|A portable circular mill from Climax Portable Machine Tools machines wind tower flanges for assembly on-site. |
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.
|A Climax Portable Machine Tools 3-axis portable mill can run horizontally or vertically. |
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.
|J-S Machine & Valve uses a BB5000 portable boring machine to repair huge circulating pumps on-site at coal-fired power-generation plants. |
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.
|J-S Machine & Valve tackles the repair challenge of blind boring highpressure valves with its BB5000 portable boring machine. |
Sometimes customers request a combination of power supplies — powering the machine’s mill spindle hydraulically and its X axis electrically, for example. And the company recently introduced a servo electric drive that delivers the power of hydraulics without the associated power units, hoses and oil of hydraulics to haul around.
On the company’s LM6000 portable linear mill, shops can get a heavy duty 25-hp spindle that easily handles cutter heads to 8 in. in diameter, even when running in a vertical orientation. Beefy electric feed motors and special selfcleaning ballscrew drive systems drive the machine’s X and Y axes, and a Z-axis power drive is available.
According to Andy Becker, vice president of marketing and business development at Climax Portable Machine Tools, one of the company’s most popular machines is its BB5000 portable boring machine. Accessories allow the machine to be used for blind boring, line boring, drilling, facing, threading, valve repair and trepanning.
The boring machines often are used in power plants to repair, rebuild or upgrade turbine shells/ housings to get more power out of existing generating facilities. With the company’s mounting components, the BB5000 is flexible enough and well suited for this type of operation, which is typically done in cramped tight workspaces.
For coal-fired power generation facilities, portable machine tools, such as the BB5000, often prove to be valuable assets. They help to reduce plant downtime, and they streamline the repair process. That was the case at a Northeast Oklahoma coal-fired power plant.
The facility’s circulating pumps needed to be repaired before they were converted to mechanical seals from traditional packing. The mechanical seals were designed to prevent pump shaft wear and to improve the control of leakage. The traditional packing caused wear on the pump shaft because it contacted the shaft while it was rotating. The result was frequent maintenance — adjustment and/or replacement — to maintain efficiency.
The plant manager contacted J-S Machine & Valve Inc., a company that specializes in repairing and maintaining equipment used in the petrochemical and power generation industries. The company has been doing pump and valve field work, and has used portable machine tools for 15 of its 25-year existence.
The pump job required a BB5000 portable boring machine equipped with a 12-ft bar and heavy-duty facing attachment. To position the machine’s bar from one end of the pump to the other, a J-S Machine & Valve machinist had to crawl inside the pump and set up the tool’s I.D. bearing mount brackets.
With the top half of the pump casing removed, the bar was set in the bore with the I.D. bearings. The top was put back on and mounts were made to place the adjustable bearing on the outboard ends of the pump. That allowed the bar to be adjusted and the drive and feed to be hooked up.
After the bar was in place, machinists used an indicator to ensure it was perpendicular to the shaft and parallel with the installed bearings. Using the facing attachment, the BB5000 cut the surfaces at each end of the pump at a flatness of 0.003 in. over 20 in. This setup ensured proper alignment of the mechanical seal.
This job could take as long as 80 hours to complete. But because it was done on-site with a portable machine tool, it took less than 25 hours.
Nick Hughes, vice president of field services at J-S Machine & Valve, said that, besides pump work, his company most often uses its BB5000 portable boring machine to repair pressure seal valves.
These valves have a tapered metal seal inside that is fitted to the valve’s precision-machined internal surface. As pressure is applied to the valve’s bonnet, the tapered seal wedges against the valve wall. This is a metal-to-metal seal that requires smooth machined surfaces.
When these seals go bad, J-S Machine & Valve builds up the bad surfaces with weld and re-machines them to original dimensions. What makes the job challenging is that it is a blind bore.
“Personally, we wouldn’t even attempt such repair jobs — pressure seal valves and circulating pumps — without portable machines. I don’t know how someone would accomplish such tasks without some sort of portable machine, other than maybe hand dressing surfaces,” Hughes said.
“We work on components large enough for a man to crawl inside of and those that are part of expansive assemblies. You just can’t economically remove these parts and send them out to a local machine shop for repair,” he added.
The company does about two or three valve repair jobs a year. But Hughes said his crew often works on several valves for each job.
Sometimes the jobs are planned ahead of time, but for the most part, they are last-minute emergency jobs. And in those instances, said Hughes, a power plant will do whatever it takes to avoid prolonged shutdowns. Even a day or two can result in huge amounts of lost money.
Climax Portable Machine Tools has been teaching the fundamentals and fine points of portable machine tool operation for almost as long as it has been in existence.
At the company’s Portable Machining Training Institute, located at its corporate headquarters in Newberg, Ore., Climax Portable Machine Tools trains machine tool operators on portable machine tool safety, machine set up and operation. Trainees also receive technical tips and tools to improve operational efficiencies. The majority of every program is devoted to hands-on activities and skill development.
Also at the institute, the company offers a special program called “five machines in five days.” In that program, attendees get a day’s training on each of the company’s machines. If an attendee wants more information on a particular machine, he can return to take a class devoted to just that type of machine.
In addition, Climax Portable Machine Tools works closely with local trade schools to stay in contact with them and to keep them informed of the opportunities in machining. And the company belongs to manufacturing associations to help promote manufacturing/ machining as a career.