EP0757110B1 - Method for heat treating railway track elements - Google Patents

Abstract

The heat treatment of a track element which is heated over its entire length and then cooled in a coolant bath in such a way that, if necessary, the element is dipped - with its head portion leading - partially and with interruptions into the bath. According to a predetermined time sequence, the element is alternatingly dipped completely and partially into the coolant bath.

Description

The invention relates to a method for tempering a track part, in particular Turnout part like spring tongue or centerpiece over the entire cross-section, the track part preferably has changing cross-sectional shapes along its length.

A method for the heat treatment of rails can be found in WO 94/02652. Around The rail becomes an undesirable hardening of the much thinner webs partially immersed in a coolant bath containing synthetic additives with her head, while the rail foot is cooled with compressed air and / or a water-air mixture becomes. With such a process, desired hardness or hardness distributions can be achieved in the rail head can be achieved because the splint is the same over its entire length in the head area Has cross sections.

To achieve a fine pearlitic structure in the head area of a rail, according to the EP 0 088 746 A1 the rail head using a cooling medium from an in the austenite area lying temperature cooled to a temperature at which the pearlite transformation is completed. Water with synthetic coolant is used as the cooling medium like polyglycol used. DE-C 582 957 also describes a process for tempering known from railroad tracks, in which only the head once in a coolant is immersed.

In order to compensate for track parts with changing cross-sectional shapes, especially switch parts, In order to achieve a fine pearlitic structure, it is known from DE 25 41 978 C3 the switch part to the austenitizing temperature by means of a burner or inductor heat and then press air only from above onto the switch parts standing on the foot to blow, the width of the compressed air jet at least the size and width of the switch part corresponds. After completing the pearlite transformation, the switch part can be added be quenched with water.

DE-C-262 970 describes a method and an apparatus for achieving various Degrees of hardness and toughness of elongated objects are known. To do this, the subject passed through various baths of oil and water.

DE-A 28 20 784 shows a method for producing rails, at which the rail head should be hardened. There is the Possibility of completely or solely in the head area in a coolant immerse, which has aggregates to the heat transfer from the rail to the Increase bath.

According to DE-C-826 304, in order to harden rail tracks, that the rail is immersed in coolant only in the area of its elevation becomes. In order, if necessary, to change the course of the hardness along the rail achieve, there is the possibility of immersing the rail in a coolant at an incline.

To z. B. to harden Vignol rails or rods, DE-C-396 946 provides that the curing object is immersed several times in a cooling bath.

The present invention is based on the problem of a method as described in the introduction Kind in such a way that track parts in particular along with their length changing cross-sectional shapes over the entire cross-section to a desired structure such as preferably fine pearlitic training can be reproducibly remunerated.

• Erwärmen und Halten des Gleisteils auf Austenitisierungstemperatur,
• Eintauchen des Gleisteils in ein mit Wasser mischbares synthetisches Medium enthaltendes Kühlmittelbad allein im Kopfbereich über eine Zeit t₁,
• anschließendes vollständiges Eintauchen des Gleisteils über eine Zeit t₂,
• anschließendes erneutes Eintauchen des Gleisteils allein in seinem Kopfbereich über eine Zeit t₃,
• anschließendes Herausnehmen des Gleisteils aus dem Kühlmittelbad,
• anschließendes Anlassen des Gleisteils und
• schließlich Kühlen des Gleisteils.

According to the invention, the problem is solved by the method steps:

• Heating and holding the track part to the austenitizing temperature,
• Immersing the track part in a coolant bath containing water-miscible synthetic medium alone in the head region for a time t ₁ ,
• Subsequent complete immersion of the track part over a time t ₂ ,
• Subsequent immersion of the track part alone in its head area over a time t ₃ ,
• then removing the track section from the coolant bath,
• then starting the track section and
• finally cooling the track section.

The teaching according to the invention makes the cooling rate more uniform about the cross section of the track part, with an adaptation to different cross-sectional shapes this is done in that the track part alternately in cyclical sequence or completely and / or inclined in the coolant. Hereby conditionally the desired equalization of remuneration takes place across the entire cross-section, so that voltage differences are largely avoided without the There is a risk that undesired hardening will occur in the areas of the track part. in which there are reduced cross sections compared to the head area.

Through the teaching of the invention, rail parts, in particular switch parts, are in their Travel areas, whereby finished machined track parts are heat treated. After Remuneration is then only necessary that necessary holes are drilled or for example a spring point is milled.

