Hydraulic piping systems improving manufacturing

Paul Boughton

A powerful Unison all-electric pipe bending machine is helping Frank Mohn Piping (FMP) to improve the production accuracy and throughput of complex large-bore hydraulic piping systems. The machine is also designed to help the company improve manufacturing efficiency by reducing the number of steps required to fabricate piping parts.

Recently installed at FMP’s manufacturing facilities in Frekhaug, Norway, the custom pipe bender is one of the most powerful all-electric machines that Unison has delivered to date. Based on the Breeze platform, it can accommodate tubes and pipes up to 180mm (7in) in diameter. The machine’s high torque capability, combined with precision CNC control and force sensing clamp and pressure dies, means that thick-walled pipes made from hard materials can be bent easily and very accurately without deformation. Parts manufactured from duplex stainless steel are a typical example – the machine is capable of bending 130mm diameter pipes that have a wall thickness of up to 11mm.

FMP manufactures hydraulic pipes that are used in the well-known Framo brand of submerged pumping systems for shipping, offshore and underground applications. It also produces a diverse range of hydraulic pipes for the floating production, storage and offloading (FPSO) vessels that are used in the offshore oil and gas industry.

In this particular case, FMP sought a bending solution that could accommodate a range of fabrication materials and wall thicknesses for the production of large-diameter pipes, as well as addressing a particular manufacturing issue involving 131mm and 156mm diameter thin-walled stainless steel pipes. The company has been using two hydraulic CNC bending machines to produce these pipes, but with one of them it was proving extremely difficult to fabricate tight bends without wrinkles, despite the use of a mandrel, because there was insufficient control resolution over the rotary-draw bending process. Although the other machine was capable of handling the bending tasks, it was relatively old and FMP was concerned that sourcing obsolescent components was becoming time-consuming and threatening to cause production bottlenecks.

According to Helge Kolas, production manager of FMP, “This is our first all-electric bending machine. The technology has a number of important advantages over hydraulics, including faster set-up, better process accuracy and repeatability, and much higher energy efficiency. After thoroughly researching the market we chose a Unison machine because the company has a long history of producing all-electric benders that are consistently ahead of the competition, and was prepared to work with us to create a custom machine that met our needs exactly.”

The machine supplied to FMP is a single-stack, right-hand bend model, equipped with Unison’s innovative laser springback system – which facilitates right-first-time manufacturing by automatically compensating for the tendency of tubular parts to spring back slightly after being bent. The bending head is designed for exceptional rigidity to accommodate large, heavy pipe assemblies and to allow fully automated movement of the pipe in all working planes. Despite their very large physical size, the tools are designed for quick changeover, using a special set of mounting plates that are moved by an overhead gantry crane. Many of the pipes that FMP manufactures are unique to each application and are produced in very small batch sizes that range from 1 to 50; tool changeover time, as well as machine set-up time, is therefore a key issue and the company now handles this in about 20 minutes.

Every pipe that has been bent on the Unison machine in its first six weeks of operation has been to specification. As Helge Kolas points out, “Process repeatability is excellent – the machine has performed flawlessly since the day it was installed and there are no signs of any wrinkles! The bend accuracy and ovality of parts are also much better than those we produced on our hydraulic benders.”

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