CN115464100A - Method for graded filtering of pouring slag - Google Patents

Abstract

The invention provides a method for graded filtering of pouring slag, which belongs to the field of lost foam casting and pouring, and comprises the following steps of firstly, scattering a deslagging agent into molten iron for manual deslagging; step two, adopting a pouring cup with an asymmetric inner wall in a corrugated shape to feed molten iron; thirdly, mounting a primary filter screen on the cross section of the casting system direct casting pit for filtering; step four, filtering by using a secondary filter screen at the reducing position of a main cross gate of the pouring system; and fifthly, filtering by using a three-level filter screen at the internal connection position of the secondary cross gate of the pouring system. The corrugated pouring cup is in an asymmetric shape, and the inner wall of the corrugated pouring cup is a stepped step part from top to bottom, so that filter residues of molten iron in a descending process are reduced, the flow rate of the molten iron is slowed down, the phenomenon that entrainment gas enters a casting mold to form entrainment air holes in the molten iron pouring process is avoided, and the occurrence of entrainment abnormity is avoided. The scum generated in the oxidation process of the molten iron is filtered more thoroughly by the third-stage filtration, so that the purity of the poured molten iron is further purified, the quality of the pouring process is improved, and the internal quality of the casting is improved.

Description

A method for classifying and filtering pouring slag

technical field

The invention relates to the pouring field of lost foam casting, in particular to a method for classifying and filtering pouring slag.

Background technique

The treatment of slag in the process of ferrous metal lost foam casting is a common and difficult to solve a kind of abnormality. At present, the slag produced in the process of lost foam casting is usually two types, one is black slag or carbon slag; the other is It is slag; and these two types of slag abnormalities have a profound impact on the internal quality of castings, which have a negative impact on the processing of parts and components of the client, not only affecting the delivery date and progress, but also causing quality complaints.

The original material of lost foam casting is polystyrene material, which is usually referred to as foam. At present, there are basically two types: one is ordinary foam material EPS; the density is relatively low; the other is relatively advanced material EPMMA, which is denser than EPS. ; But no matter what kind of material is in the process of lost foam casting, there will be residues when thermally decomposed at high temperature. This residue is found in the casting after machining, which is the internal abnormality of the casting - black slag is carbon slag The other kind of slag is a kind of slag in a molten state produced by the melting of impurities in the metal raw materials added during the smelting process, and part of the liquid in the molten metal reacts with the oxygen in the air, which floats and melts. surface of molten metal, forming what is known as slag. The current occurrence rate of slag is about 1%; from the perspective of casting, this data is not large, but for customers, even 0.1% abnormality may mean a major defect, and even cause more serious impact.

The first type of carbon slag comes from the residue after thermal decomposition of foam. Since its properties are essentially derived from the raw material EPS/EPMMA of the mold, it can only reduce the occurrence rate of carbon slag from the perspective of quality analysis and process control. For example: use molding The process technology adds slag discharge channel and overflow block method; the other is to use EPMMA to partially replace EPS material, reduce the generation of carbon slag, and reduce the cost of process repair. Even so, it is very unlikely to completely eliminate carbon slag; the second type of slag comes from the melting of impurities in metal smelting raw materials and the oxidation of part of the molten metal, which can be processed by subsequent methods.

The current treatment method of slag in the lost foam casting process:

(1) The pouring of molten iron adopts the method of artificial slag removal, and the slag removal agent is sprinkled on the metamorphic surface of the molten liquid to manually remove the impurity slag after the molten iron reaction. Generally, the slag is removed 5 to 6 times according to the specific molten iron situation to remove floating The hard slag in the molten iron is mainly the main residue after melting scrap steel and other raw materials, so that the molten iron can obtain a higher purity in the first step.

(2) In the current lost foam casting, the gating system for gray iron or molybdenum chromium body is basically the bottom injection method; for ductile iron, the side bottom injection method is generally adopted.

In the current lost foam casting system, the filter devices for different materials are basically set up by the end of the primary and secondary runners, and there is only one filtering method. Each gate uses a filter sheet, which is uneconomical and the filtration of slag is still not up to expectations. Requirements, so there is still abnormal slag after casting processing.

Contents of the invention

In order to solve the above problems, the present invention provides a method for graded filtration of pouring slag, which is characterized in that it includes the following steps:

Step 1: Sprinkling a deslagging agent on the surface of the molten iron to manually remove the impurities after the molten iron reacts, and remove the hard slag floating in the molten iron;

Step 2: Use a sprue cup with an asymmetric inner wall to enter the molten iron. The sprue cup is trumpet-shaped, the inclination of one side is greater than that of the other side, and the inner wall of the sprue cup is stepped from top to bottom. the step part;

Step 3, primary filtration of slag: install a primary filter on the sprue socket section of the gating system, and the molten iron is filtered through the primary filter;

Step 4, secondary filtration of slag: use a secondary filter at the diameter change of the main runner of the gating system, and the molten iron is subjected to secondary filtration;

Step five, tertiary filtration of slag: use a tertiary filter at the internal connection of the secondary runner of the gating system to perform tertiary filtration.

