EP0350563B1 - Method and apparatus for monitoring the press loads of the punches in a tablet press - Google Patents
Method and apparatus for monitoring the press loads of the punches in a tablet press Download PDFInfo
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- EP0350563B1 EP0350563B1 EP89103234A EP89103234A EP0350563B1 EP 0350563 B1 EP0350563 B1 EP 0350563B1 EP 89103234 A EP89103234 A EP 89103234A EP 89103234 A EP89103234 A EP 89103234A EP 0350563 B1 EP0350563 B1 EP 0350563B1
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- 238000000034 method Methods 0.000 title claims description 6
- 238000012544 monitoring process Methods 0.000 title claims description 5
- 230000002950 deficient Effects 0.000 claims 1
- 238000003825 pressing Methods 0.000 description 34
- 238000010586 diagram Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 230000007257 malfunction Effects 0.000 description 5
- 238000011109 contamination Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- 238000000418 atomic force spectrum Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 238000009475 tablet pressing Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
- B30B11/005—Control arrangements
Definitions
- the invention relates to a device for monitoring the pressing forces of paired upper and lower punches of a tablet press, with which an average value formed from successive measurement results of the pressing forces is compared with two adjustable fixed tolerance limits and with which the maxima of the individual values of the pressing forces are compared with individual value limits.
- tablet presses which have upper and lower punches, which press the powdery material in pairs into matrices for the manufacture of the tablets.
- Different types of malfunctions can occur. Such disturbances can be based on a rupture of a stamp, as well as on other inaccuracies of the tools, such as, for example, different stamp lengths or, in some cases, slight breakouts on the stamp head surfaces or, for example Contamination of the same.
- dosage fluctuations occasionally occur during operation, which are based on irregularities in the nature of the material to be processed.
- tablet presses In order to recognize the resulting deviations of the finished products in good time, tablet presses generally have a pressing force monitoring device.
- a pressing force monitoring device usually has strain gauges, which are arranged for example on the carriers of the pressure rollers for the stamp. This makes it possible to take advantage of the fact that different pressing forces cause different press roller carrier expansions, which are to be converted into proportional tension signals.
- a known value is used to form an average value A using a known device, the course of which is monitored at two adjustable tolerance limits (G). As soon as the average value A exceeds or falls below one of these two tolerance limits G, the tablet press is stopped.
- G adjustable tolerance limits
- the tolerance range must be selected relatively wide in such a device in order to prevent the tablet press from being shut down frequently without there being any particular malfunctions. This is due, among other things, to the fact that the pressing forces of the individual pairs of punches differ in size due to manufacturing tolerances in the lengths of the punches, so that the individual values from which the mean value is formed also fluctuate accordingly. On the other hand, a relatively large distance between the tolerance limits leads to the fact that only relatively large deviations of the individual values of the pressing forces from the mean value or particularly pronounced malfunctions can be recognized.
- a known device provides for the average value A to be assigned two adjustable individual value limits B and C which follow its course, with which the maxima of the individual values of the pressing forces are to be compared.
- This has the advantage that fluctuations in the mean value within an adjustable tolerance range between the limits G can be accepted, a second tolerance range with the limits B and C for the deviations of the maxima of the individual values of the pressing forces is independent.
- the tolerance ranges can be chosen to be relatively small because the fluctuations in the mean value have no influence on the tolerance range given by the limits B and C for the deviations of the maxima of the individual values of the pressing forces from the mean value A.
- stamp breaks can be easily recognized with this known method due to the change in the pressing force that occurs, however, minor changes in the pressing force of a single pair of stamps, which are based, for example, on smaller breakouts on the stamp head surface or on upsets or sticking or soiling of the stamp head surface, are not readily possible determine because such stamp errors have less impact on fluctuations in the pressing force than unavoidable dosage fluctuations or the pressure roller impact, which therefore conceal such stamp errors.
- the object of the invention is to provide a method and a device by means of which even small defects in the stamps of the tablet press can be recognized during the manufacture of tablets.
- the individual stamp pairs are assigned average stamp pair limits with which the respective average stamp pair is compared. This takes into account, on the one hand, that the individual pairs of punches produce different mean pressures than other pairs of punches due to the inevitable differences in the length of the punches.
- the mean values assigned to the individual stamp pairs with average stamp pair limits changes on the individual tools can be determined on the other hand, for example, contamination on a stamp head surface, since the resulting average stamp pair value would lie outside these limits.
- the mean values to be assigned to the individual stamp pairs can be formed one after the other or in a sliding manner.
- Sliding means that with each new pressing force value to be processed the oldest previously determined pressing force value is eliminated.
- the mean values are formed from a larger number of tablet pressing forces measured on the respective pair of punches, which on the one hand is large enough to ensure adequate statistical security on the other hand, it is so small that it can react quickly enough if there is a significant deviation.
