US4237408A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for modifying the operation of a machine tool as a function of torque
Assignee: Glad Products Co
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Filing: 1979-08-10
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Granted: 1980-12-02
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Expires: 1999-08-10
Abstract
Abstract A method and apparatus are disclosed for controlling a machine tool as a function of the torque load on a cutting tool. The apparatus detects the spindle motor current which may vary over four decades, the spindle motor voltage which may vary over two decades and the cutting tool angular velocity which may vary over three decades. The decimal values of the detected variables are converted to corresponding logarithmic values and stored in digital form. A microprocessor utilizes the stored values to calculate the value of torque on the cutting tool which may vary over five decades. A microprocessor determines the idle torque by averaging the torque which is measured several times over one spindle revolution. The idle torque is subtracted from subsequent gross torque measurements to provide an indication of actual cutting load on the tool. The operation of the machine is modified in response to the actual torque exceeding a predetermined reference torque value.
Inventors
- 👤 Thomas R. Frecka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:55
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/416; G05B19/4163; G05B2219/00; G05B2219/30; G05B2219/34; G05B2219/34215; G05B2219/37; G05B2219/37344
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
282 words
An apparatus for modifying the operation of a machine tool as a function of the torque load on a rotating cutting tool caused by the cutting tool being in contact with a workpiece, the said machine tool having a spindle motor for rotating the cutting tool and a feed motor for providing relative motion between the tool and the workpiece in response to command signals from a numerical control, the apparatus comprising: (a) means responsive to the spindle motor for producing a voltage signal representing a spindle motor voltage magnitude occurring within a range of two decades; (b) means responsive to the spindle motor for producing a current signal representing a spindle current magnitude occurring within a range of four decades; (c) means responsive to the spindle motor for producing a speed signal representing a spindle motor velocity occurring within a range of three decades; (d) means responsive to the voltage, current and velocity signals for generating corresponding log voltage, log current and log speed signals representing logarithmic values of the voltage, current and speed signals respectively; (e) data storage means for storing the log voltage, log current and log speed signals; and (f) computer means including a processor, program store and interface means for (1) controlling the detection, conversion and storage of the signals representing the voltage, current and speed of the spindle motor, and (2) determining a torque signal in response to the stored log voltage, log current and log speed signals, said torque signal representing a spindle motor torque being generated within a range of five decades, and (3) providing a control signal to the numerical control in response to the torque signal exceeding a predetermined reference torque signal.
Claim 2
Independent Claim
282 words
An apparatus for modifying the operation of a machine tool as a function of the torque load on a rotating cutting tool caused by the cutting tool being in contact with a workpiece, the said machine tool having a spindle motor for rotating the cutting tool and a feed motor for providing relative motion between the tool and the workpiece in response to command signals from a numerical control, the apparatus comprising: (a) means responsive to the spindle motor for producing a voltage signal representing a spindle motor voltage magnitude occurring within a range of two decades; (b) means responsive to the spindle motor for producing a current signal representing a spindle current magnitude occurring within a range of four decades; (c) means responsive to the spindle motor for producing a speed signal representing a spindle motor velocity occurring within a range of three decades; (d) means responsive to the voltage, current and velocity signals for generating corresponding log voltage, log current and log speed signals representing logarithmic values of the voltage, current and speed signals respectively; (e) data storage means for storing the log voltage, log current and log speed signals; and (f) computer means including a processor, program store and interface means for (1) controlling the detection, conversion and storage of the signals representing the voltage, current and speed of the spindle motor, and (2) determining a torque signal in response to the stored log voltage, log current and log speed signals, said torque signal representing a spindle motor torque being generated within a range of five decades, and (3) providing a control signal to the numerical control in response to the torque signal exceeding a predetermined reference torque signal.
Claim 3
Dependent Claim
67 words
The apparatus of claim 1 wherein the voltage, current and speed signals represent analog values of the spindle motor voltage, current and speed, respectively, and the apparatus further comprises an analog-to-digital converter responsive to the log voltage, log current and log speed signals for producing digital log voltage, digital log current and digital log speed signals respectively, representing the digital values corresponding to the detected analog signals.
Claim 4
Dependent Claim
43 words
The apparatus of claim 2 wherein the computer means further includes a peripheral interface means in electrical communication with the numerical control and being responsive to command signals generated by the numerical control for activating one of several operating modes of the apparatus.