If necessary, the tab chambers can be equipped with compensation tabs and / or inorganic products such as concrete to be filled in these critical areas to prevent undesirable cooling speeds of the track part.

The cooling process is followed by a tempering treatment for targeted microstructure adjustment.

The necessary straightening processes are used to avoid changes in tension and structure performed at elevated temperatures.

a) Eintauchen des Gleisteils allein mit seinem Kopfbereich über eine Zeit t₁,

b) vollständiges Eintauchen des Gleisteils über eine Zeit t₂,

c) Eintauchen des Gleisteils allein mit seinem Kopfbereich über eine Zeit t₃ und anschließendes Herausnehmen des Gleisteils aus dem Kühlmittelbad oder vorheriges ein- oder mehrmaliges Wiederholen der Tauchschritte b) und c), wobei gegebenenfalls dem Tauchschritt a) ein vollständiges Eintauchen des Gleisteils in das Kühlmittelbad vorausgeht.

In particular, the method according to the invention can be used for a switch part made of rail steel of quality 900A or 1100A according to UIC conditions. In order to achieve a fixed and fine pearlitic or martensitic structure, the track part is heated to austenitizing temperature T _II , kept at temperature T _II for a time t _II , then cooled by being immersed in a coolant bath, the track part being repeated several times both with its head area as well as completely immersed in the coolant bath, and then held at a tempering temperature T _V of approximately 400 ° C T T _V 600 600 ° C for a period t _V of preferably 1 h t t _V gegebenenfalls 3 h and then optionally at a temperature T _VI ≤ T _V , preferably T _VI ≤ 300 ° C. In particular, the track part is subjected to the immersion steps with regard to the cyclical complete or partial immersion in the coolant bath:

a) immersing the track part alone with its head area over a time t ₁ ,

b) complete immersion of the track part over a time t ₂ ,

c) immersing the track part alone with its head area over a time t ₃ and then removing the track part from the coolant bath or repeating the immersion steps b) and c) one or more times beforehand, with the immersion step a) possibly completely immersing the track part in the Coolant bath precedes.

The immersion times t ₁ , t ₃ , ... t _n-2 , t _n can be selected so that the track part is specifically cooled over its entire cross-section such that t ₁ ≤ t ₃ and / or t ₃ ≤ t ₅ and / or t _n-2 ≤ t _n , in particular t ₁ <t _n . In this way, necessary predetermined structures are reproducibly achieved.

In particular, the heat or heat treatment according to the invention can be used for a track part made of rail steel of a quality such as S 1100V or 900A or 1100 according to UIC 860V with a directional analysis of, for example
0.53 - 0.62% C, 0.15 - 0.25% Si, 0.65 - 1.1% Mn, 0.8 - 1.3% Cr, 0.05 - 0.11% Mo, 0.05 - 0.11% V, ≤ 0.02 P, optionally up to 0.025 Al, optionally 0.5% Nb, residual iron as well as common contamination caused by melting.
or
0.73 - 0.79% C, 0.86 - 0.99% Mn, 0.21 - 0.32% Si, 0.07 - 0.025% P, 0.08 - 0.022% S, 0.02 - 0.14% Cr and 0.000% Nb as well as residual iron and common melting-related impurities.

Further details, advantages and features of the invention result not only from the Claims, the features to be extracted from these - individually and / or in combination -, but also from the following description of the drawings preferred embodiments.

Fig. 1

ein Temperatur-Zeit-Diagramm einer Wärme- bzw. Vergütebehandlung einer Flügelschiene,

Fig. 2

einen zeitlichen Verlauf eines Abschreckprozesses der Flügelschiene bei der Wärme- bzw. Vergütebehandlung nach Fig. 1,

Fig. 3

ein Temperatur-Zeit-Diagramm einer Wärme- bzw. Vergütebehandlung eines geschweißten Herzstücks,

Fig. 4

einen Abschreckprozeß des geschweißten Herzstückes während der Wärme-bzw. Vergütebehandlung gemäß Fig. 3 und

Fig. 5 - 7

Prinzipdarstellungen einer teilweise bzw. vollständig in einem Kühlmittelbad eingetauchten Weichenzunge.

