Remanufacturing
Remanufacturing of a MERGER type NORPA 710-4 speed reducer for the steel industry
Discover the remanufacturing of a speed reducer dedicated to lifting at an ARCELOR site
Remanufacture an industrial speed reducer
In a sector as demanding as the steel industry, each component plays a crucial role. It is in this context that MERGER was called upon by a big name in the industry to ensure the complete remanufacturing of a NORPA 710-4 type speed reducer. Strategic equipment, at the service oflifting operations reviews (motorization of the largest casting bridge in Europe at the time of its commissioning), which required tailor-made support, combining technical know-how, documentary rigor and total compliance with quality standards.
It is not uncommon to find a industrial speed reducer MERGER about rolling mills winches lifting or the conveyors band.
For 75 years, we have been designing speed reducers able to support a high torque on the output shaft allowing lifting of cheavy loads effectively for these historic markets.
A unique reducer for extreme loads
This reducer is designed to drive two lifting drums in a steel production environment. It presents rare technical specificities:
- Driven by two 690V three-phase asynchronous motors,
- High reduction ratio of 210,
- Output torque reaching 800 Nm.
With such a configuration, it is a key element in heavy handling operations, where robustness and reliability are non-negotiable.
Initial analysis and diagnosis: key to successful remanufacturing
Initial inspection
Disassembling the gearbox allows for the examination of each component: casing, gears, bearings, and seals. This step allows for the detection of any signs of wear, corrosion, or mechanical fatigue that could compromise the system's performance.
Non-destructive testing
Analyses are carried out using techniques mastered by MERGER such as sweating ultrasonic, and the dimensional controlThese methods make it possible to identify possible cracks, microcracks or internal defects invisible to the naked eye.
Statement of clearances and tolerances
The alignment of the gears and shaft spans are accurately checked to ensure that the games et tolerances are compliant. Indeed, any deviation can cause losses of efficiency, premature wear or vibes abnormal.
Manufacturing supervised by a demanding quality plan
At MERGER, quality comes through traceability. For this project, a LOFC quality plan (List of Manufacturing and Control Operations) has been implemented to ensure rigorous monitoring of each component — from gears to shafts, including welded mechanical parts.
Le reducer housing, weighing 12,5 tonnes and fitted with fixing lugs for optimised anchoring, has undergone specific treatments and controls:
- Reworking of bores for perfect integration of the bearings,
- Checking and aligning all gears,
- Checking the gearing worn in Prussian blue,
- Internal surface treatment to strengthen sustainability.
A quality file delivered, meeting the requirements
In accordance with industry standards, MERGER provided a complete quality file bringing together:
Manufacturing documents:
- Material certificates (mobile and sheet metal),
- Welding notebook,
- PV of penetrant testing, shot blasting, ultrasonic testing, KCV resilience at 0°C,
- Annealing curve, heat treatment indicators,
- Dimensional, hardness and cementation PV,
- Installation, maintenance, repair and storage instructions.
Compliance documents:
- Minutes of acceptance,
- Construction certificate,
- Certificate of conformity.
Control to maximize reducer reliability
In order to ensure the performance and safety of the reducer, MERGER implemented a series of extensive controls:
- Visual and penetrant inspection to detect possible cracks.
- Ultrasonic testing to ensure the integrity of internal components.
- Thermal testing and dimensional cementation to validate performance under stress.
- Shot blasting to strengthen mechanical resistance.
A complete solution delivered by MERGER
The reducer is not delivered bare: MERGER designed an integrated system with couplings et emergency brake. With dimensions of 1,5 m in height by 3 m in length and a width varying from 720 to 970 cm, it is designed to withstand extreme conditions with a lifting height of 37 m and a lift training 80 mN auxiliary.
This achievement is very representative of the know-how of MERGER in terms of remanufacturing of strategic equipment for the steel industry. Through its rigorous approach and technical expertise, MERGER guarantees its client, a major player in its sector, a reliable and efficient solution, compliant with the strictest requirements of the sector industrial.
Fretting: a precision operation
Among the specific operations carried out, MERGER carried out a shaft shrinkage intended to integrate the gear system precisely. This operation consists of:
- Cool the tree, often with liquid nitrogen or by cryogenic process,
- Le contract slightly, reducing its diameter,
- THEinsert into the bore of the gear,
- Once at room temperature, the shaft expands and mechanically locks extremely reliably.
MERGER, the benchmark in remanufacturing for heavy industry
This achievement perfectly illustrates the MERGER's expertise in the remanufacturing of critical equipment for the steel industry. Thanks to a rigorous approach, complete mastery of thermal and mechanical processes, and impeccable document management, MERGER provides its customers with solutions reliable, durable and compliant with the strictest requirements of the industrial sector.
Need a remanufacture? Contact our experts for personalized support.
History and environment of the NORPA speed reducer:
At the heart of the largest casting bridge in Europe
EIFFEL – Lifting – translation – steering reducers of the 505-ton cast iron bridge for SOLLAC / 13 – FOS sur MER
French manufacturer of speed reducers, MERGER had delivered 17 reducers for the motorization of the largest casting bridge in Europe.
Installed on the maritime site of SOLLAC in Fos sur Mer, this gigantic work of more than 1000 tonnes manufactured by the EIFFEL company was put into industrial production in July 2002.
View of the bridge on its rails at the entrance to the casting hall. The casting ladle is on the ground.
The steering movements are powered by two vertically mounted UNIPA 2-180 gearboxes. The main steering of the bridge is powered by four UNIPA 4-4 gearboxes.
View below the bridge. We can see the two main lifting hooks and the auxiliary lifting hook.
The trolley's translation on the beams has been cleverly placed in a vertical position in the boxes forming the very structure of the bridge. These are 6 UNIPA 315-3 type reducers.
View of the air-conditioned cabin containing all the electrical and automation systems.
La Preventive maintenance of these reducers is triggered by vibration sensors placed on sensitive points. A periodic inspection of trees by ultrasound is provided without draining the reducers. An oil sample point is also present on each reducer.
An overhead crane designed to lift a mass of 505 tonnes in the main lift
A true production bridge for the steel industry, the structure operates in difficult conditions, exposed to flames and dust, 24h / 24, 365 days per year.
Each of the two main reducers alone weighs 23,5 tonnes and measures 4,50 m long and 1,6 m high.
View of the three case-hardened, hardened and ground steel gear trains of the main lifting reducer type FLOPA 800-3.
The main lifting system is made up of a closed loop according to the know-how of the EIFFEL company: 2 primary reducers type NORPA 400-3 are motorized by 4 ABB brand motors with a power of 450 kW each, i.e. 1800 kW in total.
It is mounted floating on the splined shaft of the winch. A reaction clip holds the reducer in position.
The auxiliary lift is also powered by a large-sized reducer type NORPA 710-4 (subject of this article), weighing 11 tons.
Each primary reducer sends the multiplied torque to a main lifting reducer type FLOPA 800-3 developing a nominal torque of 365 Nm on the winch. In the event of degraded operation, this torque can reach the value of 600 Nm
View of the factory assembly of a main lifting reducer, the wheels are shrunk onto their shafts.
Le casting crane transports the ladles of molten iron to the oxygen furnace (BOF), or the molten steel from the BOF or electric arc furnace to the continuous casting machine. It can also be used for casting and foundry. security and reliability are the priority since the bridge is used to transport liquid steel.
