DE102010033473B4 - Process for the heat treatment of the wheel rim of rail vehicle wheels - Google Patents

Abstract

Process for the heat treatment of the wheel rim of rail vehicle wheels, characterized in that the tread ring (7) of a first rail vehicle wheel divides into zones, namely the tread zone (19) and wheel flange zone (17) with the hardness zones lying under the tread zone (19) and the wheel flange zone (17) (21) as well as the two tread end face zones (22, 23) adjoining the tread (5) or the wheel flange (4) as well as the tread base zone (20) and these zones depending on those to be achieved on the tread ring (7) Structural structures based on a basic program, divided into thermal phases with volume flow and time control, are acted upon with at least one cooling medium, with - first cooling of the tread zone (19) and the subsequent flange zone (17) starting at the outer profile of the rim (7) up to a depth of 0.5% of the diameter of the rail vehicle wheel (1), which at low cooling speed Windy with a stabilizing formation of a homogeneous pearlitic structure, to form a cooling medium transfer belt (15), which subsequently dampens the cooling effect of the cooling medium that continues to act for heat conduction to the actual hardening process of the underlying hardness zones (21) - at the same time, the two The cooling medium (12, 13) is acted upon by the cooling medium face zones (22, 23) in order to prevent the return flow of heat into the hardening zones (21) in connection with the heat dissipation zone and their influence on the structure already formed in the hardening zones (21), whereby In addition, in the lateral area of the wheel flange (4) there is cooling by means of a cooling medium (14), - after the heat treatment of the first rail vehicle wheel has been completed, the wheel is subjected to a material-technical sample evaluation and from the target-actual comparison with regard to the microstructure The structure and the hardness values for optimizing the heat treatment process are correction values (cooling medium quantities assigned to the thermal phases, the type of cooling medium and the determination of the heat dissipation from the secondary area of the rail vehicle wheel (1) and the speed of the rotary drive of the rail vehicle wheel (1)) for the hardening of a further rail vehicle wheel specified and - the values found in this way are stored in a database and are available for series production of rail vehicle wheels (1) of this special type.

Description

The invention relates to a method for heat treatment of the wheel rim of rail vehicle wheels, in particular of railway wheels.

From the EP 1 215 291 A1 For example, a method of heat treating heated, rotationally symmetrical bodies, such as rail vehicle wheels, from metallic materials is known, in which the body in question is first descaled and then functionalized, defined and reproduced, adjusting mechanical properties (eg, hardness within a hardening process) by means of complex Cooling takes place, which are performed differently for different volume or surface areas of the body to be treated, such that the predetermined areas of the body by spraying or blowing at least one cooling medium (water and / or air) online-controlled or cooled online become. During volume and surface specific cooling, the rotationally symmetric body is rotationally driven about its axis of rotational symmetry and the cooling media are simultaneously sprayed or inflated onto a plurality of the surface areas of the body to be cooled. For this purpose, the rotationally symmetrical body is in a horizontal, position such that its axis of rotational symmetry is vertical, and the cooling medium is applied by a plurality of cooling jets or cooling streams ring or forceps on the surface areas to be cooled. This is done by the fact that the rotationally symmetrical body is coated or lapped at the same time or approximately simultaneously by the cooling streams or cooling jets over its entire circumference at the surface areas to be cooled.

In this case, there is also the possibility that successively different cooling media with different cooling effect, for example air and / or water with hardness additives and / or air-water mixtures are applied to the surfaces to be cooled surface of the rotationally symmetrical body and the supply of the cooling medium time-dependent.

The focus of the volume of the cooling medium supply depending on the temperature of the heated rotationally symmetrical body, in particular its continuously measured surface temperature by means of a Temperaturmeßkamera realized, and thereby made the supply of the cooling medium in dependence of empirically determined Gefügewerte the body time-dependent.

The rotationally symmetrical body is simultaneously cooled during its rotary drive on its top and bottom and on its peripheral surface by the volume flows of the cooling medium, optionally to different surface areas and / or delayed by simultaneously the tread and the Radunter- and the Radoberseite by the cooling medium or the cooling media are acted upon. With the cooling of edge regions and / or the top and bottom of the body, the hub of the rotationally symmetrical body can be cooled by one or more volume flows at the same time.