- stamps Since the size of the stamp pair mean values specific to the respective stamp pairs is dependent on the specific length of the stamp of this stamp pair, there is the advantage that stamps can be exchanged to such an extent that the stamp pair mean values are close to the curve which represents the desired pressing forces.
- the tablet press partially shown in FIG. 1 has a circumferential die plate with a plurality of die holes 16, each of which is assigned a pair of an upper punch 1 and a lower punch 2.
- These stamps 1 and 2 with the stamp head surfaces 1 'and 2' are pressed into the die by pressing rollers 3 and 4 when pressing a tablet.
- the pressure rollers 3 and 4 are held by supports, which are provided with strain gauges 5 and 5 '. With these strain gauges, the deflection of the carrier and thus the pressing force of the punches 1 and 2 can be measured and converted into voltage signals that are proportional to the size of the pressing force.
- strain gauges 5 and 5 ' are switched according to the principle of a Wheatstone bridge according to Figure 2.
- the voltage change that occurs in the strain gauges 5 and 5' during pressing is amplified via an amplifier 8.
- These signals are fed into an analog-digital converter 15 to which a computer 9 with a monitor 10 is connected.
- the device also includes a proximity switch 7 which, when passing through a pair of punches 1, 2 between the press rolls 3 and 4, emits a pulse to the computer 9.
- a relay 11 is provided, by means of which the machine is brought to a standstill if a determined average stamp pair value exceeds or falls below the limit assigned to it.
- a mean value corresponding to curve A is formed from the individual successive measurement results of the pressing forces in a known manner.
- This mean value A can be compared with two adjustable fixed tolerance limits G1 and G2.
- two independently adjustable individual value limits B and C can be set for the mean value A, that follow the course of the mean curve A. With these individual value limits B and C, the measured maximum individual values of the pressing forces of the individual pairs of punches and thus their distances from the average value A can be compared.
- stamp stations are numbered consecutively from 1 to 43, a break of a stamp 1 or 2 can be displayed on the screen 10 with this arrangement, for example.
- the individual stamp pairs 1, 2 are each assigned stamp pair mean values S, which are compared in each case with a lower and an upper stamp pair mean value limit S u or S o .
- FIG. 4 shows a diagram of the individual pressing forces that were measured in three rotations of a die plate for the individual punch pairs 1 to 43. This shows that the pressing forces of the individual pairs of punches 1 to 43 are of different sizes, which is also the case, for example different stamp lengths.
- an average stamp pair value which is assigned to the respective pair of stamps, for example the pair of stamps 30, the average value is formed from the pressure force measurements of this pair of ten revolutions of the die plate. Thereafter, this pair of stamp pairs is continuously updated for a sliding formation of the mean by adding a new value and deleting the oldest value.
- the respective average stamp pair value is compared in accordance with FIGS. 5 and 6 with the associated upper and lower limits S o and S u . According to FIG. 6, these limits are at a greater distance from one another than the spreading range of the pressing force of the individual punches in size a1 according to FIG. 5, so that the machine is only stopped after it has left the spreading range.
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- Medical Preparation Storing Or Oral Administration Devices (AREA)
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- Presses And Accessory Devices Thereof (AREA)
- Medicinal Preparation (AREA)
Description
Die Erfindung betrifft eine Einrichtung zum Überwachen der Preßkräfte von paarweise wirksamen Ober - und Unterstempeln einer Tablettenpresse, mit der ein aus aufeinanderfolgenden Meßergebnissen der Preßkräfte gebildeter Mittelwert mit zwei einstellbaren festen Toleranzgrenzen verglichen wird und mit der die Maxima der Einzelwerte der Preßkräfte mit Einzelwertgrenzen verglichen werden.The invention relates to a device for monitoring the pressing forces of paired upper and lower punches of a tablet press, with which an average value formed from successive measurement results of the pressing forces is compared with two adjustable fixed tolerance limits and with which the maxima of the individual values of the pressing forces are compared with individual value limits.
Zum Herstellen von Tabletten werden Tablettenpressen benutzt, die Ober - unter Unterstempel aufweisen, welche in Matrizen das pulverförmige Material für die Herstellung der Tabletten paarweise zusammenpressen. Dabei können Betriebsstörungen unterschiedlicher Art auftreten. Solche Störungen können auf einem Bruch eines Stempels beruhen, wie auch auf anderen Ungenauigkeiten der Werkzeuge, wie beispielsweise unterschiedlicher Stempellängen oder teilweiser geringfügiger Ausbrüche an den Stempelkopfflächen oder auch beispielsweise Verschmutzungen derselben. Weiterhin treten im Betrieb gelegentlich Dosierungsschwankungen auf, die auf Ungleichmäßigkeiten in der Beschaffenheit des zu verarbeitenden Materials beruhen.For the manufacture of tablets, tablet presses are used which have upper and lower punches, which press the powdery material in pairs into matrices for the manufacture of the tablets. Different types of malfunctions can occur. Such disturbances can be based on a rupture of a stamp, as well as on other inaccuracies of the tools, such as, for example, different stamp lengths or, in some cases, slight breakouts on the stamp head surfaces or, for example Contamination of the same. In addition, dosage fluctuations occasionally occur during operation, which are based on irregularities in the nature of the material to be processed.
