How to replace the control assembly of the circular knife of the rewinder of papermaking machinery?

Complete replacement process of circular knife control assembly of paper rewinder

Circular cutter control assembly generally includes: cutter seat slider assembly, lifting cylinder, guide linear guide rail, adjusting mechanism, bearing, cutter body of circular cutter, and locking assembly. Some models have servo drive units, which belong to an integral detachable unit. When replacing them, it is necessary to strictly implement power-off tag locking machine to prevent misoperation and personal injury.

First, preparation before replacement

1. Safety locking: the rewinder stops completely, press the emergency stop, cut off the main power supply of the whole machine, and execute the tag-out locking LOTO；; The pneumatic model turns off the air source and releases the residual compressed air in the cylinder pipeline to prevent the cylinder from falling suddenly and being injured.

2. Protection and tools: wear cut-resistant gloves and goggles; Prepare torque wrench, hexagon socket set, copper bar, dust-free cloth and oil pan; Prepare a new assembly, and check that the model, mounting hole distance, cylinder stroke and slider specifications are consistent with the original.

3. Station cleaning: clean the paper dust and pulp residue around the beam of the circular knife, and leave room for disassembly and assembly; Mark the horizontal position and height adjustment scale of the original assembly, and take photos to record the wiring position of the trachea connector and sensor for easy reassembly and alignment.

Second, the old assembly disassembly steps

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> do not disassemble a single set of circular knife control assembly directly on the high-speed running beam violently, and give priority to lifting the knife assembly to a safe position for operation.

1. Lift the original round knife, and move the knife assembly to a vacant position where the beam is easy to disassemble; Make sure that the knife is in the raised high position.

2. Pipeline removal

-Pneumatic type: mark the two air pipes of the cylinder, unplug the quick connector and mark the A/B port;

-Servo drive: disconnect the power line of servo motor and encoder cable, loosen the aviation plug and mark the number.

3. Loosen the locking handle/pressure plate bolt between the slider and the beam guide rail, slide the assembly horizontally and move out of the working position.

4. Dismantle the fixing bolt of the assembly: loosen the connecting bolt between the linear slider and the base of the tool rest, and remove the whole set of round knife control assembly (including cylinder, tool holder, bearing and round knife) from the guide rail of the cross beam and put it on the rubber pad. It is forbidden to drop or bump the blade directly.

5. Disassemble the old assembly on the backing plate: remove the round knife locking gland, round blade, spacer and bearing assembly in turn; Check core wear: bearing clearance, cylinder piston rod for strain, slider ball for damage, and adjusting thread for seizure.

> note: don't disassemble the blade separately on the beam, and then disassemble the blade after the whole assembly is disassembled, so as to prevent the blade from falling and hurting people.

Iii. Assembly of new round knife control assembly

1. Pre-assembly of new assembly (completed on the ground)

1. Clean the mounting surface of the new assembly slider and tool holder, and remove rust-proof oil and iron filings; Check that the linear slider slides smoothly without sticking.

2. Install the bearing and spacer, and put the round knife into it, and the cutting edge has no crack; Lock the gland nut according to the original factory torque, and it is forbidden to twist violently to prevent the blade from deforming. Manually rotate the round knife, which is flexible and free from movement and jamming.

3. Confirm that the cylinder is installed firmly and the piston rod is not eccentric; Lift adjusting screw and limit stop are assembled in place.

2. Hoist back to the equipment beam.

1. Hang the whole set of new assembly into the linear guide rail of the cross beam smoothly, align the guide rail slot and push it into the guide rail;

2. Install the slider fastening bolts, and tighten them diagonally for several times. Do not lock them at one time; Refer to the original horizontal scale marked before, and initially locate the cutting position.

3. Restore the pipeline

-Pneumatic: the air pipe is connected back to the A/B port of the cylinder according to the mark;

-Servo type: recovery encoder, power aviation plug, locking buckle.

4. Push the assembly manually, and make sure that the lateral movement is smooth, without blocking or abnormal sound.

IV. Precision debugging (replacing the core link of the assembly)

1. Transverse positioning: according to the width of the cutting process, fine-tune the transverse position of the assembly to ensure that the circular knife edge is aligned with the slit of the bottom knife (lower knife roller).

2. Adjustment of cutter depth/meshing amount: adjust the cylinder limit and height adjustment screw to control the meshing depth of the upper circular cutter pressed into the bottom cutter; The conventional meshing amount of paper rewinding is 0.1‑0.3mm；; Engage the cutter and burn the cutting edge; If it is too small, there will be continuous cutting, paper edge fuzzing and knife jumping.

3. Parallelism check: Visually+feeler gauge check that the full length of the round knife is parallel to the bottom knife roller, and the clearance at both ends is consistent to avoid unilateral wear.

4. Manual rewinder, the round knife rotates without rubbing the knife and striking abnormal sound.

Five, electrical ventilation commissioning acceptance

1. Remove the lock and tag, and send electricity and gas; First, inching the tool lifting and dropping to confirm that the lifting direction of the cylinder is correct and there is no air leakage; The servo model confirms that the motor returns to zero normally.

2. Run at low speed with no load, and observe the running state of the whole set of circular cutter control assembly: no jitter, no abnormal noise and no sliding block.

3. Trial cutting with paper: feed the paper, observe the cut of the paper, and the paper edge is smooth without burrs, wiredrawing or trimming; Try cutting at low speed and process speed respectively, and confirm that the cutting is stable at different speeds.

4. Review the torque of all bolts, and check that there is no air leakage in the trachea joint; Clean up the paper dust at the cutter position and make a record of changing parts.

VI. Common Faults and Precautions

1. Rough trimming after replacement: the high probability is parallelism deviation, incorrect meshing depth, or burr on the cutting edge of the new blade; It is forbidden to directly increase the amount of depression to forcibly cut off.

2. Shaking and abnormal sound of the tool holder: the slider bolt is not locked diagonally, the guide rail has paper dust impurities, and the bearing assembly clearance is too large.

3. The cylinder tool dropping is not in place: the air pipe is connected reversely, the sealing ring inside the cylinder is damaged, and the position of the limit stop is offset.

4. Safety red line: It is forbidden to disassemble and assemble the assembly with electricity and gas; The blade is sharp, and it is forbidden to touch the cutting edge with bare hands all the time; When disassembling, it is forbidden to stand below to prevent the assembly from falling.

> tip: the assembly structure of rewinders (domestic and imported high-tech models) from different manufacturers is slightly different, and the final parameters are subject to the original equipment manual.