CN105779745A

CN105779745A - Technology and device for heat treatment of rail

Info

Publication number: CN105779745A
Application number: CN201410773434.5A
Authority: CN
Inventors: 范勤德
Original assignee: Qingdao Qinde Rigging Hardware Co Ltd
Current assignee: Qingdao Qinde Rigging Hardware Co Ltd
Priority date: 2014-12-13
Filing date: 2014-12-13
Publication date: 2016-07-20

Abstract

The invention discloses a technology for online heat treatment of a rolled rail. The technology guarantees that a uniform and fine pearlite structure is obtained in the whole pre-determined surface thickness of the head of the rail. The invention further discloses a novel device for heat treatment of the rail on the same line as a rolling system. Compared with a known device, the novel device is of a simpler structure, has high solidity and needs little maintenance.

Description

The process of thermal treatment of track and device

Technical field

The present invention relates to the heat treated technique on line of track for rolling, described technique is for improving the mechanical property of at least one surface layer of track head, and relate to the heat-treating apparatus of track, more particularly to the heat-treating apparatus on line being used for the track discharged from rolling system.

Background technology

Include the heat-treating apparatus of track for rolling and the different solution of technique at known technology, these devices and technique make head harden more particularly to by hardening step.

Many in these devices do not arrange on one wire with rolling-mill housing (rollingstand).This means that the grain bin of the track rolled before carrying out quenching heat treatment is put the heating follow-up with it and had considerable energy expenditure and poor efficiency.

In other system, alternatively, these devices arrange along roll line: the track of rolling is discharged in the roller tables (rollertable) being fixed on ground；Then, track is taken out by operator, and aforesaid operations device includes the lever system of precision, and controls the manipulation of track during track stands heat treatment；And track is launched eventually through suitable ejection mechanism to cooling bed or plate.

Heated or directly from milling train track injects, by using, the injection nozzle cooling down fluid (water, air or the water mixed with air) on track head, or stands quick cooling by being immersed by track head in the tank holding cooling fluid.

When using injection nozzle, due to the non-uniform temperature in some part of track and due to follow-up different thermal expansion, it may appear that the defect that track distorts in the longitudinal direction.

Although in any case, the temperature difference between base portion and the head cooled down of hot orbit results in the bending of track, but when alternatively using steeping tank, it is achieved that better cool down homogeneity in the longitudinal direction；The rigidity that shortcoming is the operator adopted is not enough, and is insufficiently resistant to and suppresses described bending.Another disadvantage is that of such operator, during processing, operator, all the time at identical fulcrum and rail contact, therefore produces less desirable lightpenia territory on track itself.

Summary of the invention

The main purpose of the present invention is the heat treated on line new technology of the track obtaining rolling, described new technology guarantees to obtain homogeneous fine pearlitic texture in the whole predetermined surface thickness of track head, due to the toughness improved, this track is particularly suitable for the use in perishing environment.

Another object of the present invention is to obtain the heat-treating apparatus for track, described device and rolling system placement into a line, compared with existing device, simple on this apparatus structure, has high robustness, and needs less maintenance.It is contemplated that by providing the process of thermal treatment on line of the track for discharging from rolling system to realize purpose disclosed above, described technique comprises the following steps:

Aerial first cooling step of track, until the surface temperature of track head reaches at least 720 DEG C；By cooling down the second cooling step of fluid, until the surface temperature of track head reaches higher 50 DEG C to 150 DEG C than Ar3 temperature, to avoid from austenite to the phase transformation of pearlite；

Aerial 3rd cooling step with the predetermined persistent period, by the 3rd cooling step, surface temperature balance is until the temperature of surface layer of track head, and described surface layer has the degree of depth of the scope between distance surface 15mm to 25mm；

By cooling down the 4th cooling step of fluid, until the surface temperature of track head reaches, lower than 500 DEG C, by the 4th cooling step, to occur from austenite to the phase transformation of pearlite；

Wherein said pearlite has the homogeneous structure with fine granularity in described surface layer.

Another aspect of the present invention provides the heat-treating apparatus on line for the track discharged from rolling system, and described device includes at least one moveable chassis, and described moveable chassis then includes:

Longitudinal roller tables, described roller tables includes roller pair, and roller, to being suitable for receiving, along rolling axle, the track discharged from described system, keeps the rolling position of track, and the longitudinal axis that described roller tables is suitable for around being parallel to rolling axle rotates, so that track head is downward；And the tank of longitudinal direction, described longitudinal tank is used for holding cooling fluid, and track head can be soaked in cooling fluid.

