Overbygning/Overgangsskinner
Innhold
1 Scope
This specification sets out objective requirements for transition rails where one profile has part of its length forged to a different profile. This document specifies the requirements for forging, welding, production and product acceptance for transition rails. The specification applies to transitions in Table made from new Vignole rails according to EN 13674-1.
| Profile transition | Rail grade | Total length |
|---|---|---|
| 60E1 / 54E3 Right | R260Mn | 12000 mm |
| 60E1 / 54E3 Left | R260Mn | 12000 mm |
| 60E1 / 54E3 Right | R350HT | 12000 mm |
| 60E1 / 54E3 Left | R350HT | 12000 mm |
| 60E1 / 49E1 Right | R260Mn | 12000 mm |
| 60E1 / 49E1 Left | R260Mn | 12000 mm |
2 Functional requirements
2.1 Loads
Transition rails must be designeddesigned and produced to tolerate the following combinations of speed and axle load:
- Axle load = 18 tonnes at speed = 250 km/h
- Axle load = 22.5 tonnes at speed = 200 km/h
- Axle load = 25 tonnes at speed = 70 km/h
- Axle load = 30 tonnes at speed = 50 km/h
2.2 Dimensions
The transitions shall be made from two different rail profiles where the largest profile is forged into the shape of the smallest profile in one of the rail ends. The forged end of the large rail shall be flash-butt welded to the small rail. Each rail in the transition shall have a length of 6000 mm. The total length of the transition shall be 12000 mm, see Figur 1.
The transitions shall be made from rails in profile class X and straightness class A according to EN 13674-1
The transition rails shall be delivered with the running edge aligned to either right or left rail string seen from the larger to the smaller rail.
3 Forging
3.1 General
All heating, forging and cooling shall be carried out in a controlled process.
3.2 Forging parameters
The forging process and any post heat treatment, including the working ranges, shall be determined prior to production. They shall not be changed without prior purchaser approval. The parameters shall be monitored and records shall be referenced to the relevant products.
3.3 Cutting to length
The transition rails shall be cut square, in accordance with Table 9 in EN 13674-1, to the length according to Dimensions. Burrs shall be removed from all edgings. Flame cutting is not allowed for the final cut.
3.4 Dimensions of forged rail transition
Figur 2 indicates the parts of the transition rail that shall be checked.
The dimension of the transition rail before welding shall comply with the requirements in Tabell 2:
| Dimension | Length | Tolerances |
|---|---|---|
| Total length of transition rail LG | 6000 mm | ± 20 mm |
| Length of forged rail transition LT | Min 5 x HD | |
| Length of forged vignole part measured on the foot LF | 100 mm | ± 20 mm |
- Vertical deviation from flat across the running surface shall not exceed -0,1 mm and + 0,2 mm measured over 1 meter moving base.
- Horizontal deviation on the running edge, 14 mm below the running surface shall not exeed ± 0,3 mm measured over 1 meter moving base.
3.5 Hardness distribution
The hardness values of the transition rail shall be in the range of the specifications in Tabell 3 . Zone S is defined in Figur 3.
| Rail grade | head | foot | |
|---|---|---|---|
| R 260 Mn | measured hardness of parent rail ± 40 HBW | ||
| R 350 HT | HAZ except zone S | Zone S | Forged part |
| 350 – 390 HBW | min 280 HBW | max 390 HBW | |
Hn = nominal hardness of the parent rail grade
Hm = minimum hardness in zone S according to Table 3
S = width between the two nominal hardness points on the hardness distribution curve
1 = HAZ
2 = Parent rail
3.6 Finishing
The profile finishing shall be carried out in the longitudinal direction using machining and optionally additional grinding. The roughness limit shall be 6,3 Ra. The profile finishing shall not cause any thermal or mechanical damage. The rail profile in the wheel contact area shall be maintained during profile finishing.
3.6.1 Surface quality
The depth of hot marks and seams shall not exceed:
- 0,35 mm for the running surface and the underside of the foot
- 0,5 mm for the rest of the profile
In the case of longitudinal marks, there shall be a maximum of two, to the-depth limits specified, at any point along the length of the rail but no more than one of these shall be on the rail running surface.
The maximum width of the marks shall be 4 mm. The width to depth ratio of allowable marks shall be minimum 3:1.
No cracks are allowed.
3.7 Identification
The identification shall permit traceability to production records. Every forged rail blank shall be encoded by:
- the sign of the manufacturer;
- the year of manufacturing;
- the identification number for the forged part.
The identification shall permit the traceability of the product for at least 5 years.
4 Welding
The forged end of the transition rail shall be flash-butt welded to a 6000 mm long vignole rail in the smaller profile of the transition. The welding shall be carried out in accordance with EN 14587-1.
The rails shall be aligned to the running edge. Weld straightness and flatness shall meet the requirements according to class 2 in EN 14587-1.
5 Production testing and acceptance
The manufacturer shall ensure the quality of transition rails by testing according to Tabell 4 .
| Test | Frequency | Acceptance criteria |
|---|---|---|
| Visual inspection | Each piece | Surface quality |
| Surface finish | Each piece | Surface quality |
| Geometry | Each piece | Dimensions of forged rail transition |
| Hardness | The first and last produced piece of one day | Hardness distribution |
5.1 Hardness testing
The transition rail shall be investigated by a Brinell hardness testing device or a device allowing conversion toHBW. To prepare the hardness tests on the head, 0,5 mm shall be removed locally, outside the running surface. The hardness of the rail head shall be measured 3 times at each position (Figur 4).
- place of inspection 1 in the forged profile (50 mm);
- place of inspection 2 in the transition zone;
- place of inspection 3 in the parent rail, outside the heat affected zone.
To prepare the hardness tests on the foot, the measurement position shall be ground until clean. The
hardness of the rail foot shall be measured 3 times at each position (Figure ):
- place of inspection 4 in the middle of the forged zone;
- place of inspection 5 in the parent rail.
The average hardness value at each position on the head and the foot shall be in the range of specification of Table . Deviations to the reference values depending on the use of mobile testing devices shall be arranged with the purchaser. Values outside the specifications lead to rejection of the piece N, additionally all the pieces produced before the rejected piece have to be checked beginning with the piece N1 and continuing until 3 pieces in accordance with the specifications have been found. All pieces outside the specifications are rejected (1 retreatment is allowed).
6 Documentation
A drawing of the transitions shall be supplied by the manufacturer prior to delivery.
Records with test results from production testing according to Production testing and accepatance shall be supplied from the manufacturer.
7 References
- EN 13674-1 Railway applications - Track - Rail - Part 1: Vignole railway rails 46 kg/m and above
- EN 14587-1 Railway applications - Track – Flash butt welding of rails – Part 1: New R220, R260, R260Mn and R350HT rail grades in a fixed plant
