Actuator available in controlled environment

摘要

A clean environmental actuator is less in weight, height in transverse section and compact in construction, even with ensuring accurate position control and conformable to high speed operation and high acceleration/deceleration. Both a bed and a slider are stowed in an enclosure and packings are in T-slots in side walls of the bed to seal clearances between the bed and the enclosure. The enclosure is composed of an end bracket to cover one end of the bed, a motor bracket to cover another end of the bed, a pair of side coverings to enclose the side surfaces and tops of the side walls of the bed, a sealing panel to cover an upward opening between the side coverings, and a table covering to overlay an area of the sealing panel lying on the slider and side areas of the table bulging out from side edges of the sealing panel.

主权项

1. An actuator suitable to work in clean environment, comprising:
an elongated bed of U-shape in a transverse section having a bottom plate and a pair of side walls standing at side edges of the bottom plate to extend lengthwise in parallel with each other, a slider movable lengthwise between the pair of side walls of the bed through rolling elements, a driving unit to force the slider back-and-forth with respect to the bed, an enclosure shrouding lengthwise opposite ends, lengthwise side surfaces and tops of the bed, and a table integral with the slider and exposing itself out from the tops of the enclosure; wherein the enclosure comprises:
an end bracket covering one end of the bed,a motor bracket covering another end of the bed,a pair of side coverings enclosing the lengthwise side surfaces and tops of the pair of side walls of the bed, one to each side wall,a sealing panel covering from above an upward opening between the pair of side coverings, anda table covering overlaying from above an area of the sealing panel lying on an upper surface of the slider and side areas of the table bulging sidewise out from side edges of the sealing panel; wherein each of the side walls of the bed have a first T-slot groove into which a packing fits to make close engagement or contact with the pair of side coverings enclosing the pair of side surfaces of the bed to hermetically close a clearance between each of the side coverings and the bed, wherein the packing comprises:
a packing major part fitting into the first T-slot groove,a locking part bulging out from the major part to make engagement with flanged portions of the first T-slot groove,a bottom lip extending out from the major part to come into abutment against a bottom of the first T-slot groove, anda sealing lip extending out from the packing major part to extend through an opening of the first T-slot groove so as to come into close contact with the pair of side coverings; wherein each of the side coverings has a substantially L-shape in a transverse section, and comprises:
a lengthwise side plate to come into close engagement with one of the lengthwise side walls of the bed anda lengthwise upper plate lying perpendicular to the side plate to extend over the top of the side wall, the side plate being depressed inwardly of an outward surface of the side plate at a location above the side wall of the bed along a lengthwise corner of the L-shape in a transverse section, thereby forming a second T-slot groove to install a sensor therein anda bottom of a wall to define the second T-slot groove is formed into a shoulder which is snugly placed against the to of the side wall of the bed; wherein the slider has vents extending lengthwise through the slider between forward and aft ends of the slider at an upper location closer to the table to prevent a pumping phenomenon caused by movement of the slider in a closed interior space inside the enclosure; and wherein the driving unit comprises:
a motor and a ball screw assembly, the ball screw assembly being comprised of a ball screw shaft driven by the motor and supported for rotation at lengthwise opposite ends by bearings in the end bracket and the motor bracket, anda lead nut or ball screw nut mating with the ball screw shaft and fastened to the slider, and wherein the end bracket and the motor bracket each have a pair of suction ports to suck air with airborne dirt and dust out of the enclosure, the suction ports being disposed neighboring the lengthwise opposite ends of the ball screw shaft bearings, where the airborne dirt and dust are most liable to occur.