A disadvantage of this solution is the fact that for the targeted influencing of the desired material properties, the regulation and control of the cooling processes by a corresponding volume for the cooling medium supply, based on the measurement of the surface temperature of the rotationally symmetrical body. This surface temperature can be measured under production conditions but only outside the impact areas of the cooling medium on the rotationally symmetrical body and takes place on the tread-side Laufkranzstirnfäche the rail vehicle wheel. The determined surface temperature is thus not significant for the heat flow taking place in the body cross-section and the resulting qualitative and quantitative material property images of homogeneous microstructure or Brinell hardness (HB). A control of the volume of the required cooling medium supply, which is based on the measurement of the surface temperature during an online operation, is fundamentally not suitable for achieving the desired material properties of the rotationally symmetrical body because it has no relation to the heat conduction in the cross section of the body and is also too sluggish for the Homogeneous perlitic microstructure in a narrow time window.

The object of the invention is to propose a method in which realizes a homogeneous, substantially pearlitic structure over the entire cross section of the rim of the rotationally symmetrical body designed as rail vehicle and at the same time the required strength and hardness values in the wheel rim of the rail vehicle wheel by optimizing the heat dissipation the time and the amount of heat can be precisely adjusted to the functional cross section of the rim. It should be achieved in particular to the inner of the rim towards increasing strength and hardness values.

This object is achieved with the features specified in claim 1.

The advantages of the invention are that targeted in the first zone of the primary area (tread and flange) a cooling medium transfer belt is established, through which the actual hardening process takes place, and the gentle cooling of the geometrically secondary region (both Laufkranzstirnflächen and the Laufkranzboden) a supporting Function in the optimal hardening and structure formation in the primary area belongs. As a result, the complex processes in the structure formation can be reliably influenced so that increasing strength and hardness values can be achieved towards the interior of the wheel rim.

The invention will be explained in more detail below using an exemplary embodiment and associated drawings.

Show it:

1 a sectional view of a rotationally symmetrical body in the form of a rail vehicle wheel

2 a block diagram of the procedure for the heat transfer

three a simplified representation of the Radkranzquerschnittes with the zoning, indicated cooling media streams and hardness testing

4 a diagram of the volume flows for heat dissipation within a curing cycle

5 Table for an exemplary basic program for a railway vehicle wheel in the form of a railway wheel

In the 1 is the heat-treated, station-symmetrical body in the form of a rail vehicle wheel 1 shown. This includes the rail vehicle wheel consisting of a metallic material (eg steel or steel alloy) 1 a hub 2 , their associated sheet three the connection to a wheel flange 4 , a tread 5 and a crawler bottom 6 containing treadmill 7 manufactures, which on both sides of Laufkranzstirnflächen 8th . 9 is limited. For the required heat treatment (hardening process) the rail vehicle wheel becomes 1 around its vertical axis 10 rotationally driven and its surface areas subjected to the setting of reproducible mechanical properties cooling processes in which the surface areas with at least one cooling medium (water and / or air) are applied.

The general requirements for a rail vehicle wheel are defined in the railway standard UCI 812-3.

For a long service life of the rail vehicle wheel 1 it is necessary that the tread 5 has the same or increasing hardness to the wheel interior despite the wear occurring on the surface. The ideal state in this regard is exemplary at the cross-sectional area of the tread 7 with the hardness test lines and the assignment of the hardness values in three and for the hardening process of superficial importance.

For hardening, the blank of the rail vehicle wheel heated to a material-specific hardening temperature (for example, approximately 840 ° C.) is used 1 divided into different areas (geometric zones) for the heat treatment.

Regarding three On the one hand, this concerns those on the treadmill 7 of the rail vehicle wheel 1 located, the primary area representing tread zone 19 and flange area 17 with the under the tread zone 19 and the wheel flange zone 17 lying hardness zones 21 and the two representing the secondary area, to the tread 5 or the wheel flange 4 subsequent tread front zones 22 . 23 as well as the overhead floor zone 20 , as well as the area of the leaf three , the hub 2 with relatively low HB values, these zones being dependent on the treadle 7 volume and time controlled to be achieved with at least one cooling medium to be achieved, which with respect to the tread zone 19 and the wheel flange zone 17 as a mean water volume flow 11 with respect to the tread end face zones 22 . 23 as upper or lower water volume flow 12 . 13 and additionally in the lateral area of the wheel flange 4 as an air volume flow 14 is designed. The control lines 16 include the control zone 18 along which the hardness test points lie at intervals.

