Presses – Methods
Patent
1996-07-02
1997-10-07
Gerrity, Stephen F.
Presses
Methods
100 50, B30B 1518
Patent
active
056736150
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a slide control method in a hydraulic press in which a slide is moved up and down with a hydraulic pressure.
BACKGROUND ART
Press machines in the prior art are classified into a mechanical press in which the slide is moved up and down by a crank mechanism or a link mechanism and a hydraulic press in which the slide is moved up and down with a hydraulic pressure. It has been recognized that the hydraulic press is advantageous in that the motion of the slide can freely be changed in accordance with pressing conditions.
It may also be noted that a variety of methods and devices have been proposed for controlling the slide in the hydraulic press in the prior art.
For example, in Japanese Examined Utility Model Publication No. Hei 03-53829, there is proposed an apparatus for detecting a completion of the pressurizing step in the hydraulic press in which the completion of the pressurizing step is accurately detected by making a discrimination as to whether a slide descending velocity becomes equal to or lower than a predetermined reference velocity for discriminating a stop of the slide in the pressurizing step, timing with a timer means the predetermined time period of a pressure rise from a point of time at which the said slide descending velocity has been discriminated to be equal to or lower than the said reference velocity, setting the said reference velocity for the said slide stop discrimination at a value that is close substantially to the zero and setting the said time period of pressure rise to coincide with a time period that is required from the point of time at which the said slide descending velocity becomes approximately the zero to the point of time at which the applied pressure becomes a set pressure.
Also, in Japanese Unexamined Patent Publication No. Hei 01-192500, there is proposed a control method in the hydraulic press in which the velocity of movement in a hydraulic cylinder is controlled until the pressing of a workpiece is initiated and the applied pressure in the hydraulic press is controlled after the pressing of the workpiece has been commenced.
Further, in Japanese Examined Patent Publication No. Hei 04-2360, there is proposed a hydraulic pressing apparatus in which a movable platen is pressed against a fixed platen with a pressure cylinder, and a given workpiece is controlledly pressed in accordance with a preset program between a pair of pressing plates which are disposed between the said fixed platen and the said movable platen. And, the said apparatus comprises a detecting means being provided with a hydraulic sensor for detecting a hydraulic pressure of the operating fluid in a pressing cylinder as noted above and detecting an arrival of the above mentioned movable platen at a given pressing commencement position, a bearing pressure control means for being composed of an electromagnetic relief valve that is connected to a feed path for the operating fluid into the above mentioned pressing cylinder and controlling the hydraulic pressure of the operating fluid that is supplied into the said pressing cylinder in accordance with a preset bearing control pattern so as to control the bearing pressure acting on the above mentioned workpiece, a distance control means being composed of an electromagnetic flow rate control valve that is connected to the feed path for the operating fluid into the above mentioned pressing cylinder and controlling the rate of flow of the operating fluid into the said pressing cylinder in accordance with a preset plate thickness control pattern, thereby controlling the distance between the above mentioned pressing plates. Thus, in the operation of the said apparatus, the above mentioned detecting means will be operative to detect an arrival of the above mentioned movable platen at the above mentioned pressing commencement position to initiate an pressing control as noted above while one of the bearing pressure control means and the distance control means mentioned above will act as a limiter for the other s
REFERENCES:
patent: 3819774 (1974-06-01), Eggenberger et al.
patent: 4195563 (1980-04-01), Budraitis et al.
patent: 4367115 (1983-01-01), Bohn et al.
patent: 4429627 (1984-02-01), Edso 100 35
Gerrity Stephen F.
Komatsu Industries Corporation
Komatsu Ltd.
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