Machine tools to go

A utility company orders 500 wind towers for a wind-power farm: Each tower consists of three or four monstrous sections with welded flanges used for on-site assembly.

The tower sections arrive, and workers discover that heat from the welding process has distorted the flanges. They now are out of spec, making it impossible to erect the towers. The sections have to be sent back to be re-machined.

A coal-fired power-generation plant faces an emergency situation:

It has a high-pressure valve that regulates 3,000 psi, 1,000-degree steam that needs to be repaired. To make the repair would require shutting down power generation, cutting the large valve away from its pipes, shipping it to a shop for machining, putting it back in place, then stress relieving it and X-ray inspecting the welds used to secure it in place.

Considering the amount of downtime that these repairs require, money can be saved by being able to make the repairs on-site. Rather than disassembling components and shipping them off to be machined, the machine tools that are needed for the job would come to the components.

Climax Portable Machine Tools Inc., with facilities in Newberg, Ore., and Duren, Germany, provides on-site machining capability for jobs such as these, and it is considered a pioneer in portable machine tools.

The company offers standard models and machines that are specially built for customer applications. It also rents out its portable machine tools from locations worldwide.

Portable machine tools have gained popularity for maintenance, repair and upgrade work of premachined components in the power generation — nuclear, wind, fossil fuel, and hydro — shipbuilding, service and engineering, and heavy construction industries. And for these industries, Climax Portable Machine Tools builds portable boring machines, flange facers, autobore welders, circular mills, keyway cutting mills, 3-axis mills, valve repair machines, and lathes — all of which can be found working everywhere from nuclear power plants and coal-fired power plants to wind tower sites and shipbuilding yards to bridges and dams.

Ideal workpiece candidates for portable machining are those that are too big to move or disassemble from their mating components. When it comes to portable machine tools, the bigger and bulkier the workpiece the better.

Unlike traditional machine tools that get their rigidity from their bases, portable machine tools get rigidity from the weight and heft of the components they are working on. Engineers at Climax Portable Machine Tools develop fixtures that allow users to anchor the machines to the workpieces.

Portable lathes, for example, operate by attaching to the end of the shaft to be machined. Then, the entire lathe rotates around the shaft for the machining operation. For a portable boring machine, the engineers designed a special fixture that attaches it to the curved surface of a steam generator in a nuclear power plant.

In addition to rigidity, portable machines must be just as, or even more, accurate, in some instances, as their traditional stationary counterparts.

For example, the CM6000 circular mill from Climax Portable Machine Tools can machine wind tower flanges in the field and hold a flatness tolerance of 0.002 in. over a 16.5-ft-diameter flange while generating a surface finish of 60 Rms.

Climax Portable Machine Tools also applies CNC to its portable machines when they are used in areas where a live operator cannot be. It is not safe for a human to be inside a nuclear power reactor. So the company adapts a remote control console to the portable machine that operates its servomotors with pre-programmed commands.

Portable machines are powered by electricity, hydraulics or pneumatics. Portable generators provide on-site power for electric motors and hydraulic power units when direct power is not available, and pneumatic power is used in volatile environments such as at an oil and gas refinery where there is the potential for explosions.

http://www.americanmachinist.com/304/Issue/Article/False/83648/Issue