perkeretaapian.com

Jendela Ilmu Pengetahuan dan Informasi Perkeretaapian Global untuk Masa Depan Mobilitas yang Lebih Baik

Columnists

Bordeaux Tramway

Posted by mikeefos August 11, 2011 Bordeaux ...

The path to exemplary ...

The path to exemplary working efficiency ...

Freight train from ...

Freight train from Zhenzhou to Europe container ...

LRT Palembang ...

Senin, 13 Agu 2018 08:46 WIB LRT Palembang ...

High-Speed Rail

High-speed rail (HSR) is a type of passenger rail ...

Features

Move Over Metro

Move Over MetroBy Troy Turner ...

futuristic australian train

Futuristic Australian Train ...

Guillemins TGV Railway ...

Guillemins TGV Railway ...

"The Future Tramway" designed ...

"The Future Tramway" designed ...

Infrastruktur

Flash-butt Welding

The welding process is in principle a regulated electric short circuit with the two rail ends functioning as D.C. poles. The high current produces an arc between the rail ends, the two rail cross-sections are heated to melting temperature due to the high input of current.

During the following upset stroke the rails are pressed together under high pressure causing the ends to coalesce. The upset metal is trimmed off immediately after the upset stroke.

The result is an  accurate weld without filler metal with a very small heat-affected zone and a more or less consistent progression of the hardening process with a favourable crystal-line structure.

Mobile flash butt welding2http://www.railsystem.net/wp-content/uploads/2015/06/Mobile-flash-butt-welding2-300x140.png 300w" sizes="(max-width: 608px) 100vw, 608px" width="608" height="284">

flash butt weldinghttp://www.railsystem.net/wp-content/uploads/2015/06/flash-butt-welding-300x140.jpg 300w" sizes="(max-width: 608px) 100vw, 608px" width="608" height="284">


Preparing the weld – the slight inclination

Due to the shape of the rail, there is an irregular distribution of material over the cross-section. Due to the effect of the electric current during flash-butt welding the rail is heated up to melting temperature. Consequently the rail does not cool down uniformly over the entire cross-section. The rail foot and the rail base cool down first.

Animation_of_flashing_operation_in_Flash_Butt_Welding

Because the largest proportion of material is in the rail head, this cools down far more slowly. The natural consequence is a depression of the rail in the area of the welded joint.

However, this result would have very negative effects on the track geometry and the operational safety. For this reason, a slight upward inclination of the two rail ends is performed, adapted to the respective rail profile, so that an ideal position of the rail is achieved when the weld has cooled down.


Flash Butt Welding & Alumino Thermic Welding

a) Alumino Thermic Welding

– Strength of AT joint is app. only 56% of parent rail.
– More prone to corrosion
– High failure rate.
– Poor Quality of Weld.

b) Flash Butt Welding

– Strength of FB joint is almost equal to parent rail.
– Less prone to corrosion
– Failure rate < 10 %.
– Excellent Quality of Weld. The defects like porosity, inclusions and lack of fusion are eliminated.


Mobile Flash butt welding Machine

– It is rail cum road machine that can be driven to site.
– The mobile Flash butt welding machines are either built in Standard railway vehicle or as containerized units.
– In case of m/c built on Railway Vehicle the welding head is Positioned between the bogies and can be lowered for welding in running track..
– The containerized units can be used for welding in track or on cess on the other hand the standard vehicle machine can be used only on running line.
– New machine is fully computerized.
– Once the welding head is in position, the entire process is carried out automatically at the push of button.


Welding Parameters

– Welding current,
– Upset force Pressure,
– Displacement,
– Welding time,
– Programmed identification and setting details.


Procedure Approval Tests

1) Weld Trimming
2) Weld alignment
3) Weld appearance.
4) Non-Destructive testing
5) Bend testing
6) Fatigue Testing
7) Macro Examination
8) Hardness testing
9) Statements of the result and procedures.
10) Maintenance of the records


Sources; Today published by Plasser & Theurer, indianrailways.gov.in


Related Standard;  BS EN 14587-2 – Railway applications. Track. Flash butt welding of rails.


