SU1057167A1 - Casting system for intermold inoculation - Google Patents

Abstract

Gating system for in-mold inoculation of cast iron, comprising a riser reaction chamber disposed at the bottom tyuluforme and shlakoulovitel, characterized in that, in order to stabilize the process of dissolving the modifier in the production of large castings located in two mold halves, the reaction chamber is configured as a parallelepiped and an inverted truncated tetrahedral pyramid, which is the lower extension of the parallelepiped, wherein the ratio of the volumes of the parallelepiped and the pyramid is 1:

Description

The invention relates to foundry, in particular, to the production of castings from high-strength cast iron, and can be used in the production of large-scale machine-building castings such as crankcases and cylinder blocks of diesel engines.

Gating systems for intraform modification of cast iron in a casting mold are known, which contain a hundred cubic meters, a reaction chamber and a slag trap, in which the reaction chambers have a different l-3 shape.

The disadvantage of these gating systems is the instability of the modifying process with an increase in the melt pouring time over 30-40 sec.

Closest to the proposed technical essence and the achieved result is the gating system for the internal modification of cast iron, which includes a stand, a reaction chamber located in the lower half-form and a slag trap.

This gating system is recommended for mass production of machine-building castings in casting molds with a metal consumption of 20100 kg. Depending on metal consumption, the casting time of one form is 10-30 seconds, which characterizes the transience of the processes occurring in the reaction chamber and the reduction of the influence of factors varying with time. Despite the change in mass flow rate, with a small metal intensity of the forms, the correctly calculated surface of the reaction chamber provides a fairly uniform dissolution of the modifier and the distribution of modifying their elements throughout the entire metal volume of the casting 4j.

The disadvantage of this gating system is the uneven dissolution of the modifier in the flowing melt in case of an increase in casting time over 3040 seconds, which is available in the manufacture of large castings weighing more than 100 kg.

The purpose of the invention is to stabilize the process of modifier dissolution in the manufacture of large castings located in two half-molds,

This goal is achieved by the fact that in the gating system for the intraform modification of cast iron, which includes a stand, a reaction chamber located in the lower mold half, and a slag trap, the reaction chamber is made in the form of a parallelepiped and inverted

the truncated tetrahedral pyramid, which is the lower extension of the parallelepiped, the ratio of the volumes of the parallelepiped and the pyramid is 1: (0.3-1), and the areas of the large and small base of the pyramid are 1: (O, 35-0.8).

The drawing shows the proposed gating system.

The casting system contains a reaction chamber, the upper part 1 of which is a parallelepiped and ensures the constancy of the contact area of the melt with the modifier during the filling of the lower half of the mold 2. The filling process is characterized by a practically constant mass pouring rate due to the constant pressure head defined by the height of the melt level in the bowl over the output section of the gating system. The filling of the upper half-form 3 due to a decrease in the hydraulic head H reduces the mass filling rate, and therefore it is necessary to reduce the contact area of the modifier with the melt, which provides the lower part of the reaction chamber, having the shape of an inverted four-sided pyramid 4, which is a continuation of the parallelepiped.

Gates and the system works as follows.

The process of casting molds in which (castings or their parts are located in the upper mold) is characterized by a varying mass flow rate of the liquid metal. As a result of a decrease in the hydraulic head of the difference in metal level in the stand and casting, the mass flow rate of the liquid metal that determines the speed of the latter in the runner When filling parts of the casting located above the plane of the connector, due to the decrease in the mass flow rate and the almost constant dissolution rate of the modifier, There is an uneven flow of the spheroidizer into the melt, resulting in part of the melt being overmodified (oversaturated with modifying elements), while the other is not sufficiently modified due to the absence of a modifier in the reaction chamber caused by its intensive dissolution into the previous period.

This disadvantage eliminates the design of the reaction chamber of the invention, which, due to the decreasing area of the horizontal section, reduces the intensity

the modifier interacts with the melt in the final stage of the mold casting process and thereby ensures a uniform and optimal level of metal modification.

Based on experimental data, it was found that the ratio of the volumes of the parts of the reaction chamber of the parallelepiped and the pyramid should be within 1: (0.3-1), and the areas of the larger and smaller bases of the pyramid 1: (0.35-0.8). The volume of the pyramid on one side (0.3 parallelepiped volume) is limited by the expediency of use, so how, if the mass of a part of the casting in the upper mold half is less than 0.3 mass of a part of the casting in the lower mold, the reaction chamber of the usual form (parallelepiped) is quite effective, and on the other the sides are equal to the volume of the parallelepiped, since the mass of the casting in the upper mold half usually does not exceed 0.5 of the total mass of the casting.

The ratio of the areas of the larger and smaller bases of the pyramid is explained as follows.

The area of the smaller base of the pyramid is limited on the one hand (0.35 of the area of the larger base), in that the height of the flasks for mass production of machine-building castings does not exceed 1 m, and on the other side (0.8 of the area of the larger base) How, if the height of a part of the casting in the upper mold half is insignificant;

Example In order to obtain comparative results, model tooling is used, which makes it possible to produce body castings with a profit of a total weight of 200 kg from high-strength cast iron by modifying in a mold. YOU; honeycomb flask 500 mm. The height of the casting with a profit of 600 mm, with a part of its height of 150 mm is formed in the bottom

0 half mold, and 350 mm - at the top. The weight of the part of the casting located in the bottom mold is 80 and the top 120 kg. The gating system provides for filling with a fast melt for 35–40 s, i.e. with an average mass pouring speed of 5 kg / s.

For modifying iron-magnesium ligature 7% M), having a modifier solubility factor of 0.045 kg / s-cm in the amount of 1.0% of the metal intensity of the mold, which is 2.0 kg with a volume of 400 cm.

five

The casting is carried out with molten iron, having the following chemical composition,%: carbon 3.52; silicon 1.93; manganese 0.56 and sulfur 0.021.

0

The temperature of the melt during casting is 1420-10 s. From the obtained castings, three samples are cut (1- from the lower part of the casting, 2 5 from the upper part of the casting, 3 - from the region of the half-form connector). The iron structure, magnesium content and mechanical properties are examined.

The test results are presented in the table.

$ 10571676

The results of the witness testimony show that unevenness in the structure of the distribution of the residual magra and the properties of the metal of the casting can be noted unevenly and, as a result, the known structure of the metalworker properties is uneven when used.

gating system. Despite namotlivki, which can lead to breakage of the place of mixing the liquid-5 ke items during operation,

go metal in the cavity of the casting and the non-expected economic effect

which chemical averaging is 50 000 rub. in year.

Claims (1)

A GATEWAY SYSTEM FOR INTERNAL-FORMOR MODIFICATION OF IRON, including a riser, a reaction chamber located in the lower half-mold, and a slag trap, characterized in that, in order to stabilize the dissolution process of the modifier in the manufacture of large castings located in two half-molds, the reaction chamber is paralleled truncated tetrahedral pyramid, which is the lower continuation of the parallelepiped, while the ratio of the volumes of the parallelepiped and pyramid is 1: (0.3-1), and the areas of pain the top and the bottom of the pyramid - 1: (0.35-0.8). J ... 1057167