Apparatus and method for feedback adjusting machine working condition for improving dimensional accuracy of processed workpieces

A feedback compensating apparatus for a working system including (a) a working machine for performing successive working operations on a plurality of workpieces, (b) machine control means for determining a working condition of the working machine on the basis of an extraneous compensating signal and controlling the working machine according to the determined working condition, and (c) a measuring device for measuring dimensional values of the workpieces processed by the working machine, said measuring device being positioned relative to said working machine such that there exist pre-measured workpieces which have been processed by the machine and which have not been measured by the measuring device, said feedback compensating apparatus including compensating value determining means for determining an automatic compensating value as said extraneous compensating signal for the workpieces to be processed next, on the basis of a plurality of said dimensional values which have been measured by said measuring device and stored in memory means, and compensating value applying means for applying the determined automatic compensating value to said machine control means, wherein an improvement comprises:

• said compensating value determining means being operable in an automatic compensation mode in which each automatic compensating cycle begins with commencement of the storing in said memory means of said dimensional values of the workpieces measured by said measuring device and ends with determination of a present automatic compensating value (Ui), and in a manual compensation mode in which a manual compensating value (U') is determined also as said extraneous compensating signal in response to and on the basis of a manual compensation command entered by an operator of said working system;
• said compensating value determining means includes a first and a second operating state which are selectable in said automatic compensation mode, said compensating value determining means operating in said first operating state to determine said present automatic compensating value (Ui) on the basis of a plurality of first estimated dimensional values of the workpieces which are stored in said memory means in said automatic compensating cycle, each of said first estimated dimensional values being obtained by adding a last compensating value (U') to the dimensional value (X) of the corresponding workpiece which is measured by said measuring device, on an assumption that said corresponding workpiece is processed under the working condition influenced by said last compensating value, said compensating value determining means operating in said second operating state to determine said present automatic compensating value on the basis of a plurality of second estimated dimensional values of the workpieces which are stored in said memory means in said automatic compensating cycle, each of said second estimated dimensional values being obtained by adding a sum of said last compensating value (U') and a previous compensating value (Ui-2, Ui-1) immediately preceding said last compensating value, to the dimensional value (X) of the corresponding workpiece which is measured by said measuring device;
• and
• said compensating value applying means (5) applying said present automatic compensating value and said manual compensating value to said machine control means.