Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1994-10-13
1996-01-16
Ip, Paul
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318571, 318578, 36447416, 36447423, G05B 19403, G05B 1918
Patent
active
054850690
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a numerical control apparatus provided with a skip function, and more specifically, to a numerical control apparatus for measuring a tool length and a workpiece configuration.
2. Description of the Related Art
In general, numerical control apparatuses are provided with a skip function for measuring a tool length and a workpiece configuration. The skip function is arranged such that when a skip signal is input from the outside by a contact type or non-contact type sensor having sensed the existence a workpiece and a tool, the numerical control apparatus stops an axis movement corresponding to the block of a machining program which is being executed at present and goes to a next block of the machining program (hereinafter, simply referred to as "a next block").
Consequently, when an amount of movement is not known because a cutting depth, for example, is not given in grinding machines, lathes and other machines, the amount of movement can be measured by making effective use of the skip function.
Nevertheless, when a conventional numerical control apparatus provided with the skip function is supplied with a skip signal from the outside, since the numerical control apparatus temporarily stops the movement of a workpiece and tool and then executes the movement command of a next block, a considerable period of time is needed to reach a feed speed for the movement of the next block. Thus, a problem arises in that a cycle time is increased.
SUMMARY OF THE INVENTION
Taking the above into consideration, an object of the present invention is to provide a numerical control apparatus which executes a command for the movement of a next block without temporarily stopping the movement of a workpiece and tool, even if a skip signal is input so as to reduce a cycle time.
To solve the above problem, according to the present invention, there is provided a numerical control apparatus for measuring a tool length and a workpiece configuration by a skip function, which comprises a memory device for storing a time constant used when a feed speed of a workpiece and tool is accelerated or decelerated and storing a machining program, skip signal sensing device for receiving a skip signal from a sensing device, processing the skip signal to determine a present position and sending the present position of the workpiece and tool to a predetermined storing region of the memory device as well as outputting a skip completion signal, acceleration/deceleration distribution device for outputting a first interpolation pulse for accelerating or decelerating the feed speed based on the time constant and the present position in response to the skip completion signal and outputting a distribution completion signal after the workpiece and tool have been moved to an end position commanded in the present block of the machining program, and preprocessing distribution device for determining an amount of movement of a next block from the present position of the workpiece and tool in response to the skip completion signal, preprocessing the next block of the machining program and outputting a second interpolation pulse based on the preprocessing in response to the distribution completion signal.
The memory device stores the time constant used when a feed speed of the workpiece and tool is accelerated or decelerated and the machining program.
First, the skip signal sensing device having received a skip signal output from the sensing device, determines the present position of the workpiece and tool which is stored in a predetermined memory region of the memory device as well as outputs a skip completion signal.
The acceleration/deceleration distribution device moves the workpiece and tool to an end position commanded by the present block in the machining program and then outputs a movement completion signal. Further, the preprocessing distribution device having received the skip completion signal determines an amount of movement of a next block from the present posit
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Fukui Yorikazu
Murakami Kunihiko
Otsuki Toshiaki
Fanuc Ltd.
Ip Paul
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