Adaptive control system for numerically controlled machine tools
First Claim
1. An improved adaptive control system for use in combination with a numerically-controlled machine tool including an N/C unit capable of controlling the machine tool in a sequence of desired operational steps to provide a desired machining process in response to a set of N/C instructions contained in an N/C storage medium, the N/C unit further including input means responsive to an override signal to modify at least one selected operation of the machine tool;
- an N/C storage medium containing a set of N/C instructions for a desired machining process which have been computed for a hypothetical machine tool having a predetermined operational capability, and further containing adaptive control system data including a reference value of at least one selected machining process variable which has been computed for operation of the hypothetical machine tool, the adaptive control system data further including a plurality of universal adaptive control variables containing information sufficient to allow the reference value of the selected machining process variable to be recomputed in accordance with the operational capability of the specific machine tool; and
data reading means coupled with the N/C storage medium for supplying the set of N/C instructions to the N/C unit and the adaptive control system data to the improved adaptive control system, the improved adaptive control system comprising;
a. storage means including machine constant data representing the operational capability of the specific machine tool with which the improved adaptive control system is utilized,b. a machining process sensor coupled with the machine tool for providing an output signal representing the actual value of the selected machining process variable,c. set-up means recomputing the reference value in the adaptive control system data in accordance with the universal adaptive control variables and said machine constant data to obtain a new reference value,d. control means comparing said new reference value with said output signal from said machining process sensor to obtain an override signal, ande. means coupling said override signal to the input means of the N/C unit to allow modification of the selected operation of the machine tool.
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Abstract
Prior art adaptive control systems for numerically-controlled milling machines are first discussed in which N/C instructions and adaptive control system data are obtained and stored in a storage medium utilizing a software routine which takes into consideration parameters of the milling process and parameters of a specific milling machine. The instructions and data command, for sequential steps in the milling process, such items as spindle position, feedrate and reference milling forces and are supplied to an N/C unit and to the adaptive control system at the milling machine to automatically control the milling process. The adaptive control system includes a milling force sensor and functions to override the commanded feedrate on comparison of the actual milling forces during the process with the reference milling forces. An improvement is then discussed which modifies the adaptive control system data so that the data can be used on any milling machine having an N/C unit capable of responding to the N/C storage medium in which the N/C instructions and adaptive control system data are stored. A set of universal adaptive control variables are included in the adaptive control data. The adaptive control system at the milling machine is modified to respond to these universal adaptive control variables and further to internally store machine constants for the specific milling machine with which the adaptive control system is utilized. The improved adaptive control system then recomputes the adaptive control data including reference milling forces in accordance with the universal adaptive control variables and the machine constants and utilizes the recomputed adaptive control system data to override where necessary the commanded feedrate. In addition, provision is made in the improved adaptive control system for further modifying the adaptive control system data by operator-entered manual process control inputs. Applications of such improved adaptive control systems to numerically-controlled machine tools other than milling machines are also discussed.
66 Citations
23 Claims
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1. An improved adaptive control system for use in combination with a numerically-controlled machine tool including an N/C unit capable of controlling the machine tool in a sequence of desired operational steps to provide a desired machining process in response to a set of N/C instructions contained in an N/C storage medium, the N/C unit further including input means responsive to an override signal to modify at least one selected operation of the machine tool;
- an N/C storage medium containing a set of N/C instructions for a desired machining process which have been computed for a hypothetical machine tool having a predetermined operational capability, and further containing adaptive control system data including a reference value of at least one selected machining process variable which has been computed for operation of the hypothetical machine tool, the adaptive control system data further including a plurality of universal adaptive control variables containing information sufficient to allow the reference value of the selected machining process variable to be recomputed in accordance with the operational capability of the specific machine tool; and
data reading means coupled with the N/C storage medium for supplying the set of N/C instructions to the N/C unit and the adaptive control system data to the improved adaptive control system, the improved adaptive control system comprising;a. storage means including machine constant data representing the operational capability of the specific machine tool with which the improved adaptive control system is utilized, b. a machining process sensor coupled with the machine tool for providing an output signal representing the actual value of the selected machining process variable, c. set-up means recomputing the reference value in the adaptive control system data in accordance with the universal adaptive control variables and said machine constant data to obtain a new reference value, d. control means comparing said new reference value with said output signal from said machining process sensor to obtain an override signal, and e. means coupling said override signal to the input means of the N/C unit to allow modification of the selected operation of the machine tool. - View Dependent Claims (2, 3, 4, 5, 6)
