HU190237B - Method and auxiliary alloy for producing cast-iron skid shoe produced by the method - Google Patents

Abstract

5-8 mins. before casting the melt is mixed 0.1-0.3 wt.% CaBaSi alloy comprising of (wt.%): Si 60-65, Al 0.5-1.7, Ca 1-2, Ba 9-11, the remainder being Fe. The resultant skid shoe comprises (wt.%): C 3-3.6, Si 1.8-2.5, Mn 0.3-1, S 0.1-0.16 and P 1.1-1.55 with a structure consisting of straight or vortex 25-90 microns lamellar graphite and perlite, as well as 5-55% ferrite and the eutectic cells measuring not more than 400 microns.

Description

FIELD OF THE INVENTION This invention relates to a process for making cast iron brake blocks using an auxiliary alloy. In doing so, the assembled insert is melted, molded, then poured, and the melt treated with an auxiliary alloy prior to casting.

It is known that braking of vehicles, especially rail vehicles, involves complex processes between cast-iron brake blocks and the wheel or steel tire. The system heats up, reaching temperatures of 800-900 ° C, and in some cases even higher temperatures can occur in extremely thin sections. As a result, some fabric components melt and undergo retooling and possibly hardening. When using a steel or non-alloy brake block, the braking performance would be extremely low as the martensitic surface block would slip on the steel tire.

The use of higher phosphorus brake blocks has already been proposed in the last century. In the United States, 3% phosphorus brake blocks are manufactured. However, in Europe the railways of different countries have not yet agreed on the use of uniform brake blocks.

Commonly used brake blocks include 3-4% carbon, 1-1.5% silicon, about 1% manganese, at least 1.36% phosphorus and sulfur.

Large surface contact (adequate friction) occurs by melting the phosphideutectic material at the periphery of the eutectic cells at high temperatures during braking, flowing around rough austenitic particles. The relatively high content of phosphorus is therefore required.

Of course, friction causes a great deal of wear, so the brake blocks need to be replaced quite often. High wear can practically be reduced by increasing the stopping distance, but this is usually not possible.

The disadvantage of currently used cast iron brake blocks is that their chemical composition is highly scattered, so that the required alloy ranges are difficult to adjust. However, a clear relationship between the extreme values of the variation and the braking performance cannot be practically established.

A further disadvantage of currently used alloys is that brake blocks often crack and break during operation.

The object of the present invention is to provide a solution which enables accurately reproducible production of cast iron brake blocks and wherein the produced brake blocks show significantly less wear than conventional ones and do not crack or break during operation.

The object is solved by a process of melting, forming, and casting the assembled insert, wherein the melt is treated with 0.1-0.3% CaBaSi auxiliary alloy 5-8 minutes prior to casting.

The composition of the alloy used is as follows:

silicon 60-65% aluminum 0.5-1.7% calcium 1.0-2.0% barium 9.0-11.0% iron residue

The cast iron brake block produced in accordance with the present invention comprises 3-3.6% carbon, 1.8-2.5% silicon, 0.3-1.0% manganese, 0.1-0.16% sulfur and 1.1-1. Contains 55% phosphorus.

The iron structure of the cast iron is rectilinear or vortex-shaped and contains 25 to 90 μl of graphite and perlite, and 5 to 55% ferrite, and the size of eutectic cells is up to 400 μ.

If the alloy is used as a brake block for railcars rather than locomotives, the ferritic content of the alloy is preferably 5-10%.

The present invention is based on the following insights:

The phosphorus content alone does not determine the quality of cast iron brake blocks, either in terms of braking distance or wear. More important is the higher than normal sulfur content and higher phosphorus content. The structure of the tissue is also essential. The alloy must develop graphite of appropriate shape, size and distribution, and the presence of relatively large amounts of perlite is also required. What is also important is the size of the eutectic cells and the distribution of the surrounding phosphide mesh.

The amount of phosphorus may also be lower than in conventional alloys. However, it is important that the phosphorus is distributed as finely as possible in the tissue structure. Thus, some of it is soluble in the metallic base fabric and increases the strength of the spikes. This strength-enhancing effect is more effective when perlite forming or stabilizing elements are added to the liquid cast iron production. The auxiliary alloy according to the invention serves for this purpose.

According to the present invention, brake pads of higher quality are produced by simple and safe technology. However, no modification of the batch formulation process is required for the cast iron smelting, and the basic characteristics of the prior art remain unchanged.

By reducing the manganese content of the brake blocks, it is also possible to reduce the stopping distance by reducing the risk of martensite formation during braking.

The wear of the spikes of the present invention is also reduced, with virtually no cracking or fracture.

Further details of the invention will be described by way of exemplary embodiments.

Tests were performed on conventional brake pads according to the invention. The compositions of the various samples, the method of treatment, as well as the tissue structure of the alloys obtained and the results of the braking tests are shown in Tables L, 2 and 3.

