4-roll bending machines have been developed for thick-walled offshore wind tower sections, piles, mooring posts, large vessels, and tanks.
The Gräbener 4-roll bending machine with supporting yoke is equipped with relatively slim rolls with hardly any crowning. The number of exchange rolls necessary is decreased considerably and an optimum straightness of the pipe shells to be formed is ensured - for small and large material thicknesses. Due to the small number of exchange rolls, standstill times because of roll changes can be avoided which, in turn, increases the turnout of the machine and its efficiency.
These press types serve for calibrating and straightening LSAW pipes. The pipe is calibrated step by step. The respective pipe section is placed into the semicircular lower tool. Press forces and tool geometry are designed in a way that material spring-back can be compensated. Stresses in the weld seam are reduced.
In 1921, Gräbener & Comp. was founded as a company for heavy iron and steel plate constructions. For a long time, the manufacturing of large pipes was an important line of business for the company group (up until the 90ies). Another important sector was the machine construction which was mainly focused on the forming technology.
Today, the Graebener Group represents an association of companies with technological competence in the fields of hydraulics, milling, cutting and forming technology.