Show it:

Fig. 1

a temperature-time diagram of a heat or heat treatment of a wing rail,

Fig. 2

1 shows a time course of a quenching process of the wing rail in the heat or heat treatment according to FIG. 1,

Fig. 3

a temperature-time diagram of a heat or heat treatment of a welded core,

Fig. 4

a quenching process of the welded core during the heat or. Treatment according to FIG. 3 and

5 - 7

Schematic diagrams of a switch tongue partially or completely immersed in a coolant bath.

In order to achieve a predetermined, such as fine pearlitic (steel of grade 900A) or martensitic (steel of grade S 1100V) structure over the entire length of a track part with different cross-sectional areas, the track part - preferably several corresponding track parts at the same time - is preferably lying on its head the entire length is heated, for example in a gas-heated tempering furnace, to an austenitizing temperature T _II at a controllable rate and is kept at this temperature for a predetermined time. The temperature T _II can be adjusted over a wide range of the steel brand used. Temperatures T _II between approximately 850 ° C and 900 ° C are possible.

Then all the track parts are removed from the tempering furnace and it takes place controlled immersion of the track parts in a quenching bath downstream of the tempering furnace, in which there is a water-miscible synthetic cooling medium. In doing so the track parts are subjected to a cyclical cooling process in such a way that the rail parts alternately partially or completely immersed in the coolant bath. The The cooling process itself is like monitoring and limiting the process parameters Concentration and temperature of the cooling medium, immersion cycle, immersion depth etc. certainly.

After the controlled cooling, a transformation into a given structure over the entire length of the track, all track parts are removed from the coolant bath removed and the track parts are placed again in an oven for a tempering treatment to be able to perform. This will make everyone Structure components, which may be due to cross-section due to different cooling conditions can occur, adapted to the given structure. Then a judge the track parts from the tempering heat in a temperature range depending on the steel brand respectively. This temperature range can be just below 300 ° C, for example.

Around the given structure at least in the driving range, preferably over the entire range Achieving cross-section of the track is a controlled quenching process according to the invention performed below, causing the cooling speed of the track part over its entire cross-section is evened out. To do this also in the dock area of the To ensure track parts can be arranged in these pairs of compensation tabs.

1 and 2, the heat treatment method according to the invention is to be based on a welded one Centerpiece. The centerpiece was made of high quality rail steel 900A according to UIC conditions.

Even if several corresponding welded frogs are tempered at the same time should, i.e. are heated, quenched, tempered and cooled at the same time always spoken below of a centerpiece or track part.

In the temperature-time diagram of FIG. 1, the rising edge I is intended to illustrate the heating of the track part to the austenitizing temperature. After reaching the austenitizing temperature, the track part is held at austenitizing temperature T _II for a predetermined period of time, in order then to be immediately quenched in a coolant bath, as a result of which the desired conversion into the predetermined structure takes place. This area is marked III in the diagram according to FIG. 1. This is followed by starting (flank IV) in order to then hold the track part over a period of time T _V , which can be, for example, 1-2 hours. This is followed by cooling in still air (falling flank VI), which may require straightening of the track part. This can be carried out in a temperature range that is just below 300 ° C.

According to the invention, the welded heart is cyclically partially or completely into one coolant bath (10) containing water-miscible synthetic medium in a targeted manner submerged that a desired even cooling with the cross section of the centerpiece he follows.

In order to clarify the time sequence, the diving cycles are shown by a solid line in FIG Line (120) symbolizes that with respect to the frog cross-sectional representations (12), (14), (16), (18) runs in such a way that the centerpiece either only in its head area or is completely immersed in the coolant bath (10). The cross sections (12), (14), (16) and (18) should further clarify that the centerpiece is always along its entire length completely or partially (head area) is immersed in the coolant bath (10).

In the embodiment shown in FIGS. 1 and 2, the track part is first immersed only with its head region over a period t ₁ . Over a subsequent, but shorter period of time t _{2, the track part} is completely immersed. Then the track part is partially lifted out of the coolant over a period t ₃ with t ₃ ≥ t ₁ in order to again cool only the head region in the coolant bath (10). This is followed by a period of time t ₄ , in which the track part is completely immersed, followed by an immersion of the head area alone over a period of time t ₅ ≥ t ₃ . The entire track part is immersed in the coolant over a time t ₆ with preferably t ₂ = t ₆ > t ₄ , in order then to remain in the coolant only with its head region over a time period t ₇ . After the time interval t ₇ is removed from the track member completely out of the coolant bath (10), to heat to a temperature T _v and for starting to be held at this tempering temperature T _{v v} over a period t. T _v can be between 400 and 550 ° C. The period t _v can be 1-2 hours. This creates the specified structure and a tension compensation across the cross section.

