EP2105291B1 - Device and method for measuring the vertical position of top and bottom punches of a rotary tablet press - Google Patents

Description

The invention relates to a device and a method according to claim 1 and 9 for measuring the vertical position of a rotatably driven rotor of a rotary tablet press paired and synchronously with the rotor rotating upper and lower punches during a rotor rotation in certain areas along the circumference perform a vertical movement of their rotary motion. Rotary tablet presses have long been known. The rotor of such presses usually has a die plate with a plurality of circumferentially spaced dies. The rotor is equipped with a number of press punches of the press forming upper and lower punches, each die a lower punch and a punch are assigned. During one revolution of the rotor, each ram is subject at certain positions of the circumference, in particular at the pressing stations of the press, to a vertical movement which results in a corresponding force on material to be pressed filled in the dies. In addition to a pre-press and a main press station, an ejector station must also be considered. The vertical movement of the ram is usually performed by guide curves. For example, by stationary pressure rollers in the pressing stations, a pressing force is applied to the heads of the ram and thus on the material to be pressed. Depending on the composition of the tablets to be compressed while a predetermined pressing force is observed.

Press force measuring devices have been used in rotary tablet presses for many years to monitor and control the pressing process to ensure the desired tablet quality. However, it is not always sufficient, in particular in the pharmaceutical laboratory and development sector, to assess the compression process via the press force measurement. Therefore, additional measures must be used. Of outstanding importance for determining the compression characteristics of molding compounds is the force-displacement diagram. Physically, it describes the energy expenditure during the compression phase. From this conclusions can be drawn on the compressibility and properties of the substances to be seized.

Various devices for measuring and determining the punch path have become known. So will in DE 19502596 C2 proposed to calculate the stamp path theoretically based on the geometric conditions of the press. A metrological approach is in the DE 102005051567 A1 described. In this case, the distance to a marker in the form of a horizontal plate attached to the stamp is measured during the compression phase with a preferably stationary and non-contact sensor. The distance measurement can be used to monitor the compression phase of the punches, ie the vertical movement in the pressing stations. However, desired or undesired vertical movements of the pressing dies outside of the pressing phase may also occur, the measurement of which may also be necessary. Out US 6,442,859 A An incremental position measuring system is known, comprising a ruler and a sensor, which is arranged in a housing and is located in a stationary die table. A boom attached to the punch of the press actuates a ram of the incremental measuring system, as soon as the stamp moves down. For a displacement measurement, therefore, a mechanical contact between the boom and position measuring system is required. In addition, is off US 5,760,392 A. In general, an incremental measuring system is known, which comprises a arranged on a base plate dividing section.

There are also known devices in which inductive or ohmic Wegmessaufnehmer are mounted before and after the measured stamp. However, these devices are expensive in practice. Based on the explained prior art, the present invention seeks to provide a device and a method of the type mentioned, with which in a simple manner, a reliable and accurate measurement of the vertical position of the ram at each circumferential position of the stamp is possible.

For a device of the type mentioned, the object is achieved according to claim 1.

For a method of the type mentioned, the problem is solved according to claim 9.

According to the invention, at least one, preferably more, and more preferably all, of the upper and / or lower punches is a scale, in particular a linear scale, for measuring lengths in the manner of a Scale or ruler. The reading device co-rotating with the rotor and the punches can read the scale and in this way measure the vertical position of the respective press ram. In this case, the vertical position of at least one upper and / or lower punch along the entire circumference of its rotational movement by reading the scale can be measured with the device according to the invention during at least one rotor rotation by means of the reading device. According to the invention, a precise and reliable measurement of the vertical position or movement of the punches is possible in a simple manner. The scale allows an absolute measurement of the vertical position or movement. The measurement can be carried out in the inventive method at regular intervals over the scope of the rotational movement of the stamp. It is only decisive that measurement data is collected over the entire circumference and not only in the compression phase in the pressing stations of the press, as in the prior art ( DE 10 2005 051 567 A1 ) is provided. Thus, vertical punch paths can also be measured in the up and pull-down curves or in the filling area of the press in which the material to be pressed is filled into the matrices. In this way, even unpredictable vertical stamp movements can be detected and analyzed.

