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EP0284903B1 - Presse à piston - Google Patents

Presse à piston Download PDF

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Publication number
EP0284903B1
EP0284903B1 EP88104222A EP88104222A EP0284903B1 EP 0284903 B1 EP0284903 B1 EP 0284903B1 EP 88104222 A EP88104222 A EP 88104222A EP 88104222 A EP88104222 A EP 88104222A EP 0284903 B1 EP0284903 B1 EP 0284903B1
Authority
EP
European Patent Office
Prior art keywords
controller
plunger
path
piston
piston press
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88104222A
Other languages
German (de)
English (en)
Other versions
EP0284903A3 (en
EP0284903A2 (fr
Inventor
Rolf Schmidt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG
Original Assignee
Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG filed Critical Gebrueder Schmidt Fabrik fuer Feinmechanik GmbH and Co KG
Priority to AT88104222T priority Critical patent/ATE90024T1/de
Publication of EP0284903A2 publication Critical patent/EP0284903A2/fr
Publication of EP0284903A3 publication Critical patent/EP0284903A3/de
Application granted granted Critical
Publication of EP0284903B1 publication Critical patent/EP0284903B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B30B15/18—Control arrangements for fluid-driven presses controlling the reciprocating motion of the ram
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/26—Programme control arrangements

Definitions

  • the invention relates to a piston press with a plunger, which is connected to a piston running in a cylinder, the cylinder can be pressurized with compressed air via electrically actuated valves, the plunger interacts with a displacement measuring system, an output signal of the displacement measuring system is compared in a controller with predefined setpoints is and the controller controls the valves for pressurizing the cylinder according to a predetermined path / time curve.
  • the compressed air is supplied via switching valves to the piston in generally known piston presses, which moves the plunger until it hits the workpiece.
  • the plunger is either placed on the workpiece with full force, which corresponds to the preset pressure of the compressed air, or limit switches are provided which close the valves again when the plunger reaches a predetermined end position or cause the plunger to be retrieved.
  • the known piston presses with pneumatic drive thus have the disadvantage that sensitive control, in particular displacement / time control, is not possible because of the ram
  • a displacement measuring system is assigned to the plunger, which transmits information about the state of movement of the plunger to a computer.
  • This computer acts as a controller and controls the electrically actuated switching valves.
  • a first switching valve is opened and the piston is moved downward by means of a first pressurization.
  • the piston no longer moves due to the high back pressure, which is registered by the position measuring system.
  • a second switching valve is opened so that the working stroke can now be carried out because of the higher pressure.
  • the computer switches the switching valves in such a way that the piston carries out its return stroke to the starting position.
  • the switching times of the individual switching valves are set by the computer in such a way that the dwell time of the tool on the workpiece (between the delivery stroke and the working stroke) and after the working stroke is as short as possible.
  • the combination of computer and position measuring system serves here to replace the limit switches from the prior art described above.
  • This piston press is, so to speak, "self-learning" because it recognizes because of the position measuring system the computer automatically, when the work stroke has to start and when it has ended. It is therefore no longer necessary to adjust the limit switches.
  • the invention is based on the object of developing a piston press of the type mentioned in such a way that the ram can be deflected precisely in a positionally controlled manner.
  • the electrically actuated valves are electropneumatic servo valves and that the path / time curve is divided into discrete areas of different gradients, the plunger being moved from its rest position to an end position with gradually decreasing speed.
  • the object on which the invention is based is completely achieved in this way because the pressing process can be adapted to a wide variety of pressing tasks by means of the controllable path / time profile.
  • particularly sensitive pressing tasks can be solved, and the paths to be measured and the speeds at which the paths are measured can be adapted to the respective pressing task.
  • the controller is a state controller with adjustable controller parameters, which forms control signals as a function of the travel signal, a speed signal and an acceleration signal, and the controller parameters can be switched over automatically when changing from a first area to a second area.
  • This measure has the advantage that the control can be optimally controlled in the different areas of different gradients of the path / time curve, because the parameters of the controller that determine the control process can be adapted to the respective gradients and thus the respective workpiece.
  • a pressure sensor detects the pressure acting on the cylinder or the pressing force exerted by the ram, compares these values with a predetermined target value range and actuates a display element if the range is not complied with.
  • servo valves are 3/2-servo valves with pilot valve. This combination of a directional servo valve with a pressure servo valve enables both sensitive pressure control and exact positioning of the press ram.
  • FIG. 1 10 designates an embodiment of a piston press according to the invention.
  • a machine table 11 stands on a solid surface.
  • a workpiece 12 can be seen on the machine table 11, which is to be pressed, for example, with a bolt 13.
  • a piston 16 runs in the cylinder 15 and is firmly connected to a tappet 17.
  • the plunger 17 is connected to a position measuring system 18 at a suitable point.
