Custom Design Solutions for Complex Challenges

SITUATION:  Couplings which transmit torque between turbines and generators over time experience wear in the bolt holes. The repair of couplings must take place during an outage when the turbine and generator are offline. The typical repair process involves assessing the worst case out-of-round bolt hole and then oversizing the bore diameter for all the bolt holes in both coupling halves.

PROBLEM:  The current practice was to match machine the couplings while they were on the shafts of the turbine and generator, meaning this repair process was in the critical path of the outage. Therefore any delays in this repair process could cause a delay of the entire project, exposing GE to potential liability and costs.

SOLUTION:  The Mirror Bore machine enabled the boring of both the turbine half and the generator half of the coupling independent of the turbine and generator shafts. This change in the process removed the coupling machining from the critical path and reduced the outage time for GE and its customers.

The Mirror Boring Machine is a precision machine tool that attaches to the front face of turbine coupling with an electromagnetic chuck and precisely bores the bolt holes.

To achieve proper centering and leveling of the boring machine, a fixture plate with holes (2.75” or 4.25” diameter) matching the hole pattern of the coupling is machined flat within specifications. These holes allow the boring machine to quickly align itself. A centering pilot ring, either 2.75” or 4.25” diameter is attached to the machine’s electromagnetic chuck. A particular feature of the Model 5380-S1 is a specially designed lifting arm that maintains the balance of the machine throughout its operational cycle.

THE NEED:  Customers require precision spot face grinding of coupling bolt holes. The machine should be compact, lightweight and capable of working on a wide range of coupling bore diameters and lengths.

THE CHALLENGE:  Most spot facers are limited in bore diameter range as well as coupling lengths. Additionally, the tolerances commonly achievable are not as tight as is required for today’s requirements, and setup can be time-consuming.

Current lack of a machining solution capable of performing desired operations means lower productivity, requiring multiple machines for a range of workpieces. The inability to hold tight tolerance means extended time for setup and machining as well as possible rework.

THE ANSWER:  One machine with small and large machining range options covering a wide range of couplings. Precision mounting collets, fine grinding wheel adjustment and simplicity of machine design provides a versatile, quick to set up and highly accurate spot face grinding solution.

• Grind spot faces of counterbores in a full range of coupling diameters and lengths.
• Capable of alignment to the centerline of finished bores.
• The face must be perpendicular to the bore.
• Mount to and grind counterbores of either assembled or separated couplings.
• Very precise counter bore axial run-out, counterbore flatness, perpendicularity of face to bore centerline and surface finish.

BairdMaritime (Ships&Shipping.com)

USA: Portable milling machine to repair Markland Locks
Tuesday, 11 May 2010

USA: More than US$11.6 billion a year worth of commerce pass through the Markland Locks and Dams on the Ohio River, representing approximately 55 million tonnes of goods, including coal, grain, iron, and steel.

It takes approximately 2,400 tows to carry this amount through the lock chamber. When the locks needed to be refurnished, the Army Corps of Engineers began looking for a solution that would not disrupt the flow of shipping and that could replace its current repair process which was costly and time-consuming.

CLIMAX Portable Machine Tools received the contract to design and build a portable milling machine, the best technical- and cost-effective solution for refurbishing the Markland Locks on the Ohio River within a stringent timeframe.

The award is funded under the American Recovery and Reinvestment Act (ARRA), which earmarked money for the Army Corps of Engineers for construction projects.

The Ohio River Project calls for refurbishing the lock doors and door quoins, which are the sealing surfaces between the lock wall and the steel lock doors. Over time, frequent repairs to the gates had left the surfaces uneven.

CLIMAX won the contract to design, fabricate, and fully test two large-scale, custom-made vertical milling machines capable of traveling up to 21 meters in height in a single pass, removing up to 3.8cm of materials over multiple passes, and that could also drill and tap.

This milling machine will not only enable machinists to smooth the structures’ surfaces so they will operate better and not leak, but also to complete the repairs on site within the 17-day timeframe required by the Corps.

For further information, contact:
CLIMAX Portable Machining & Welding Systems
1-503-538-2185
Email: [email protected]
Web: climaxportable.com