A further improvement is that the grid of the primary filter is square, and the side length of the grid is 10mm.

A further improvement is that the section of the sprue pocket is the interface between the sprue pocket and the straight pottery pipe.

A further improvement is that the overall specification of the secondary filter and the tertiary filter is 130x75x20mm.

A further improvement is that the secondary filter screen and the tertiary filter screen are made of ductile iron, and their grids are square, and the side length of the grids is 5×5mm.

A further improvement is that the secondary filter and the tertiary filter are made of gray iron, and the grid is square, and the side length of the grid is 3×3mm.

A further improvement is that the bottom of the sprue cup is connected to the sprue socket through a straight pottery pipe.

Beneficial effects of the present invention: firstly, the present invention sprinkles the slag remover on the molten iron to manually remove the hard slag, so as to ensure the first step of the molten iron to obtain higher purity; Cup feeding, molten iron enters into the sprue, passes through the sprue nest section and filters for a filter, and performs initial filtration after the molten iron enters the straight pottery pipe from the sprue cup; after that, the molten iron enters the main horizontal In the runner, a secondary filter is used to filter the molten iron at the diameter change of the main runner; finally, the molten iron enters the secondary runner, and a tertiary filter is used to filter the molten iron at the internal connection of the secondary runner. Three stages of filtration. In this way, the three-stage filtration can more thoroughly filter the scum produced during the oxidation process of molten iron, further purify the purity of molten iron, improve the quality of the pouring process, improve the internal quality of castings, and improve customer satisfaction.

The material of the second-stage filter screen and the third-stage filter screen of the present invention is ductile iron or gray iron. Since more alloys are added into the ductile iron, the grid is larger than that of gray iron, so that the fluidity is better.

The invention adopts three-stage filtration, which is beneficial to save the filter sheet of the overall pouring system, thereby saving costs; the setting of the pouring system is optimized, which is beneficial to the smooth operation of molten iron and achieves the effect of fast filling;

The corrugated sprue cup of the present invention adopts an asymmetric shape, so that the mouth of the sprue cup connected to the straight pottery pipe is not on the center line, so that the molten iron enters the liquid from the inner wall of the sprue cup and does not directly exit the liquid, and the inner wall is from the top. The stepped part to the bottom is beneficial to reduce the filter residue during the descending process of the molten iron, slow down the flow rate of the molten iron, and prevent the gas from entering the mold during the pouring process of the molten iron to form entangled pores and avoid joint abnormalities.

Description of drawings

Fig. 1 is the overall schematic diagram of the present invention.

Fig. 2 is a schematic diagram of the sprue cup of the present invention.

Fig. 3 is a schematic diagram of the primary filter of the present invention.

Among them: 1- sprue cup, 2- straight pottery pipe, 3- straight sprue, 4- step part, 5- primary filter, 6- main runner, 7- secondary filter, 8- secondary horizontal Sprue, 9-tertiary filter screen.

detailed description

In order to deepen the understanding of the present invention, the present invention will be further described below in conjunction with the examples, which are only used to explain the present invention, and do not constitute a limitation to the protection scope of the present invention.

As shown in Figures 1-3, this embodiment provides a method for graded filtration of pouring slag, in order to achieve more thorough filtration of slag, further purify molten iron, eliminate the influence of slag on the internal quality of castings, and improve pouring quality. On the premise that the artificial slag removal remains unchanged, we adopt the method of improving the filtering method of the pouring system - using the method of "three-stage filtration method of the pouring system + a new sprue cup" method, and the residual slag produced by oxidation during the static process of the molten iron is scum, Filtration is carried out through the gating system, that is, three-stage fine filtration. So as to achieve a more ideal effect.

Include the following steps:

S1, sprinkle the slag remover on the surface of the molten iron to manually remove the impurities after the reaction of the molten iron, remove the hard slag floating in the molten iron, and mainly remove the main residue after the melting of raw materials such as scrap steel; The slag agent is sprayed five times, and the slag is removed manually after each sprinkling, so that the first step of the molten iron obtains a higher purity.

