphon of the casting bowl.

The shape of the sleeve corresponds to the shape and dimensions of the chill mold and insulates the profitable part of the ingot.

From the prior art, no technical solutions have been identified containing features that coincide with the distinctive features of the proposed method, therefore, the proposed method meets the criterion of inventive step.

The presence of essential features distinguishing from the prototype makes it possible to recognize the proposed technical solution as new.

The possibility of implementing the claimed invention in industry allows us to recognize it as corresponding to the criterion of industrial applicability.

The essence of the claimed device is illustrated by the following drawings:

in fig. 1- shows an insulating sleeve, side view;

in fig. 2 - the insulating sleeve is shown, top view.

The inventive method is carried out as follows.

A mold is assembled for the manufacture of an insert, which is a metal mold, consisting of a body, an inner part, repeating the contour and dimensions of the product - an insulation insert. The design of the mold is designed for the manufacture of insulation inserts by the "vacuum forming" method, using a vacuum pump pumping out an aqueous solution from the inner cavity of the mold.

For this, a frame is made from a metal mesh with a hole diameter of at least 0.1 mm, made in accordance with the geometric shape of the insulation insert. If the value is less than 0.1 mm, there will be insufficient evacuation, if the value is more than 1 mm, the mullite-silica fiber will clog into the perforation of the mold and make it difficult to remove the insert from the mold. The mesh is placed on the inner surface of the mold.

This frame allows you to uniformly form the inner and outer surfaces of the product, with precise geometric parameters of the insert, without resorting to the stage of revision on turning and grinding machines.

The design of the mold is designed for the manufacture of insulation inserts by the "vacuum forming" method. This, in turn, makes it possible to obtain samples with exact geometric parameters without resorting to the stage of revision on turning and grinding machines.

Then the hydromass is prepared. Mixers with driven mixers are used to prepare the hydromass. All containers are made of stainless steel to prevent corrosion and contamination of the mixture with foreign ingredients. Hydromass contains mullite-silica fiber, binder, hardener, water with the following ratio of ingredients, wt. %:

mullite-silica fiber 1.5-3.0 binder 0.1-0.25 hardener 0.25-0.7 water rest

Mullite-silica fiber is crushed in a special crusher. The length of the fiber allows you to vary the apparent density of the product from 250-600 kg / m ³ . For molding, tap water with a pH value of 6.0-8.0 is used. Water sampling is performed before starting work. In case of discrepancy between the indicators, add soda ash. To exclude the microbiological effect on the ingredients of the mixture, add 0.1-0.5% of an antiseptic (based on hydrogen peroxide) from the mass of water.

Then prepared water 1/3 of the volume is poured into clean mixers, after which the shredded fiber is partially loaded until complete mixing. Binder and hardener are added last. The ingredients are mixed until the binder is completely dissolved, then the remaining 2/3 of the water is added.

The finished hydromass from the mixers through the gravitational separator of non-fibrous inclusions enters the hydroacoustic grinder, then is pumped into the forming tank equipped with a transfer pump.

The mold is immersed in the finished hydromass, which is an aqueous suspension of the base material with the addition of a binding ingredient and a hardener.

The use of pumping out an aqueous solution from the inner cavity of the mold by a vacuum pump ensures uniform distribution of the hydromass over the metal perforation of the mold. This allows you to uniformly form the inner and outer surface of the product, with exact geometric parameters of the insert, without resorting to the stage of rework on turning and grinding machines.

The molded products are removed from the mold and stacked on a metal pallet.

Pallets with products are installed on a trolley, which is placed in a drying chamber.

Drying of products is carried out in a drying chamber at a temperature equal to 80-140 ° C and, depending on the geometric shape of the product, the drying time is 8-24 hours. At temperatures below 80 ° C, the physicochemical properties of the product are not achieved. Above 140 ° C, the binder is decomposed.

This temperature is necessary for the formation of physicochemical bonds between the fiber and the binder, for imparting the required mechanical hardness to the product.

The mass fraction of moisture of products after drying should not exceed 1.0%. Products with a moisture content of more than 1.0% are re-dried.