The reading device according to the invention comprises a sensor for reading the scale. At least one evaluation device for determining the vertical position from the read-out scale data may be associated with the reading device (s). In particular, all the rams can have a scale, so that their vertical position can be determined. This can be a corresponding number of the scales be assigned to each associated reading devices. Each reading device can be assigned its own evaluation device. However, it can also be provided a common evaluation device for several or all reading devices.

The device according to the invention is particularly suitable for carrying out the method according to the invention. Thus, the inventive method can be carried out with a device according to the invention, wherein the vertical positions of the at least one upper and / or lower punch are measured by means of the reading device by reading the scale.

The problem underlying the invention is also solved by a rotary tablet press with a rotatably driven rotor and the rotor paired and synchronously rotating with the rotor upper and lower punches, which during a rotation of the rotor in certain areas along the circumference of its rotational movement a vertical Execute movement, wherein the rotary tablet press has a device according to the invention. In this case, the rotor in a conventional manner have a die plate with a plurality of matrices, which in turn is associated with a plurality of upper and lower punches in pairs. During one revolution of the rotor, each of the punches undergoes vertical movement at certain positions of the circumference, resulting in a force on material to be pressed inserted in the dies. The leadership of the stamp can be done in a conventional manner via guide curves. In addition to a pre-press and In this case, a main pressing station is also to be considered, in particular, an ejection station, on each of which a vertical movement of the stamp takes place. The pressing force for pressing the tablet material can for example be applied by stationary pressure rollers on the heads of the ram.

The scale can be an incremental scale, ie a line measure, which represents a length by the distance of graduation markings. However, the scale may also be an absolute scale, in particular an absolute coded scale, e.g. Has numerical values at which the vertical position of the respective stamp is absolutely readable. The reading device can be designed to read the scale optically, magnetically, capacitively and / or inductively. Accordingly, the scale may be optically, magnetically, capacitively and / or inductively readable. The reading device can for this purpose have an optical, magnetic, capacitive and / or inductive sensor.

In a structurally particularly simple manner, the scale can be arranged on a circumferential surface of the respective upper and / or lower punch, in particular be introduced into the peripheral surface. The reading device can also be arranged in a structurally particularly simple manner on a receptacle of the respective upper and / or lower punch. In this case, the scale may be arranged on or in the stamp such that its readable section faces outwards in the circumferential direction. The reading device can be attached to the stamp holder at a small distance from the scale. In particular, it may be arranged so that the in the stamp integrated scale with rotating rotor and a vertical movement of the respective stamp also vertically past the reader device and in particular the measuring window of the reading device.

According to a further embodiment which is particularly practical, a transmitting device which also rotates synchronously with the rotor and a receiving device arranged stationarily outside the rotor can be provided, wherein position data measured by the reading device by means of the transmitting device can be transmitted wirelessly to the receiving device. By means of such a wireless transmission, data can be transmitted from the rotating system to a stationarily arranged receiving device in a particularly simple and reliable manner. The reading device can read out the incremental pulses or the absolutely coded position of the respective stamp at any time and supply this information to the transmitter attached to the rotor. The wireless data transmission between the transmitting device and the receiving device can take place, for example, by radio. Subsequently, the data received by the receiving device can be routed to a control and / or operating device, for example, also stationarily arranged outside the rotor, for further processing. The evaluation of the data read out to position data can be done in the reading device or in the transmitting device or in the receiving device or in the control and / or operating device. The reading and transmitting device can also form a combined device. Then, a wireless transmission of the position data to the external receiving device can take place in a direct manner. The external receiving device or the control device or the operating device can then from the received position data on the condition and operation of the system close and, if necessary, countermeasures, such as a stop of the plant cause.

