Ball screw
introduction
The main function of the ball screw
system is to efficiently transfer the rotation movement as a linear movement,
sometimes with extremely high precision, accuracy and repeat-ability. Ball
screws are distinguished by the way in which the threads of the bearings are
manufactured by a bulk deformation process or a precision grinding process,
commonly called rolling.
However, more information can be obtained from specific
examples of common mechanical applications, sometimes using rolled or grounded
ball screws. This type of illustration gives the engineer some real productive
illustrations that are used as a general principle of operation to help the
selection process between the roller ball and the ground ball screws for new
applications.
Precision X / Y
positioning table:-
Dimensional inspection tables are available in a variety of
designs, shapes and styles, and are widely used in manufacturing, inspection
and other related research applications. In general, they generally use a
precision ball screw system to achieve the level of precision required to
position the table for a given application. The ground ball screw in the center
of the large and small positioning table is driven by a servomotor. This servo
motor / ball screw system can achieve very high levels of accuracy (1 micro
inch in certain cases) with excellent repeat ability.
Steppers used in
lithography equipment
The ball screw is also in a stepped photo-lithography machine
that manufactures the latest generation of fine integrated circuits that help
to significantly improve the performance of raw computing. At a high level,
photo-lithography is a micro-fabrication process that uses the reaction caused
by exposure to thin film substrates present in silicon wafers. This process
effectively engraves geometric patterns on the wafer to form the base of the
integrated circuit. To achieve this, a component called step by step must
control the exposure position and the position in the wafer and, therefore,
must be able to operate at micro scale with very high precision.
Within this step by step, ball screw actuators are combined
with servo motors and harmonic gear
reducers similar to the X / Y positioning table. Only a high precision ground
ball screw can achieve high accuracy and repeat-ability. Necessary to accurately
control wafer exposure with the high level of repeat-ability required for the
process. These precision ground ball screws are smooth, quiet and efficient to
work with and are more suitable for machine applications that require a level
of precision similar to lithography machine applications.
Automotive power
steering
Finally, the most common ball screw in everyday life is the
power steering system of a typical car. Unlike the previous two examples, a
typical automotive power steering system does not require almost the same
degree of accuracy and repeat-ability of position as the X / Y table. The
rotational movement that the driver applies to the steering wheel turns the
ball screw , turning it into a corresponding ball nut that acts as a piston
within the pressurized fluid system in the car power steering core. The ball
nut hooks the Pit-man arm through the teeth that fit into the base. This Pit-man
arm serves as the main connection from the power steering box to the central
link that really moves the wheels. In this figure, it is not difficult to see
how the movement of the ball nut moves the Pit-man arm. This controls the
movement of the central joint and the movement of the front wheels of the car.
In applications such as automotive power steering, the main
function of the ball screw is simply to convert the rotational movement into a linear motion
in the piston of the power steering, so that the ball screw is feasible and
much more economical. Because of this, the roller ball screw nuts are
sufficient to achieve the required movement conversion and low positioning for
this application.
