SI9210331A - Process for making a frog - Google Patents

Abstract

In the process of making a heart piece for rails switches and junctions with the tip of the heart piece from carbon steel and with connecting rails tip the heart piece of the cylinder and undergoes heat treatment at which ends of the heart piece all over it transforms the cross - section into a fine - ply structure, whereby then the tip of the heart piece is loosened and at least in The area where the bike is running undergoes trimming material to remove structure in the area wheels other than fine - ply structures, and thereafter the tip of the heart piece is welded with the connecting pieces rails to simplify the manufacture of the heart piece and allow heat treatment in normal devices.

Description

VOEST-ALPINE Eisenbahnsysteme Gesellschaft m.b.H.

The process of making a heart piece

The invention relates to a method of manufacturing a heart piece for rail switches and junctions with a carbon steel heart tip and connecting rails.

Various methods have become known for the manufacture of heart pieces, in which they essentially welded the connecting rails directly to the tip of the heart piece, or indirectly connected these connecting rails to the heart piece tip via intermediate pieces. The tips of the heart pieces are usually made as castings, especially as castings of hard steel. When using manganese hard steel, intermediate pieces are usually used to avoid defective changes in the structure by diffusion when welding between the tip of the heart piece and the connecting rail. After welding, they connected a more or less demanding heat treatment to improve the surface, and so for example. from DE PS 25 41 978 it is known that this kind of heat treatment of the switch parts is carried out in a by-pass process. The choice of this kind of by-pass procedure is to some extent palmed, since the tips of the heart pieces with the welded connecting rails represent relatively large components that cannot be further heat treated in the oven without having to choose the sizes of the oven excessively large. A further procedural method of heat treatment of the switch parts can be seen, e.g. from AT-PS 384 624. Even with this process, the necessary quality and / or quality were achieved through relatively demanding control of heat treatment conditions. surface hardness.

The heart pieces can be designed with a flexible tip or with movable wing rails and of different materials, such as e.g. hard manganese steel, maraging steels or other high wear materials. Conditional on different cross-sectional designs and different analysis of such tips of the heart pieces, the formation of non-lamellar structures, such as martensite, or the structure of the lower interspace may occur when producing the tips in the surface area. As a result of different heating during quenching, as a consequence, a twist appears, which must be eliminated separately, unless special measures are taken during the warming to eliminate this twist. Until now, the necessary conditions of heating during quenching have been able to be controlled only by transient quenching after welding the tip of the heart piece with connecting rails.

The invention is now directed to simplify the manufacture of heart pieces of the aforementioned type and, in particular, heat treatment to achieve the desired structure and surface tempering can be carried out by conventional devices. To accomplish this task, there is a method according to the invention of the aforementioned type essentially in that the tip of the heart piece is rolled and subjected to heat treatment, in which the tip of the heart piece is transformed into a fine-plylite structure along its entire cross section, and then the heart piece tip is loosened and at least in the area where the wheel is running, it is subjected to trimming to remove the wheel structure that is different from the fine-ply structure, and subsequently weld the tip of the heart piece with connecting rails. With the rolling tip of the heart piece in service, it is possible to incorporate different qualities of steels for the tips of the heart pieces, and by undergoing such heat-treatment of the tips of the heart pieces before being welded with connecting rails, this kind of heat treatment can be carried out in conventional furnaces. In addition, the thermal treatment of such tips of the heart pieces does not then require any excessive care when the tip of the heart piece is loosened and, at least in the area where the wheel is running, is subjected to removal treatments. With this kind of treatment or. trimming can eliminate unwanted structures in the edge areas or in the plane of the tip of the heart-piece on which the wheel flows, facilitating this relief, and, without the demanding control of temperature conditions, the whole-section of the heart-piece, such as that left after cutting by cutting, may be provided with a fine-ply structure. By welding the fine-pearl-like structure of the fine-ply structure with its entire cross-section afterwards, it is then welded to the connecting rails with little difficulty, even with a little difficulty in ensuring adequate strength properties even in the area of the weld, with only adequate heat treatment after welding. of the weld area to prevent fragility from occurring with reliability.

Preferably, the process according to the invention is performed in such a way that after welding with the compressed air connecting rails, the welding spot is cooled and dipped, whereby in a particularly preferred mode, the heart piece is subsequently annealed in the weld area, thereby also obtaining in the weld area fine-perlite structure.