Videos; 

Buffer Stop

A buffer stop or bumper is a device to prevent railway vehicles from going past the end of a physical section of track. The design of the buffer stop is dependent in part upon the kind of couplings that the railway uses, since the coupling gear is the first part of the vehicle that the buffer stop touches.


1- Friction Buffer Stops

The purpose of a friction buffer block is to secure the track end and its direct surroundings as well as the rail vehicles themselves. If the brakes fail, the buffer stop should be designed to decelerate the vehicle safely and in controlled manner until it stops.

50fa78b42ae819261ddb927837bde84bhttp://www.railsystem.net/wp-content/uploads/2015/04/50fa78b42ae819261ddb927837bde84b.jpg 468w" sizes="(max-width: 550px) 100vw, 550px" width="550" height="264">

If a single friction buffer stop is not sufficient due to the high kinetic energy of the potential impact of a vehicle, additional brakes are needed which increase the braking force in steps in case of an impact. In view of the high braking forces in such a case and to prevent damage to the track, a reinforcement of the track is required in many cases.

typ-10-eb_refer_400x0http://www.railsystem.net/wp-content/uploads/2015/04/typ-10-eb_refer_400x0-300x116.jpg 300w" sizes="(max-width: 550px) 100vw, 550px" width="550" height="213">


2- Fixed Buffer Stops

a- Fixed Buffer Stop With Hydraulic Dampers  
In tracks with space only for a fixed buffer stop the buffer effect can be improved by a braking device on buffer level. The braking devices can be mechanical or hydraulic, however, their kinetic energy absorption capacity is limited. Fixed buffer stops without the possibility of kinetic energy absorption merely mark the end of the track

43e7cfdbb01b14bb384e5b9b933b3fbbhttp://www.railsystem.net/wp-content/uploads/2015/04/43e7cfdbb01b14bb384e5b9b933b3fbb.jpg 468w" sizes="(max-width: 550px) 100vw, 550px" width="550" height="264">

Fixed buffer stops with hydraulic dampers can be fastened to the track end in different ways:

  • by clamps at the rail head (no drilling of rail)
  • by bolting to the rail web
  • by fastening to an available concrete foundation or plinth
  • by fastening to an available concrete wall

Advantages over friction buffer stops include smaller footprint area and maintenance-free dampers; drawbacks are lower energy absorption capacity and higher cost.

typ-hydaulic_hsl_toledo_400x0http://www.railsystem.net/wp-content/uploads/2015/04/typ-hydaulic_hsl_toledo_400x0-300x125.jpg 300w" sizes="(max-width: 550px) 100vw, 550px" width="550" height="228">

b- Fixed Buffer Stop with Mechanical Dampers

In fixed buffer stops, a mechanical buffer device absorbs the energy and converts it into friction and heat.

Advantages include little footprint space, maintenance-free operation (after an impact, this buffer stop merely needs repositioning) and lower cost; a drawback in comparison with friction buffer stops is the lower energy absorption capacity.

The following design versions are used:

  • ‘Tube-in-tube’ with hydraulic cylinder
  • with anti-torsion lock for positioning of the impact plate or housing
  • with double shaft guide for positioning of the impact plate or housing

c- Simple Fixed Buffer Stop

The only purpose of the smple fixed buffer stop is to mark the end of track, it cannot absorb energy. It does not protect persons or the vehicle.


3- Folding / Retractable Buffer Stop Systems

For temporary blocking a track, folding buffer stops can be used – either as fixed buffer stops or with hydraulic absorbers or as conventional friction buffer stops whose braking elements can also be fastened to braking rails arranged parallel with the running track. A special design version of this buffer stop type is a retractable or sinking buffer stop.

