Laser shaft alignment

The video below shows how we perform the work “Laser alignment of shafts, coupling halves”

Shaft alignment means correcting the relative position of two articulated machines (e.g. motor and pump, motor and blower, motor and fan, motor and smoke evacuator, motor and compressor) so that the center line of the axes of the coupling halves and shafts are concentric during normal operation.

Types of misalignment

The misalignment of mechanisms is expressed by parallel and angular misalignment of shafts. In practice, they are most often present at the same time. The different types of misalignment are shown in Figure 1 :

Fig. 1 Types of shaft misalignment

Parallel and angular misalignment is defined in two mutually perpendicular planes. In each of the planes the position of the movable mechanism will be corrected in order to eliminate parallel and angular misalignment. For mechanisms with horizontal shafts – the position of the movable mechanism is corrected in the horizontal and vertical planes. For mechanisms with vertical shafts, the operator determines the location of the position correction planes for convenience and manufacturability of moving mechanism movement.

Fixed mechanism (S) – the position of this mechanism does not change during the process of eliminating misalignment.

Moving mechanism (M) – the mechanism whose position is adjusted to eliminate parallel and angular misalignment.

The measuring system calculates the values of parallel and angular misalignment in the plane of the coupling (in two mutually perpendicular planes), as well as the amount of machine movement required to eliminate this misalignment. Figure 2 shows the misalignment and its correction values for the vertical plane only.

Рис. 2 Коррекция механизма М для устранения угловой и параллельной несоосности в вертикальной плоскости.

The operating principle of the system is to measure the movements of the laser beam across the receiver-detector window when rotating the shafts with the measuring blocks mounted on them.

In order for the system to be able to perform the calculation, data must be entered at three positions of the mechanism shafts, e.g. 9 – 12 – 3 o’clock. I.e. a rotation of the shafts within 180º is sufficient.

If the design features of the machines do not allow for 180º rotation of the shafts with the measuring units mounted on them, the instrument provides the possibility of entering data in three positions when the shafts are rotated by an angle of less than 120º.

“Soft” paw

Before starting alignment work, be sure to check the mechanisms for a “soft” foot. This is an unloaded tine, i.e. a tine that is not tightened by the fixing bolt to the foundation or a tine that is overtightened, which creates a misalignment of the structure. The presence of a “soft” foot is checked before performing the alignment, both on the movable and immovable mechanism and, if necessary, eliminated (Fig.3).

Fig. 3 The presence of a “soft foot” on the mechanism