DD251160B1 - CASTING MATERIAL FOR SURFACE ROLLERS AND ROLLERS IN PROCESSING MACHINES - Google Patents

Abstract

The invention relates to a cast material for mechanically highly stressed, thermally stable and aggressive gases and dusts exposed cylindrically shaped rollers and rings, preferably with a wall thickness of 80 to 250 mm, for rotary kilns, drying drums and mills of the cement industry. The cast material used is characterized in that the alloying constituents carbon with 3.5% and silicon at 2.1%, while maintaining a carbon equivalent of 4.2% and nickel of 1.25%, copper with 1.0% and the Accompanying elements manganese with 0.2%, phosphorus with 0.06%, sulfur with 0.008% and chromium with 0.15% are included and the molten cast iron with magnesium in the proportion of 0.05% is modified.

Description

Characteristic of the known state of the art

Casters and rings are used for the storage of elongate large plants rotating about their longitudinal axis, such as rotary kilns, drying drums and mills.

During the rolling process, these massive, cylindrically shaped components take on the weight of the entire system, including the contents. The running rings also have to fulfill a support function for the drum shell against the effect of the transverse force stress. The larger Hertzian pressure and the much higher number of revolutions of the roller compared to the race naturally lead to a faster wear of the roller. At the tread it comes through strain hardening for pitting and embrittlement of the surface parts. The special application conditions place the highest demands on the material in terms of strength, hardness, wear behavior, emergency running properties, damping capacity and temperature resistance as well as resistance to aggressive dusts and gases. In known construction designs come as materials cast iron with lamellar or nodular graphite, but also cast steel materials such. GS 28 Mn 6, GS42 Cr Mo4, GS-60, GS-50. The larger dimensions of modern rotary kilns made it necessary to use other cast materials and processing techniques instead of cast iron with lamellar graphite.

From British patent specification 1417435 an alloyed cast iron material with nodular graphite is known, which is applicable for thick-walled castings. In this material, the alloying shares carbon, silicon, phosphorus, sulfur in known per se and

MgO, 3 ... 1.4%

Ni 0.5 ... 2.5%

Cu0.3 ... 1.0%

Mo0,1 ... 0,26%

Sn 0.03 ... 0.2%

contain.

This casting material can be used for thick-walled castings (50-100 mm wall thickness). Due to insufficient mechanical characteristics, this casting material is unsuitable for the special requirements placed on the material of rollers and rings. The disadvantages are also apparent from the Werkstorfzusammensetzung (DE-PS 1908856 and DE-OS 2428822), which does not create the conditions for securing the necessary component properties for races and rollers in the wall thickness range of 80 to 250 mm.

From the journal "Foundry Practice" No.21 / 1975, pages 350 to 357, investigations are made on cast irons with nodular graphite in the wall thickness range of 25 to 150 mm were made.The dependence of the wall thickness on the formation of a pearlitic The reported results do not accurately reflect practical issues.

Object of the invention

The aim of the invention is to reduce the repair and maintenance of rotary kilns, drying drums and mills by a significant increase in the reliability of the running rings and rollers to increase the performance of these cement plants.

-2- 251 160 Outline of the Essence of the Invention

The invention has for its object to develop a casting material for rollers and rings to rotary kilns, drying drums and mills of the cement industry, the highest demands on strength, hardness, wear behavior under the special conditions of use and environmental conditions under which these cement plants are operated , Runflat properties, damping capacity and temperature resistance as well as resistance to aggressive atmospheres containing dust and harmful gases.

According to the invention, this object is achieved in that the alloying constituents carbon with 3.5% and silicon with 2.1% while maintaining a carbon equivalent of 4.2% and nickel of 1.25%, copper with 1.0% and the accompanying elements manganese with 0.2%, phosphorus with 0.06%, sulfur with 0.008% and chromium with 0.15% are included and the molten cast iron with magnesium in the proportion of 0.05% is modified.

embodiment

The invention will be explained in more detail with reference to an example, roller for a rotary kiln. For this roller alloyed ductile iron with the designation GGG 350 NiCu 5.9 is used. The material has the following chemical composition:

carbon 3.5%) CE = 4.2% silicon 2.1%) nickel 1.25% copper 1.0%

This material is modified with 0.05% magnesium. The proportions of the accompanying elements sulfur, phosphorus, manganese and chromium were determined as follows:

manganese 0.2% chrome 0.15% phosphorus 0.06% sulfur 0.008%

The molding and core fabrication is done by known methods using standard patterning equipment. After casting and pre-brushing the casting a heat treatment is applied. After this heat treatment, this casting material has the following properties:

Tensile strength at least 800 MPa

0.2% proof strength at least 600 MPa

Elongation at break min. 2%

Brinell hardness at least 270 HB

The subsequent machining is unproblematic for this casting material.

Claims (1)

Casting material for running rings and rollers in processing machines, especially rotary kilns in the cement industry, preferably for wall thickness between 80-250 mm, the microstructure in the cast state, especially after a heat treatment, while maintaining the cooling conditions homogeneous, finely-striated perlitic forms, characterized in that the alloying constituents carbon with 3.5% and silicon with 2.1% with a carbon equivalent of 4.2% and nickel of 1.25%, copper with 1.0% and the accompanying elements manganese with 0.2%, phosphorus with 0.06%, 0.008% sulfur and 0.15% chromium are included, and the molten cast iron is modified with 0.05% magnesium. Field of application of the invention The invention relates to a cast material for mechanically highly stressed, thermally stable and aggressive gases and dusts exposed cylindrically shaped rollers and rings, preferably with a wall thickness of 80 to 250mm, for rotary kilns, drying drums and mills the cement industry.
Furthermore, this invention is applicable in the fields of the chemical industry and in large-scale systems for ore processing.