This is to realize a homogeneous pearlitic structure over the entire wheel cross-section, except the areas of the hub 2 , of the leaf three and the cooling medium transfer belt 15 , with a precisely adjustable hardness in the tread area 5 performed a thermal phase control. In the areas of the hub 2 and the leaf three There is no active cooling, only free convection.

Starting with a basic program ( 5 ) whose parameters are based on relevant experience in the previous heat treatment on the basis of tests on different wheel cross sections and materials (eg low alloyed steel ER6, ER7, ER8 according to DIN EN 13262) Support rail vehicle wheels, and thus represent universal basic values, the Ersthärtung a new rail vehicle wheel using a hardening machine, as for example from the EP 1 215 291 B1 is known carried out. This is done by a water volume flow 11 (Temperature, for example, 34 to 36 ° C) running cooling medium, first a cooling of the tread zone 19 and the adjacent wheel flange zone 17 starting at the outer profile of the tread 7 to a depth of, for example, about 7 mm (0.5% of the diameter of the rail vehicle wheel 1 ==> 0.5% × 1.460 mm = 7.3 mm), which at low cooling rate under stabilizing, completed at temperatures <620 ° C formation of a homogeneous microstructure, to form a cooling medium transfer belt 15 is carried out, by which subsequently a damping of the cooling effect of the further acting cooling medium for the heat dissipation in the actual hardening process of the underlying hardness zones 21 he follows. This cooling medium transfer belt acts practically as a guard ring and typically has a substantially lower hardness than the underlying areas of the hardness zones 21 , The thickness of this cooling medium transfer belt 15 is about 2 to 7 mm.

The achieved hardness and microstructure in 2 to 7 mm depth of secondary importance, since these areas are removed in the mechanical post-processing. Through this stabilized zone (cooling medium transfer belt), which later undergoes no further structural transformation, the actual hardening process takes place, in which the heat exchange between the amount of heat removed and the internal heat content only via this cooling medium transfer belt 15 at the tread zone 19 and the wheel flange zone 17 he follows.

Due to the design of this cooling media transfer belt 15 from 2 to 7 mm thick and cooled to a temperature of 70 to 200 ° C, heat guides for curing can be achieved using water, which are otherwise accessible only by means of a salt or lead bath.

At the same time the two tread front surfaces 8th . 9 or their Laufranzstirnflächenzonen 22 . 23 (secondary area) with a cooling medium (upper or lower water volume flow 12 . 13 ) to return, in conjunction with the heat dissipation zone, heat from the interior of inactive areas to the hardness zones 21 and their negative influence on the already formed microstructure or the hardness result in the hardness zones 21 to prevent. The primary hardness range is thus procedurally of refluxing heat in particular from the Laufkranzstirnflächen 8th . 9 unaffected.

With the greatest possible provision of the water volume flow 11 in this area will be the cooling of the wheel 1 completed and short cycle times are reached. Without this supportive heat dissipation, it is not possible to reliably achieve the maximum possible hardness in the zones in the relevant areas 21 to produce a homogeneous structure or would significantly higher amounts of cooling media in the tread area necessary, which lead to an exact control hardness / Gefügeverhaltnisses is impossible. Additionally takes place in the lateral area of the wheel flange 4 the cooling by an air flow 14 ,

In the 2 is the basic procedure for the heat transfer starting from the curing machine, as for example from the EP 1 215 291 B1 is known, with its actuators, the cooling medium quantity control and nozzle settings, the associated control with the modular options with regard to the effect on the thermal phases and geometric areas associated with the rail vehicle wheel and associated database for storing and calling wheel-specific program parts.

With a new rail vehicle wheel, the first rail vehicle wheel hardening is carried out with a basic program.

After the heat treatment of the first railway vehicle wheel has been completed by hardening, the wheel is subjected to a material-technical sample evaluation, metallographic and mechanical test values, with regard to microstructure, hardness test values, tensile test values and impact test results. The target / actual value comparison is carried out and from this the correction values for the manipulated variables for the geometric and thermal ranges are determined. In detail, it is the cooling medium dosing with respect to the thermal phases and geometric areas, the type of media, the design of heat dissipation from the secondary wheel areas, as well as the speed of the rotary drive of the rail vehicle wheel 1 ,

These parameters and setting values are stored in the specific wheel program and provided for the 2nd heat control on the next rail vehicle wheel. If evaluated positively, the data from the database is available for mass production.

