DD251160A1 - CASTING MATERIAL FOR SURFACE ROLLERS AND ROLLERS IN PROCESSING MACHINES - Google Patents

Abstract

The invention relates to the use of cast materials for races and rollers in processing machines, in particular Drehrohroefen, drying drums and -muehlen the cement industry. The aim of the invention is, by a substantial increase in the reliability of these solid, cylindrical castings with wall thicknesses in the range of 80 ... 250 mm, to reduce the repair and maintenance effort to increase the efficiency of the cement plants. According to the invention, this object is achieved by alloyed spheroidal graphite cast iron, that at a CE value of 4.0 to 4.5%, the alloying components in the combination Ni / Cu, Cu / Mo or Ni / Cu / Mo or Shares of Ni, Cu and Mo individually or jointly, partially or completely substituted by Sn. As a result of the special combination of the alloy constituents, a homogeneous, finely-grained pearlitic structure is formed in the cast state after heat treatment, so that this cast material fulfills high demands on strength, hardness, wear behavior, emergency running properties, damping properties and temperature resistance as well as resistance to aggressive gases and dust.

Description

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 250 mm, for rotary kiln, 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.

Characteristic of the known technical solutions

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 races also have a support function for the drum shell against the effect of the transverse force stress to meet. 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 operating 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

Mg 0.3 ... 1.4%

Ni 0.5 ... 2.5%

Cu 0.3 ... 1.0%

Mo 0.1 ... 0.26%

Sn contains 0.03 ... 0.2%.

This casting material can be used for thick-walled castings (50-100 mm wall thickness). For the special requirements that are placed on the material of rollers and rings, this casting material is not suitable because of insufficient mechanical properties.

From the journal "Foundry Practice" No.21 / 1975, pages 350 to 357, investigations are known that have been made on cast iron with nodular graphite in the wall thickness range of 25 to 150mm., The dependence of the wall thickness was on the formation of a pearlitic structure and the mechanical characteristics of heat-treated cast samples are being investigated, and these reported results are not accurate in terms of content to practical issues.

Object of the invention

The aim of the invention is to reduce the repair and maintenance of rotary kiln, 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- 251160 Presentation of the Essence of the Invention

The invention has for its object to develop a casting material for rollers and rings of rotary kiln, 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 3.0 ... 4.0% and silicon with 1.5 ... 3.0% while maintaining a carbon equivalent in the range of 4.0 ... 4, 5% and nickel in the limits of 0.8 ... 1.5%, copper with 0.5 ... 1.3% and the interference elements manganese, phosphorus, sulfur and chromium in the alloy only in small parts, preferably below the limits 0.2% for manganese, 0.06% for phosphorus, 0.008% for sulfur and 0.2% for chromium, and the molten cast iron with magnesium in the proportion of 0.04 ... 0.08% or other Sphärolithenbildnern is modified.

The invention further includes that the molten cast iron in addition to or instead of nickel molybdenum in the proportion between 0.2 added to 0.8%, and that tin in the proportion of 0.02 to 0.5%, the alloying constituents nickel , Copper and molybdenum singly or together, partially or fully substituted.

embodiment

The invention will be explained in more detail with reference to an example.

The roller of a rotary kiln has the following dimensions:

Roll diameter 1400 mm

Hub diameter 500 mm

Roller height 900 mm

Wall thickness (wreath) 120 mm

Wall thickness (hub) 120 mm

For this casting is alloyed cast iron with nodular graphite GGG 350 Ni Cu 5.9

used.

The material has the following chemical composition:

Carbon 3.5%)

Silicon 2.1%) ^CE - ⁴ ' ^2%

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 plastering the casting, the following heat treatment technology is used:

- Austenitizing at 870 to 900 ⁰ C, wherein continuously heated at about 60 K / h, then holding austenitizing temperaturca. 6h; Cooling in the air,

- Stress relief annealing at 520 to 500 ° C, at 4h holding time, cooling in the oven to 300 ° C, then cooled in air to room temperature.

After this heat treatment, this casting material has the following properties:

Tensile strength 850 M Pa

0.2% rotation limit 640MPa

Elongation at break 3%

Brinell hardness 280HB

The subsequent machining is unproblematic for this casting material.

Claims (3)

Invention claim: 1. Casting material for races and rollers in processing machines, especially rotary kiln in the cement industry, preferably for wall thicknesses between 80 ... 250mm, consisting of alloyed cast iron with nodular graphite, the microstructure in the cast state after heat treatment in compliance with the cooling conditions homogeneous, finely striated perlitic characterized in that the alloying constituents comprise carbon with 3.0 to 4.0% and silicon with 1.5 to 3.0% while maintaining a carbon equivalent in the range from 4.0 to 4.5% and nickel in the limits of 0.8 to 1.5%, copper with 0.5 to 1.3% and the interference elements manganese, phosphorus, sulfur and chromium in the alloy only in small parts, preferably below the Limits 0.2% for manganese, 0.06% for phosphorus, 0.008% for sulfur and 0.2% for chromium, and the molten cast iron with magnesium in the proportion of 0.04 to 0.08% or others Sphärolithenbildnern is modified. 2. casting material according to claim 1, characterized in that the molten cast iron in addition to or instead of nickel molybdenum in a proportion of 0.2 to 0.8% is added. 3. casting material according to claim 1 and 2, characterized in that tin in the proportion of 0.02 to 0.5%, the alloy components nickel, copper and molybdenum individually or jointly, partially or completely substituted.