The device has a rotary encoder, with which the circumferential positions of at least one upper and / or lower punch taken during a rotor rotation can be measured, wherein the vertical positions of the at least one upper and / or lower punch measured by the reading device correspond to the one with the Rotary encoder measured circumferential positions of the respective upper and / or lower punch can be assigned. The rotary encoder can be, for example, a so-called angle encoder. It is then an incremental or absolute measurement of the rotational movement of the stamp, in particular the angular positions along the scope of their rotational movement possible. Subsequently, the evaluating device assigns the measured vertical positions to the circumferential positions. This can be determined in a particularly simple manner for the entire circumference of the rotational movement of the punch a complete course of movement in the vertical and in the direction of rotation. On this basis, an evaluation is then possible as to whether the measured vertical movement takes place in the desired areas of the circumference. If necessary, countermeasures can be initiated. In particular, the circumferential positions of all stamps can be measured and assigned to the respective vertical positions. The evaluation device carries out the assignment between vertical and circumferential movements. The evaluation device can be the same device which also performs the determination of the vertical position data from the data measured by the reading device. Such an evaluation device can be integrated in the reading device. But it can also be arranged separately and, for example, also rotate synchronously with the rotor or be integrated into other devices of the device, such as a rotary encoder or a transmitting device. In particular, it can also be arranged in a stationary manner outside the rotor, for example integrated in a receiving device or a control or operating device.

Fig. 1

einen Ausschnitt einer erfindungsgemäßen Rundläufer-Tablettenpresse mit einer erfindungsgemäßen Vorrichtung in einer Abwicklung,

Fig. 2

einen erfindungsgemäßen Pressstempel in einer seitlichen Ansicht,

Fig. 3

den Pressstempel aus Fig. 2 in einem Querschnitt,

Fig. 4

einen teilweisen Querschnitt eines Rotors einer RundläuferTablettenpresse mit einer erfindungsgemäßen Vorrichtung, und

Fig. 5

ein Blockdiagramm zur Veranschaulichung des erfindungsgemäßen Verfahrens.

An embodiment of the invention will be explained in more detail with reference to a drawing. They show schematically:

Fig. 1

a detail of a rotary tablet press according to the invention with a device according to the invention in a development,

Fig. 2

a press ram according to the invention in a side view,

Fig. 3

the press stamp Fig. 2 in a cross section,

Fig. 4

a partial cross section of a rotor of a rotary tablet press with a device according to the invention, and

Fig. 5

a block diagram illustrating the inventive method.

In the figures, like reference numerals designate like objects. In Fig. 1 is shown a rotary tablet press. Such presses are known per se to the person skilled in the art. The press has a by means of a drive device, not shown, for example, an electric motor, rotatably driven rotor 12. The rotor 12 has a die plate 14 with a plurality of die holes 16. Each die 16 are associated in pairs with a punch 18 and a lower punch 20. The upper and lower punches 18, 20 are respectively held on an upper punch holder 22 and a lower punch holder 24 and rotate upon rotation of the rotor 12 in synchronism therewith, as shown for the upper punch holder 22 by the arrow 26 illustrating the direction of rotation. The upper and lower punches 18, 20 are also guided in a conventional manner by guide curves. In Fig. 1 A filling curve 28, a metering curve 30 and an ejection curve 32 for the lower punches 20 are shown by way of example. For the upper punches, for example, a pull-down curve 34 and an elevation curve 36 are shown. With a filling device 38 tablet material to be tabletted in powder form is filled into the dies 16 of the die plate 14. By means of an upper pre-pressure roller 40 and a lower pre-pressure roller 42 of a pre-pressing station, the powdery material is pre-pressed in the dies 16. Subsequently, by upper and lower main pressure rollers 44, 46 in a conventional manner, the final compression in the main press station. Of course, several such pressing and filling stations may be provided, for example for the production of multilayer tablets. By means of the Ausstoßkurve 32, the compressed tablets 48 are then on the surface of the die plate 14 and routed in a stripping device 50 into an exit channel 52 for further use.