Folding fixed buffer stop 1Folding fixed buffer stop 2


4- Wheel Braking And Wheel Holding Systems – Wheel Locks

If a buffer stop cannot be used – e.g., on rail vehicles which have no suitable facilities at their front – braking facilities can be applied at the wheel directly.

a- Chock

To prevent a rail vehicle from rolling off, a fixed, non-braking chock is mounted or folded over the track rails.

Chock 1http://www.railsystem.net/wp-content/uploads/2015/04/Chock-1-155x110.jpg 155w" sizes="(max-width: 210px) 100vw, 210px" width="210" height="150">

b- Track Lock

If the primary task is that of protecting people and assets, a track section can be protected by a track lock which causes a controlled derailment of the rail vehicle.

Track lockhttp://www.railsystem.net/wp-content/uploads/2015/04/Track-lock-155x110.jpg 155w" sizes="(max-width: 210px) 100vw, 210px" width="210" height="150">

c- Brake Shoes

Brake shoes are clamped into the track rails and linked to a brake element. If a vehicle impacts the shoe, the braking action is obtained by the incipient friction in relation to the moving mass of the rail vehicle. Brake shoes should always be applied in pairs.

Brake shoes 2http://www.railsystem.net/wp-content/uploads/2015/04/Brake-shoes-2-155x110.jpg 155w" sizes="(max-width: 210px) 100vw, 210px" width="210" height="150">

Special designs are available for trams and light-weight vehicles.

Brake shoes can be attached to be folding on one or two additional rails so that they can be hinged away from the track rails.

  • on central rail, inside – The braking force is distributed evenly on both wheels of the vehicle on a single central rail .
  • on additional rails, outside – If no internals can be installed in the track outside brake shoes are a solution

d- Dowty Retarder

Dowty retarder is an hydraulic device that regulates the speed of rail cars as they roll down an inclined track. The devices are built for a specified speed, set at the factory. If the rail car is below the set speed, the device offers no resistance. If the car speed is at or greater than the speed setting, an internal valve is activated to provide a resistance to the wheel, thus slowing the car. This keeps cars rolling within a relatively narrow range of speeds.

 OLYMPUS DIGITAL CAMERAhttp://www.railsystem.net/wp-content/uploads/2015/04/Dowty-21-155x110.jpg 155w" sizes="(max-width: 210px) 100vw, 210px" width="210" height="150">


Videos:


Source: rawie.de, wikipedia.com

Thermit Welding

When applied to the reduction of Iron oxides, the exothermic reaction generates sufficient energy to raise the reaction product temperature to in excess of 3,000°C at which both the metal and aluminium oxide are both liquid:

Iron Oxide + Aluminium > Aluminium Oxide + Iron + Heat
3FeO + 2Al > Al2O3 + 3Fe + 880 kJ
Fe2O3 + 2Al > Al2O3 + 2Fe + 850 kJ

The process was first used to provide the thermal energy for a method for forge welding rails in 1899, when a number of welded joints were installed in the Essen Tramway. The process was first used in the UK to weld tram rails installed in Leeds in 1904.

Further development leading to the addition of alloying elements to the basic Aluminothermic reaction produced a steel with a compatible metallurgy to the parent rails, thus enabling a full fusion welding process to be developed. While early welds were produced by casting the Thermit steel into hand produced moulds encompassing the two rails to be joined together, subsequent development lead to the introduction of pre formed refractory moulds designed to fit specific rail profiles.

While the basic Aluminothermic process still forms the heart of the Thermit welding processes, continuous development coupled with modern production technology, statistical process control and quality assurance, has resulted in processes which more than match the service demands of modern high speed, high axle load railway systems.

  • Conventional “Flat bottom” or “Vignole” Rails
  • Special Section Railway rails
  • Grooved Tram Rails
  • Heavy Section Crane Rails
  • Electrical Conductor Rails

In addition, products are available to suit special types of track support, confines spaces, environmental restrictions, and for joining rails of differing types or with differing degrees of wear.


