The transmission mode of large centrifugal fans mainly depends on the coupling. The selection and installation of the coupling usually refer to many factors, but no matter what kind of coupling, it is necessary to align the fan and the motor shaft during installation. It is correct, and accurate centering can also make the operation of the fan more reliable. The following editor has sorted out the installation centering standard and centering method of the centrifugal fan coupling for your reference.
1)Centrifugal fan coupling installation alignment standard
In fact, all mechanical equipment cannot avoid errors during installation, and the same is true for centrifugal fans. When installing couplings, there will also be deviations in the main shafts of the fan and the motor, and this deviation in the alignment of the two shafts is basically divided into radial deviations , angular deviation, combined radial and angular deviation, and ideal alignment. During installation, the alignment standard is as follows:
| Allowable deviation standard for two-axis connection | ||
| Axle hole diameter/mm | Axial displacement/mm | Angle deviation |
| ≤100 | 0.025 | 0.05° |
| ＞100~180 | ||
| ＞180~250 | 0.1° | |
| ＞250~315 | 0.05 | |
| ＞315~450 | 0.15° | |
| ＞450~560 | 0.075 | 0.2° |
| ＞560~630 | ||
| ＞630~710 | 0.1 | 0.25° |
| ＞710~800 | 0.3° | |
In actual installation, the radial and angular deviations of the two shafts should be as small as possible. This is mainly due to the unavoidable existence of foundation sinking, uneven thermal expansion of various components, bending of the shaft, and zero during the operation of the equipment. Various conditions such as wear and tear of components will adversely affect the alignment of the centrifugal fan coupling installation. Therefore, the radial and angular installation deviations are controlled during installation. Generally, it can be controlled to 1/8 of the allowable deviation. ~1/3, which will leave a certain compensation space for new offsets during operation, so as to ensure that the two axes can still be well centered and run safely during operation.
2)the method of installation alignment
1. Align with straightedge and plug gauge: Use straightedge to measure the coaxiality error of the coupling, and use the plug gauge to measure the parallelism error of the coupling. This method is simple, but the error is large. Generally used for machines with low speed and low precision requirements.
2. Alignment with dial indicator: There are many ways to use dial indicator for alignment, such as single-table method, double-table method, three-table method, etc. It is recommended to use the double-meter method which is easy to operate, convenient for reading, data processing and adjustment, and has a good centering effect. The double-meter method is to install a dial indicator on the hub flange of the reference shaft and the adjusted shaft, and judge the alignment of the two shafts and adjust them according to the measured radial runout.
3) Coupling double-meter method alignment measurement steps
1. Select measuring points: Divide the roughly adjusted two half-shaft hub flange cylindrical surfaces into four measuring points, respectively use a1, a2, a3, a4 and b1, b2, b3 , b4 represent the measured values of the corresponding points, where a represents the measured value on the reference axis, and b represents the measured value on the adjusted axis, as shown in the figure:
2. Install the dial indicator: Install and fix the dial indicator on the reference shaft and the half-coupling of the adjusted shaft. The frame should be rigid enough and the installation should be firm. After installation, zero the dial indicator. Note that during horizontal alignment, the dial indicator on the reference axis is zeroed on the right, and the dial indicator on the adjusted axis is zeroed on the left. When vertically centered, the dial indicator on the reference axis is zeroed at the top, and the dial indicator on the adjusted axis is zeroed at the bottom.
3. Measurement: Rotate the two semi-axes 180° at the same time, and measure a1~a4 and b1~b4.
4. Check the rigidity of the stand: The rigidity of the stand directly affects the accuracy of the measurement results, which in turn affects the alignment accuracy. Therefore, before the formal measurement, the rigidity of the watch frame should be checked, which should generally satisfy a1+a2≈a3+a4 and b1+b2≈b3+b4. If the error is greater than 0.05mm, the rigidity of the stand should be strengthened.
5. Other data measurement: Measure the distance c between the two dial indicator probes, and measure the distances f1 and f2 from the dial indicator probe on the back adjustment shaft to the front and rear supports of the adjusted shaft.
Since the alignment is usually horizontal first and then vertical, a1, a2 and b3, b4 are usually set to zero, so that A can be used to represent the measured values of a3 and a4, and B to represent the measured values of b1 and b2. Based on this, it can be judged that The direction and amount of adjustment are adjusted.