At a stamp pair is in Fig. 1 exemplified a device according to the invention for measuring the vertical position of a punch 20 and a lower punch 20 shown. In particular, a parallel to the vertical direction of movement of the respective upper and lower punch 18, 20 extending scale 54, in particular length scale, are arranged on a top punch 18 and a lower punch 20 respectively. The Längemaßstäbe 54 are introduced into the peripheral surface of the respective upper punch 18 and lower punch 20. This is in the illustrations in Fig. 2 and Fig. 3 exemplified enlarged for the upper punch 18. The scales 54 may be, for example, incremental scales or absolutely coded scales. Furthermore, two measuring devices 54 assigned to the scales 54 are provided. The reading devices 56, in the illustrated example magnetic reading devices, are arranged on the upper punch holder 22 and the lower punch holder 24 and thus also rotate synchronously with the rotor 12. The scales 54 and their associated reading devices 56 do not move horizontally relative to each other ,

The arrangement of the readers 56 with respect to the scales 54 is shown in FIG Fig. 4 shown enlarged. In this case, the reading devices 56 are attached at a small distance from the scales 54 on the respective punch holder 22, 24. The scales 54 are so inserted into the peripheral surface of the punch 18, 20 that they are in the circumferential direction of the rotational movement of the Stamp 18, 20 point outward. When the rotor 12 rotates and stamps 18, 20 rotate with it as well as with rotating reading devices 56, the scales 54 integrated into the punches 18, 20 move in the vertical direction past the measuring window of the reading devices 56. The reading devices 56 read the incremental pulses or the absolutely coded positions of the punches 18, 20 at each point in time of the rotary movement. An evaluation device respectively integrated into the reading devices 56 determines therefrom the vertical positions or movements of the punches 18, 20 along the entire circumference of their rotary movements. Of course, the evaluation devices can also be provided separately from the reading devices 56. In particular, a common evaluation device for several, in particular all reading devices is possible. Furthermore, an angle encoder, not shown, is provided, with which the circumferential positions of the punches 18, 20 taken during a rotor rotation can be measured. By means of the evaluation devices, the vertical positions of the punches 18, 20 measured with the reading devices 56 can be assigned to the circumferential positions of the punches 18, 20 measured with the angle encoder. In this way, a complete monitoring of the punch movements in both the vertical and in the direction of rotation is possible.

As in Fig. 5 by way of example for the upper punch 18, the position data determined by the reading device 56 are subsequently sent to a transmitting device 58 which is likewise arranged on the rotor and rotates with the rotor 12, as illustrated by the arrow 57. From the transmitting device 58, the measured position data becomes wireless, For example, by radio, sent to a stationary outside of the rotor 12 receiving device 60, as illustrated by the arrow 62. From the receiving device 60, the position data can be sent to a control device 64, which is likewise arranged stationarily outside the rotor, as illustrated by the arrow 66. If necessary, the data may be sent by the control device 64 to a control device 68 by means of corresponding control commands for controlling the tablet press, as illustrated by the arrow 70. In particular, the control device 64 can influence it by means of suitable control commands, provided that the determined position data deviate from desired position data, so that the desired tablet quality is reliably guaranteed at all times. On the operating device 68 corresponding instructions for an operator can be output or appropriate inputs of the operator to be received. It is also possible that the position data received by the receiving device 60 are sent directly to the operating device 68 without passing through the control device, as indicated by the arrow 72 in FIG Fig. 5 illustrated. In this case, the operator of the system can manually compare the determined position data with target data and, for example, also manually initiate appropriate countermeasures.

Of course, several, in particular all of the press dies of the press may have a device according to the invention with corresponding associated reading devices.

