Can Doctor Blade Removal Be Simple and Safe?
Removing sharp doctor blades can be a challenging task. The function of a doctor blade is to scrape glues, wood pitch, stickies, and fibers from rolls. The glue, wood pitch, and other debris work into the blade holder to complicate blade removal. After a shutdown cycle or two, the blades become very difficult to remove. To add risk, the blade is worn and extremely sharp. Pulling an extremely sharp blade from a holder with compacted fibers, glues and wood pitch is a safety risk especially without the proper tools.
There are two forces required to remove a doctor blade, grip force and pull force. It is not uncommon to require the use of an external power source such as a tow motor or come-along cable to generate enough pull force to remove a doctor blade. The grip force of current tools are not great enough to overcome the pull force required to extract a doctor blade. Therefore, blade changes can take hours and consume valuable resources during a shutdown. Too often, blade removal attempts are aborted prematurely for these reasons, leaving worn-out blades in machines and runnability issues.
Conventional tools are not sufficient for the demands of today. Mills are using tow motors to unsafely pull blades. We have seen tools slip off and spring from the machine to slam against the tow motor or the rope break and recoils uncontrollably.
With a clear picture of the inefficiencies of the conventional tools, one of our front line team members developed a successful concept called the BladeShark™ Doctor Blade Extractor.
The BladeShark Doctor Blade Extractor has three major design criteria:
- As the pull forces increases, the grip force should increase.
- The design needs to be robust and modular.
- It must be rugged enough for mill use.