The inserts obtained by the claimed method consist of 1 flange part, which helps to hold the product in the chill mold and at the same time serves as a heat-insulating gasket between the pouring bowl and the chill mold, a recess 2 for a pouring siphon on the bowl, which prevents air from entering during pouring, a round heat-insulating part 3, located in the chill mold and insulating the profitable part of the ingot.

The flange part 1 helps to keep the product in the chill mold and at the same time acts as a heat-insulating gasket between the pouring bowl and the chill mold, the flange part 1 with a recess 2 for the pouring siphon on the bowl allows you to keep the product in the chill mold and at the same time acts as a heat-insulating gasket between the pouring bowl and the chill mold eliminates splashing, loss of metal, reduces contact with the external environment, ensuring the preservation of the temperatures of the molten metal, which will lead to the preservation of the physical and mechanical properties of the ingot. The shape of the recess 2 corresponds to the geometric parameters of the pouring siphon on the bowl.

Example 1

A mold is assembled for the manufacture of an insert, which is a metal mold, consisting of a body, an inner part, repeating the contour and dimensions of the product - an insulation insert. The design of the mold is designed for the manufacture of insulation inserts by the "vacuum forming" method, using a vacuum pump pumping out an aqueous solution from the inner cavity of the mold.

For this, a frame is made from a metal mesh with a hole diameter of at least 0.1 mm, made in accordance with the geometric shape of the insulation insert. If the value is less than 0.1 mm, there will be insufficient evacuation, if the value is more than 1 mm, the mullite-silica fiber will clog into the perforation of the mold and make it difficult to remove the insert from the mold. The mesh is placed on the inner surface of the mold.

This frame allows you to uniformly form the inner and outer surfaces of the product, with precise geometric parameters of the insert, without resorting to the stage of revision on turning and grinding machines.

The design of the mold is designed for the manufacture of insulation inserts by the "vacuum forming" method. This, in turn, makes it possible to obtain samples with exact geometric parameters without resorting to the stage of revision on turning and grinding machines.

Then the hydromass is prepared. Mixers with driven mixers are used to prepare the hydromass. All containers are made of stainless steel to prevent corrosion and contamination of the mixture with foreign ingredients. Hydromass contains mullite-silica fiber, binder, hardener, water with the following ratio of ingredients, wt. %:

mullite-silica fiber 1.5 binder 0.1 hardener 0.25 water rest

Mullite-silica fiber is crushed in a special crusher. The length of the fiber allows you to vary the apparent density of the product from 250-600 kg / m ³ . For molding, tap water with a pH value of 6.0-8.0 is used. Water sampling is performed before starting work. In case of discrepancy between the indicators, add soda ash. To exclude the microbiological effect on the ingredients of the mixture, add 0.1-0.5% of an antiseptic (based on hydrogen peroxide) from the mass of water. Then prepared water 1/3 of the volume is poured into clean mixers, after which the shredded fiber is partially loaded, until complete mixing. Binder and hardener are added last. The ingredients are mixed until the binder is completely dissolved, then the remaining 2/3 of the water is added. The finished hydromass from the mixers through the gravitational separator of non-fibrous inclusions enters the hydroacoustic grinder, then is pumped into the forming tank equipped with a transfer pump. The mold is immersed in the finished hydromass, which is an aqueous suspension of the base material with the addition of a binding ingredient and a hardener.

The use of pumping out an aqueous solution from the inner cavity of the mold by a vacuum pump ensures uniform distribution of the hydromass over the metal perforation of the mold. This allows you to uniformly form the inner and outer surfaces of the product, with exact geometric parameters of the insert, without resorting to the stage of reworking on turning and grinding machines.

The molded products are removed from the mold and stacked on a metal pallet. Pallets with products are installed on a trolley, which is placed in a drying chamber. Drying of products is carried out in a drying chamber at a temperature equal to 80-140 ° C and, depending on the geometric shape of the product, the drying time is 8-24 hours. At temperatures below 80 ° C, the physicochemical properties of the product are not achieved. Above 140 ° C, the binder is decomposed. This temperature is necessary for the formation of physicochemical bonds between the fiber and the binder, for imparting the required mechanical hardness to the product.

The mass fraction of moisture of products after drying should not exceed 1.0%. Products with a moisture content of more than 1.0% are re-dried.

