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A high-productivity welding production line of towers for wind mills
by Per Ivarsson, ESAB Welding Equipment AB, Laxå, Sweden
First published: Svetsaren 1/2000
Keywords: windmill towers, CaB 460, A2 welding heads, A6 S Arc Master, LAF 1250 Arc Power, SAW
Segment: Power generation
Summary: The article discusses the role of ESAB welding products in the fabrication of windmill towers at Sonderjylland Maskinfabrik in Denmark.
The promotion of renewable “green” energy has recently been stepped up by quite a number of governments. There is no question that the genuine cost of producing wind electricity is far higher at present than that of the electricity generated by non-renewable energy sources like fossil and nuclear energy.
Needless to say, there are aspects other than the purely commercial ones when pushing for wind power; they include safety, purity and, fundamentally, renewability. At the end of 1998, wind power capacity worldwide amounted to roughly 10,000 MW, 25% of which was installed during that year. The predictions are that the growth rate will be 20% annually in 1998-2003. Consequently, this energy segment is expected to experience extremely powerful trends in the years to come.
Denmark is the leader in Europe and is expanding the segment. Capacity here is already approaching 10%, while the target is 50% wind-powered electricity consumption by 2030, including pioneering the development of offshore wind power. Danish industry is also concentrating heavily on the production of wind mills, primarily to satisfy the domestic market, but even with successful exports to countries far and near, with the focus on the United States.
Need for high-efficient, accurate welding equipment
There are two main manufacturers of complete wind mills in Denmark, NEG Micon and Vestas Wind Systems. They purchase most of what they need for the foundations, i.e. the steel towers supporting the rotor and generator, from sub-suppliers in Denmark and other countries in Europe.
Tower production by these sub-suppliers has necessitated an increase and improvement in machinery facilities and interest has focused on high-productivity welding equipment in order to reduce door-to-door times, not to mention the rigorous quality and environmental requirements.
ESAB has recently delivered quite a number of mechanised welding stations to sub-suppliers in Europe in general and in Denmark in particular.
One of the largest sub-suppliers of these towers is Sönderjyllands Maskinfabrik A/S, located at the south of the Danish peninsula of Jylland.
In the contract between this customer and ESAB Engineering, it was agreed that ESAB would plan, design, deliver, install and commission a complete welding production line to meet the customer’s demands.
Huge workpieces
A complete wind tower consists of two to three sections, giving a hub height of up to 78 m, and each section has a maximum weight of 50 tonnes, consisting of 10-15 shells with a width of 1,500-2,400 mm. The diameter of the bottom shell is 4,800 mm at its maximum and 1,700 mm at the top. Plate thickness is 12-35 mm, joint-prepared for I, Y and X joints.
Efficient production flow
From the bending machine or buffer, one shell is placed in one of the 10T roller beds to position it for internal and external longitudinal submerged arc welding carried out by the CaB 460 column and boom. While one shell is being welded in one roller bed, another shell is prepared in the other roller bed set. This procedure definitely increases the arc time factor. In addition, each shell at the end of a tower section has a mounting flange. The flanges are also welded to these shells at this station.
At the next station, a head and tail stock positioner, one sub-arc welding head for internal circumferential welding and one CaB 460 column and boom for external circumferential welding are integrated. Furthermore, there is a support roller bed and a rounding jig. The tower section is built up here until it reaches its full length. The first shell with the flange is clamped into the withdrawn tail stock, while the second shell is clamped into the head stock in the corresponding manner. The two shells are tightened by pushing the movable tail stock towards the head stock, whereupon tack welding takes place. The ESAB A2 welding head carried by the support arm performs the internal welding and, finally, the external circumferential welding is performed by the A6 head of the CaB 460 station. Step by step, the tower grows, as shell by shell is added, until the last shell with its flange completes the tower section. In order to maintain the roundness of the gradually extended tower, a rounding jig adapts the tower ends, using hydraulically operated pressure arms with rollers, in order to make them fit the shells that are added.
Specification of welding equipment for the complete production line Station 1:
One movable CaB 460 ArcCenter 6x3 column and boom is used for external and internal longitudinal submerged arc welding and for the circumferential welding of flange to shell. The vertical column is connected to the boom in a saddle using guide rollers to provide maximum load-bearing capacity with ample safety margins for reliable operation. The lift drive has a reliable safety factor and is equipped with a security device which, regardless of boom position, immediately locks the boom to prevent it travelling downwards in the event of a breakdown. The horizontal boom can be positioned in both the vertical and horizontal direction. The rack and pinion drive secures an even, stable welding speed. The control system has been designed with totally integrated functions; welding head manipulation and operation of the column and boom – all handled from a remote control.
The A6S ArcMaster SAW welding head is used for the productive twin-wire process, incorporating the microprocessor controller. There are two 100-kg wire reels at the rear of the boom. An electro-mechanical sensor with photo transistors ensures accurate joint tracking in the V joints – exact corrections are made by the motorised ball-bearing slides.
