Metal deforming – With use of control means energized in response to activator... – Sensing tool or tool-linked part
Patent
1992-03-23
1993-08-03
Crane, Daniel C.
Metal deforming
With use of control means energized in response to activator...
Sensing tool or tool-linked part
72405, B21D 4305
Patent
active
052318605
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a work feeder which is used in automatic press system and which automatically brings a work into and out of the press machine in relation to the operation of the press machine and, more particularly, to a work feeder controller which operates with high degrees of reliability and efficiency.
BACKGROUND ART
Hitherto, automatic feed of a work into and out of an automatic press system was conducted by means of a work feeder (abbreviated as "feeder", hereafter) which operates in accordance with a predetermined motion curve by being triggered by, for example, a signal from a limit switch which operates when a predetermined angle has been reached by the crank of the press machine. The feeder operates so as to feed the work into and out of the press machine so as to follow a predetermined motion curve, by a specific construction of a link mechanism and a suitable control of the operation speed of a motor. The arrival of the feeder at a predetermined position is detected by, for example, a limit switch and a signal output from the limit switch is transmitted to the press machine, thereby causing the press machine to initiate the next cycle of operation.
In another known method, shafts of a feeder are controlled by a specific combination of cams operatively associated with the crank of the press machine or by other mechanical action linked with the crank.
The method which relies upon a limit switch suffers from a disadvantage in that the next cycle of operation has to be commenced before confirming completion of the instant cycle of operation, in view of a time tolerance or variation in the mechanical operation triggered by the signal from the limit switch. On the other hand, the method relying upon mechanical means is disadvantageous in that there is a practical limit in the operation speed. Therefore, in order to realize a higher speed of operation of the press machine system with higher degree of reliability, it is necessary to obtain a closer correlation between the feeder operation and the crank angle of the press machine. Under this circumstance, in recent years, it has become popular to use, for example, a servo mechanism in which the feeder position is electrically controlled with high precision in accordance with the crank angle which is measured by a synchronous measuring device.
A description will now be given of a circuit for effecting the above-described control, with specific reference to FIG. 9. Referring to FIG. 9, numeral 82 designates a synchronous transmitter which is attached to the crank shaft of a press machine and which can measure the absolute value of the angle of rotation of the crank, while 83 denotes a conversion circuit which converts the angle information derived from the synchronous transmitter into digital codes. The digital codes indicative of the crank angle of the press machine are delivered to a computer 81. The computer 81 reads position information for each of a feed shaft, a lift shaft and a clamp shaft of the press machine, the information being beforehand determined in relation to the crank angle and stored in a memory device. The computer 81 then forms a position command signal in accordance with the read information. Numeral 88 collectively designates position detecting synchronous transmitters which are attached to respective operational shafts. In FIG. 9, the construction is shown in regard to only one shaft, because the constructions for the other two shafts are similar. Position information measured by the synchronous transmitter 88 attached to, for example, the feed shaft, is converted into digital code by means of a conversion circuit 89 and is inputted to a controlling computer 81. The feed shaft position information thus inputted to the computer is compared with a previously determined position command signal and the computer 81 forms an offset signal in accordance with the result of the comparison. Subsequently, a speed command signal for a feed shaft drive motor, which is beforehand stored in the memory device a
REFERENCES:
patent: 4120185 (1978-10-01), Schneider
patent: 4627253 (1986-12-01), Tennessen
patent: 4653311 (1987-03-01), Tack
Eiju Matsunaga, "Transfer Press Forming", Nikkan Kogyo Shinbunsha, pp. 165-197, Jun. 30, 1975.
Microcomputers and Applications, edited by Association of Electronic Communication Engineering, Corona Corporation, pp. 1-3 and 126-129, Tokyo, Apr. 10, 1981.
Tsuruta Katsuji
Yoshikawa Eiji
Crane Daniel C.
Kabushiki Kaisha Komatsu Seisakusho
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