190 237

Table 1

Chemical composition of the brake block

Example C Ski (%) Mn S P 1 3.11 1.32 1.00 0.037 1.35 2 3.00 2.28 0.38 0.103 1.15 3 3.31 2.32 0.35 0,065 1.16 4 3.25 2.33 0.52 0,115 1.11

Table 2

* Graphite Tissue (%) The eutectic cells shape size El- from splitting perlite ferrite size El- from splitting Gal Gml80 Ge 2 80 0 E 1250 Foe 2 GA2 Gm90 Ge 2 5 80 E 650 Foe 3 GA2 GM45 Ge 2 25 55 E 400 Foe 2 GA2 Gm25 Ge 2 60 25 E 400 Foe 2

* According to MS 5716-74

Table 3

Braking performance * reached 80%. It can be seen that, although the eutectic cell size has decreased, the braking distance and wear remain at a value similar to that in Example 1.

Example 3

A pad was made as described in Example 2 and the dose was thawed. After thaw ol ¹⁰ was added 0.15% of the alloy segédötvözetet. The auxiliary alloy contained 60% silicon, 0.7% aluminum, 1.2% calcium, 10% barium and iron. The auxiliary alloy was injected into the melt 3 minutes before casting.

It can be seen from the table that the size of the graphite in the tissue of the brake block is 45 μ, which is a vortex plate graphite. The ferrite content is 55% and the size of the eutectic cells does not exceed 400 μ. Accordingly, both braking distance and wear are favorable.

brake line wear, g / brake

755 82.8 758 56.8 702 28.3 694 26.5

* Suburban braking with brake pads from 120 km / h to stop (V43 locomotive).

Example 1

The pad is assembled in accordance with the usual manufacturing technology for cast iron brake blocks. The insert contained cast iron waste, scrap and steel scrap, foundry pig iron, steel pig iron as well as alloys, ferro-silicon, manganese and phosphorus, as well as coke, limestone and slag-forming materials.

The insert was thawed, then molded, and after casting, the usual finishing was performed.

The table shows that the fabric contains coarse graphite and perlite, and the alloy did not contain ferrite. The eutectic cells are large, the braking distance and abrasion are high. This is mainly due to low silicon and high manganese content.

Example 4

A portion was prepared as described in Example 3 for further casting. After melting, the melt was treated with 0.25% CaBaSi auxiliary alloy. The composition of the alloy was as follows: silicon 65%, aluminum 1.6%, calcium

1.9%, barium 1%. Casting was carried out 5 minutes after the addition of the alloy.

The ferritic content of the resulting cast iron tissue was 25% and the size of the eutectic cells did not exceed 400 μ. Again, the wear and stopping distance were very favorable.

Field experiments with conventional brake blocks according to Example 1 and compositions according to the invention were also carried out. During the experiments, 12 sets of both types of materials were made and incorporated into ⁴⁰ operating locomotives. The results of the experiments are shown in Table 4.

He reached _{je u mz} ile s Traditional average 129.9 days tuskokeszlet average 60 836 km> 0 I wear tolerance

wear II.

stump set 5/12 set 111.2 kg set

1.8413 -

Table 4

According to the invention

143 2 ^na P ^x Locomotive Block Set

074— Set of paints

0/12 stock kg

102.5 sets

1.3129 Λ

Example 2

An insert was also made as described in Example 1, except that steel scrap was not used to make the insert. The resulting alloy contained lower phosphorus content and significantly lower manganese content. The fabric showed less coarse graphite, ferrite

From the table it can be seen that the cast iron brake blocks made according to the invention exhibit extremely good performance. Their wear is significantly less than that of conventional brake blocks and, consequently, their mileage, both in kilometers and in time, is significantly better. In addition, no cracking or fracture occurred between the brake blocks according to the invention.

The stated above that the solution according to the document are ₆₅ really allows one to 31

190 237 like and reliable technology to produce brake blocks that are less abrasive than conventional and that do not crack or break during operation.

Claims (4)

Claims 1. A process for producing cast iron brake blocks, which comprises melting the assembled napkin lesalakoljuk, poured, characterized in that the melt is treated with ¹⁰ 5-8 minutes 0.1-0.3% of CaBaSi segédötvözettel prior to casting. ^; Auxiliary alloy for carrying out the process of claim 1, characterized in that it comprises silicon 60-65% aluminum 0.5-1.7% calcium 1.0-2.0% barium 9.0-11.0% iron residue 3. Cast iron brake block containing carbon, silicon, manganese, sulfur and phosphorus, characterized in that the carbon is 3-3.6% silicon 1.8-2.5% manganese 0.3-1.0% sulfur 0 , 1-0.16% and phosphorus 1.1-1.55%, the structure of which consists of rectangular or swirl sheets of 25 to 90 μl sheet graphite and perlite and 5 to 55% ferrite and of a maximum eutectic cell size of 400 μ. Brake block according to claim 3, characterized in that it contains 5-10% ferrite.