Furthermore, a colour TV-monitoring system including a distinct hair-cross generator deals with the I -joints. There is an operator’s platform at the foot of the column for control and supervision. The improvement in continuity and savings in material costs that result from a rational flux handling system make it a wise investment. At the same time as flux consumption is reduced, the workplace is kept clean and free from flux spillage. This flux feed and recovery system is powerful, 3 kW, and reliable, to correspond with the requirements in every respect.
Last but not least, the welding rectifier with its very high capacity and properties designed for twin-wire welding – LAF 1250 ArcPower – complies with the customer’s requirements in every way. There are two self-aligning roller bed sets of the 10 T size, each consisting of an idler and a powered unit to operate in conjunction with the CaB welding station.
Taken as a whole, this is an advanced piece of equipment for high productivity and consistent weld quality.
Station 2:
It comprises one movable CaB 460 Arc Center column and boom, identical to station 1, which is used for external circumferential submerged arc welding.
There is one head and tailstock positioner of the 20000 HTLM type, with motorised rotation and hydraulic height adjustment of the centre height. The head stock has an hydraulic stroke and the tailstock can be moved on rails using a motor. The maximum weight of the section is 50 tonnes, 25 tonnes a side. The unit features an hydraulic clamping cross-unit for workpiece clamping with outer diameters of 1,020-5,060 mm.
This is an outstanding handling tool, designed for applications requiring purposeful solutions.
There is one A2S Minimaster SAW welding head for the internal circumferential, single-wire process welding mounted on the movable support arm supplied with the head stock. There are motorised telescopic slides for sufficient accessibility. Accurate electro-mechanical joint tracking is also featured, together with a powerful flux feed and recovery system and a colour TV-monitoring system. The operator’s platform is connected to the head stock. The system also includes an LAF 800 ArcPower welding rectifier. This mechanised constellation eliminates the need for an automatic tractor with another operator to work inside the workpiece – a major advantage in terms of productivity and the environment.
In addition, there is one idling support roller bed of 60 TNE type equipped with an hydraulic height adjustment system. The roller bed is assembled on motorised rail bogies of the 60 RBVS type. Maximum capacity is 30 tonnes.
Finally, there is one rounding jig with seven hydraulically-adjustable roller pairs to compensate for the ovality of the workpiece. It can be adjusted to suit different plate thicknesses. There is also a rail bogie with motorised movement to obtain proper access to the workpiece.
This is an indispensable piece of equipment, which fundamentally reduces the time that is used for handling in the workshop to a minimum.
New production line
Sönderjyllands Maskinfabrik A/S has now decided to invest in another production line and ESAB has once again been favoured to continue the excellent partnership by delivering this new line.
First published: Svetsaren 1/2000
Keywords: windmill towers, CaB 460, A2 welding heads, A6 S Arc Master, LAF 1250 Arc Power, SAW
Segment: Power generation
Summary: The article discusses the role of ESAB welding products in the fabrication of windmill towers at Sonderjylland Maskinfabrik in Denmark.
The promotion of renewable “green” energy has recently been stepped up by quite a number of governments. There is no question that the genuine cost of producing wind electricity is far higher at present than that of the electricity generated by non-renewable energy sources like fossil and nuclear energy.
Needless to say, there are aspects other than the purely commercial ones when pushing for wind power; they include safety, purity and, fundamentally, renewability. At the end of 1998, wind power capacity worldwide amounted to roughly 10,000 MW, 25% of which was installed during that year. The predictions are that the growth rate will be 20% annually in 1998-2003. Consequently, this energy segment is expected to experience extremely powerful trends in the years to come.
Denmark is the leader in Europe and is expanding the segment. Capacity here is already approaching 10%, while the target is 50% wind-powered electricity consumption by 2030, including pioneering the development of offshore wind power. Danish industry is also concentrating heavily on the production of wind mills, primarily to satisfy the domestic market, but even with successful exports to countries far and near, with the focus on the United States.
Need for high-efficient, accurate welding equipment
There are two main manufacturers of complete wind mills in Denmark, NEG Micon and Vestas Wind Systems. They purchase most of what they need for the foundations, i.e. the steel towers supporting the rotor and generator, from sub-suppliers in Denmark and other countries in Europe.
Tower production by these sub-suppliers has necessitated an increase and improvement in machinery facilities and interest has focused on high-productivity welding equipment in order to reduce door-to-door times, not to mention the rigorous quality and environmental requirements.
ESAB has recently delivered quite a number of mechanised welding stations to sub-suppliers in Europe in general and in Denmark in particular.
One of the largest sub-suppliers of these towers is Sönderjyllands Maskinfabrik A/S, located at the south of the Danish peninsula of Jylland.
In the contract between this customer and ESAB Engineering, it was agreed that ESAB would plan, design, deliver, install and commission a complete welding production line to meet the customer’s demands.
Huge workpieces
A complete wind tower consists of two to three sections, giving a hub height of up to 78 m, and each section has a maximum weight of 50 tonnes, consisting of 10-15 shells with a width of 1,500-2,400 mm. The diameter of the bottom shell is 4,800 mm at its maximum and 1,700 mm at the top. Plate thickness is 12-35 mm, joint-prepared for I, Y and X joints.
