MACHINE TOOL ADAPTIVE CONTROL

• US 3,571,834 A
• Filed: 04/15/1968
• Issued: 03/23/1971
• Est. Priority Date: 04/15/1968
• Status: Expired due to Term

• Current Assignee: Richard A. Mathias
• Original Assignee: Richard A. Mathias
• Inventors: Mathias, Richard A.
• Application Number:
  US04/721,508
• Time in Patent Office: 1,072 Days
• US Class Current: 408/9
• CPC Class Codes: B23Q 15/12 Adaptive control, i.e. adjusting itself to have a performance which is optimum according to a preassigned criterion
• CPC Class Codes: G05B 2219/37344 Torque, thrust, twist, machining force measurement
• CPC Class Codes: G05B 2219/37355 Cutting, milling, machining force
• CPC Class Codes: G05B 2219/37357 Force, pressure, weight or deflection
• CPC Class Codes: G05B 2219/37502 Input signal converted to logarithmic value
• CPC Class Codes: Y10T 408/165 to control Tool rotation
• CPC Class Codes: Y10T 408/172 Responsive to Tool
• CPC Class Codes: Y10T 408/175 to control relative positioning of Tool and work
• CPC Class Codes: Y10T 409/304536 including means to infeed work to cutter

Abstract

A mechanism controls both the speed of rotation of a cutting tool for performing machine tool operations on a workpiece and the relative feedrate between the cutting tool and the workpiece. The control mechanism includes means to indicate when the life of the cutting tool has ended. The control mechanism has means to provide a minimum relative feedrate between the workpiece and the cutting tool. The mechanism also includes means to permit a relatively rapid movement between the cutting tool and the workpiece when the cutting tool is not engaging the workpiece.

Claims

1. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece, and means to move the cutting tool and the workpiece relative to each other to advance the cutting tool and the workpiece relative toward each other, a mechanism for controlling the relative moving means comprising:

first means to produce a first signal in accordance with the cutting force between the cutting tool and the workpiece;

second means to produce a second signal in accordance with the axial thrust of the cutting tool;

means to regulate the feedrate of the relative moving means;

said regulating means including first means to produce a signal in accordance with the cutting conditions to regulate the feedrate of the relative moving means, said first means of said regulating means receiving a signal from said first producing means as an input signal varying in accordance with the cutting conditions during certain cutting operations and a signal from said second producing means as an input signal varying in accordance with the cutting conditions during other cutting operation; and

said regulating means including second means responsive to the absence of a signal from both said first producing means and said second producing means to increase the feedrate to a predetermined feedrate of said relative moving means irrespective of the signal from said first means of said regulating means.

2. The control mechanism according to claim 1 including third means to produce a third signal in accordance with the resultant deflection of the cutting tool;

said second responsive means being activated only when there is the absence of a signal from said third means in addition to the absence of a signal from both said first producing means and said second producing means; and

means to render said third means active only when the cutting tool is performing a milling or boring operation.

3. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece and one of the cutting tool and the workpiece being rotatable relative to the other, means to rotate the rotatable one of the cutting tool and the workpiece, and means to move the cutting tool and the workpiece relative to each other, a mechanism for controlling the rates of operation of the rotating means and the movable means comprising:

first means to produce a first signal proportional to the cutting force between the cutting tool and the workpiece;

second means to produce a second signal proportional to the resultant deflection of the cutting tool;

third means to produce a third signal proportional to the axial thrust of the cutting tool;

means to receive an input from at least one of said first means, said second means, and said third means;

said receiving means producing an output logarithmically related to its input;

fourth means to regulate the speed of the rotating means in accordance with the output of said receiving means; and

fifth means to regulate the relative moving means, said fifth means being responsive to the output of said receiving means.

4. The control mechanism according to claim 3 including:

means to connect the second signal from said second means as an input to said receiving means that is inversely logarithmically proportional to the output of said receiving means only when the tool is performing a milling or boring operation;

means to connect the third signal from said third means as an input to said receiving means that is inversely logarithmically proportional to the output of said receiving means only when the tool is performing a drilling, spot facing, or counterboring operation; and

means to connect the first signal from said first means as an input to said receiving means that is inversely logarithmically proportional to the output of said receiving means only when the tool is performing a tapping or reaming operation and to connect the first signal from said first means as an input to said receiving means that is directly logarithmically proportional to the output of said receiving means only when the tool is performing a milling or boring operation.

5. The mechanism according to claim 3 including means to maintain the feedrate of the relative moving means at a predetermined minimum irrespective of the signal from said fifth means. 6. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece, and means to move the cutting tool and the workpiece relative to each other, a device for determining the end of the life of the cutting tool comprising:

first means to produce a first signal in accordance with the cutting force between the cutting tool and the workpiece;

second means to produce a second signal in accordance with the axial thrust of the cutting tool; and

means to produce a signal only when the first and second signals are equal to indicate the end of the life of the cutting tool.

7. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece, and means to move the cutting tool and the workpiece relative to each other, a device for determining the end of the life of the cutting tool comprising:

first means to produce a first signal in accordance with the cutting force between the cutting tool and the workpiece;

second means to produce a second signal in accordance with the resultant deflection of the cutting tool; and

means to produce a signal only when the first and second signals are equal to indicate the end of the life of the cutting tool.

8. The device according to claim 6 including:

third means to produce a third signal in accordance with the resultant deflection of the cutting tool;

means to receive the first signal and one of the second and third signals, said receiving means including said end of tool life signal producing means; and

means to connect the second signal from said second means to said receiving means only when the cutting tool is performing a drilling, spot facing, or counterboring operation and to connect the third signal from said third means to said receiving means only when the cutting tool is performing A milling or boring operation.

9. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece, and means to move the cutting tool and the workpiece relative to each other, a mechanism for controlling the relative moving means comprising:

means to produce a first signal in accordance with the cutting conditions to regulate the feedrate of the relative moving means to produce relative advancement of the cutting tool and the workpiece toward each other;

means to produce a second signal to maintain the feedrate of the relative moving means at a predetermined minimum to produce continued relative advancement of the cutting tool and the workpiece toward each other; and

means to render the second signal effective to control the feedrate of the relative moving means when the first signal produces a feedrate below the predetermined minimum so that continued and uninterrupted relative advancement of the cutting tool and the workpiece toward each other occurs.

10. The control mechanism according to claim 9 including means to produce a third signal to maintain the feedrate at a predetermined maximum when the cutting tool is not engaging the workpiece and means to render said producing means for the third signal inactive when the cutting tool engages the workpiece.

11. The control mechanism according to claim 9 including means to reverse the direction of feed of the relative moving means when a predetermined cutting condition exists.

12. In a machine tool having a workpiece supported thereon, a rotatable tap therein extending toward the workpiece, means to rotate the tap, and means to move the tap and the workpiece relative to each other, a mechanism for controlling the relative moving means comprising:

means to regulate the speed of the rotating means in accordance with the cutting conditions;

means to regulate the feedrate of the relative moving means in accordance with the speed of the rotating means; and

means to simultaneously reverse the direction of rotation of the rotating means and the feed of the relative moving means to withdraw the tap from the workpiece by coordinating the reverse feed of the relative moving means with the reverse rotation of the rotating means when a predetermined cutting condition occurs.

13. The control mechanism according to claim 12 including means to maintain the feedrate of the relative moving means at a predetermined maximum irrespective of the speed of the rotating means when the tap is not engaging the workpiece.

14. The control mechanism according to claim 12 including means to deactivate said simultaneous reversing means after a predetermined period of time;

and means to inactivate said deactivating means after a predetermined number of actuations of said simultaneous reversing means in a predetermined period of time.

15. The control mechanism according to claim 1 in which said regulating means includes third means responsive to one of a first signal from said first producing means exceeding a predetermined value and a second signal from said second producing means exceeding a predetermined value to decrease the feedrate of the relative moving means irrespective of the signal from said first means of said regulating means.

16. The control mechanism according to claim 15 including means to maintain a minimum feedrate of the relative moving means irrespective of the signal from said first means of said regulating means and the signal from said third means of said regulating means.

17. The control mechanism according to claim 1 in which said first means of said regulating means produces a signal logarithmically related to its input.

18. The control mechanism according to claim 1 including means to maintain a minimum feedrate of the relative moving means irrespective of the signal from said first means of said regulating means.

19. The control mechanism according to claim 2 including:

fourth means to receive an input from each of said first and third producing means during a milling or boring operation;

said fourth means comparing the signals from said first and third producing means and producing an output in accordance with the difference therebetween; and

means to connect the output of said fourth means to said regulating means when the output from said fourth means exceeds a predetermined value with the signal to said fourth means from said first producing means being larger than the signal from said third producing means to reduce the feedrate as the output of said fourth means increases beyond the predetermined value whereby the finish of the surface of the workpiece is controlled.

20. The control mechanism according to claim 2 including:

means to produce relative rotation between the cutting tool and the workpiece;

said rotation producing means being responsive to the signal of said first means of said regulating means to control the relative speed of rotation;

means to connect the first signal from said first producing means as an input to said first means of said regulating means when the tool is performing a tapping, reaming, milling or boring operation, the first signal varying in accordance with the cutting conditions;

means to connect the second signal from said second producing means as an input to said first means of said regulating means only when the tool is performing a drilling, spot facing, or counterboring operation, the second signal varying in accordance with the cutting conditions; and

means to connect the third signal from said third producing means as an input to said first means of said regulating means only when the tool is performing a milling or boring operation, the third signal varying in accordance with the cutting conditions.

