A client is seeking technologies for repairing alloy gear either on site or at a local workshop with minimal facilities.
Industrial gearboxes are deployed in various applications, like mills, belt conveyors, mixers, fans and other equipment in steel plants, mines, the tire industry, and many other applications. Due to the importance of the process, once a gearbox defects, this will create a bottleneck in the entire process, causing wasted time and money to replace the gear or the whole gearbox. Independent from the field of deployment, we need to find a technology/method/solution to repair damaged teeth inside industrial gearboxes in place.
In industrial gearboxes with spur/helical/bevel or herringbone gearing, teeth are mostly made out of alloy steel of 18CrNiMo7-6 as per DIN EN 10084 or equivalent and case hardened to 58 to 63 HRC. Gear teeth can be damaged on the surface or can be cracked and broken. This can happen from improper maintenance, errors in manufacturing or improper operation. Assuming only improper maintenance (which may cause broken teeth, damage to the surface, or anything that makes the teeth pitted or broken), we seek to find a way to repair the damaged gears to put them back in service with minimal downtime. In other words, a solution to repair the existing gear (e.g. by applying some material on damaged surfaces, or by pasting the broken parts and filling the space with some material), or any other way that avoids the need to make a completely new gear is desired. Preferably the solution must be able to be performed on site or at a local workshop with minimal/low facilities.
Some existing methods involve grinding sharp edges of damaged teeth or by welding broken teeth with arc welding. Grinding sharp edges does not fill the holes from pitting so the total contact area will not correctly meet the original specifications. Consequently, the stress will be on a smaller surface area than for the original gear, it therefore will be overloaded and the surface damages starts to increase again. On the other hand, arc welding of broken teeth will cause deformation due to very high temperature of welding and it implies effects on material properties like case hardened of tooth flank. This way is not desired in general.
Gear manufacturers mostly prefer to get orders for new gears rather than repairing the existing damaged ones. If the repair proposed solution does not completely satisfy the technical specifications of original gear, then it is not of interest. Shutdowns, further repairs or overhauls are costly for such cases.
The technology or method we seek must:
The seeker's priority is to find a solution which has already been proven or may be already in use or at least in adjacent areas. Prototypes and proof-of-concept solutions are also welcome. Theoretical solutions are not of interest.