3 and 4, a heat treatment of a wing rail (22) from a Material S 1100V can be clarified in principle, with regard to heating up Austenitizing temperature, holding to austenitizing temperature, tempering and cooling in principle a process - even if it differs in time and temperature - takes place, which corresponds to that which has been illustrated with reference to FIGS. 1 and 2.

On the track part, i.e. adapted in the present case to the wing rail (22), but takes place a different chronological sequence of the quenching (edge III in FIG. 3), as in FIG. 4 clarifies.

Thus, the wing rail (22) is first initially over a time period t ₀ completely into the coolant bath (10) immersed in order to then via one of the time duration t ₀ corresponding time t ₁ alone head in the coolant bath (10) to leave. This is followed by the complete or partial immersion of the wing rail (22) over the same time sequences t ₂ t ₃ and t ₄ , and then over a period of time compared to the periods t ₀ or t ₁ or t ₂ or t ₃ and t ₄ t ₅ considerably longer period of time to leave the head of the wing rail (22) in the coolant bath (10) alone. The coolant bath (10) is then removed in order to leave the wing rail (22) on - in accordance with the procedure shown in FIG. 1. This is followed by cooling in still air (flank VI), whereby the wing rail (22) can be straightened. This temperature range can be just below 300 ° C.

Has been clarified with reference to FIGS. 1-4 that the track parts either only in their Head area or completely immersed in the coolant bath (10) in a certain time sequence 5 - 7 - there is also the possibility of a Track part such as a switch tongue (24) inclined to the surface (26) of the coolant bath (10) to immerse in addition to significantly different cross-sectional areas along the switch tongue (24). For example, according to FIG Switch tongue (24) more immersed in the area of its end (28) than in the area of its Initially (30). After complete immersion (Fig. 6) there is then another Pulling the switch tongue (24) out of the coolant bath (10), the beginning (30) the switch tongue (24) completely, but the end (28) still within the coolant bath (10) runs. Regardless of this, however, there is an immersion sequence based on the principle ago corresponds to that of FIGS. 2 and 4.

Claims (9)

1. Process for hardening a track part, in particular a point mechanism part such as flexible tongue or cross frog, over the entire cross-section, the track part preferably having changing cross-sectional shapes along it length, characterised by the process steps:

   heating the track part to and holding it at austenitising temperature,

   dipping the top region only of the track part in a coolant bath containing synthetic medium which can be mixed with water over a time t₁,

   subsequent complete dipping of the track part over a time t₂,

   subsequent repeated dipping of the top region only of the track part over a time t₃,

   subsequent removal of the track part from the coolant bath,

   subsequent annealing of the track part and

   finally, cooling of the track part.
2. Process according to claim 1, characterised in that complete dipping of the track part and dipping of the top region only of the track part is repeated several times in succession.
3. Process according to claim 1, characterised in that the track part is aligned after the annealing treatment, preferably at a temperature T_VI such as 250 ≤ T_VI ≤ 300°C.
4. Process according to claim 2, characterised in that with multiple dipping at intervals of the top region only of the track, the dipping of the top region is shorter at the start of the cooling process than at the end of the cooling process.
5. Process according to one of the preceding claims, characterised in that only dipping of the top region of the track part takes place calculated from the start of the cooling process over intervals t₁, t₃, t₅, t₇, t_n-2, t_n, wherein t₁ ≤ t₃ and/or t₃ ≤ t₅ and/or t_n-2 ≤ t_n, but in particular t₁ < t_n.
6. Process according to one of the preceding claims, characterised in that the track part is partially or completely dipped into the coolant bath, at an inclination to the coolant bath surface as viewed in the longitudinal direction.
7. Process according to claim 1, intended for a point mechanism part made of rail steel of 900 A or S 1100 V or 1100 grade to UIC requirements.
8. Process according to claim 7, characterised in that the track part is aligned at a temperature T_VI before complete cooling.
9. Process according to claim 8, characterised in that the point mechanism part is held at austenitising temperature T_II over a time t_II where 10 min ≤ t_II ≤ 30 min and/or at an annealing temperature T_V of approximately 400° ≤ T_V ≤ 600°C over a period t_V of approximately 1 h ≤ t_V ≤ 3 h and is preferably aligned at a temperature T_VI of approximately 300°C.

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