Control system for a machine tool

Claim 2

In a control system for a machine tool in which a tool and a workpiece are adapted for relative advance and retraction therebetween, said control system comprising in combination: first gate means for effecting relative advance between a tool and a workpiece, second gate means for effecting relative retraction between the tool and the workpiece; sensing means sensing the instantaneous dimension of the workpiece for producing an output representing at least the last significant digit of such dimension as a parallel-bit digital word; reference means for producing an output which is the parallelbit complement of that digital word representing the desired value to which said last significant digit of the workpiece dimension is to be reduced; adder means having the output of said sensing means and of said reference means as respective inputs thereto for producing a first output only when the sum of such inputs produces a carry and a second output only when said parallel-bit complement is the complement of the input from said sensing means; and enabling means for enabling said first and said second gate means when the other digits of the workpiece dimension are equal to desired values, and said first output of the adder means being connected to said first gate means to cause relative advancing between the tool and workpiece when such first output is present and said second output of the adder means being connected to said second gate means to cause relative retraction between the tool and workpiece when such second output is present, whereby automatically to reduce the workpiece dimension to the desired value and then to effect relative retraction between the tool and workpiece.

Claim 3

In a control system as defined in claim 1 wherein said enabling means includes a second adder means and third gate means; said sensing means having a second output representing the next-to-last significant digit of the sensed dimension as a second parallel-bit digital word; said reference means having a second output which is the complement of that digital word representing the desired value to which said next-to-last significant digit of the workpiece dimension is to be reduced; said second outputs of the sensing means and the reference means being connected as respective inputs to said second adder means; said second adder means having a first output only when the sum of its inputs produces a carry and a second output only when said second parallel bit word is the complement of the other input to the second adder means; said second output of the second adder means being connected as an input to said third gate means; and said third gate means having an output connecTed as inputs to said first and second gate means to complete the inputs thereto.

Claim 4

In the control system as defined in claim 2 wherein the second outputs of said first and second adder means are the parallel-bit digital sums of the respective inputs thereto.

Claim 5

In the control system as defined in claim 3 wherein said first, second and third gate means are AND gates.

Claim 6

In the control system as defined in claim 1 wherein said second output of said adder means is the parallel-bit digital sum of the inputs to said adder means.

Claim 7

In the control system as defined in claim 5 wherein said first and second gate means are AND gates.

Claim 8

In a control system for a machine tool adapted to effect relative advance and retraction between a tool and a workpiece, in combination; sensing means for producing a plurality m of digital word outputs representing the instantaneous values of a corresponding plurality of decimal digits which, in descending order of significance, are digits representing of value of the instantaneous dimension of the workpiece; reference means for producing a plurality m of outputs which are the digital word complements of those digital words representing the desired values to which said decimal digits of descending order to significance are to be reduced; a plurality m of adder means, each having corresponding outputs of corresponding ones of said sensing means and said reference means as inputs thereto, each for producing a carry output only when the digital word input from said corresponding reference means is greater than the digital word input from said corresponding sensing means and a parallel-bit logical ''''ones'''' output only when its inputs are complements, whereby said carry output indicates that the sensed decimal digit of the particular significance involved is greater than the desired value of such digit and said logical ''''ones'''' output indicates equality between the sensed value of the decimal digit and the desired value thereof; first AND gate means for each of said adder means; second AND gate means for each of said adder means; each first AND gate means having said parallel-bit logical ''''ones'''' output of a corresponding adder means as n- 1 inputs thereto, each said second AND gate means having the carry output of the corresponding adder means as one of two inputs thereto; the first AND gate means corresponding to said digit of least significance having an output for effecting relative retraction between the tool and the workpiece, said second AND gate means corresponding to said digit of least significance having an output for effecting relative advance between the tool and the workpiece; and said first AND gate means corresponding to the other digits of significance being connected as the second inputs to the second AND gate means and as the last input to the first AND gate means corresponding to the next lower order of significance in each case, whereby said second AND gate means corresponding to said digit of least significance causes relative advance between the tool and workpiece only when all of the other sensed digits correspond with the desired values thereof and, as soon as said sensed digit of least significance reaches equality with the desired value thereof, said first AND gate means corresponding to the digit of least significance causes relative retraction between the tool and workpiece.

Claim 9

In a control system for a machine tool adapted to effect relative advance and retraction between a tool and a workpiece, in combination; sensing means for producing a plurality m of digital word outputs representing the instantaneous values of a corresponding plurality of decimal digits which, in descending order of significance, are digits representing of value of the instantaneous dimension of the workpiece; reference means for producing a plurality m of outputs which are the digital word complements of those digital words representing the desired values to which said decimal digits of descending order to significance are to be reduced; a plurality m of adder means, each having corresponding outputs of corresponding ones of said sensing means and said reference means as inputs thereto, each for producing a carry output only when the digital word input from said corresponding reference means is greater than the digital word input from said corresponding sensing means and a parallel-bit logical ''''ones'''' output only when its inputs are complements, whereby said carry output indicates that the sensed decimal digit of the particular significance involved is greater than the desired value of such digit and said logical ''''ones'''' output indicates equality between the sensed value of the decimal digit and the desired value thereof; first AND gate means for each of said adder means; second AND gate means for each of said adder means; each first AND gate means having said parallel-bit logical ''''ones'''' output of a corresponding adder means as n- 1 inputs thereto, each said second AND gate means having the carry output of the corresponding adder means as one of two inputs thereto; the first AND gate means corresponding to said digit of least significance having an output for effecting relative retraction between the tool and the workpiece, said second AND gate means corresponding to said digit of least significance having an output for effecting relative advance between the tool and the workpiece; and said first AND gate means corresponding to the other digits of significance being connected as the second inputs to the second AND gate means and as the last input to the first AND gate means corresponding to the next lower order of significance in each case, whereby said second AND gate means corresponding to said digit of least significance causes relative advance between the tool and workpiece only when all of the other sensed digits correspond with the desired values thereof and, as soon as said sensed digit of least significance reaches equality with the desired value thereof, said first AND gate means corresponding to the digit of least significance causes relative retraction between the tool and workpiece.

Claim 10

In a control system as defined in claim 7 wherein said sensing means comprises a caliper engaging the workpiece and having an analog output indicating the sensed dimension thereof, and encoder means for converting said analog signal to said plurality of digital word outputs in parallel, each such word being of parallel-bit form.

Claim 11

In a control system as defined in claim 8 wherein said reference means comprises reference dimension signal generating means for producing parallel-bit digital words corresponding to said plUrality of desired decimal digits and bit by bit complement means for each such parallel-bit digital word providing the corresponding sensing mean input to a corresponding one of said plurality of adder means.

Claim 12

In the control system as defined in claim 7 wherein the output of said second AND gate means corresponding to each of said other digits is available for effecting relative advance between the tool and workpiece.