US 4,527,244 AGranted

Electro-hydraulic position control for a machine tool with actual and commanded position feedback

OwnerMerrill E. Graham, Jr., Ronnie L. Blankenshipinventors

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Abstract

An automated control system and method for control of hydraulically positionable machine tools is disclosed. A servo motor is coupled to a servo valve spool such that the angular displacement of the motor shaft directly corresponds to the resultant rotation of the spool, which in turn threadably engages a precision lead screw fixed to a tool slide. In the preferred embodiment, a position encoder provides signals indicative of the angular displacement of the motor shaft. The position encoder signals are fed back to an electronic central processor which controls motor operation. The controller is programmed with the lead screw pitch information, and a series of instructions to advance or reverse the spool along the lead screw in a series of movements precisely corresponding to the desired movements of the slide.

Claims11

Dependent claims

In a machine tool wherein a tool implement is positioned by at least one hydraulic ram controlled by at least one hydraulic valve, an improved control system comprising:

rotary electric drive means;
a rotating member coupled to and driven by said rotary electric drive means, and coupled to each said hydraulic valve, comprising at least a spool member coupled to a fixed lead screw such that the axial position of said spool member along said screw is substantially directly related to the movement of said tool implement, and controls the flow of hydraulic fluid to said coupled hydraulic valve for driving said valve;
sensing means for directly sensing the action of said electric drive means and generating a signal indicative of said action;
and
central controller means coupled to said electric drive means and said sensing means for controlling the operation of said drive means in response to said sensing means indicator signal so as to cause said spool member to change position along said screw and control the flow of hydraulic fluid to said coupled hydraulic valve, thereby causing said hydraulic ram to controllably position said tool implement.

2 more elements

Dependencies are inferred from the claim text.