Cutting treatment to remove unwanted structures can be accomplished in a particularly simple manner by planing or milling, with the advantage of proceeding such that the tip of the heart piece in the cross-sectional dimension, which at least in the area where the wheel is running, exceeds the final dimension, cylinders and to eliminate 1 to 5 mm of surface thickness by cutting. Depending on the section depth of 1 to 5 mm, in particular 2 to 3 mm, depending on the carbon content of the steel used to make the rolled tip of the heart piece, a small pearlitic structure is also available on the surface of the heart piece tip, offering the largest wear resistance. In a known manner, tempered rails may be used as connecting rails and, if appropriate, wing rails.

The fact that the tip of the heart piece, and thus its relatively small component, undergoes heat treatment, allows the heart pieces in the oven to be heated throughout the cross section to the austenitizing temperature, in particular temperatures between 810 and 900 ° C. After an adequate retention time of the heart pieces, which is essentially uncritical at the temperatures indicated above, the heart pieces are placed in a heated extinguishing medium, in particular an oil warm bath or a salt bath, to cool down to allow a cooling rate of 1 to 7 ° C / in the range 800 to 500 ° C. The temperature of the germination medium is easily controllable so that the batch can be viewed in a particularly simple way at different masses. After quenching the tip of the heart piece, a new annealing at 300 to 550 ° C can be provided, with such annealing at 300 to 550 ° C, preferably in those areas where the material has not been removed, leading to the depleted martensite. Thus, at a relatively low cost, a homogeneous, fine-ply structure at the tip of the heart piece is achieved, whereby a large number of cardiac tips are subjected to heat treatment together, resulting in a small number of cardiac tips together, thereby rationalizing and further simplifying . The possibility of simultaneously undergoing multiple treatment of cardiac tips provides substantially the same structure for a large number of cardiac tips, whereas in known procedures the thermal cycle was subsequently subjected to oscillations during subsequent post-treatment heat treatment, as a result of which were irregular structures.

For wing and connecting rails, rails whose heads are large-series tempered may be used.

As a material for cardiac tip tips for making a rolled cardiac tip tip, steel with directional analysis (in wt.%) Has proved to be a particular priority:

C 0.7-0.85 P max 0.04

Si 0.3-0.5 S max 0.04

Mn 0.8-1.5 other iron

With this kind of material for the tip of the heart piece, the following properties of the materials can be achieved with high constancy:

Surface hardness greater / equal Extension limit Re

The tensile strength Rm

Elongation A

Notch punch work

380 - 450 HV 800 N / mm ² 1200 N / mm ² 10%

JDVMF

To achieve the desired structure, a relatively low austenitization temperature, as indicated above, can be selected to achieve a finer grain in the secondary structure, which associates higher toughness at high tensile strength and tensile strength with higher abrasion resistance. Non-lamellar structures that appear in a range of analyzes based on different shapes of the intersection of the tips of the cardiac pieces, ie structures such as martensite and the lower intermediate stage in the surface region, can be reliably removed by post-heat treatment as well as decarburization, which in the given case occurs so as to achieve the desired surfaces with a reliability which is greater against the state of the art.

Claims (6)

Patent claims A method of manufacturing a heart piece for rail switches and junctions with a carbon steel heart tip and connecting rails, characterized in that the heart piece tip is rolled and subjected to a heat treatment in which the heart piece tip is converted into its entire cross section into fine-ply structure to undergo the tip of the heart piece afterwards, and at least in the area where the wheel is running, undergo treatment by removing material to remove the structure of the wheel area other than the fine-plyle, and subsequently weld the tip of the heart piece with connecting rails. Method according to claim 1, characterized in that after welding with the connecting rails, the welding spot is cooled and dewaxed with compressed air. Method according to claim 1 or 2, characterized in that the heart piece is subsequently annealed in the area of the weld. Method according to claim 1, 2 or 3, characterized in that the material removal treatment is carried out by planing or planing. by milling. Method according to one of Claims 1 to 4, characterized in that the tip of the heart piece of the cylinder is in cross-sectional dimension, which exceeds the end dimension at least in the area where the wheel is running, and is removed by removal by material removal from 1 to 5. mm of surface thickness. Method according to one of Claims 1 to 5, characterized in that rails with hardened heads are used as connecting rails and optionally as wing rails.