I. The core objective of coupling installation: getting the two shafts "tightly aligned"
The key to coupling installation is to ensure that the motor shaft and the load shaft are aligned as closely as possible to minimize wear and vibration caused by "misalignment". Ideally, the radial misalignment of the two shafts should be so small as to be indiscernible to the naked eye (close to 0.05mm or less), and the angular misalignment should be kept to a very small degree (similar to that of chopsticks placed parallel to each other). Do a good job of centering, can make the bearing life several times longer, the equipment also runs more quietly and smoothly.
Second, the preparation before installation: tools and inspection are indispensable.
1. Check the status of components
Carefully check the coupling for cracks or deformation, such as diaphragm coupling metal sheet is flat without distortion;
Confirm that the shaft diameter matches the size of the coupling bore, there should be a slight resistance when test fitting by hand but it can be pushed in smoothly to avoid over-loosening or over-tightening. There have been cases where the coupling was loosened due to wear of the shaft diameter, resulting in a "thumping" noise during operation.
2. Prepare the necessary tools
Measuring tools: laser alignment meter (very high precision, can measure the deviation of 0.001mm), micrometer, plug ruler;
Installation tools: torque wrench (for precise control of the strength when screwing), hydraulic pulling horse (for non-destructive dismantling and installation), copper rod (soft tool to avoid knocking the parts);
Cleaning materials: anhydrous ethanol (wipe off the shaft and coupling oil), grease (coated in the keyway to facilitate installation).
Third, standardized installation of the seven-step process
1. Cleaning and lubrication
Wipe the shaft and coupling bore clean with anhydrous ethanol to make sure there is no oil or rust;
Smear a thin layer of grease into the keyway, just like "lubricating" the shaft and key, to make the coupling slide in more easily and prevent the key from getting stuck.
2. Temporarily installing the coupling
Put the two halves of the coupling on the motor shaft and load shaft respectively, gently push them into the shoulder position and do not tighten the screws for the time being;
If it is an interference fit (tightly clamped type), it is necessary to install the coupling by using a hydraulic ram or heating the coupling (e.g., heating to 80°C to allow expansion of the bore), and never use a hammer to knock it down. There have been cases in which a worker knocked down the diaphragm coupling, resulting in severe vibration when the equipment was turned on.
3. Initial Alignment Measurement
Detect the deviation of two axes with laser alignment instrument: install the laser transmitter and receiver on two axes respectively, manually rotate the axes, the instrument will show the radial (left/right/up/down offset) and angular (whether the two axes are parallel or not) errors;
Example: If it is measured that the motor shaft is 0.12mm higher than the load shaft and is offset to the left by 0.08mm, it is necessary to adjust the position of the motor.
4. Adjusting the motor position
Radial Deviation Adjustment: Put stainless steel shims (thickness of 0.01mm, 0.1mm, etc.) under the motor base, for example, if the left side is lower than 0.1mm, put 0.1mm shims until the height difference between the two sides is less than 0.02mm;
Angular deviation adjustment: If the two axes are "high on one side and low on the other", it can be corrected by panning the motor or slightly sanding the surface of the base to make the two axes as parallel as possible.
5. Tightening Bolt Tips
Tighten the bolts in 2-3 times, in diagonal order (similar to screwing car tire screws), first to half strength, then review the alignment, and finally use a torque wrench to the specified strength (e.g., M10 bolts usually require a force of 40-50 Nm);
After tightening, apply anti-loosening glue on the bolts and mark them, so that it is convenient to check whether they are loose in the future.
6. Commissioning and final inspection
Turn the coupling by hand to make sure the rotation is smooth and not stuck;
Turn on the machine and let it run at low speed for a few minutes, and then check it again with the laser centering instrument, because the temperature of the machine may cause the shaft to expand slightly after running, and the deviation should be controlled within 1.2 times of that in cold state.
7. Recording and archiving
Write down key data during the installation process, such as the deviation value before and after alignment, bolt torque, date of installation, etc;
One factory found that the failure rate of couplings installed in strict accordance with the procedure was 80% lower than that of "empirically installed" couplings.
Common wrong operation and consequences
1. Do not use instruments, only rely on the naked eye alignment
Naked eye is difficult to find more than 0.1mm deviation, so a fan in the operation of the bearing overheating, 3 months on the replacement of the bearing twice, a waste of tens of thousands of dollars.
2. No axial clearance
In the high temperature environment, the shaft will expand, if the coupling is installed too dead, may be the bearing squeeze. For example, a drying equipment coupling did not leave a gap, the motor shaft was bent after the boot, can only be dismantled for overhaul.
3. Keyway loose and continue to use
If there is a significant gap between the key and the keyway (e.g., more than 0.05mm can be inserted with a ruler), the torque will slip when it is transmitted. When the key of a fan coupling was worn out, the motor idled but could not take the impeller, causing the production line to shut down for 8 hours. 4.
4. Screw too tight
Excessive force may break the coupling, for example, a heavy equipment diaphragm coupling, because the bolt is too loose, suddenly broke during operation, and the debris also crashed next to the sensor.
Fifth, intelligent tools to make the installation more efficient
Wireless laser alignment instrument: through the cell phone APP real-time look at the deviation data, but also can give advice on adjustment, a person can operate, than the traditional method faster than half the time. An automobile factory used it to shorten the installation time of a single piece of equipment from 4 hours to 2 hours.
Electric torque wrench: preset strength, screwed to the appropriate torque will automatically stop, to avoid manual screwing over or not tightened, a workshop with the bolt pass rate increased from 85% to 99.5%.
Summarize: installation to do a good job "three keys"
Alignment: accurate alignment with a laser meter, do not rely on the naked eye estimate;
Strength: use torque wrench to control bolt torque, don't tighten by feeling;
Record: leave the installation data for future traceability and maintenance.
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