The Process of Thermit Welding

Thermit welding is an effective, highly mobile, method of joining heavy section steel structures such as rails. Essentially a casting process, the high heat input and metallurgical properties of the Thermit steel make the process ideal for welding high strength, high hardness steels such as those used for modern rails.

Thermit Welding is a skilled welding process and must not be undertaken by anyone who has not been trained and certificated to use it.

Detailed operating instructions are provided for each of our processes, but the welding methods all comprise of 6 main elements:

1- A carefully prepared gap must be produced between the two rails, which must then be accurately aligned by means of straightedges to ensure the finished joint is perfectly straight and flat.

welding1

2- Pre-formed refractory moulds which are manufactured to accurately fit around the specific rail profile are clamped around the rail gap, and then sealed in position. Equipment for locating the preheating burner, and the Thermit container is then assembled.

welding2

3- The weld cavity formed inside the mould is preheated using an oxy fuel gas burner with accurately set gas pressures for a prescribed time. The quality of the finished weld will depend upon the precision of this preheating process.

welding3

4- On completion of the preheating, the container is fitted to the top of the moulds, the portion is ignited and the subsequent exothermic reaction produces the molten Thermit Steel. The container incorporates an automatic tapping system enabling the liquid steel – which is at a temperature in excess of 2,500°C – to discharge directly into the weld cavity.

welding4

5- The welded joint is allowed to cool for a predetermined time before the excess steel and the mould material is removed from around the top of the rail with the aid of a hydraulic trimming device.

welding5

6- When cold the joint is cleaned of all debris, and the rail running surfaces are precision ground the profile. The finished weld must then be inspected before it is passed as ready for service.

welding6


Videos:


See Also: http://www.asa.transport.nsw.gov.au/sites/default/files/asa/railcorp-legacy/disciplines/civil/tmc-222.pdf

Source: thermit-welding.com

http://www.goldschmidt-thermit.com/en/

Video Pilihan

New Amtrax

Tram Tour

Lrt Jakarta Kelapagading

Shinkansen 600 km/h

New templates

Who's Online

Kami memiliki 14 guests dan tidak ada anggota yang online

Lokasi

  • Bandung, Jawa Barat, Indonesia
  • Alamat email ini dilindungi dari robot spam. Anda memerlukan Javascript yang aktif untuk melihatnya.
  • 08112291110 

New templates

Selamat datang di perkeretaapian.com, Siapa kami ?

Who's Online

Kami memiliki 14 guests dan tidak ada anggota yang online

Statistics

OS:  
Windows
PHP:  
5.3.24
MySQLi:  
5.5.32
Waktu:  
06:10
Cache:  
Nonaktif
GZip:  
Nonaktif
Pengunjung:  
2
Artikel:  
529

For using special positions

Special positions are: sticky_left, sticky_right, notice, tool_bottom. You can use them for any module type. For using this, please go to Module Manager and config your module to your desired position.

These can be disable by:

  • Go to Administrator » Template Manager » Your_Template » Tab: Advanced » Use special positions » select: No for all special positions
  • Go to Administrator » Module magager » Your_Module(by postion: sticky_left/ sticky_right/ notice/ tool_bottom) » Status: Unpublished for that module

For customize module in special position

The solution is used Module Class Suffix. You can customize button, module content follow Module Class Suffix

E.g. Module Class Suffix: bg-white @bullhorn then:
- Class of button is 'ico-bullhorn'. If without @... the default is 'icon-pushpin'
- Class of module is 'bg-white'

Live chat

Live chat

To help us serve you better, please provide some information before we begin your chat.

Template Settings

Color

For each color, the params below will be given default values
Blue Oranges Red

Body

Background Color
Text Color

Header

Background Color

Spotlight3

Background Color

Spotlight4

Background Color

Spotlight5

Background Color

Footer

Select menu
Google Font
Body Font-size
Body Font-family
Direction