  • a rod 19 extends from the upper end face of the plunger 17 and carries an inductive element 20.
  • the element 20 interacts with a coil 21.
  • any other suitable displacement measuring system for example a capacitive or an optical or some other displacement measuring system, can be used.
  • an electrical line 30 leads once directly, once via a differentiating stage 31 and again via a double differentiating stage 33 to a control unit 34. If the path signal detected by the measuring system 18 is denoted by s, then the signals s, ⁇ and on the control unit 34.
  • Setpoints s0, s1, s2, s3 ... of the travel path 17 of the plunger 17 can be specified to the control unit 34 via a first keyboard 35.
  • Additional setpoints can be entered into the control unit 34 via a second keyboard 36, for example an upper and a lower limit value p0, p u of an operating pressure p of the piston press 10.
  • the control device 34 comprises a controller 37, which is preferably a state controller of a type known per se.
  • the controller characteristic can be defined in a manner known per se via controller parameters.
  • the controller 37 is provided with adjustable controller parameters, as will be explained further below.
  • control unit 34 comprises, in addition to comparators (not shown) for comparing the actual path s with the target values s0, s1 ... a comparator 38 for comparing pressure values p, as will be explained further below.
  • an upper space 40 extends in the cylinder 15. This is connected with a pneumatic line 41 to an electropneumatic 3/2-servo valve which is internally provided with a pilot valve, as described in detail for example in DIN ISO 1219 under 7.2 .
  • a lower space 43 of the cylinder 15 below the piston 16 is connected to a further electropneumatic 3/2 servo valve 45 by a pneumatic line 44.
  • the servo valves 42, 45 are controlled separately by the controller 37.
  • a pressure sensor 50 detects, for example, the differential pressure between the spaces 40 and 43 and supplies a corresponding signal p to the comparator 38 in the control unit 34, the further input of which is connected to the limit values p0, p u specified by the second keyboard 36.
  • a force sensor 70 for example a piezoelectric sensor, can be arranged on the plunger 17 in order to detect the pressing force F which the plunger 17 exerts on the workpiece 12/13.
  • limit values F o , F u can then be specified using the second keyboard 36.
  • the output of the comparator 38 controls a display element 51.
  • the operation of the piston press 10 according to FIG. 1 is as follows: The user of the piston press 10 first enters 35 paths using the first keyboard, depending on the workpiece 12, 13 to be machined, s0 being the rest position of the ram 17 when the piston 16 has assumed its upper end position in FIG. 1. Between the value s0 and a further value s1, the plunger 17 measures the empty space until it is placed on the workpiece 12, 13. From the value s1 to a value s2, there is now a working stroke in which the essential pressing work, for example the pressing in of the bolt 13 into the workpiece 12. Finally, there is a small way from the value s2 to a further value s3, in which, for example, the bolt 13 is positioned exactly on the final value. The user also specifies travel speeds for the plunger 17 in the various stroke ranges.
  • the user also uses the second keyboard 36 to enter a pressure range between a lower value p u and an upper value p o or a pressing force range F o - F u , it being checked whether the pressure p or the pressure required to deflect the plunger 17 the applied pressing force F lies within this range of values p o - p u or F o - F u .
  • the piston press 10 is now switched on by means of a switch (not shown in FIG. 1).
  • the first servo valve 42 is switched from the position shown in FIG. 1 so that compressed air flows from a reservoir via the pneumatic line 41 into the upper space 40.
  • the piston 16 now moves downward, the instantaneous position of the piston 16 or the plunger 17 being detected by means of the displacement measuring system 18 and readjusted if necessary by actuating the valves 42, 45 in accordance with the specified displacement / time dependence.
  • controller 37 becomes a displacement signal s, a speed signal ⁇ and an acceleration signal fed, and the controller 37 generates depending on predetermined controller parameters, which were determined from the predetermined values s o , s1, s2 and s3 and the travel speeds, the analog control signal for the servo valves 42 and 45.
  • the associated path / time diagram is plotted in FIG. 2.
  • the piston press 10 was turned on at time t0 and up to time t1 the idle stroke between the upper starting position s0 and touchdown s1 measured on the bolt 13. As can be seen from the relatively steep course in the interval t0 to t1, this idle stroke happens with a relatively high travel speed.
  • the measuring system 18 recognizes that the predetermined value s 1 has been reached.
  • the controller parameters are now switched in the controller 37, as can be seen from the short overshoot in FIG. 2.
  • the piston 16 with the plunger 17 continues its path somewhat more slowly until the working stroke has ended t 2 and the bolt 13 is almost in its end position.
  • a short holding phase then preferably follows until the piston 16 returns to its upper starting position by corresponding actuation of the servo valves 42, 45.
  • the control unit 34 has compared the pressure applied in each case with the pressure interval p u - p o by means of the comparator 38.
  • the corresponding characteristic of the comparator 38 is shown in FIG. 3. It can be seen that a quality signal Q is derived which assumes the value 1 in the interval p o - p u and the value 0 outside this interval.
  • a display element 51 is therefore only (or with appropriate logic only then not) driven if a pressure had to be applied to measure the path up to the value s 3, which was in the interval p o - p u .
  • the same applies in the case of the monitoring of the pressing force if it is determined whether the pressing force F is in the interval F u - F o .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Presses (AREA)

Claims (5)