Um die sich dabei ergebenden Abweichungen der fertigen Erzeugnisse rechtzeitig zu erkennen, weisen Tablettenpressen allgemein eine Preßkraftüberwachungseinrichtung auf. Eine solche Einrichtung besitzt in der Regel Dehnungsmeßstreifen, die beispielsweise auf den Trägern der Druckrollen für die Stempel angeordnet sind. Damit läßtsich der Umstand nutzen, daß unterschiedliche Preßkräfte unterschiedliche Dehnungen der Druckrollenträger hervorrufen, die in proportionale Spannungssignale umzuwandeln sind.In order to recognize the resulting deviations of the finished products in good time, tablet presses generally have a pressing force monitoring device. Such a device usually has strain gauges, which are arranged for example on the carriers of the pressure rollers for the stamp. This makes it possible to take advantage of the fact that different pressing forces cause different press roller carrier expansions, which are to be converted into proportional tension signals.
Für die Erkennung von Fehlern wird mit einer bekannten Einrichtungausaufeinanderfolgenden Meßergebnissen ein Mittelwert A gebildet, dessen Verlauf zu zwei einstellbaren festen Toleranzgrenzen (G) überwacht wird. Sobald der Mittelwert A eine dieser beiden Toleranzgrenzen G über oder unterschreitet wird die Tablettenpresse stillgesetzt. Mit einer derartigen Einrichtung lassen sich jedoch nicht alle Ursachen für Betriebsstörungen rechtzeitig erkennen, da beispielsweise eine leichte Beschädigung eines einzelnen Stempels einer Maschine mit einer Vielzahl von Stempeln den Mittelwert nicht wesentlich ändert. Außerdem läßt sich mit einer solchen Einrichtung nicht bei einer Inbetriebnahme einer Maschine ein bereits vorhandener Stempelbruch feststellen, da sich ein solcher Fehler nicht nachträglich in einer deutlichen Verschiebung des Mittelwertes erkennbar macht. Im übrigen muß bei einer derartigen Einrichtung der Toleranzbereich verhältnismäßig weit gewählt werden, um zu verhindern, daß die Tablettenpresse häufig stillgesetzt wird, ohne daß ansich besondere Betriebsstörungen vorliegen. Das ist unter anderem darauf zurückzuführen, daß sich die Preßkräfte der einzelnen Stempelpaare in ihrer Größe unterscheiden infolge von Fertigungstoleranzen in den Längen der Stempel, so daß dementsprechend auch die Einzelwerte schwanken, aus denen der Mittelwert gebildet wird. Ein relativ großer Abstand der Toleranzgrenzen zueinander führt andererseits aber wiederum dazu, nur verhältnismäßig starke Abweichungen der Einzelwerte der Preßkräfte vom Mittelwert bzw. besonders ausgeprägte Betriebsstörungen erkennen zu können.For the detection of errors, a known value is used to form an average value A using a known device, the course of which is monitored at two adjustable tolerance limits (G). As soon as the average value A exceeds or falls below one of these two tolerance limits G, the tablet press is stopped. With such a device, however, not all causes of malfunctions can be recognized in good time, since, for example, slight damage to a single stamp of a machine with a large number of stamps does not significantly change the mean value. In addition, such a device cannot be used during commissioning detect a stamp break already existing on a machine, since such an error cannot subsequently be identified by a clear shift in the mean value. In addition, the tolerance range must be selected relatively wide in such a device in order to prevent the tablet press from being shut down frequently without there being any particular malfunctions. This is due, among other things, to the fact that the pressing forces of the individual pairs of punches differ in size due to manufacturing tolerances in the lengths of the punches, so that the individual values from which the mean value is formed also fluctuate accordingly. On the other hand, a relatively large distance between the tolerance limits leads to the fact that only relatively large deviations of the individual values of the pressing forces from the mean value or particularly pronounced malfunctions can be recognized.
Um dem abzuhelfen sieht eine bekannte Einrichtung (DE-PS 25 20 662) vor, dem Mittelwert A zwei einstellbare, seinem Verlauf folgende Einzelwertgrenzen B und C zuzuordnen, mit denen die Maxima der Einzelwerte der Preßkräfte zu vergleichen sind. Derartiges hat den Vorteil, daß Schwankungen des Mittelwertes innerhalb eines einstellbaren Toleranzbereiches zwischen den Grenzen G in Kauf genommen werden können, von dem ein zweiter Toleranzbereich mit den Grenzen B und C für die Abweichungen der Maxima der Einzelwerte der Preßkräfte unabhängig ist. Dabei können die Toleranzbereiche verhältnismäßig klein gewählt werden, weil die Schwankungen des Mittelwertes keinen Einfluß haben auf die durch die Grenzen B und C gegebene Toleranzbreite für die Abweichungen der Maxima der Einzelwerte der Preßkräfte vom Mittelwert A.In order to remedy this, a known device (DE-PS 25 20 662) provides for the average value A to be assigned two adjustable individual value limits B and C which follow its course, with which the maxima of the individual values of the pressing forces are to be compared. This has the advantage that fluctuations in the mean value within an adjustable tolerance range between the limits G can be accepted, a second tolerance range with the limits B and C for the deviations of the maxima of the individual values of the pressing forces is independent. The tolerance ranges can be chosen to be relatively small because the fluctuations in the mean value have no influence on the tolerance range given by the limits B and C for the deviations of the maxima of the individual values of the pressing forces from the mean value A.
Wenngleich mit diesem bekannten Verfahren Stempelbrüche ohne weiteres erkennbar sind aufgrund der eintretenden Veränderung der Preßkraft, lassen sich jedoch geringere Veränderungen der Preßkraft eines einzelnen Stempelpaares, welche beispielsweise beruhen auf kleineren Ausbrüchen an der Stempelkopffläche oder auf Stauchungen oder Verklebungen bzw. Verschmutzungen der Stempelkopffläche nicht ohne weiteres feststellen, weil derartige Stempelfehler sich weniger auswirken auf Preßkraftschwankungen, als sich unvermeidliche Dosierungsschwankungen oder der Druckrollenschlag, die deshalb solche Stempelfehler verdecken.Although stamp breaks can be easily recognized with this known method due to the change in the pressing force that occurs, however, minor changes in the pressing force of a single pair of stamps, which are based, for example, on smaller breakouts on the stamp head surface or on upsets or sticking or soiling of the stamp head surface, are not readily possible determine because such stamp errors have less impact on fluctuations in the pressing force than unavoidable dosage fluctuations or the pressure roller impact, which therefore conceal such stamp errors.
Andererseits haben Stauchungen der Stemepel und Teilausbrüche an den Werkzeugen wie auch Verklebte Reste auf den Stempelkopfflächen auf die Festigkeit, Zerfallgeschwindigkeit und auf die Form der Tabletten einen entscheidenden Einfluß. Vorteilhaft ist es deshalb, beim Automatischen Herstellen von Tabletten auch derartige Fehler erkennen zu können, um die Produktion automatisch stoppen zu können.On the other hand, compressions of the stem and partial breakouts on the tools as well as glued residues on the stamp head surfaces have a decisive influence on the strength, disintegration speed and on the shape of the tablets. It is therefore advantageous to be able to recognize such errors in the automatic manufacture of tablets in order to be able to stop production automatically.
Aufgabe der Erfindung ist es, ein Verfahren und eine Einrichtung zu schaffen, durch die auch kleine Fehler an den Stempeln der Tablettenpresse während der Herstellung von Tabletten zu erkennen sind. Gemäß der Erfindung ist dafür vorgesehen, daß den einzelnen Stempelpaaren Stempelpaarmittelwertgrenzen zugeordnet werden, mit denen der jeweilige Stempelpaarmittelwert verglichen wird. Damit wird einerseits berücksichtigt, daß die einzelnen Stempelpaare aufgrund vorgegebener unvermeidlicher Unterschiede in den Stempellängen andere Preßkraftmittelwerte erzeugen, als andere Stempelpaare. Durch den zusätzlichen Vergleich der den einzelnen Stempelpaaren zugeordneten Mittelwerte mit Stempelpaarmittelwertgrenzen, lassen sich jedoch andererseits Veränderungen an den einzelnen Werkzeugen feststellen wie beispielsweise Verschmutzungen an einer Stempelkopffläche, da der sich hierbei ergebende Stempelpaarmittelwert außerhalb dieser Grenzen liegen würde.The object of the invention is to provide a method and a device by means of which even small defects in the stamps of the tablet press can be recognized during the manufacture of tablets. According to the invention, it is provided that the individual stamp pairs are assigned average stamp pair limits with which the respective average stamp pair is compared. This takes into account, on the one hand, that the individual pairs of punches produce different mean pressures than other pairs of punches due to the inevitable differences in the length of the punches. By additionally comparing the mean values assigned to the individual stamp pairs with average stamp pair limits, changes on the individual tools can be determined on the other hand, for example, contamination on a stamp head surface, since the resulting average stamp pair value would lie outside these limits.
Die den einzelnen Stempelpaaren zuzuordnenden Mittelwerte können nacheinander oder gleitend gebildet werden. Dabei bedeutet gleitend, daß mit jedem neuen zu verarbeitenden Preßkraftwert der älteste zuvor ermittelte Preßkraftwert ausscheidet. Die Mittelwerte werden dafür aus einer größeren Anzahl von an dem jeweiligen Stempelpaar gemessenen Tablettenpreßkräften gebildet, die einerseits groß genug ist, eine ausreichende statistische Sicherheit zu gewährleisten, auf der anderen Seite jedoch so klein ist, daß ausreichend schnell reagiert werden kann, wenn eine wesentliche Abweichung eintritt. Dazu hat es sich als ausreichend gezeigt, wenn der Mittelwert aus zehn aufeinanderfolgend gemessenen Einzelpreßkraftwerten eines Spempelpaares ermittelt wird, wobei dann beispielsweise eine Korrektur erfolgt bei Messung des elften Wertes durch Streichung des zuerst gemessenen Wertes und danach, daß heißt bei Messung der zwölften Einzelpreßkraft durch Streichung der zweiten gemessenen Einzelpreßkraft, so daß fortlaufend ein Mittelwert aus zehn Einzelwerten errechnet aktuell ist.The mean values to be assigned to the individual stamp pairs can be formed one after the other or in a sliding manner. Sliding means that with each new pressing force value to be processed the oldest previously determined pressing force value is eliminated. For this purpose, the mean values are formed from a larger number of tablet pressing forces measured on the respective pair of punches, which on the one hand is large enough to ensure adequate statistical security on the other hand, it is so small that it can react quickly enough if there is a significant deviation. For this purpose, it has been shown to be sufficient if the mean value is determined from ten successively measured individual pressing force values of a pair of punches, a correction then being made, for example, when the eleventh value is measured by deleting the value measured first and then, i.e. when measuring the twelfth individual pressing force by deleting it the second measured single pressing force, so that an average of ten individual values is continuously calculated.
Diese so ermittelten Stempelpaarmittelwerte der einzelnen Stempelpaare werden jeweils mit zugeordneten Grenzenverglichen. Die Presse kann dann gestoppt werden bei Über oder Unterschreiten einer solchen Grenze, wobei das entsprechende fehlerhafte Stempelpaar angezeigt wird.These average stamp pair values of the individual stamp pairs are compared with assigned limits. The press can then be stopped when such a limit is exceeded or undershot, the corresponding faulty pair of stamps being displayed.
Da die Größe der den jeweiligen Stempelpaaren eigenen Stempelpaarmittelwerte abhängig ist von der spezifischen Länge der Stempel dieses Stempelpaares ergibt sich der Vorteil, einen Austausch von Stempeln soweit vornehmen zu können, daß die Stempelpaarmittelwerte nahe an der Kurve liegen, welche die Sollpreßkräfte darstellt.Since the size of the stamp pair mean values specific to the respective stamp pairs is dependent on the specific length of the stamp of this stamp pair, there is the advantage that stamps can be exchanged to such an extent that the stamp pair mean values are close to the curve which represents the desired pressing forces.
Ein Ausführungsbeispiel der Erfindung ist nachstehend unter Bezugnahme auf eine Zeichnung erläutert. Darin zeigen:
- Figur 1: einen Ausschnitt einer Tablettenpresse mit Stempel, Druckrollen und Matrize;
- Figur 2: einen Schaltplan für die Einrichtung zur Überwachung der Preßkräfte;
- Figur 3: ein Diagramm der Preßkraftwerte mit ihren Grenzen;
- Figur 4: ein Diagramm der Preßkräfte nach drei Umläufen der Matrizenscheibe;
- Figur 5: ein Diagramm vom Streubereich der Preßkräfte aufeinanderfolgender Stempelpaare und
- Figur 6: die den einzelnen Stempelpaaren zugeordneten Mittelwerte mit Mittelwertgrenzen im Diagramm.
- Figure 1: a section of a tablet press with stamp, pressure rollers and die;
- Figure 2: a circuit diagram for the device for monitoring the pressing forces;
- Figure 3: a diagram of the pressing force values with their limits;
- FIG. 4: a diagram of the pressing forces after three rotations of the die plate;
- Figure 5: a diagram of the scattering range of the pressing forces of successive pairs of punches and
- Figure 6: the mean values assigned to the individual stamp pairs with mean value limits in the diagram.
Die in Figur 1 teilweise dargestellte Tablettenpresse besitzt eine umlaufende Matrizenscheibe mit einer Vielzahl von Matrizenbohrungen 16, denen jeweils ein Paar eines Oberstempels 1 und eines Unterstempels 2 zugeordnet ist. Diese Stempel 1 und 2 mit den Stempelkopfflächen 1' und 2' werden beim Pressen einer Tablette durch Druckrollen 3 und 4 in die Matrize hineingedrückt. Die Druckrollen 3 und 4 sind von Trägern gehalten, die mit Dehnungsmeßstreifen 5 und 5' versehen sind. Mit diesen Dehnungsmeßstreifen läßt sich die Durchbiegung der Träger und damit die Preßkraft der Stempel 1 und 2 messen und in Spannungssignale umwandeln, die der Größe der Preßkraft proportional sind.The tablet press partially shown in FIG. 1 has a circumferential die plate with a plurality of
Die Dehnungsmeßstreifen 5 und 5' sind dafür nach dem Prinzip einer Wheatstoneschen Brücke geschaltet entsprechend Figur 2. Dazu wird die Spannungsänderung, die in den Dehnungsstreifen 5 und 5' beim Pressen auftritt über einen Verstärker 8 verstärkt. Diese Signale werdenin einen Analogdigitalwandler 15 gegeben, an den ein Rechner 9 mit einem Monitor 10 angeschlossen ist.The
Zu der Einrichtung gehört weiterhin ein Näherungsschalter 7, der beim Durchlauf eines Stempelpaares 1, 2 zwsichen den Preßrollen 3 und 4 einen Impuls an den Rechner 9 abgibt. Außerdem ist ein Relais 11 vorgesehen, durch das die Maschine stillgesetzt wird , wenn ein ermittelter Stempelpaarmittelwert die ihm zugeordnete Grenze über- oder unterschreitet.The device also includes a
Entsprechen Figur 3 wird in bekannter Weise aus den einzelnen aufeinanderfolgenden Meßergebnissen der Preßkräfte ein Mittelwert entsprechend der Kurve A gebildet. Dieser Mittelwert A läßt sich mit zwei einstellbaren festen Toleranzgrenzen G₁ und G₂ vergleichen. Außerdem lassen sich zu dem Mittelwert A zwei unabhängig verstellbare Einzelwertgrenzen B und C einstellen, die dem Verlauf der Mittelwertkurve A folgen. Mit diesen Einzelwertgrenzen B und C lassen sich die gemessenen maximalen Einzelwerte der Preßkräfte der einzelnen Stempelpaare und damit ihre Abstände zu dem Mittelwert A vergleichen.Corresponding to FIG. 3, a mean value corresponding to curve A is formed from the individual successive measurement results of the pressing forces in a known manner. This mean value A can be compared with two adjustable fixed tolerance limits G₁ and G₂. In addition, two independently adjustable individual value limits B and C can be set for the mean value A, that follow the course of the mean curve A. With these individual value limits B and C, the measured maximum individual values of the pressing forces of the individual pairs of punches and thus their distances from the average value A can be compared.
Überschreitet oder unterschreitet der Mittelwert A die Grenzen G₁ oder G₂ oder überschreitet ein maximaler Einzelwert einer Preßkraft die obere Einzelwertgrenze entsprechend Kurve B oder liegt er unterhalb der Einzelwertgrenze C, so tritt eine Außerbetriebsetzung der Maschine ein.If the average value A exceeds or falls below the limits G₁ or G₂ or if a maximum individual value of a pressing force exceeds the upper individual value limit according to curve B or if it is below the individual value limit C, the machine is shut down.
Da die Stempelstationen fortlaufend von 1 bis 43 nummeriert sind, kann mit dieser Anordnung beispielsweise ein Bruch eines Stempels 1 oder 2 auf dem Bildschirm 10 angezeigt werden. Um darüber hinaus jedoch kleinere Störeinflüsse zu ermitteln, sind den einzelnen Stempelpaaren 1, 2 jeweils Stempelpaarmittelwerte S zugeordnet, die jeweils mit einer unteren sowie oberen Stempelpaarmittelwertgrenze Su bzw. So verglichen werden.Since the stamp stations are numbered consecutively from 1 to 43, a break of a
In der Figur 4 ist ein Diagramm wiedergegeben von den einzelnen Preßkräften, die bei drei Umläufen einer Matrizenscheibe zu den einzelnen Stempelpaaren 1 bis 43 gemessen wurden. Daraus zeigt sich, daß die Preßkräfteder einzelnen Stempelpaare 1 bis 43 von unterschiedlicher Größe sind, was beispielsweise auch auf unterschiedliche Stempellängen zurückzuführen ist.FIG. 4 shows a diagram of the individual pressing forces that were measured in three rotations of a die plate for the
Für die Bildung eines Stempelpaarmittelwertes, der dem jeweiligen Stempelpaar zugeordnet ist, beispielsweise dem Stempelpaar 30, wird der Mittelwert gebildet aus den Preßkraftmessungen dieses Paares von zehn Umläufen der Matrizenscheibe. Danach wird dieserStempelpaarmittelwert für eine gleitende Bildung des Mittelwertes fortlaufend aktualisiert durch Hinzunahme eines neuen Wertes und Streichung des ältesten Wertes. Der jeweiligen Stempelpaarmittelwert wird entsprechend Figur 5 und 6 mit der dazugehörigen oberen und unteren Grenze So und Su verglichen. Diese Grenzen stehen entsprechend Figur 6 in einem größeren Abstand zueinander als der Streubereich der Preßkraft der einzelnen Stempel in der Größe a1 gemäß Figur 5, so daß also erst nach Verlassen des Streubereiches eine Stillsetzung der Maschine erfolgt.For the formation of an average stamp pair value which is assigned to the respective pair of stamps, for example the pair of
Da der Abstandder Stempelpaarmittelwerte S wie beispielsweise S₁ und S₂ von der Sollpreßkraftkurve A im Wesentlichen abhängig ist von unterschiedlichen Stempellängen, läßt sich durch einen Austausch von Stempeln bestimmter Länge eine Annäherung der Mittelwerte entsprechend dem Mittelwert S₃ an die Sollwertkurve A erreichen. Von besonderem Vorteil ist es jedoch, daß bereits geringe Betriebsstörungen wie beispielsweise Verschmutzungen auf den Stempelkopfflächen 1' oder 2' oder geringfügige Ausbrechungen an den Stempelkopfflächen 1' oder 2' sofort dadurch erkennbar werden, daß der dann ermittelte Stempelpaarmittelwert S außerhalb der Mittelwertgrenzen So oder Su liegt.Since the distance between the average pair of stamps S, such as S₁ and S₂, depends essentially on the desired compression force curve A for different lengths of the stamp, an exchange of stamps of a certain length can bring the average values closer to the setpoint curve A according to the average value S₃. It is of particular advantage, however, that even minor malfunctions, such as, for example, contamination on the stamp head surfaces 1 'or 2' or slight breakouts on the stamp head surfaces 1 'or 2' can be recognized immediately by the fact that the average stamp pair S then determined lies outside the average limits S o or S u .
Claims (7)
- Method for monitoring the press loads of the upper and lower punches, which are effective by pairs, of a tabletting press with which a mean value, which is formed from successive measuring results of the press loads, is compared to two adjustable tolerance thresholds (G), two adjustable individual value thresholds (B, C), fixed or following the course of the mean value (A), being assigned to the mean value (A), thresholds to which the maximal values of the individual values of the press loads are compared, characterized in that mean value thresholds for the pairs of punches (Su, So) are assigned to the different pairs of punches (1, 2, 3) to which the mean value of the pair of punches is compared respectively.
- Method according to claim 1, characterized in that the mean values of the pairs of punches (S) are formed floating.
- Method according to claim 1, characterized in that the measured press load values of the punches are entered into an analog to digital converter (9) and are evaluated by this converter.
- Apparatus for monitoring the press loads of upper and lower punches, which are effective by pairs, of a tablet press with which a mean value (A), which is formed from successive measuring results of the press loads, is compared, to which two individual value thresholds (B, C), fixed or following its course, are assigned to which the maximal values of the individual values of the press loads are compared, characterized in that mean value thresholds for the pairs of punches (So, Su) are assigned to the different pairs of punches (1, 2) to which the mean value of the pair of punches (S1, S2) is compared respectively with a computer.
- Apparatus according to claim 4, characterized in that the mean value thresholds for the pairs of punches (Su, So) are adjustable.
- Apparatus according to claim 4, characterized in that the apparatus has an analog to digital converter.
- Apparatus according to claim 4, characterized in that the machine is switched off when the mean value thresholds for the pairs of punches exceed or fall below the mean value thresholds for the pairs of punches and that the defective pair of punches is displayed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3823417 | 1988-07-11 | ||
| DE3823417A DE3823417A1 (en) | 1988-07-11 | 1988-07-11 | METHOD AND DEVICE FOR MONITORING THE PRESSING FORCE OF THE STAMP OF A TABLET PRESS |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0350563A2 EP0350563A2 (en) | 1990-01-17 |
| EP0350563A3 EP0350563A3 (en) | 1991-06-19 |
| EP0350563B1 true EP0350563B1 (en) | 1993-08-04 |
Family
ID=6358405
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP89103234A Expired - Lifetime EP0350563B1 (en) | 1988-07-11 | 1989-02-24 | Method and apparatus for monitoring the press loads of the punches in a tablet press |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5004576A (en) |
| EP (1) | EP0350563B1 (en) |
| DE (2) | DE3823417A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19844390A1 (en) * | 1998-09-28 | 2000-04-06 | Fette Wilhelm Gmbh | Method for monitoring production of tablets |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2638118A1 (en) * | 1988-10-20 | 1990-04-27 | Adl Automation | METHOD AND APPARATUS FOR COMPRESSION AND CONTROL OF COMPRESSION OF PULVERULENT AND PRESSED MATERIALS BY APPLYING |
| JPH0780076B2 (en) * | 1992-04-28 | 1995-08-30 | 株式会社菊水製作所 | Attachment load cell inspection method of rotary tablet machine |
| US5322655A (en) * | 1993-02-19 | 1994-06-21 | Thomas Engineering, Inc. | Method for monitoring and controlling the weights of each layer of a multilayer tablet |
| DE19502596C2 (en) * | 1995-01-28 | 1997-08-28 | Fette Wilhelm Gmbh | Measuring device and computer for checking the tablets of the current production made on a rotary press |
| US5838571A (en) * | 1996-01-29 | 1998-11-17 | Alza Corporation | Tablet press monitoring and controlling method and apparatus |
| DE19717217C2 (en) * | 1997-04-24 | 1999-12-02 | Fette Wilhelm Gmbh | Method and device for producing compacts from hard metal, ceramic, sintered metal or the like |
| DE10135283C2 (en) * | 2001-07-19 | 2003-09-18 | Fette Wilhelm Gmbh | Process for pressing powder material |
| DE502004000723D1 (en) * | 2003-02-12 | 2006-07-20 | Thilo Kraemer | APPARATUS FOR QUALITY CONTROL OF SOLID, PHARMACEUTICAL PRODUCTS |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3255716A (en) * | 1962-12-10 | 1966-06-14 | Upjohn Co | Measurement of forces within a tableting machine |
| GB1152061A (en) * | 1966-06-14 | 1969-05-14 | Upjohn Co | Pelleting Apparatus |
| CH475759A (en) * | 1967-07-21 | 1969-07-31 | Ciba Geigy | Device for tablet weight monitoring on a tablet machine |
| GB1179350A (en) * | 1967-09-15 | 1970-01-28 | Ici Ltd | Particle Shaping Method |
| DE2520662C3 (en) * | 1975-05-09 | 1983-11-03 | Wilhelm Fette Gmbh, 2053 Schwarzenbek | Device for monitoring the pressing forces of the punches of a tablet press |
| GB1551954A (en) * | 1975-05-28 | 1979-09-05 | Hoffmann La Roche | Standardization of a physiochemical parameter of a batch of formulation in tabletted form |
| US4100598A (en) * | 1975-09-05 | 1978-07-11 | Hoffmann-La Roche Inc. | Tablet press related instrumentation for use in development and control of formulations of pharmaceutical granulations |
| US4030868A (en) * | 1976-03-15 | 1977-06-21 | Hoffmann-La Roche Inc. | Force measurement and analysis particularly relating to rotary tablet presses |
| DE2742572B1 (en) * | 1977-09-22 | 1979-03-29 | Fette Wilhelm Gmbh | Method of making tablets and tablet press |
| DE2742571B1 (en) * | 1977-09-22 | 1979-03-29 | Fette Wilhelm Gmbh | Process for the creation of documents about the production of tablets and tablet presses |
| US4570229A (en) * | 1983-09-19 | 1986-02-11 | Pennwalt Corporation | Tablet press controller and method |
| WO1986005743A1 (en) * | 1985-03-29 | 1986-10-09 | Thomas Engineering, Inc. | Pharmaceutical tablet press control mechanism |
| DE3520203A1 (en) * | 1985-06-05 | 1986-12-11 | Wilhelm Fette Gmbh, 2053 Schwarzenbek | ROTARY ROTARY TABLETING MACHINE AND METHOD FOR CONTROLLING YOUR PRINT ROLLERS |
-
1988
- 1988-07-11 DE DE3823417A patent/DE3823417A1/en not_active Withdrawn
-
1989
- 1989-02-24 DE DE8989103234T patent/DE58905120D1/en not_active Expired - Lifetime
- 1989-02-24 EP EP89103234A patent/EP0350563B1/en not_active Expired - Lifetime
- 1989-05-03 US US07/347,335 patent/US5004576A/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19844390A1 (en) * | 1998-09-28 | 2000-04-06 | Fette Wilhelm Gmbh | Method for monitoring production of tablets |
| DE19844390B4 (en) * | 1998-09-28 | 2005-09-22 | Wilhelm Fette Gmbh | Process for producing tablets in a rotary tablet machine |
Also Published As
| Publication number | Publication date |
|---|---|
| US5004576A (en) | 1991-04-02 |
| EP0350563A2 (en) | 1990-01-17 |
| DE58905120D1 (en) | 1993-09-09 |
| DE3823417A1 (en) | 1990-01-18 |
| EP0350563A3 (en) | 1991-06-19 |
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