S2, the molten iron is fed into the sprue cup 1 with asymmetric inner wall corrugation, the bottom of the sprue cup is connected with the sprue 3 nests through the straight pottery tube 2, the sprue cup 1 is trumpet-shaped and the inclination of one side is larger than the other The slope of one side; the inner wall of the sprue cup 1 is a stepped part 4 from top to bottom; this is beneficial to reduce the filter residue during the descending process of the molten iron, slow down the flow rate of the molten iron, and avoid the entrained gas entering the mold during the pouring process of the molten iron The formation of involved stomata avoids the occurrence of joint abnormalities.

S3, primary filtration of molten slag: Install a primary filter 5 on the third sprue section of the pouring system. The third sprue section is the interface between the third sprue and the straight pottery pipe 2, and the molten iron passes through a Stage filter screen 5 filters, and the grid of primary filter screen 5 is a square, and the side length of its grid is 10mm.

S4, secondary filtration of molten slag: the secondary filter 7 is used at the variable diameter of the main runner 6 of the pouring system, and the molten iron is subjected to secondary filtration; the overall specification of the secondary filter 7 is 130x75x20mm, and it is made of ductile iron. The grid is a square, and the side length of the grid is 5X5mm.

S5, three-stage filtration of slag: use three-stage filter 9 at the internal connection of the secondary runner 8 of the gating system for three-stage filtration; the overall specification of the three-stage filter 9 is 130x75x20mm, made of ductile iron, and its mesh is Square, the side length of its grid is 5X5mm.

Firstly, sprinkle the slag remover on the molten iron to manually remove the hard slag, so as to ensure the high purity of the molten iron in the first step; after that, the molten iron is fed from the sprue cup with asymmetric inner wall corrugation, after the molten iron Enter the sprue, pass through the sprue nest section and perform a filter through the filter to perform the initial filtration after the molten iron enters the straight pottery pipe from the sprue cup; the molten iron then enters the main runner and passes through the main runner A secondary filter is used at the variable diameter for secondary filtration of the molten iron; finally, the molten iron enters the secondary runner, and a tertiary filter is used for tertiary filtration of the molten iron at the internal connection of the secondary runner. In this way, the three-stage filtration can more thoroughly filter the scum produced during the oxidation process of molten iron, further purify the purity of molten iron, improve the quality of the pouring process, improve the internal quality of castings, and improve customer satisfaction.

The use of three-stage filtration is conducive to saving the filter pieces of the overall gating system, thereby saving costs; optimizing the setting of the gating system is beneficial to the smooth operation of molten iron and achieves fast filling effects; the corrugated sprue cup adopts an asymmetric shape, and the inner wall It is a stepped step from top to bottom, which is beneficial to reduce the filter residue during the descending process of the molten iron, slow down the flow rate of the molten iron, and avoid the formation of entanglement pores caused by entrained gas entering the mold during the molten iron pouring process, avoiding joint exception occurs.

This technical solution lasted more than a year of production testing, tracking a total of 2,146 test pieces, and no slag phenomenon occurred after the client machined; the product has been recognized by the market and improved customer satisfaction.

Claims (7)

1. The pouring slag graded filtering method is characterized by comprising the following steps of:

step one, a deslagging agent is thrown on the surface of molten liquid iron to manually remove impurities after the iron liquid reacts, and hard slag floating in the iron liquid is removed;

step two, adopting a pouring cup with a corrugated asymmetric inner wall to feed molten iron, wherein the pouring cup is in a trumpet shape, the inclination of one side of the pouring cup is greater than that of the other side of the pouring cup, and the inner wall of the pouring cup is a step-shaped step part from top to bottom;

step three, primary filtering of slag: installing a primary filter screen on the cross section of the direct casting runner pit of the casting system, and filtering molten iron through the primary filter screen;

step four, secondary slag filtration: a secondary filter screen is used at the reducing position of a main cross gate of the pouring system, and the molten iron is subjected to secondary filtration;

step five, slag three-stage filtration: and a tertiary filter screen is used at the internal connection part of the secondary cross gate of the pouring system for tertiary filtration.

2. The method for fractional filtration of casting slag according to claim 1 wherein said primary filter screen has a square mesh with 10mm sides.

3. The method for fractional filtration of casting slag according to claim 1, wherein the cross-section of the direct runner cavity is the interface of the direct runner cavity and the straight ceramic pipe.

4. The method for fractional filtration of casting slag according to claim 1 wherein the secondary and tertiary screens are 130x75x20mm in overall size.

5. The method for fractional filtration of casting slag according to claim 4 wherein said secondary and tertiary filters are made of ductile iron with a square mesh having a side length of 5X5mm.

6. The method for fractional filtration of casting slag according to claim 4, wherein said secondary and tertiary filters are made of gray iron, the grid is square, and the side length of the grid is 3X3mm.

7. The method for fractional filtration of casting slag according to claim 1 wherein the bottom of the tundish is connected to the vertical tundish through a vertical ceramic pipe.

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