With the device according to the invention or the method according to the invention, unpredictable vertical stamp movements can be recorded and analyzed in a structurally simple and reliable manner. In turn, precise conclusions can be drawn on the compressibility and the properties of the substances to be pressed in each case.

Claims (12)

1. Device for the measurement of the vertical position of upper and lower punches, pairwisely associated to a rotatably driven rotor of a rotary tablet press and rotating synchronously with the rotor, which perform a vertical movement in certain regions along the circumference of their rotational movement during a rotation of the rotor, wherein at least one scale (54) arranged on at least one of the upper and/or lower punches (18, 20), running in parallel to the vertical movement direction of the respective upper and/or lower punch (18, 20), and
   at least one reading device (56) associated to the scale (54), also rotating synchronously with the rotor (12), by means of which a vertical position of the respective upper and/or lower punch (18, 20) can be measured by reading out the scale (54),
   wherein the device has an angular sensor, by which the circumferential positions of at least one upper and/or lower punch (18, 20) occupied during a rotation of the rotor can be measured, wherein the vertical positions of the at least one upper and/or lower punch (18, 20) measured by the reading device (56) can be assigned to the circumferential positions of the respective upper and/or lower punch (18, 20) measured by the angular sensor by means of an analysing device.
2. Device according to claim 1, characterised in that the scale (54) is an incremental scale.
3. Device according to claim 1, characterised in that the scale (54) is an absolute scale.
4. Device according to any one of the preceding claims, characterised in that the reading device (56) is adapted to read out the scale (54) optically, magnetically, capacitively and/or inductively.
5. Device according to any one of the preceding claims, characterised in that the scale (54) is arranged on a circumferential surface of the respective upper and/or lower punch (18, 20), being incorporated into the circumferential surface in particular.
6. Device according to any one of the preceding claims, characterised in that the reading device (56) is arranged on an accommodation element (22, 24) of the respective upper and/or lower punch (18, 20).
7. Device according to any one of the preceding claims, characterised in that a sending device (58), also synchronously rotating with the rotor (12), and a receiving device (60) arranged stationarily outside of the rotor (12) are provided, wherein position data measured by the reading device (56) can be sent to the receiving device (60) by means of the sending device (58) via a wireless transmission.
8. Rotary tablet press with a rotatably driven rotor and upper and lower punches, pairwisely associated to the rotor and rotating synchronously with the rotor, which perform a vertical movement in certain regions along the circumference of their rotational movement during a rotation of the rotor, characterised by a device according to any one of claims 1 to 7.
9. Method for the measurement of the vertical position of upper and lower compression punches, pairwisely associated to a rotatably driven rotor of a rotary tablet press and rotating synchronously with the rotor, which perform a vertical movement in certain regions along the circumference of their rotational movement during a rotation of the rotor,
   wherein vertical positions of at least one upper and/or lower punch (18, 20) are measured along the complete circumference of its rotational movement during at least one rotation of the rotor,
   wherein the circumferential positions of at least one upper and/or lower punch (18, 20) occupied during a rotation of the rotor are measured, wherein the measured vertical positions of the at least one upper and/or lower punch (18, 20) are assigned to the measured circumferential positions of the respective upper and/or lower punch (18, 20).
10. Method according to claim 9, characterised in that it is performed with a device according to any one of claims 1 to 8, wherein the vertical positions of the at least one upper and/or lower punch (18, 20) are measured by means of the reading device (56) by reading out the scale (54).
11. Method according to any one of claims 9 or 10, characterised in that the scale (54) is read out optically, magnetically, capacitively and/or inductively by the reading device (56).
12. Method according to any one of claims 9 to 11, characterised in that by means of a sending device (58) also synchronously rotating with the rotor (12), position data measured by the reading device (56) can be sent to a receiving device (60) arranged stationarily outside of the rotor (12) via a wireless transmission.

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