How to replace the scraper of Three roll mill after it is worn?

1. Preparation before replacement
1. Preparation of tools and spare parts
Required tools: special wrench (matched according to the equipment model, mostly hexagonal wrench or open-end wrench), screwdriver, gloves (anti-scratch), cleaning cloth, special cleaning agent (such as kerosene, alcohol, selected according to the nature of the material).
Spare parts: new scraper blade (must match the original model, the material is usually high-speed steel, carbide or stainless steel, pay attention to the direction of the blade), spare screws (if the original screws are rusted, they can be replaced).
2. Prerequisites for safe operation
Make sure the equipment is completely powered off (turn off the power switch and unplug the plug) to avoid danger caused by accidental startup.
Clean up the materials around the equipment and lay a clean rag in the contact area between the roller and the scraper to prevent parts from falling or tools from scratching the roller surface.
2. Steps to remove the old scraper
1. Loosen the scraper fixing mechanism
Find the fixing screws of the scraper holder (usually 2-4, distributed on both sides or the bottom of the holder), and loosen them counterclockwise with the corresponding wrench (if the screws are rusted, you can drip 1-2 drops of lubricating oil and soak them for 5 minutes before tightening to avoid forced disassembly and causing thread slippage).
The scraper and the holder of some models are connected by buckles or slots. You need to loosen the buckle lock first, and then gently pull out the old blade.
2. Remove the old blade
Wear gloves to hold both ends of the old blade (avoid touching the blade to prevent scratches or contamination by residual materials), and slowly remove it from the holder (if the blade fits too tightly with the holder, you can use a screwdriver to gently pry the edge of the holder, and do not use excessive force to avoid damaging the holder).
Check the wear of the old blade (such as whether there are serious gaps or bends), and observe whether there is material accumulation or foreign matter inside the holder. If there is, use a cleaning agent and cloth to clean it thoroughly (to prevent affecting the installation accuracy of the new blade).
3. Key steps for installing a new scraper
1. Pretreatment of new blades
Wipe the surface of the new blade with a clean cloth dipped in a cleaning agent to remove the anti-rust oil or dust at the factory, and check whether the new blade has been bumped during transportation (such as deformation and notch of the blade, if any, a spare part needs to be replaced).
If the new blade is split (the blade is separated from the blade holder), it is necessary to confirm the installation direction of the blade (usually the blade faces the surface of the roller, do not install it upside down, otherwise the material cannot be scraped).
2. Fix the new blade to the blade holder
Put the new blade smoothly into the installation slot of the blade holder, and ensure that both ends of the blade are aligned with the blade holder (no skew, otherwise it will cause uneven fit with the roller after installation).
Press the blade lightly with your hand to make it fit tightly with the blade holder, then pass the fixing screw through the hole of the blade holder and pre-tighten it clockwise (do not lock it for the time being, leaving space for fine-tuning).
3. Adjust the position of the blade (after initial fixation)
Observe whether both ends of the blade exceed the edge of the blade holder (need to be flush with the blade holder to avoid interference with other parts during operation). If there is an offset, gently push the blade to adjust it to the center position.
IV. Calibration and fixation after installation
1. Calibrate the parallelism between the blade and the roller
Use a feeler gauge to measure the gap between the two ends of the new blade and the roller surface (make sure to measure when the machine is stopped), and make the gaps at both ends consistent by fine-tuning the position of the blade holder (usually ≤0.05mm is required to ensure uniform fit).
If the blade holder has a horizontal adjustment bolt, the lateral position of the blade can be adjusted by rotating the bolt until the gap meets the standard.
2. Tighten the fixing screws
Gradually tighten the fixing screws in diagonal order (avoid deformation of the blade caused by tightening one side first), and tighten each screw to a moderate force (the blade cannot shake, too tight may cause the blade to bend, and too loose may cause it to loosen during operation).
After tightening, check again whether the blade is flat, and gently push the two ends of the blade with your hand to confirm that there is no looseness or warping.
V. Testing and adjustment after replacement
1. Cleaning and inspection
Wipe away the debris dropped during installation with a cloth, and ensure that there are no foreign objects (such as screws, debris) between the blade holder and the roller to avoid scratching the roller surface after starting the machine.
2. Test run and fine-tuning
Power on and idle for 1-2 minutes, listen for any abnormal friction sound at the contact between the scraper and the roller (normally there should be no obvious noise, if there is any abnormal noise, stop the machine immediately, and check if the blade is skewed or the screw is loose).
Add a small amount of material to test the scraping effect: observe whether there is no residue on the surface of the roller, whether the scraped material is continuous and uniform, if there is local residue, fine-tune the pressure or parallelism according to the "scraper adjustment method" (refer to the scraper adjustment steps in the previous article).
VI. Precautions
1. When replacing the blade, it is forbidden to wear rings, bracelets and other accessories to avoid being involved in the equipment or scratching your hands.
2. If the new blade is made of carbide, it must be handled with care to prevent the blade from colliding with hard objects and causing collapse.
3. After replacement, properly dispose of the old blade (do not discard it at will, especially the sharp blade must be wrapped with thick paper and then recycled in a classified manner to avoid accidental injury to others).