  1. Presse à piston (10) comportant un coulisseau (17) qui est relié à un piston (16), se déplaçant dans un cylindre (15), dans laquelle le cylindre (15) est alimenté en air comprimé par des soupapes (42, 45) commandées électriquement, le coulisseau (17) coopère avec un système de mesure de distance (18), un signal de sortie (s) du système de mesure de distance (18) est comparé, dans un régulateur (37), à des valeurs de consigne (S₀, S₁, S₂, S₃) données et dans laquelle le régulateur commande des soupapes (42, 45) en vue d'alimenter en pression le cylindre (15), suivant une courbe distance/temps (S(t)) donnée, caractérisée en ce que les soupapes (42, 45), commandées électriquement, sont des servo-soupapes électropneumatiques (42, 45) et en ce que la courbe distance/temps (S(t)) est divisée en zones discrètes de pente différente, le coulisseau (17) étant déplacé d'une position de repos (S₀) vers une position finale (S₃), avec une vitesse décroissant progressivement.
  2. Presse à piston selon la revendication 1, caractérisée en ce que le régulateur (37) est un régulateur d'état avec paramètres réglables, qui forme des signaux de positionnement en fonction du signal de distance (s), du signal de vitesse (ṡ) ainsi que du signal d'accélération (
    Figure imgb0003
    ) et en ce que les paramètres du régulateur sont commutables automatiquement, au passage d'une première zone à une seconde zone.
  3. Presse à piston selon la revendication 1, caractérisée en ce qu'un capteur de pression (50) détecte la pression (P) agissant sur le cylindre (15), la compare à une plage de valeurs de consigne (Po -Pu) donnée et actionne un élément d'affichage (51), en cas de non-respect de la plage (Po -Pu).
  4. Presse à piston selon la revendication 1 ou 2, caractérisée en ce qu'un capteur de force (70) détecte la force de pression (F), exercée par le coulisseau (17), la compare à une plage de valeurs de consigne (Fo -Fu) donnée et actionne un élément d'affichage (51) en cas de non-respect de la plage (Fo -Fu).
  5. Presse à piston selon l'une des revendications 1 à 4, caractérisée en ce que les servo-soupapes sont des servo-soupapes 3/2 (42, 42) avec soupape pilote.
EP88104222A 1987-04-01 1988-03-17 Presse à piston Expired - Lifetime EP0284903B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88104222T ATE90024T1 (de) 1987-04-01 1988-03-17 Kolbenpresse.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3710289 1987-04-01
DE3710289 1987-04-01
DE3716220 1987-05-14
DE19873716220 DE3716220A1 (de) 1987-04-01 1987-05-14 Kolbenpresse

Publications (3)

Publication Number Publication Date
EP0284903A2 EP0284903A2 (fr) 1988-10-05
EP0284903A3 EP0284903A3 (en) 1989-09-20
EP0284903B1 true EP0284903B1 (fr) 1993-06-02

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP88104222A Expired - Lifetime EP0284903B1 (fr) 1987-04-01 1988-03-17 Presse à piston

Country Status (2)

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EP (1) EP0284903B1 (fr)
DE (2) DE3716220A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5100113A (en) * 1988-10-18 1992-03-31 Aida Engineering Co., Ltd. Pneumatic die cushion equipment
US5042336A (en) * 1989-03-03 1991-08-27 Capps David F Control apparatus and method for progressive fracture of workpieces
JP2788675B2 (ja) * 1990-11-06 1998-08-20 住友重機械工業株式会社 型開閉制御装置
DE4331017C2 (de) * 1993-09-13 1999-09-23 Langenstein & Schemann Gmbh Verfahren zum Steuern einer Presse für Steinformlinge
DE10023164B4 (de) * 1999-05-12 2006-11-30 Hornung Gmbh Indupress & Co. Kg Bügelmaschine

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1518720A (en) * 1975-11-21 1978-07-26 Ishikawajima Harima Heavy Ind Hydraulic servomechanism
DE2937998A1 (de) * 1979-09-20 1981-04-02 Beche & Grohs GmbH, 5609 Hückeswagen Verfahren zur steuerung des arbeitsablaufes einer druckmittelbeaufschlagten arbeitsmaschine sowie druckmittelbeauschlagte arbeitsmaschine mit druckmittelsteuerung
DE3230930A1 (de) * 1982-08-20 1984-02-23 Schirmer, Plate und Siempelkamp Hydraulische Pressen GmbH, 4150 Krefeld Regeltechnische schaltungsanordnung bei einer umformpresse
DE3401203C1 (de) * 1984-01-14 1985-05-30 Hoesch Ag, 4600 Dortmund Hydraulische Presse zum Verpressen von Kunststoff-Halbzeug
FR2600120B1 (fr) * 1986-06-12 1990-06-29 Bertin & Cie Procede et dispositif d'asservissement en position d'un verin pneumatique

Also Published As

Publication number Publication date
DE3881424D1 (de) 1993-07-08
DE3716220A1 (de) 1988-10-20
EP0284903A3 (en) 1989-09-20
EP0284903A2 (fr) 1988-10-05

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