It is the property of the rail vehicle materials that the quality of the structure formation and, associated with it, the mechanical properties at constant heat transfer according to the process 4 for the hardening process is quality-appropriate and clearly reproducible.

The determination of the required quantities required for heat dissipation is defined individually according to wheel type, size, material, geometry of the cross-sectional profile and with regard to the given properties as well as to the properties, microstructure and associated hardness values required in the wheel areas.

The values thus found are stored in a database and are available for series production of rail vehicle wheels of this special type.

The representation of the water and air volume flows 11 . 12 . 13 . 14 and their assignment to the rail vehicle wheel are over the heat treatment time in the 4 Therein, the design of the heat dissipation by the cooling media in a characteristic curve as a function of the cooling medium amounts and type over time with the division into thermal phases (phase 1 to 3) is reproduced.

Determining the hardness is the heat dissipation per unit time, d. H. the volume flow of the acting cooling medium.

The correction values required after the sample evaluation for setting the desired microstructure and hardness values of the wheel rim 7 are from the diagram ( 4 ) in the area of the zone 2 on both sides in the direction of the dotted line extending, drawn through solid lines. A very steep increase in the straight line causes a high hardness, a flat rise guarantees a homogeneous structure.

• – Phase 1 = Bildung des Kühlmediumübertragungsbandes,
• – Phase 2 = Härtevorgang,
• – Phase 3 = Wärmeableitung aus dem bereits gehärteten Bereich, die Informationen zum Anfahr-, Verlaufs- und Endverhalten aufweisen.

This diagram is divided into thermal phases

• Phase 1 = formation of the cooling medium transfer belt,
• - Phase 2 = hardening process,
• - Phase 3 = heat dissipation from the already hardened area, which has information on start-up, progress and end behavior.

LIST OF REFERENCE NUMBERS

1

Railway vehicle

2

hub

3

leaf

4

flange

5

tread

6

Tread ground

7

tread

8th

Tread face

9

Tread face

10

axis

11

mean water volume flow

12

upper water volume flow

13

lower water volume flow

14

Airflow

15

Coolant transfer belt

16

Control line for the hardness test points

17

Flanged zone

18

Control zone with lines along which the hardness test points lie at intervals

19

Tread zone

20

Tread soil zone

21

Hardiness zones

22

Tread face zone

23

Tread face zone

Claims (1)

Process for the heat treatment of the wheel rim of railway vehicle wheels, characterized in that the raceway ( 7 ) of a first rail vehicle wheel in zones, namely the tread zone ( 19 ) and wheel flange zone ( 17 ) with the under the tread zone ( 19 ) and the wheel flange zone ( 17 ) hardening zones ( 21 ) as well as the two, to the tread ( 5 ) or the wheel flange ( 4 ) subsequent tread end face zones ( 22 . 23 ) as well as the running floor zone ( 20 ) and these zones depending on the tread ( 7 ) to be achieved microstructures on the basis of a basic program, divided into thermal phases volume flow and timed with at least one cooling medium are applied, wherein - at first a cooling of the tread zone ( 19 ) and the subsequent wheel flange zone ( 17 ) starting at the outer profile of the tread ( 7 ) to a depth of 0,5% of the diameter of the rail vehicle wheel ( 1 ), which at low cooling rate with stabilizing formation of a homogeneous pearlitic structure, to form a cooling medium transfer belt ( 15 ) is carried out, by which subsequently a damping of the cooling effect of the further acting cooling medium for heat conduction to the actual hardening process of the underlying hardness zones ( 21 ), - at the same time the two tread end face zones ( 22 . 23 ) with the cooling medium ( 12 . 13 ) in connection with the heat dissipation zone, the return flow of heat into the hardness zones ( 21 ) and their influence on the already formed microstructure in the hardness zones ( 21 ), in addition in the lateral region of the wheel flange ( 4 ) a cooling by means of a cooling medium ( 14 ) takes place, - after the completed heat treatment of the first rail vehicle wheel, the wheel of a material technology sample evaluation from the target / actual comparison with regard to the microstructure and the hardness values for optimizing the heat treatment process, correction values (cooling medium quantities assigned to the thermal phases, the cooling medium type and the determination of the heat dissipation from the secondary region of the rail vehicle wheel ( 1 ) and the speed of the rotary drive of the rail vehicle wheel ( 1 )) for the hardening of another rail vehicle wheel and - the values thus found are stored in a database and stand for a series production of rail vehicle wheels ( 1 ) of this special type.

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