How to replace the cutter assembly of rewinder in papermaking machinery if it fails?

Replacement operation of cutter assembly of paper rewinder (circular cutter assembly, commonly used in paper mills)

> Important premise: * * LOTO must be locked and tagged * *, the whole machine will be cut off from power and gas, and the pressure of main drive and tool rest cylinder will be released, and a warning sign "No closing during maintenance" will be hung; Wear anti-cutting gloves and goggles, and it is forbidden to touch the cutting edge with bare hands regardless of whether the blade is old or new.

> application: rewinder upper cutter assembly (circular cutter holder+blade+cutter holder/bearing seat assembly); If it is a bottom roller assembly, the idea is the same, but the hoisting and positioning are different.

First, the fault confirmation and preparation before replacement

1. Confirm the fault: the blade is cracked, the cutting edge is worn, the bearing of the tool holder is stuck, the tool holder is deformed, and the air cylinder knife swinging mechanism is damaged; Distinguish whether it is * * single-knife assembly * * or whole-row tool rest assembly.

2. Preparation tools: socket wrench, hexagon socket, feeler gauge, copper bar, small lifting chain (large assembly), clean rag, original cutter assembly, grease and protective articles.

3. Cleaning the cutter area: clean the paper wool, dust and shredded paper, and take photos to record the original position of the assembly, gasket, positioning scale and pipeline joint, so as to facilitate reassembly and alignment.

Second, remove the old cutter assembly

1. Manually lift the upper tool rest to the highest safe position, and lock the mechanical limit of the tool rest to prevent the tool rest from accidentally falling.

2. Remove the cutter guard (safety guard) and put it in a safe area.

3. Disconnect the accessories of the assembly: the air pipe of the tool holder cylinder, the cable of the induction sensor and the cooling oil pipe (if any), mark them well, and block the nozzle to prevent impurities from entering.

4. Loosen the fixing bolts on both sides of the cutter assembly (* * diagonally loosen several times, and do not dismantle * * unilaterally at one time to prevent the cutter seat from deforming); For the heavier assembly, support the bearing with the lifting chain in advance, and then remove the fixing bolts.

5. Carefully pull out the whole cutter assembly (including cutter seat, circular blade, cutter holder and bearing) and move it out slowly to avoid the blade bumping against the bottom roller and scratching the roller surface; Put the old blades into the special knife box separately, and don't pile them up at will.

6. Clean the installation datum plane: clean the shaft seat and positioning groove, and check whether the spindle/cutter shaft is strained or corroded, and whether the bearing position is worn; If the shaft is damaged, handle it synchronously.

Iii. Assembly of new cutter assembly

1. Unpack and inspect the new assembly: check the model, the blade edge without collapse, the bearing rotating smoothly and the tool holder without deformation; The front and back of the blade are installed according to the original factory logo (with the logo facing outwards).

2. Hoist/translate the new assembly in place, align the locating pin and locating step, and put it in place gently, without hard knocking.

3. Pre-tighten the fixing bolts: tighten them diagonally evenly, pre-tighten them first, and then drive them to the specified torque several times to prevent the tool holder from being skewed.

4. Restore accessories: connect the gas circuit, sensor cable and cooling pipeline, and make sure that the connector is airtight and the signal line is firmly fixed.

5. Install safety shield and fix it temporarily.

Four, the knife, gap adjustment (the most critical, directly determine the quality of paper cutting, to prevent knife collision)

> paper rewinding circular knives are generally upper circular knives+lower bottom knives (bottom rollers) for meshing and cutting.

1. Turn the car manually, and slowly lower the upper cutter assembly. * * It is forbidden to power on the cutter directly.

2. Adjust the meshing overlap of the upper and lower knives: the cultural paper/toilet paper is rewound, and the overlap is generally 0.2 ~ 0.5 mm (subject to the equipment manual); Use a feeler gauge to check that the clearance on both sides is even and there is no one-sided rubbing knife.

3. Manually consolidate the root cutter shaft, and there is no jamming and continuous scraping noise during the whole rotation; Slightly even rubbing sound is normal. If there is sharp impact sound, immediately lift the knife and readjust it.

4. Check the axial position of the knife: align the cutting marks to ensure that the cutting position is aligned with the paper web tangent line.

5. Add a small amount of high-temperature resistant grease to the sliding part of the tool holder, clean up excess grease and avoid paper powder.

Five, no-load test machine+try cutting with paper

1. Before dismantling LOTO, make sure there are no tools and sundries in the knife area, and evacuate personnel from the dangerous area.

2. Start inching, run at low speed and no load, and observe that there is no abnormal vibration or abnormal sound, the cylinder of the tool rest operates normally, and the sensor signal is normal.

3. Try to cut the paper at low speed, and observe the edge of the paper: the cut is smooth, without galling and fiber drawing;

-galling/cutting continuously: increase the overlap of upper and lower knives;

-Paper edge crushing, rapid blade wear: excessive overlap, callback;

-One-sided burr: the assembly installation is skewed, and the tool holder level is re-calibrated.

4. Gradually increase to the production speed, run 3 ~ 5 volumes continuously, and deliver to production after stabilization.

Six, common fault judgment (distinguish before changing the assembly, avoid white change)

-The edge of the paper is brushed and cut continuously: the blade is worn first, and the blade can be changed separately; If the tool holder bearing shakes and the tool holder is deformed, it is only necessary to replace the whole assembly.

-Periodic abnormal sound and jitter: the tool holder bearing is damaged and the dynamic balance of the assembly is invalid, so the assembly is directly replaced.

-Incorrect tool collision and tool rest return: cylinder/knife swinging mechanism is faulty, not necessarily the cutter body.

Seven, safety taboo

1. It is forbidden to assemble and disassemble the knife assembly with electricity and pressure; It is forbidden to switch off the motor without locking the tag.

2. Don't enter the meshing area of the upper and lower knives when adjusting the gap.

3. Before starting the new assembly, direct high-speed commissioning is prohibited; Once the knife is hit, the blade and the bottom roller will be scrapped directly, and the loss is great.

4. Don't discard the old blades directly, and collect them according to the hazardous waste standard of tools.