Claim 5
Independent Claim
236 words
A method for controlling the operation of a machine tool as a function of the torque load on a rotating cutting tool caused by said cutting tool being in contact with a workpiece, the said machine tool having a spindle motor for rotating the cutting tool and a feed motor for providing relative motion between the cutting tool and the workpiece in response to command signals from a numerical control, the method comprising the steps of: (a) detecting (1) a current signal representing a spindle motor current occurring within a range of four decades, (2) a voltage signal representing a voltage across the spindle motor occurring within a range of two decades, and (3) a speed signal representing an angular velocity of the cutting tool occurring within a range of three decades; (b) converting the current, voltage and speed signals into corresponding log current, log voltage and log speed signals representing the logarithmic values of the current, voltage and speed signals, respectively; (c) storing the log current, log voltage and log speed signals; (d) generating in response to the stored signals a torque signal representing a spindle motor torque occurring within a range of five decades; (e) comparing the torque signal to a predetermined torque reference signal; and (f) producing a control signal in response to the torque signal exceeding the predetermined torque reference signal to cause the operation of the machine tool to be modified.
Claim 6
Independent Claim
236 words
A method for controlling the operation of a machine tool as a function of the torque load on a rotating cutting tool caused by said cutting tool being in contact with a workpiece, the said machine tool having a spindle motor for rotating the cutting tool and a feed motor for providing relative motion between the cutting tool and the workpiece in response to command signals from a numerical control, the method comprising the steps of: (a) detecting (1) a current signal representing a spindle motor current occurring within a range of four decades, (2) a voltage signal representing a voltage across the spindle motor occurring within a range of two decades, and (3) a speed signal representing an angular velocity of the cutting tool occurring within a range of three decades; (b) converting the current, voltage and speed signals into corresponding log current, log voltage and log speed signals representing the logarithmic values of the current, voltage and speed signals, respectively; (c) storing the log current, log voltage and log speed signals; (d) generating in response to the stored signals a torque signal representing a spindle motor torque occurring within a range of five decades; (e) comparing the torque signal to a predetermined torque reference signal; and (f) producing a control signal in response to the torque signal exceeding the predetermined torque reference signal to cause the operation of the machine tool to be modified.
Claim 7
Dependent Claim
36 words
The method of claim 4 wherein the step of detecting a current signal further comprises the step of detecting a current signal representing spindle motor current over the range of from 100 milliamps to 1000 amps.
Claim 8
Dependent Claim
37 words
The method of claim 4 wherein the step of detecting a voltage signal further comprises the step of detecting a voltage signal representing a spindle motor voltage over the range of from 10 volts to 1000 volts.
Claim 9
Dependent Claim
44 words
The method of claim 4 wherein the step of detecting a speed signal further comprises the step of detecting a speed signal representing an angular velocity of the cutting tool over a range of from 10 revolutions per minute to 10,000 revolutions per minute.
Claim 10
Dependent Claim
46 words
The method of claim 4 wherein the step of determining a torque signal further comprises the step of determining a torque signal representing a torque load on the cutting tool over the range of from less than 0.1 foot pound to more than 1000 foot pounds.
Claim 11
Dependent Claim
78 words
The method of claim 4 wherein the order of executing the steps of detecting, converting and storing is further defined by the steps of: (a) executing the steps of converting and storing a first detected signal before detecting a second signal; (b) executing the steps of converting and storing the second detected signal before detecting a third signal; and (c) executing the steps of converting and storing the third detected signal before detecting the first signal another time.
Claim 12
Dependent Claim
59 words
The method of claim 4 wherein the step of generating a torque signal further comprises steps of: (a) producing a log torque signal in response to the difference between the log speed signal and the sum of the log current and log voltage signals; and (b) generating the torque signal by providing the antilog of the log torque signal.
Claim 13
Dependent Claim
46 words
The method of claim 4 wherein the current, voltage and speed signals represent analog values and the method further comprises the step of converting the log current, log voltage and log speed signals into corresponding digital log current, digital log voltage and digital log signals respectively.
Claim 14
Dependent Claim
123 words
The method of claim 4 wherein the method further comprises the steps of: (a) executing steps (a) through (d) a predetermined number of times in response to a spindle rotation in the absence of tool contact with the workpiece to produce a predetermined number of idle torque signals; (b) summing the predetermined number of idle torque signals; (c) dividing the sum of the predetermined number of idle torque signals by said predetermined number to produce an average idle torque signal; (d) storing the average idle torque signal; and (e) subtracting the average idle torque signal from a subsequent torque signal to produce a net torque signal representing the load on the cutting tool exclusively as a function of its contact with the workpiece.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |