DE4103408A1 - Device and method for producing mass-containing form bodies from pastoesen masses - Google Patents

Device and method for producing mass-containing form bodies from pastoesen masses

Info

Publication number
DE4103408A1
DE4103408A1 DE4103408A DE4103408A DE4103408A1 DE 4103408 A1 DE4103408 A1 DE 4103408A1 DE 4103408 A DE4103408 A DE 4103408A DE 4103408 A DE4103408 A DE 4103408A DE 4103408 A1 DE4103408 A1 DE 4103408A1
Authority
DE
Germany
Prior art keywords
die
mass
ram
pressing
pressure
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.)
Withdrawn
Application number
DE4103408A
Other languages
German (de)
Inventor
Lutz Beyer
Peter Kluge
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Priority to DE4103408A priority Critical patent/DE4103408A1/en
Publication of DE4103408A1 publication Critical patent/DE4103408A1/en
Application status is Withdrawn legal-status Critical

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS, SLAG, OR MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B13/00Feeding the unshaped material to moulds or apparatus for producing shaped articles; Discharging shaped articles from such moulds or apparatus
    • B28B13/02Feeding the unshaped material to moulds or apparatus for producing shaped articles
    • B28B13/021Feeding the unshaped material to moulds or apparatus for producing shaped articles by fluid pressure acting directly on the material, e.g. using vacuum, air pressure
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS, SLAG, OR MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B17/00Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
    • B28B17/0063Control arrangements
    • B28B17/0081Process control
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B30PRESSES
    • B30BPRESSES IN GENERAL
    • B30B11/00Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
    • B30B11/005Control arrangements
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B30PRESSES
    • B30BPRESSES IN GENERAL
    • B30B15/00Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/30Feeding material to presses
    • B30B15/302Feeding material in particulate or plastic state to moulding presses

Abstract

The invention concerns a device for the production of accurately dimensioned mouldings, e.g. oxide magnets, from moulding paste by wet-pressing. The invention also concerns a process for the production of such mouldings, and the mouldings themselves. The moulding paste is fed into the moudling die (6) by a pump (1), the die containing a punch (7) capable of exerting a pressure on the paste. The measurement and control electronics proposed by the invention includes a sensor element (8) which detects relative motion between the punch (7) and the die (6), plus control electronics which determine, from the measured data, the punch-travel distance and controls the pump feed pressure if punch travel lies outside a given range.

Description

State of the art

The invention relates to a further embodiment and improvement of known methods and devices for the production of moldings from pasty Masses in the wet-pressing, as z. B. in the production of Oxidmagneten be applied from metal oxide pastes, as well as the produced Shaped body as such. In these methods, the aim is a high Product quality, d. H. faultless, dimensionally stable within narrow tolerances over the entire volume of homogeneous moldings, at the same time short Generate cycle times. A method for producing oxide magnets By Maßverpressen of metal oxide material is in DE-OS 33 47 035 be wrote. You can distinguish two levels. In the first stage, the filling process, the die, which is the shape of the desired compact corresponds, filled with pasty metal oxide paste. In the second stage, the Pressing process, the paste in the die becomes the shaped body (or compact) pressed (or compressed). The method improves on previously known work by ensuring that in the first stage the optimal maximum filling pressure is maintained for an optimal period of time. in the individual is the pasty mass by means of a mass pump by a Filling via a controllable, pressure-regulating shut-off valve in the Guided matrix. Between check valve and die is a pressure sensor arranged, which measures the filling pressure and reports to a control electronics. This controls the check valve so that during a predetermined time, z. B. between 0.3 and 1.0 sec, a predetermined maximum inflation pressure, z. B. between 30 and 50 bar, and thereby filled the die optimally  becomes. The control electronics continue to conduct after expiration of the mentioned predetermined time automatically the second stage of the process, the Pressing, by acting on the hydraulics of the punch, which in the die generates a predetermined maximum pressing pressure, the z. B. between 200 and 800 bar. The check valve is in this phase closed, so that no reflux of pasty mass in the mass pump can take place.

The method provides for shorter cycle times moldings of better Quality than the older, unregulated procedures. It does, however, require one relatively complicated hydraulic control device. This disadvantage avoids the control device for timing the filling pressure when filling a press tool according to DE-OS 38 44 334. In this case, the maximum filling pressure given by the pressure of the mass pump, a regulation the maximum filling pressure is eliminated. The pressure sensor (or Pressure sensor) gives its signal to a first threshold level and, parallel thereto, via a differentiator to a second threshold level. The output signals of both threshold levels go into a logical Gate, which transmits a trigger signal to a downstream timer, if at the same time a first threshold - a predetermined voltage - in exceeded the first threshold level and a second threshold - a predetermined differential quotient of the voltage after the time - in the falls below second threshold level. The timer has a Hold on, the previously determined optimum hold time for the Maximum filling pressure corresponds and thus ensures optimal filling the matrix. The control device according to DE-OS provides with reduced Effort similar good results as the method of DE-OS 33 47 035. However, the dimensional accuracy of the shaped body is not always sufficiently good.

Advantages of the invention

The devices and methods according to the claims provide moldings with improved dimensional stability, since the rain ment attaches to the pressing of the press ram, in the end position of the punch, which in turn the dimension of the  Shaped body determined in the pressing direction. This is the critical dimension for dimensional accuracy, since the other dimensions through the walls of the Are clearly defined. The scheme according to the invention sets thus directly at the critical parameter. For the fully automatic Operation of a pressing tool for the production of moldings from paste-like Mass self-adaptation of individual parameters is an important Requirement. Fluctuations in the properties of the pasty mass, especially in the flow and filling properties, as well as discontinuities other causes are compensated by meaningful control processes, the one constantly optimal coordination of hydraulic mass pump pressure, filling pressure, Fill quantity, press weight and press thickness effect.

drawing

An embodiment of the invention is shown in the drawing and explained in more detail in the following description. It shows

Fig. 1 is a block diagram of an apparatus according to claim 1,

Fig. 2 shows the pressing path for a pressing operation as a function of time, and

Fig. 3 shows the pressing path as a function of Preßtakte in an iterative approaching process, which leads to a shaped body in the desired range.

Description of the embodiment

The pasty mass - in the example of the preparation of an oxide magnet the finely ground (particle size 0.1 to 2.0 microns) metal oxides, with water and the usual excipients pasted into a paste with 60 to 80 wt.% Solids content - is from the mass pump ( 1 ) are pumped through the delivery line ( 2 ). It then happens, if necessary, a sieve, which restrains the coarse fractions. The pasty mass then passes to the shut-off valve ( 4 ), which is designed as a check valve or otherwise prevents pasty mass flows back into the mass pump during the pressing process. The pressure sensor ( 5 ) measures the filling pressure immediately before the die ( 6 ).

The die, which corresponds in its inner shape to the dimensions of the desired shaped body, has a ram ( 7 ), which is suitably operated hydraulically and in the case of the production of oxide magnet generally pressures of 200 to 800 bar on the pasty mass located in the die allowed to exercise. He continues to push after completion of the pressing process, the molding from above, as soon as the upper limit of the die releases the way.

The measuring element or the displacement transducer ( 8 ), which is attached to the ram or on its extension, and the following components form the measurement and control electronics, which is an essential feature of the invention.

The transducer can work according to different measuring systems, eg. B. analog as capacitive, inductive or resistance transducer or digitally with optical measurement on a marked glass rod (increment sensor). He tracks the relative movements between punch and die. The Wegmeß signal is supplied via the measuring amplifier ( 9 ) and, if an analog transducer is used, via the A / D converter ( 10 ) to the computing element ( 11 ). Here, the difference between the initial value X F (filling position of the press ram) and during the punch feed continuously supplied Wegmeßwert X. In this way, the entire path-time curve of the pressing operation is detected. In Fig. 2, 3 such curves are shown. The curve ( 1 ) shows the course for a pressing process, which leads to a shaped body in the desired range. Curve ( 2 ) relates to the case "pressing path too short - shaped body too thick", curve ( 3 ) the reverse case "pressing path too long - shaped body too thin".

The value obtained in the final press position X E at the output of the computing element for X P = X F -X E , that is to say the pressing path, holds the sample and hold circuit with timer ( 12 ) and sends it to the window comparator ( 13 ) in the the desired thickness of the shaped body has been entered in the form of a tolerance range for the pressing path X P. The comparator compares the reported X P value with the tolerance range (the so-called window width). If the reported X P value is outside the window width, the comparator sets a positive or negative count pulse on the count memory ( 14 ), depending on the direction of deviation.

The change of the count memory setting is converted via the D / A converter ( 15 ) into a corresponding control voltage change of the hydraulic pressure control valve ( 16 ) of the mass pump ( 1 ). When using a proportional pressure reducing valve rated at 0 to 70 bar and operating with a control voltage range of 0 to 10 V and an 8-bit memory, a control voltage change of 0.04 V corresponds to a pressure change of 0.27 bar. For a piston area ratio (hydraulic side to ground side) of 1: 1, the following table applies:

filling pressure control voltage (bar) (V) 20 2.86 25 3.57 30 4.29 35 5.01 40 5.71

If there is an X P setpoint deviation below the window width (mold body too thick) during a pressing operation, the comparator ( 13 ) gradually reduces the count memory setting from press to press operation. The corresponding control voltage reduction at the pressure control valve ( 16 ) reduces, in turn, gradually, the filling pressure of the mass pump ( 1 ) and thus the amount of introduced into the die ( 6 ) pasty mass. Since the pressing thickness of the molded body is strictly proportional to the filling amount, the control process is completed when the pressing target d s has set with the setpoint of the controlled variable X PS according to d s = X F -X PS .

Accordingly, at X P deviations above the allowable window width (molding too thin) cyclically counting steps in the count memory ( 14 ) added and thereby the control voltage at the pressure control valve ( 16 ) and thus the filling pressure of the mass pump ( 1 ) increases, due to increase in the amount in the die ( 6 ) of the pressing X P is in the desired value range, that is, the shaped body has the desired thickness.

The stepwise adjustment to the desired thickness of the shaped body within the tolerance limits (or the window area) is shown in FIG . A corresponding picture arises, of course, if instead of the pressing path, the control voltage at the control valve ( 16 ), which in turn corresponds to the filling pressure and thus the filling quantity, is plotted against the number of pressing operations.

The interaction of the individual components of the device after the The invention can be found in the following scheme:

In Fig. 1, the control electronics is shown for the sake of clarity in the form of individual components. All these individual components are known to the person skilled in the art. Of course, their functions can also be exercised by a suitably dimensioned and programmed computer.

Claims (6)

1. Apparatus for producing dimensionally stable shaped bodies from pasty masses in Naßpreßverfahren with a mass pump to promote the pasty mass in the forming die, which contains a ram, which is able to exert on the pasty mass in the die hydraulic pressure, and with a measuring and Control electronics, characterized by a measuring element which receives the relative movement between ram and die, and an electronic control unit which determines the pressing path of the ram from the recorded values and regulates the delivery pressure of the mass pump ( 1 ) when the pressing path is outside a predetermined nominal range.
2. Apparatus according to claim 1, characterized by an analog or digital position transducer ( 8 ) as a measuring element and by a control electronics, comprising: a measuring amplifier ( 9 ), an A / D converter ( 10 ), provided that the position transducer ( 8 ) analog operates, the computing element ( 11 ), which determines the pressing path of the press ram ( 7 ) by subtracting, by the sample and hold circuit ( 12 ), which forwards the determined pressing path to the window comparator ( 13 ) through the counting memory ( 14 ) the window comparator sets a count when the determined pressing travel is outside the predetermined target range, and a D / A converter ( 15 ) which changes the settings of the number memory into corresponding changes in the control voltage of the hydraulic pressure regulating valve ( 16 ) on the mass pump ( 1 ) implements.
3. Device according to one of claims 1 or 2, characterized in that it comprises a pressure sensor ( 5 ) in front of the die ( 6 ), which is part of a control device for the timing of the filling pressure according to the patent 38 44 334.
4. A process for the preparation of dimensionally stable shaped bodies from pastö sen masses in Naßpreßverfahren, wherein a mass pump promotes the pasty mass in a forming die and a ram on the pasty mass in the die hydraulic pressure exerts and where provided with a measuring and control electronics, characterized in that the relative movement between ram ( 7 ) and Ma trize ( 6 ) by a measuring element ( 8 ) is received and that a Re gelelektronik determined from the recorded values, the pressing path and regulates the delivery pressure of the mass pump ( 1 ) when the Preßweg except half of a predetermined target range is.
5. The method according to claim 4, characterized in that a analo ger or digital position transducer ( 8 ) as a measuring element receives the relative movement between the ram and die and that a control electronics with a measuring amplifier ( 9 ), an A / D converter ( 10 ) , If the transducer ( 8 ) works analogously, and a computing element ( 11 ) determined by subtraction the Preßweg of the press ram ( 7 ) through the sample & hold circuit ( 12 ) the determined pressing path to the Fen sterkomparator ( 13 ) passes through the Count memory ( 14 ) sets a count pulse, when the determined pressing path is outside the predetermined range specified range, and by a D / A converter ( 15 ) the changes of the settings of the count memory in corresponding amendments of the control voltage of the hydraulic pressure control valve ( 16 ) on the Mass pump ( 1 ) converts.
6. Shaped body, characterized in that it according to the method were prepared according to claim 4 or 5.
DE4103408A 1991-02-05 1991-02-05 Device and method for producing mass-containing form bodies from pastoesen masses Withdrawn DE4103408A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE4103408A DE4103408A1 (en) 1991-02-05 1991-02-05 Device and method for producing mass-containing form bodies from pastoesen masses

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4103408A DE4103408A1 (en) 1991-02-05 1991-02-05 Device and method for producing mass-containing form bodies from pastoesen masses
PCT/DE1992/000029 WO1992013692A1 (en) 1991-02-05 1992-01-18 Process and device for the production of accurately dimensioned mouldings from moulding pastes

Publications (1)

Publication Number Publication Date
DE4103408A1 true DE4103408A1 (en) 1992-08-06

Family

ID=6424402

Family Applications (1)

Application Number Title Priority Date Filing Date
DE4103408A Withdrawn DE4103408A1 (en) 1991-02-05 1991-02-05 Device and method for producing mass-containing form bodies from pastoesen masses

Country Status (2)

Country Link
DE (1) DE4103408A1 (en)
WO (1) WO1992013692A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4323668A1 (en) * 1992-09-03 1994-03-10 Abb Patent Gmbh Mold for production of a molding
ES2112176B1 (en) * 1995-09-11 1998-11-16 Taulell S A Method of automatic control of the pressing cycle in the semidry process compacting ceramic tiles.
ES2144935B1 (en) * 1997-10-15 2001-02-01 Juguetes Oliver S A Procedure for obtaining figures by molding and device for its practice.
JP2009111169A (en) * 2007-10-30 2009-05-21 Tdk Corp Method for producing magnet, magnet obtained by the method, apparatus for producing molding product for magnet

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1584543C3 (en) * 1964-11-28 1979-04-05 Laeis-Werke Ag, 5500 Trier
US4447198A (en) * 1982-10-26 1984-05-08 Wehr Corporation Hydraulic refractory press including product thickness or density control means
JPH042410B2 (en) * 1983-06-28 1992-01-17
JPH0440178B2 (en) * 1983-12-28 1992-07-02 Fanuc Ltd
JPH0523575B2 (en) * 1988-03-24 1993-04-05 Komatsu Mfg Co Ltd
DE3844334C1 (en) * 1988-12-30 1990-06-28 Robert Bosch Gmbh, 7000 Stuttgart, De

Also Published As

Publication number Publication date
WO1992013692A1 (en) 1992-08-20

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