21. The control mechanism according to claim 2 including:

means for determining the end of the life of the cutting tool;

said determining means including;

means to receive the first signal from said first producing means and one of the second signal from said second producing means and the third signal from said third producing means, said receiving means producing a signal only when the received signals are equal to indicate the end of the life of the cutting tool; and

means to connect the second signal from said second producing means to said receiving means only when the cutting tool is performing a drilling, spot facing, or counterboring operation and to connect the third signal from said third producing means to said receiving means only when the cutting tool is performing a milling or boring operation.

22. The control mechanism according to claim 3 including means to supply a signal to said fifth means to decrease the feedrate of said relatively moving means when a signal to said fifth means from any of said first means, said second means, and said third means exceeds a predetermined value.

23. The control mechanism according to claim 3 including:

means for determining the end of the life of the cutting tool;

said determining means including;

means to receive the first signal from said first means and one of the second signal from said second means and the third signal from said third means, said receiving means producing a signal only when the received signals are equal to indicate the end of the life of the cutting tool; and

means to connect the second signal from said second means to said receiving means only when the cutting tool is performing a drilling, spot facing, or counterboring operation and to connect the third signal from said third means to said receiving means only when the cutting tool is performing a milling or boring operation.

24. The control mechanism according to claim 3 including:

sixth means to receive an input from each of said first and second means during a milling or boring operation;

said sixth means comparing the signals from said first and second means and producing an output in accordance with the difference therebetween; and

means to connect the output of said sixth means to said fifth means when the output from said sixth means exceeds a predetermined value with the signal to said sixth means from said first means being larger than the signal from said second means to reduce the feedrate as the output of said sixth means increases beyond the predetermined value irrespective of the output of said receiving means whereby the finish of the surface of the workpiece is controlled.

25. The control mechanism according to claim 4 including means to maintain the feedrate of the relative moving means at a predetermined minimum irrespective of the signal from said fifth means when the tool is performing a milling, boring, drilling, spot facing, or counterboring operation.

26. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece and one of the cutting tool and the workpiece being rotatable relative to the other, and means to rotate the rotatable one of the cutting tool and the workpiece, a mechanism for controlling the rate of rotation of the rotating means comprising:

first means to produce a first signal proportional to the cutting force between the cutting tool and the workpiece;

second means to produce a second signal proportional to the resultant deflection of the cutting tool;

third means to produce a third signal proportional to the axial thrust of the cutting tool;

means to receive an input from at least one of said first means, said second means, and said third means;

said receiving means producing an output logarithmically related to its input; and

fourth means to regulate the speed of the rotating means in accordance with the output of said receiving means.

27. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece and one of the cutting tool and the workpiece being rotatable relative to the other, and means to move the cutting tool and the workpiece relative to each other, a mechanism controlling the relative moving means comprising:

means to control the feedrate of the relative moving means in response to the speed of rotation of the one of the cutting tool and the workpiece that is rotated;

means to render said control means ineffective when certain cutting conditions exist to reduce the feedrate of the relative moving means in accordance with the cutting conditions; and

means to maintain a minimum feedrate of the relative moving means irrespective of the signal from said rendering means.

28. The control mechanism according to claim 27 including means to connect said maintaining means to receive a signal depending on the speed of rotation of the one of the cutting tool and the workpiece that is rotated to maintain the feedrate of the relative moving means at a predetermined minimum relative to the speed of rotation of the one of the cutting tool and the workpiece that is rotated.

29. In a machine tool having a workpiece supported thereon, a cutting tool therein extending toward the workpiece and one of the cutting tool and the workpiece being rotatable relative to the other, and means to move the cutting tool and the workpiece relative to each other to relatively advance the cutting tool and the workpiece toward each other, a mechanism for controlling the relative moving means to control the finish of a surface being cut during a milling or boring operation comprising:

first means to produce a first signal proportional to the cutting force between the cutting tool and the workpiece;

second means to produce a second signal proportional to the deflection of the cutting tool;

third means to receive signals from said first and second means, said third means comparing the signals from said first and second means and producing an output in accordance with the difference therebetween;

means to regulate the feedrate of the relative moving means; and

said regulating means regulating mEans including means to receive a signal from said third means when the signal from said third means exceeds a predetermined value with the signal to said third means from said first means being larger, said regulating means reducing the feedrate as the signal from said third means increases beyond the predetermined value.