Difference of lead screw and motor connection interface:-
There are three basic ways to connect the lead screw to the
hollow shaft motor to create an external linear actuator system. The following
are the advantages, disadvantages and performance impacts associated with each
of these methods.
Coupling method:-
There are several
styles of motion control couplers that can be used to transfer the rotation
movement of the motor to the connected lead
screw. This coupler is installed on a bolt shaft that extends from the
motor and also connects to the machined stump at one end of the screw. This
type of configuration requires more physical space to accommodate the length of
the coupler and the associated accessory housing. Due to the greater number of
parts, the accumulation of tolerances and the complexity of the assembly, the
coupler are more vulnerable to misalignment, which makes it difficult to fix
each part to the center line. The result of this misalignment has a cam-like
effect on the coupler and the screw, transferring additional force to the motor
or screw and shortening the life of the system.
Traditional motor
and screw settings:-
· Multiple components that require assembly
· Alignment difficulties
· Loss due to regeneration and accumulation of tolerance between components.
· Greater probability of failure
· Higher cost
Integrated hybrid linear actuator configuration:-
· Feed screw directly aligned and fixed with motor
· Less components
· Greater precision
· High stiffness
· Higher value
Tapered locking
method:-
Another common method used to assemble the actuator using an
external feed screw motor is to insert a machined journal from one end of the screw into a
tapered hole in the motor. Then, the bolt can be used to mechanically fix the
screw from the back. This mounting method is chosen more frequently when a
large amount of maintenance is required. Fixing and disassembly by means of
fixing screws in place using the threaded mechanical method. The disadvantage is
the difficulty in establishing and maintaining alignment. The result of the
deviation and misalignment is the "snow cone" effect, which amplifies
the inaccuracy of the screw length. This is especially evident in applications
where longer screws are required. This "snow cone" or screw
oscillation effect creates a force that is transmitted to other components
within the system. As a result, nut wear and additional engine load may shorten
the life of the system, require additional maintenance or cause premature
failures.
Permanently fixed method:-
For external drive screw motor actuators,
its connects the screw directly to the motor. Machined journals from one end of
the screw are manufactured with tolerances and sliding adjustments with small
spaces in the hollow shaft of the motor. This method ensures maximum coupling
between the screw and the motor, allowing the most accurate alignment possible.
Then apply laser welding to the entire diameter of the rear of the engine to
permanently fix the screw. In some cases, welds can be replaced with industrial
adhesives, creating a similar permanent joint between the screw and the motor.
Precise tolerances, maximum screw and motor coupling, and
permanent welding minimize the need for calibration, eliminating the highest
levels of accuracy, minimum screw eccentricity and "snow cone"
effects.
