Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1989-05-03
1990-03-27
Miska, Vit W.
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318484, 318 85, 36447412, 361189, 361188, G05D 310
Patent
active
049123840
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an emergency stop control circuit for controlling emergency stop signals of a numerically controlled machine tool. More particularly, the present invention relates to an emergency stop control circuit which can be easily incorporated into a numerically controlled machine tool.
BACKGROUND ART
In numerically controlled machine tools, an emergency stop signal is used for protection of the operator and to prevent damage to machinery. It is essential that the machine tools are immediately stopped when an emergency stop signal is generated. Accordingly, the emergency signal cannot be treated in the same way as ordinary control signals, since if an error occurs in an IC, for example, the machine cannot be brought to an emergency stop. Therefore, a small-sized relay or the like is used, together with a button for generating an emergency stop signal. Switches and the like are all connected in series to the relay, and the relay is maintained in an ON state at all times. This ensures that, when the contacts thereof are opened, the power supply to all units is cut off.
This arrangement, however, requires a complicated wiring of connections between various units, such as a machine operator panel, machine switches, a servo amplifier, etc. Thus, difficulties arise not only in design and manufacture but also in maintenance. For example, when an emergency stop signal is generated, it is difficult to identify the cause thereof.
SUMMARY OF THE INVENTION
The object of the present invention is to solve the above problems and provide an emergency stop control circuit which can be easily incorporated into a numerically controlled machine tool.
To solve the aforementioned problems, the present invention provides an emergency stop control circuit for controlling emergency stop signals of a numerically controlled machine tool. The emergency stop control circuit comprises a terminal connected to an emergency stop button of a machine operator panel, a terminal connected to an overtravel release button of the machine operator panel, a terminal connected to an overload switch of a machine, a terminal connected to an overtravel switch of the machine, a relay connected in series to the emergency stop button, the overload switch and the overtravel switch, and terminals for connecting contacts of the relay to a numerical control apparatus (CNC), a servo amplifier, and a spindle amplifier.
The emergency stop control circuit is provided with input terminals corresponding to all possible causes of an emergency stop signal generated by the numerically controlled machine tool, and terminals for outputting signals to the relevant units. Accordingly, only these terminals need be connected, and thus complicated wiring becomes unnecessary.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit diagram of an emergency stop control circuit according to an embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
One embodiment according to the present invention will now be described with reference to the drawing.
In FIG. 1, which is a circuit diagram of an emergency stop control circuit according to the embodiment of the invention, a relay circuit 1 is mounted on a printed circuit board. The printed circuit board is small in size, and thus can be easily incorporated into a compact control circuit of a numerically controlled machine tool. A relay 2, connected in parallel with a diode 3 serving as a noise suppressor, is provided with contacts 2a, 2b, and 2c from which emergency stop signals are output to various units described later.
A numerical control apparatus (CNC) 10 includes a PC (programmable controller). A machine operator panel 20, used for manual operation of the machine tool, is provided with an emergency stop button 22 and an overtravel release switch 21.
A servo amplifier 31 is adapted to drive a servomotor (not shown). Note, although in practice a plurality of units are provided for a plurality of axes used, the figure shows only one unit for simp
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Kinoshita Yasunori
Nakashima Yoshihiro
Fanuc Ltd.
Ip Paul
Miska Vit W.
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