The inserts obtained by the claimed method consist of 1 flange part, which helps to hold the product in the chill mold and at the same time serves as a heat-insulating gasket between the pouring bowl and the chill mold, a recess 2 for a pouring siphon on the bowl, which prevents air from entering during pouring, a round heat-insulating part 3, located in the chill mold and insulating the profitable part of the ingot.

The flange part 1 helps to keep the product in the chill mold and at the same time acts as a heat-insulating gasket between the pouring bowl and the chill mold, the flange part 1 with a recess 2 for the pouring siphon on the bowl allows you to keep the product in the chill mold and at the same time acts as a heat-insulating gasket between the pouring bowl and the chill mold eliminates splashing, loss of metal, reduces contact with the external environment, ensuring the preservation of the temperatures of the molten metal, which will lead to the preservation of the physical and mechanical properties of the ingot. The shape of the recess 2 corresponds to the geometric parameters of the pouring siphon on the bowl.

Example 2.

The inventive method is carried out according to example 1 with the following ratio of ingredients, wt%:

mullite-silica fiber 3.0 binder 0.25 hardener 0.7 water rest

Example 3.

The inventive method is carried out according to example 1 with the following ratio of ingredients, wt%:

mullite-silica fiber 1.5 binder 0.25 hardener 0 water rest

Example 4.

The inventive method is carried out according to example 1 with the following ratio of ingredients, wt%:

mullite-silica fiber 4.5 binder 0,4 hardener 1.0 water rest

Example 5.

The inventive method is carried out according to example 1 with the following ratio of ingredients, wt. %:

mullite-silica fiber 1.0 binder 0.07 hardener 0.5 water rest

The optimal ratios of ingredients, depending on the geometric parameters, are described in examples 1, 2. With an increase in the claimed ratios of ingredients, example 4, it becomes difficult to uniformly set the hydromass on the perforation of the mold and the preparation time of the hydromass doubles, and with a decrease in the claimed ratios of ingredients, example 5, the time of the hydromass collection on the mold increases, which reduces the productivity of the insulation inserts per shift. With the exclusion of the hardener from the composition, example 4, the content of the binding ingredient increases, which entails an increase in the cost of insulation inserts.

To achieve the technical result, examples 1-2 are the best. Drying of products is carried out in a drying chamber at a temperature equal to 80-140 ° C and, depending on the geometric shape of the product, the drying time is 8-24 hours.

The use of the proposed method will make it possible to create a product from a heat-insulating material, the geometric parameters of which ensure reliable fixation of the product in the chill mold, which excludes additional ingot trimming, casting tightness and completely prevents splashing of molten metal.

In addition, the inserts produced by the applicant have high manufacturability and allow to increase the yield of good casting on large castings up to 25%, to reduce the metal consumption of the casting to 40%, to reduce the technological allowances for machining profitable places of castings from 15-20 mm to 4-5 mm, to reduce several times the costs of metalworking tools, completely eliminate the laboriousness of the process of firing the profits, provide the ability to install profits on any surfaces without disrupting the configuration of the casting, improve the quality of casting to reduce shrinkage defects (shells, looseness, cracks), as well as non-metallic and gas inclusions and the possibility of serial production of insulation inserts according to the customer's individual technical specifications (shape and geometric parameters of insulation inserts depending on the size of chill molds and casting bowls to improve the quality of molten metal castings).

Claims (3)

A method of manufacturing an insulating chill insert containing a flange part with a recess for installing a pouring bowl siphon during metal pouring from a pouring bowl into a chill mold and a round heat-insulating part, with an outer diameter of 45-790 mm, an inner diameter of 30-730 mm and a height of 50-500 mm , including its molding from a fibrous material and a binder, characterized in that vacuum molding is carried out, before which a mold is assembled containing a body and an inner part repeating the contour and dimensions of an insulating insert, on the inner surface of which a mesh frame with a hole diameter equal to at least 0.1 mm, and a hydromass is made containing mullite-silica fiber, a binder, a hardener and water in the following ratio of ingredients, wt%: mullite-silica fiber 1.5-3.0 binder 0.1-0.25 hardener 0.25-0.7 water rest the produced hydromass is directed into the molding container, into which the mold is immersed and vacuum molding is carried out with uniform distribution of the hydromass over the mesh frame, the mold is removed from the molding container and drying is carried out at a temperature of 80-140 ° C for 8-24 hours.

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