Boots – shoes – and leggings
Patent
1986-12-08
1988-10-25
Lastova, John R.
Boots, shoes, and leggings
318632, G06F 1518, G06F 1546
Patent
active
047808292
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a numerical control apparatus having an overtravel check function and, more particularly, to a numerical control apparatus of this type which reliably drives a control shaft so that the control shaft is not moved beyond an overtravel preset value.
BACKGROUND ART
It is known to control a machine having one or more moving portions by a numerical control apparatus (to be referred to as an NC apparatus hereinafter), and to control respective moving portions by one or more control shafts (to be referred to as shafts hereinafter). In a conventional numerical control apparatus (to be referred to as an NC apparatus hereinafter) of this type, pulse distribution to each shaft is performed based on an NC program at predetermined cycles, and a servo motor for each shaft is driven to drive the shaft. On the other hand, check for overtravel of each shaft is performed by checking whether the shaft is moved beyond the overtravel preset value after completion of pulse distribution processing for each cycle.
Since overtravel check is delayed by one cycle of pulse distribution from pulse distribution, a shaft is stopped beyond the overtravel preset value by an amount equal to a product of its feeding speed and a pulse distribution cycle. Therefore, when the pulse distribution cycle is 8 msec and the maximum feeding speed is 10 m/min, the shaft may overrun a maximum of about 1.33 mm (10,000.times.1/60.times.8/1,000).
For this reason, conventionally, a real moving limit position of a machine cannot be set as the overtravel preset value, but a value added with a margin equal to the product of the maximum feeding speed and the pulse distribution cycle described above must be set, resulting in a narrow actual moving range.
However, according to a machine or an apparatus to be controlled by an NC apparatus, the machine must be moved from an end to the other end of a moving range of the machine. For example, when an injection molding machine is controlled by an NC apparatus, the machine must be moved from an end to the other end of the moving range of the machine by JOB feeding during purging or lock up adjustment of a clamp. In such an operation, for the above-mentioned reason, a stop position of the machine is not fixed according to the feeding speed and the distribution processing timing, and the machine cannot be moved in the maximum moving range.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide an NC apparatus capable of exactly controlling each shaft of a machine to be controlled to an overtravel preset value, and setting the preset value equal to a machine moving limit position, thereby substantially enlarging a moving range of the machine and exactly stopping the machine at a predetermined limit position.
In order to achieve the above object, according to the present invention, a check means checks whether a value obtained by adding an amount of distribution from a pulse distribution means and a stored value of a present machine position register for storing a present position of the machine falls within a preset movable range. If the value falls within the moving range, the above amount of distribution is output, and an updating means adds the present machine position with the amount of distribution to update the machine position. On the other hand, if the value falls outside the moving range, a distribution correction means is operated to output a corrected amount of distribution obtained by subtracting the present machine position from the overtravel preset value, and the updating means adds the corrected amount of distribution to the present machine position register to update the present machine position.
As described above, according to the present invention, the pulse distribution to each shaft controlled by an NC apparatus is performed. When the present position of the machine obtained by distribution exceeds the overtravel preset value, the corrected amount of distribution equal to the amount of from the present machine position to t
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patent: 4131837 (1978-12-01), Whetham
patent: 4250441 (1981-02-01), Chapman et al.
patent: 4353019 (1982-10-01), Sweeney, Jr.
patent: 4379987 (1983-04-01), Kohzai et al.
patent: 4549271 (1985-10-01), Nozawa et al.
Fanuc Ltd
Lastova John R.
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