Efficient production flow
From the bending machine or buffer, one shell is placed in one of the 10T roller beds to position it for internal and external longitudinal submerged arc welding carried out by the CaB 460 column and boom. While one shell is being welded in one roller bed, another shell is prepared in the other roller bed set. This procedure definitely increases the arc time factor. In addition, each shell at the end of a tower section has a mounting flange. The flanges are also welded to these shells at this station.
At the next station, a head and tail stock positioner, one sub-arc welding head for internal circumferential welding and one CaB 460 column and boom for external circumferential welding are integrated. Furthermore, there is a support roller bed and a rounding jig. The tower section is built up here until it reaches its full length. The first shell with the flange is clamped into the withdrawn tail stock, while the second shell is clamped into the head stock in the corresponding manner. The two shells are tightened by pushing the movable tail stock towards the head stock, whereupon tack welding takes place. The ESAB A2 welding head carried by the support arm performs the internal welding and, finally, the external circumferential welding is performed by the A6 head of the CaB 460 station. Step by step, the tower grows, as shell by shell is added, until the last shell with its flange completes the tower section. In order to maintain the roundness of the gradually extended tower, a rounding jig adapts the tower ends, using hydraulically operated pressure arms with rollers, in order to make them fit the shells that are added.
Specification of welding equipment for the complete production line Station 1:
One movable CaB 460 ArcCenter 6x3 column and boom is used for external and internal longitudinal submerged arc welding and for the circumferential welding of flange to shell. The vertical column is connected to the boom in a saddle using guide rollers to provide maximum load-bearing capacity with ample safety margins for reliable operation. The lift drive has a reliable safety factor and is equipped with a security device which, regardless of boom position, immediately locks the boom to prevent it travelling downwards in the event of a breakdown. The horizontal boom can be positioned in both the vertical and horizontal direction. The rack and pinion drive secures an even, stable welding speed. The control system has been designed with totally integrated functions; welding head manipulation and operation of the column and boom – all handled from a remote control.
The A6S ArcMaster SAW welding head is used for the productive twin-wire process, incorporating the microprocessor controller. There are two 100-kg wire reels at the rear of the boom. An electro-mechanical sensor with photo transistors ensures accurate joint tracking in the V joints – exact corrections are made by the motorised ball-bearing slides.
Furthermore, a colour TV-monitoring system including a distinct hair-cross generator deals with the I -joints. There is an operator’s platform at the foot of the column for control and supervision. The improvement in continuity and savings in material costs that result from a rational flux handling system make it a wise investment. At the same time as flux consumption is reduced, the workplace is kept clean and free from flux spillage. This flux feed and recovery system is powerful, 3 kW, and reliable, to correspond with the requirements in every respect.
Last but not least, the welding rectifier with its very high capacity and properties designed for twin-wire welding – LAF 1250 ArcPower – complies with the customer’s requirements in every way. There are two self-aligning roller bed sets of the 10 T size, each consisting of an idler and a powered unit to operate in conjunction with the CaB welding station.
Taken as a whole, this is an advanced piece of equipment for high productivity and consistent weld quality.
Station 2:
It comprises one movable CaB 460 Arc Center column and boom, identical to station 1, which is used for external circumferential submerged arc welding.
There is one head and tailstock positioner of the 20000 HTLM type, with motorised rotation and hydraulic height adjustment of the centre height. The head stock has an hydraulic stroke and the tailstock can be moved on rails using a motor. The maximum weight of the section is 50 tonnes, 25 tonnes a side. The unit features an hydraulic clamping cross-unit for workpiece clamping with outer diameters of 1,020-5,060 mm.
This is an outstanding handling tool, designed for applications requiring purposeful solutions.
There is one A2S Minimaster SAW welding head for the internal circumferential, single-wire process welding mounted on the movable support arm supplied with the head stock. There are motorised telescopic slides for sufficient accessibility. Accurate electro-mechanical joint tracking is also featured, together with a powerful flux feed and recovery system and a colour TV-monitoring system. The operator’s platform is connected to the head stock. The system also includes an LAF 800 ArcPower welding rectifier. This mechanised constellation eliminates the need for an automatic tractor with another operator to work inside the workpiece – a major advantage in terms of productivity and the environment.
In addition, there is one idling support roller bed of 60 TNE type equipped with an hydraulic height adjustment system. The roller bed is assembled on motorised rail bogies of the 60 RBVS type. Maximum capacity is 30 tonnes.
Finally, there is one rounding jig with seven hydraulically-adjustable roller pairs to compensate for the ovality of the workpiece. It can be adjusted to suit different plate thicknesses. There is also a rail bogie with motorised movement to obtain proper access to the workpiece.
This is an indispensable piece of equipment, which fundamentally reduces the time that is used for handling in the workshop to a minimum.
New production line
Sönderjyllands Maskinfabrik A/S has now decided to invest in another production line and ESAB has once again been favoured to continue the excellent partnership by delivering this new line.
