Specimen load control mechanism for automatic polishing apparatus

In an automatic polishing machine of the type for polishing specimens for purposes of microstructural analysis, said machine including a housing, a polishing member on the housing having a flat polishing surface over which a specimen is moved during a polishing operation, and a specimen drive member supported on said housing and having a portion of said drive member engageable with a specimen holder for moving the same over said polishing surface, power means for operating said drive member, and a tension spring connected to said drive member for applying a controlled load on said drive member and on said specimen holder to press said specimen down against said polishing surface, the improvement comprising, in combination, a microprocessor controlled stepper motor mounted to said housing and connected through a plurality of mechanical means to said tension spring for loading the (later) latter, (whereby) the number of pulses to said stepper motor (will control) controlling the magnitude of said controlled load, said stepper motor having a threaded rod extending through it which is moved axially in either direction through operation of said stepper motor, and said threaded rod being connected through a plurality of mechanical means to said tension spring, said mechanical means including a pivotally mounted lever which is pivoted through axial movement of said threaded rod, whereby consistent controlled loads may be applied even when the specimens to be polished are of different heights.

In an automatic polishing machine of the type for polishing specimens for purposes of microstructural analysis, said machine including a housing, a polishing member on the housing having a flat polishing surface over which a specimen is moved during a polishing operation, and a specimen drive member supported on said housing and having a portion of said drive member engageable with a specimen holder for moving the same over said polishing surface, power means for operating said drive member, and a tension spring having its upper end connected to said drive member for applying a controlled downward load on said drive member and on said specimen holder to press said specimen down against said polishing surface, the improvement comprising, in combination, motor means mounted to said housing and connected through a plurality of mechanical means to a lower end of said tension spring whereby operation of said motor means will impose a downward load on said tension spring and on said drive member and specimen holder, a switch mounted on one of said mechanical means, and another of said mechanical means comprising a switch actuating member having one end connected to the lower end of said tension spring and being positioned to actuate said switch, said switch actuating member being located so that application of a downward load to said tension spring will move said switch actuating member upwardly causing it to actuate said switch, said switch being connected to control said motor means to permit said motor means to apply a predetermined controlled downward load to said specimen measured from the time an initial downward load is applied to said tension spring.

In an automatic polishing machine of the type for polishing specimens for purposes of microstructural analysis, said machine including a housing, a polishing bowl on said housing having a flat bottom or polishing surface over which a specimen is moved during a polishing operation, and a specimen drive arm supported on said housing and having an outer end of said drive arm engageable with a specimen holder for moving the same over said polishing surface, motor means for operating said drive arm, and a tension spring having its upper end connected to said drive arm for applying a controlled downward load on said drive arm and on said specimen holder to press said specimen down against said polishing surface, the improvement comprising, in combination, a frame connected to said housing, a stepper motor mounted to said frame, a threaded rod extending through said stepper motor and movable axially in either direction through operation of said stepper motor, a lever pivotally mounted to said frame, said lever being connected at one end to an end of said threaded rod whereby operation of said stepper motor will cause said lever to be pivoted, said lever being connected at its opposite end through mechanical means to a lower end of said tension spring so that pivotal movement of said lever will load said tension spring whereby operation of said stepper motor will impose a downward load on said tension spring and on said drive arm and specimen holder, a switch mounted on said lever, and said mechanical means comprising a switch actuating member having one end connected to a lower end of said tension spring and being positioned to actuate said switch, said switch actuating member being located so that application of a downward load to said tension spring will move said switch actuating member upwardly causing it to actuate said switch, said switch being connected to control said stepper motor to permit said stepper motor to apply a predetermined controlled load to said specimen measured from the time an initial load is applied to said tension spring.