Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1989-10-17
1991-04-23
Shoop, Jr., William M.
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318567, 318571, 36447401, 364513, 36447416, G05B 1918
Patent
active
050102850
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a numerical control system having a plurality of channels, and more particularly to a numerical control system with improved control over a single block mode of operation.
BACKGROUND ART
There have widely been used numerical control systems for controlling a number of axes or spindles with a plurality of channels (functional arrangements). Such numerical control systems include a numerical control system for controlling a four-axis at he having two spindles and two tool rests. A workpiece can be machined at a high speed by the spindles or tool rests. With the multiple-channel numerical control system, when a single block signal is on, the machining program for a channel is interrupted after a single block, the execution of which is first finished, and the machining program for another channel is executed.
Therefore, the execution of the machining program for one channel is stopped, and the execution of the machining program for another channel is continued. As a result, the machining programs for the channels are not synchronized, the workpiece is machined out of balance, and a machining interference occurs.
SUMMARY OF THE INVENTION
In view of the aforesaid problems of the conventional numerical control systems, it is an object of the present invention to provide a numerical control system with improved control over a single block mode of operation.
According to the present invention, the above object can be achieved by a numerical control system for controlling a plurality of axes with a plurality of channels (functional arrangements), comprising single block control means for controlling the channels so that when a machining program for a first channel is interrupted after a single block in response to a single block signal, the feeding of commands of a machining program for other channels is suspended.
At the time the machining program for the first channel is interrupted after a single block, the feeding of commands of the machining program for the other channels is suspended. The machining programs for the channels are therefore held in synchronism with each other.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a numerical control system according to the present invention; and
FIG. 2 is a timing chart of operation of the numerical control system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention will hereinafter be described with reference to the drawings.
FIG. 1 shows in block form a numerical control system according to the present invention. A channel bus 1 comprises a multiple-channel master bus interconnecting a plurality of channels. The channel bus 1 has a number slots 1a, 1b, . . . 1g to which the channels (described later) are connected.
A CRT/MDI unit 2 can display data and graphic information for the numerical control system and also receive data from a keyboard thereof. Each of axis control modules 3, 4 can control servomotors for 2 or 3 axes. An I/0 circuit 5 receives and transmits input and output signals. A single block signal 6SB from a control panel is applied to the I/0 circuit 5. Actually, the signals applied to the I/0 circuit 5 are first processed by a PC (programmable controller) contained in the numerical control system, and then transferred to the channels. The PC (programmable controller) is omitted from illustration in FIG. 1.
Each of channels 10, 20, 30 has a function equivalent to the function of a conventional numerical control apparatus. Thus, one channel can read, decode, and execute numerical control commands. Each channel can also control a component such as the CRT/MDI unit 2 or the like. Therefore, each individual channel can process commands for a certain number of axes which a conventional numerical control apparatus has processed.
For example, to control a numerically controlled lathe having two heads, the channel I 10 can control a first spindle, an X1 axis, and a Z1 axis, the channel II 20 can control a second spindle, an X2 axis, and a Z2 axis, and the cha
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patent: 4536849 (1985-08-01), Borisch et al.
patent: 4607327 (1986-08-01), Kishi et al.
patent: 4631684 (1986-12-01), Akasofu et al.
patent: 4684862 (1987-08-01), Rohrle
Fujibayashi Kentaro
Hitaka Yosato
Kawamura Hideaki
Bergmann Saul M.
Fanuc Ltd.
Shoop Jr. William M.
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