Controller for cutting machine

• US 5,247,452 A
• Filed: 05/30/1991
• Issued: 09/21/1993
• Est. Priority Date: 05/31/1990
• Status: Expired due to Fees

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Takagi, Masahiro, Takagi, Shigeyoshi, Ueda, Tokio
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): GORDON, PAUL P
• Application Number:
  US07/707,734
• Time in Patent Office: 845 Days
• Field of Search: 364/474.17, 364/551.02, 364/474.16, 364/474.01
• US Class Current: 700/175
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition
• CPC Class Codes: G05B 2219/37348 Power, wattmeter voltage times current
• CPC Class Codes: G05B 2219/37391 Null, initial load, no load torque detection or other parameter at no load
• CPC Class Codes: G05B 2219/37493 Use of different frequency band pass filters to separate different signals
• CPC Class Codes: G05B 2219/37497 Summing, integration of signal
• CPC Class Codes: G05B 2219/37498 Variable amplification, gain for detected signal, select correct level range
• CPC Class Codes: G05B 2219/37501 Delay detected signal avoids transients, start up noise
• CPC Class Codes: G05B 2219/37525 Mean, average values, statistical derived values
• CPC Class Codes: G05B 2219/37543 Set, compare to maximum, peak, minimum value
• CPC Class Codes: G05B 2219/37544 Compare detected signal to several references to derive several control actions

Abstract

A controller for a cutting machine has a machining power extracting unit for extracting machining power related to machining from the consumed power of the cutting machine, a detection range setter for setting a detection range for the machining power thus extracted, an integrator for integrating output values of the machining power extracting unit within the detection range thus set, a maximum value detector for detecting the maximum value of the output values of the machining power extracting unit within the detection range, and a judging unit for comparing an input signal with a variable comparative reference value and producing a control signal if the input signal exceeds the comparative reference value. The judging unit has an input which is selectively connectable to the machining power extracting unit, the integrator and the maximum value detector.

Claims

1. A controller for a cutting machine comprising:

a machining power extracting means for extracting a machining power related to a machining from consumed power of the cutting machine, said machining power extracting means comprises a cyclic noise removing circuit for removing cyclic noise components from the consumed power, a smoothing circuit for smoothing the output values of said cyclic noise removing circuit, a no-load power extracting circuit for extracting no-load power from the output values of said cyclic noise removing circuit and said smoothing circuit, and machining power computing circuits for subtracting the output of said no-load power extracting circuit from the output values of said cyclic noise removing circuit and said smoothing circuit;

a detection range setting means, connected to said machine power extracting means, for setting a detection range for the machining power thus extracted;

an integration means, connected to said machining power extracting unit, for integrating the output value of said machining power extracting means within the detection range thus set;

a maximum value detecting means, connected to said machine power extracting means, for detecting the maximum value of the output values of said machining power extracting means within said detection range; and

a judging means for comparing an input signal with a variable comparative reference value and producing a control signal if said input signal exceeds said comparative reference value, said judging means having an input which is selectively connectable to said machining power extracting means, integration means and maximum value detecting means.

2. A controller for a cutting machine as claimed in claim 1, wherein said respective machining power computing circuits being connected with said integration means and said maximum value detecting means and being selectively connectable with the input of said judging means.

3. A controller for a cutting machine as claimed in claim 1 or 2, wherein said detection range setting means has a gate circuit adapted to open and close with external signals.

4. A controller for a cutting machine as claimed in claim 3, wherein said judging means has a plurality of inputs, each of which has a comparison unit for comparing said input signals and said comparative reference values, and an output for outputting said control signals.

5. A controller for a cutting machine as claimed in any of claims 1 or 2, wherein said judging means has a plurality of inputs, each of which has a comparison unit for comparing said input signals and said comparative reference values, and an output for outputting said control signals.