1-side plate edge milling machine with one or two milling heads, type GPE

small or medium plate lots of various sizes, usual tolerance requirements on
straightness and parallelism, high precision of root face

1-side plate edge milling machine with pivotable milling head, type GPE-S

small or medium plate lots of various sizes

milling head pivotable by ± 45

Pull-through plate edge milling machine
with fixed milling supports without clamping traverses, type GPD-Z

medium or large plate lots of various sizes, low requirements
on straightness and parallelism, low requirements on precision of root face

2-side plate edge milling machine, type GPZ

medium plate lots of various sizes, high tolerance requirements on
straightness and parallelism, high precision of root face

Tandem plate edge milling machine system, type GTWP

medium or large plate lots of various sizes, high tolerance requirements on
straightness and parallelism, high precision of root face

Tandem plate edge milling machine system, type GPZ-T

medium or large plate lots of various sizes, high tolerance requirements on
straightness and parallelism, high precision of root face

2-head plate edge milling machine, type GPF-D

medium or large plate lots of the same sizes, high tolerance requirements on
straightness and parallelism and precision of root face

Plate edge milling machine for the processing of 4 edges, type GPV

small or medium plate lots of various sizes, usual tolerance requirements straightness and parallelism, high precision of root face, also available with vacuum plate clamping system

4-side plate edge milling machine, type GPZ-V

medium or large plate lots of various sizes, high tolerance requirements on
straightness and parallelism, high precision of root face of all four plate edges

Combined two side plate edge milling machine for simultaneous processing of longitudinal and cross edges, with movable clamping traverse and, as an option, with integrated welding unit, type GTWP-V

large plate lots of various sizes, highest tolerance requirements on straightness, parallelism, for processing of either 1, 2, 3, or 4 plate edges, welding gap "0" also available as 2-side plate milling machine with movable clamping traverse (longitudinal and cross machine)

Circ Seam Milling Machines

for narrow-gap preparation of the welding seam

Gräbener gained its experiences during the period when it ran its own pipe mill. It was a major task to produce extremely long piles. The importance of a clean and fast preparation of external circumferential weld seams on pipes, vessels, and apparatus became apparent. For this reason, the Gräbener longitudinal and circumferential milling machines were developed. The longitudinally welded shells are used to produce apparatus, reactors, pipe constructions, dolphins and spud piles. They are internally submerged-arc welded, milled from the outside and then welded from the outside.

Circumferential milling can sometimes reduce the costs for one metre weld seam by more than 50 %. This is, on the one hand, due to a reduction of the time necessary to prepare the weld seam and, on the other hand, due to the reduced weld metal volume being applied, as well as the reduction of the welding time. The machines are equipped with a sensor system which automatically follows the ovality of the pipe, thus guaranteeing a constant seam depth (seam geometry).

Various models of Gräbener circ seam milling machines are available for three different milling depths, with and without undercarriage.

Long Seam Milling Machines 

for narrow-gap preparation of the welding seam
 

In accordance to the circumferential milling machines, a clean and fast external longitudinal seam preparation on pipes, vessels, and apparatus is most important.

The external longitudinal seam preparation on internally submerged-arc welded (SAW) pipes, shells, etc., is carried out by a longitudinal milling machine. In order to compensate probable surface roughness, ovality and deviations in straightness, the longitudinal milling machines are likewise equipped with a copying system. This guarantees a constant milling depth during the milling process. Depending on the machine design, pipe sizes of 3,000 - 22,000 mm length and a diameter of 406 - 9,000 mm can be milled.

Two models of Gräbener long seam milling machines are available for two different milling depths.

The latest  development of the world market leader in seam milling technology is the longitudinal seam milling machine as a floor-mounted construction. It does not need a foundation pit. Thus, it can be used as an on-site machine for the seam milling of large and heavy-walled pipes, shells, vessels, apparatus etc. The work piece is being milled in a 45 degrees angle.

The overground long seam milling machine with capacities of 45 and 55 kW can be erected on the bare shop floor - not causing extra costs for foundation work.

It has been constructed for

• external diameters from 2.500 up to 8.000 mm
• work piece lengths from 2.000 up to 4.500 mm
• milling depths from 25 up to 120 mm

The floor-mounted machine is equipped with

• a sensor system for ensuring a constant groove depth
• a camera travelling along with the milling process to correct the process easily via screen
• horizontally and vertically adjustable pipe turning devices for the adjustment of the work piece. The turning devices guarantee a constant milling depth for any pipe diameter.

End Bevelling Machines

End bevelling machines prepare the ends of pipes, shells, fittings, reducers, etc. for the welding process.

In order to ensure a universal end bevelling of dished ends, pipes or shells, Gräbener has developed a system, which reduces set-up times, can copy ovalities either mechanically or by using a laser, depending on the requirement, can predefine the existing ovality of the component as set-point value for the component to be processed.

End bevelling machines for large pipe mills can either be designed as one-sided or two-sided systems. The pipe transport into and out of the machine can be carried out automatically.