- an N/C storage medium containing a set of N/C instructions for a desired machining process which have been computed for a hypothetical machine tool having a predetermined operational capability, and further containing adaptive control system data including a reference value of at least one selected machining process variable which has been computed for operation of the hypothetical machine tool, the adaptive control system data further including a plurality of universal adaptive control variables containing information sufficient to allow the reference value of the selected machining process variable to be recomputed in accordance with the operational capability of the specific machine tool; and
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7. An improved adaptive control system for use in combination with a numerically-controlled milling machine including an N/C unit capable of controlling the milling machine in a sequence of desired operational steps to provide a desired milling process in response to a set of N/C instructions contained in an N/C storage medium, the N/C unit further including input means responsive to a feedrate override signal to proportionally modify a feedrate of the milling machine'"'"'s spindle with respect to a workpiece as commanded by a set of N/C instructions;
- an N/C storage medium containing a set of N/C instructions for a desired milling process which have been computed for a hypothetical milling machine which is stiffer and more powerful than any milling machine with which the N/C storage medium will be used, the set of N/C instructions including a feedrate command designating a predetermined feedrate of the milling machine'"'"'s spindle with respect to a workpiece during the milling process, the N/C storage medium further containing adaptive control system data including a reference value of milling force exerted on a cutter held in the milling machine'"'"'s spindle during the milling process, the reference value having been computed for operation of the hypothetical machine tool, the adaptive control system data further including a plurality of universal adaptive control variables containing information sufficient to allow the reference value of milling force to be recomputed in accordance with the operational capability of a specific milling machine; and
data reading means coupled with the N/C storage medium for supplying the set of N/C instructions to the N/C unit and the adaptive control system data to the improved adaptive control system, the improved adaptive control system comprising;a. storage means including machine constant data representing the operational capability, including stiffness, of the specific milling machine with which the improved adaptive control system is utilized, b. a milling force sensor coupled with the milling machine for providing an output signal representing the actual value of milling force during the milling process, c. set-up means recomputing the reference value of milling force in the adaptive control system data in accordance with the universal adaptive control variables and said machine constant data to obtain a new reference value, d. control means comparing said new reference value with said output signal from said milling process sensor to obtain a first feedrate override signal, and e. means coupling said first feedrate override signal to the input means of the N/C unit to allow modification of the feedrate command in the set of N/C instructions during operation of the milling machine. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
- an N/C storage medium containing a set of N/C instructions for a desired milling process which have been computed for a hypothetical milling machine which is stiffer and more powerful than any milling machine with which the N/C storage medium will be used, the set of N/C instructions including a feedrate command designating a predetermined feedrate of the milling machine'"'"'s spindle with respect to a workpiece during the milling process, the N/C storage medium further containing adaptive control system data including a reference value of milling force exerted on a cutter held in the milling machine'"'"'s spindle during the milling process, the reference value having been computed for operation of the hypothetical machine tool, the adaptive control system data further including a plurality of universal adaptive control variables containing information sufficient to allow the reference value of milling force to be recomputed in accordance with the operational capability of a specific milling machine; and
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20. An improved adaptive control system for use in combination with a numerically-controlled machine tool including an N/C unit capable of controlling the machine tool in a sequence of desired operational steps to provide a desired machining process in response to a set of N/C instructions contained in an N/C storage medium, the N/C unit further including input means responsive to an override signal to modify at least one selected operation of the machine tool;
- an N/C storage medium containing a set of N/C instructions for a desired machining process which have been computed for a hypothetical machine tool having a predetermined operational capability, and further containing adaptive control system data including a reference value of at least one selected machining process variable which has been computed for operation of the hypothetical machine tool; and
data reading means supplying a set of N/C instructions to the N/C unit and the adaptive control system data to the improved adaptive control system, the improved adaptive control system comprising;a. a machining process sensor coupled with the machine tool for providing an output signal representing the actual value of the selected machining process variable, b. manual process control input means for providing a first signal representing an operator-selected reference value of the selected machining process variable, c. storage means having said first signal coupled thereto for storing said operator-selected reference value, d. control means comparing said reference value with said output signal from said machining process sensor to obtain an override signal, e. means supplying said operator-selected reference value to said control means in place of said reference value, and f. means coupling said override signal to the input means of the N/C unit to allow modification of the selected operation of the machine tool. - View Dependent Claims (21, 22, 23)
- an N/C storage medium containing a set of N/C instructions for a desired machining process which have been computed for a hypothetical machine tool having a predetermined operational capability, and further containing adaptive control system data including a reference value of at least one selected machining process variable which has been computed for operation of the hypothetical machine tool; and
Specification