Advantageously, the inventive system comprises at least one roller tables, described roller tables allows preferably along roll line guide rail, thus the position that maintenance is identical from the position that last rolling-mill housing is discharged with track, namely the axis of symmetry of track is maintained at substantially horizontal position.Identical roller tables also provides for the firm support to track, during heating treatment unloads on the cooling plate to the manipulation of track and by track.Therefore, perform all these functions in the way of different from traditional roller tables according to the roller tables of assembly of the invention, and traditional roller tables, alternatively, only for transporting the track of rolling, and it is thus desirable to combine with special operator device.

The further advantage of assembly of the invention shows as described device and provides two roller tables with wheel, and roller tables is alternately and to be axially directed at roll line, it is allowed to two tracks almost while heat treatment, improve the volume of production of described system.By this way, compared with the volume of production using known device to realize, it is achieved that the volume of production of twice, and there is the rolling speed of scope between 8m/s to 10m/s.

Advantageously, it is immersed in tank by the whole length of track to guarantee the uniformity processed, rigidity due to this device, the thermal deformation of track is substantially avoided or is reduced to minimum, and also ensure that the greater flexibility of manipulation to last cooling step, last cooling step is most important for obtaining final desired structure.The result of fine pearlitic grain depends on the cooldown rate in this final step and depends on the deformation of the material obtained in rolling-mill housing.It is therefore preferable that high cooldown rate, high cooldown rate causes less desirable bainite and/or the formation of bainite-sorbite structure in no instance.

Process according to the invention advantageously provides four cooling steps, and two of which passes through air and two water passing through to have additive or by other suitable cooling liquid.The head of the track obtained by this technique shows following character: high rigidity (340-420HB)；High-wearing feature；Enough toughness；High fatigue durability；Mechanical property mentioned above is kept at low-down operation temperature (until-600 DEG C)；At least homogeneous fine pearlite structure of the degree of depth of 15-25mm；When process terminates, the good surface quality of track and good glacing flatness；It is absent from crizzle.

Detailed description of the invention

The process of thermal treatment on line of the track for discharging from rolling system realizes purpose disclosed above, and described technique comprises the following steps:

Claims

1. a process of thermal treatment on line, the heat treatment on line of this technique track for discharging from rolling system, described technique comprises the following steps: aerial first cooling step of track, until the surface temperature of track head reaches at least 720 DEG C；By the second cooling step that described track head soaks in the tank holding cooling fluid, until the surface temperature of track head reaches higher 50 DEG C to 150 DEG C than Ar3 temperature, to avoid from austenite to the phase transformation of pearlite；Aerial 3rd cooling step with the predetermined persistent period, by described 3rd cooling step, the heat of internal layer by surface layer tempering until the temperature of 720-840 DEG C, and described surface temperature balance is until the temperature of surface layer of track head, and described surface layer has the degree of depth of the scope between distance surface 15mm to 25mm；By the 4th cooling step that described track head soaks in the tank holding described cooling fluid, until the surface temperature of track head reaches, lower than 500 DEG C, by described 4th cooling step, to occur from austenite to the phase transformation of pearlite；Wherein, the cooldown rate in described 4th cooling step is equal to 2-7 DEG C/s；And wherein, described pearlite has the homogeneous structure with fine granularity in described surface layer, obtain homogeneous mechanical property hence along described surface layer.

2. technique according to claim 1, it is characterised in that described 3rd cooling step is undertaken by being taken out from described tank by track head.

3. one kind is used for heat-treating apparatus on line, the heat treatment on line of the described device track for discharging from rolling system, described device is adapted for carrying out the technique described in claim 1, described device includes at least one moveable chassis, described moveable chassis includes: longitudinal roller tables, it is placed against the outlet of described rolling system and includes roller pair, described roller is to having the profile being endowed shape consistently to receive along rolling axle with waist-end juncture area, guide and clamp the track discharged from described rolling system, keep the rolling position of described track, the longitudinal axis that described roller tables is configured to around being parallel to rolling axle rotates, so that track head is downward；And the tank of longitudinal direction, it is used for holding cooling fluid, and track head can be immersed in cooling fluid, and described longitudinal tank has the longitudinal extent of the longitudinal extent at least equal to track, and is arranged on the base portion of described chassis.