SU1526897A2 - Method of centrifugal casting of rolling mill rolls with necks - Google Patents

Abstract

The invention relates to foundry, in particular to the technology of centrifugal casting rolls with necks. The purpose of the invention is to improve the quality of the cast. The metal jet for shaping the outer layer of the roll is directed to the area separated from the front end of the working cavity of the mold by an amount of 0.35-0.40 in the length of this cavity. The metal jet of the first and second portions of the melt for the inner layer is directed to the portion of the front end of the working cavity of the mold. The method makes it possible to eliminate defects such as nestlitin and nespai, as well as eliminate blockages and exogenous inclusions. 1 tab.

Description

The invention relates to foundry, in particular to the technology of centrifugal casting of rolls with necks, and is an improvement of the method according to the authors. No. 1156835.

The purpose of the invention is to improve the quality of the cast.

The method is carried out as follows.

The metal of the outer layer is poured through a moving chute with a horizontal axis of rotation of the mold. The jet of the poured metal of the outer layer is directed to the area separated from the front end of the roll barrel by an amount of 0.35-0.40 in the length of the roll barrel. The size of the site is determined empirically when casting mill rolls with necks of various sizes. Metal jet

the outer layer to the area separated from the front end of the roll barrel by an amount of 0.35-0.40 in the length of the roll barrel provides for its uniform distribution along the roll barrel length, eliminates the erosion of the upper non-stick and lining coatings rolls with high-quality outer working layer. It has been established experimentally that when a metal stream of the outer layer is poured into an area separated from the front end of the roll barrel by an amount less than 0.35 the length of the roll barrel, the lining spills in the dumbbell area of the upper neck, the area of the rear end of the roll barrel on its perimeter. Fill the same jet of metal of the outer layer to the area separated by

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from the front end of the roll barrel by an amount of more than 0.40 roll barrel lengths leads to erosion of the lining in the lower neck dumbbell and to the formation of nestilin and nespayev in the front end of the roll barrel around its perimeter.

The flow of metal jets — the first and second portions of the inner layer melt, carried out respectively when the mold rotates around the horizontal axis and at an angle of 30–45 °, to the front end portion of the roll barrel creates a mass transfer along the perimeter and length of the roll roll in the solidifying metal; to improve the quality of the cast rolls. When the second portion of the inner layer melts is poured into the area of the front end of the roll barrel, there is no hydraulic impact of the jet of falling metal in the neck area, which leads to a reduction in the burn, and also prevents destruction of the lining and contamination of the metal with exogenous inclusions. portions of the inner layer melt into the front end section of the roll barrel will help clean the entire area of the contact free surface of the filled metal of the first portion of the inner layer metal from metallic inclusions and planned and, as a result, lead to improved weldability flooded metal layers.

Testing of the method is carried out in the centrifugal casting area of the mill rolls of the mill mill with a variable angle of rotation of the mold. Cast sheet rolling two-layer rolls.

In order to obtain comparative data, one roll is cast by a known method, and the subsequent ones - according to the proposed method. The assembled, heated to 120-150 ° C and painted with anti-stick coating form mounted on a centrifugal machine. The form consists of a chill part to form a roll barrel and insert glasses from sand-clay mixture to form necks and a profitable part of the cast roll. The working (outer) layer is filled by rotating the mold around a horizontal axis of rotation. At tol0

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On the working layer of the sheet rolling roll of 5 cm, the radius of the inner surface is R 27 cm, the gravitational coefficient K 38, the nominal frequency of rotation of the mold is 355 rpm.

The dosed working layer (1188 kg) is poured into a mold rotated with a nominal frequency (355 rpm), and the melt temperature is 1280-1320 0. The stream of the cast metal of the outer layer is directed to the area separated from the front end roll barrels by an amount of 0.35-0.40 in the length of the roll barrel. The weight pouring speed is 25-40 kg / s. The chemical composition of the metal of the working layer is determined by express analysis. The solidus temperature for cast iron used for casting rolls is 1013-1136 ° C. The temperature control of the free surface of the cast metal of the working layer is controlled by a TERA-50 radiation pyrometer interlocked with a recording potentiometer. When the free surface of the molten metal of the outer layer reaches a predetermined temperature (20-49 ° C below the solidus), the frequency of rotation of the mold increases by 1.1-1.15 times the nominal one and 10-15% (582-872 kg) of the internal metal is cast. lay This is necessary to form a contact layer of the desired design thickness. The temperature of the metal pouring of the inner layer is 1300-1340 0. The jet of the first portion of the metal of the inner layer is fed to the section of the front end of the roll barrel. The weight rate of the metal casting of the inner layer is 60-85 kg / s.

The metal of the inner layer is poured in a volume of 45-50% (2616-2907 kg) when the axis of the mold is tilted to the horizontal axis by 30-45 °, where the frequency of rotation of the form is 0.05-0.20 of the nominal, and the jets are carried out on a portion of the front end of the roll barrel.

The remaining part of the metal of the inner layer, which forms the profitable part of the roll, is refilled when the mold stops in a vertical position before the final casting is made.

The cast sheet rollers after cooling are subjected to ultrasonic flaw detection. In addition, the quality of the material of the cast rolls is determined by metallographic analysis by micro etching and removing sulfur prints on samples (templates) transversely cut from the material of the barrel and the necks of the rolls.

The technological parameters of the cast two-layer sheet rolling rolls and the results of their quality are shown in the table.

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As can be seen from the table, the quality of the material of the rolls cast by the proposed method is significantly better than the material of the roll cast in the prototype. On the surface of the outer layer of the rolls, cast by the proposed method, there are no defects such as nestilin and nespai. There are no blockages and exogenous inclusions in the material of the roll blanks. The burner in the area of the upper and lower necks is minimal and is easily removed by blasting. The quality of weldability of the poured metal layers is satisfactory.

Claims (1)

Invention Formula Method of centrifugal casting of rolling rolls with necks on auth.St. No. 1156835, characterized in that, in order to improve the quality of the casting, the metal jet for the outer layer is directed to a section spaced from the front end of the working cavity of the mold, etching by the roll barrel by an amount equal to 0.35-0.40 the lengths of this cavity and the jet The metal of the first and second portions of the melt for the inner layer is directed to the portion of the front end of the working cavity of the mold, etching the roll barrel.