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Saturday, April 11, 2009

Linear Actuator III

By Gordon Petten

Mechanical motion is produced by actuators through a conversion of different energy forms into mechanical energy and this is a basis of major exploration. Through science, new ways are found for utilizing actuators daily including for purposes of medicine. An actuator is basically something capable of energy conversion into motion. A linear actuator can be described as a device used for developing force as well as motion from any available source of energy in a linear-like manner and not rotationally like electric motors.

There are different types of linear actuators including a mechanical linear actuator which is typically used in the conversion of a handle or control knob's rotary motion into a form of linear displacement through gears and/or screws to which the handle or knob is attached. A car jack or jack screw is a mechanical linear actuator that is familiar. Another mechanical linear actuator family is based on a segmented spindle. The jack handle rotation is converted mechanically into the jack head's linear motion. These actuators are commonly applied in the optic and laser field for position manipulation of rotary stages, linear stages goniometers, mirror mounts as well as various positioning instruments. For repeatable and accurate positioning, users may use index marks on the control knobs.

Some mechanical linear actuators are inclusive of encoders and digital readout positions. There is a similarity of the micrometer adjustment knobs except that they are used for position adjustment rather than for position measurement.A, hydraulic linear actuator or hydraulic cylinder typically involves a hollow cylinder with a piston insertion in it. The two piston sides are alternately de-pressurized or pressurized to achieve a controlled and precise piston linear displacement and the piston entity connection. Physically, the linear displacement is along the cylinder or piston axis and this design is generally based on the hydraulic principles. A hydraulic car-jack is an ideal example of a hydraulic linear actuator that is manually activated although typically, a hydraulic linear actuator is used to refer to an appliance controlled through a hydraulic pump.

A piezoelectric linear actuator effect is present in particular materials whereby the voltage application to a certain material causes its expansion. When the voltages are very high, this is only correspondent to tiny expansions thus the linear actuator achieves an extremely fine resolution positioning, although the motion range is very small. Additionally, the materials exhibit hysteresis and make the expansion control difficult in a manner that is repeatable.

An electro-mechanical linear actuator has similarities to a mechanical linear actuator although the handle or control knob is replaced using an electric motor. The motor's rotary motion is converted into the actuator's linear displacement. There are numerous modern designs and respective manufacturing companies tend to have individual proprietary methods. In electro-mechanical actuators a rotary driver is connected mechanically to a screw lead to ensure that the electric motor rotation makes the lead screw to rotate. In most designs of linear actuator, the basic operational principle is of one of a plane that is inclined.

1 comment:

Dupont Hydro Industries said...

Dupont Hydro is a leading manufacturer and supplier of hydraulic cylinders, hydraulic jacks, power packs and repairs.