Rotary tablet press and pressure rail as curve portion of a control curve for the ram of a rotor of the rotary tablet press

Abstract

The invention relates to a rotary tablet press having a rotor 10, and having, distributed over the rotation path of the rotor 10, at least one filling station 3, a compacting station 5 and a discharge station 6, and having positionally fixed control curves for controlling the movement of the upper ram and lower ram along the rotation path, wherein the control curves have a plurality of curve portions and at least one curve portion forms a pressure rail for the lower ram in the region of the compacting station, said pressure rail at least partially sloping upwards in the direction of rotation. In order to improve the compression of the starting material to form tablets, the invention proposes that the pressure rail 50 for the lower ram has, in the compacting station 6, a curved top side 54, at least partially. The invention also relates to a correspondingly designed pressure rail 50 as a curve portion of a control curve. According to a further inventive concept, pressure rollers are dispensed with and only pressure rails are used in the compacting station.

Description

[0001]OUR SIGNO URREF .KL398PCT D atu mD at e12.03.2024Applicant: Romaco Kilian GmbH, Scarletallee 11, DE-50735 Cologne Title: Rotary tablet press and pressure rail as a cam section of a control cam for the punches of a rotor of the rotary tablet press The invention relates to a rotary tablet press, with a housing, with a rotor arranged in the housing so as to be drivable, which has an upper punch guide ring with guides for the upper punches, a lower punch guide ring with guides for the lower punches and a die plate arranged between the punch guide rings with dies for producing tablets or other compacts in the dies by means of the upper punches and lower punches, with at least one filling station, a compaction station and an ejection station for compacts produced in the dies distributed over the rotation path of the rotor,and with stationary control cams for the upper punches and the lower punches for controlling the movement of the upper punches and the lower punches along the rotation path, wherein the control cams have several curve sections distributed over the rotation path, and at least one curve section for the lower punches in the region of the pressure station forms a pressure rail with a pressure rail body having an upper side, which is designed to rise at least partially in the direction of rotation between a first point on the upper side and a second point spaced therefrom in the arc direction of the pressure rail body by an arc angle. Rotary tablet presses or rotary tablet presses are used to produce pellets such as single- or multi-layer medicinal tablets, detergent tablets, etc. from a mostly powdery starting material. The tablet presses have a rotating die plate,which is usually equipped with a multitude of interchangeable dies in order to produce different tablets / pressed pieces with the same tablet press without changing the die plate. For each die, both an upper punch and a lower punch are provided, whose up and down movement is guided in associated guide rings and controlled by stationary control cams or guide slots. In order to increase the number of dies in the die plate, it is known to form the die plate by means of several segments detachably attached to a rotor of the tablet press, and at the same time, instead of interchangeable dies, to provide only one bore in the respective segments, via which the size and shape of the tablet produced with this die plate is determined. Along the rotation path, there is at least one filling station,A compaction station and an ejection station are provided. In the filling station, the dies are filled with the material to be compressed, particularly powder. In the compaction station or compression station, the material is compressed using the upper and lower punches. In the ejection station, the finished compressed pellets / tablets are ejected and forwarded to downstream stations outside the tablet press. In most tablet presses used, pressure rollers are used in the compression station, which press against the appropriately designed heads of the lower and upper punches to compress the material like powder. In another design of rotary tablet presses, additional pressure rails can be used. For example, reference is made to EP 1600285B1 or EP 2313259B1. In EP 2313259 B1, a pressure rail for the lower punch is used.whose upper side initially rises in the direction of rotation along a straight line at a predetermined angle before the upper side of the pressure rail transitions into a horizontal section. Pressure rollers are arranged in front of and behind the pressure rail, and the lower punches are provided with rollers to improve the sliding of the lower punches along the pressure rail. In EP 1600285B1, pressure holding rails are located between a pre-compression pressure roller and a main compression pressure roller for the upper punches and the lower punches. The object of the invention is to improve the compression of the starting material into tablets in rotary tablet presses. To achieve this object, the invention proposes, according to a first solution concept,that the pressure rail for the lower punches has a curved upper surface, at least partially between the first and second positions. In a rotary tablet press with a pressure rail with a curved upper surface, at least for the lower punches, a surprisingly significantly improved compression behavior of the starting material is observed due to the gradually increasing compression pressure caused by the curvature, which can be specifically influenced via the curvature of the upper surface, even over a comparatively short rotational path. The curvature of the pressure rail can be used or modified accordingly to control the pressure curve in the material to be compressed. This also enables quick changeover when changing materials or dies. The above task is also solved accordingly using a pressure rail as a curved section of a control cam for the punches of a rotor of a rotary tablet press.in which the pressure rail comprises a pressure rail body with an upper side, which preferably rises continuously between a first point on the upper side and a second point spaced therefrom in the arc direction of the pressure rail body by an arc angle, in that the upper side is curved between the first point and the second point. According to a particularly advantageous embodiment, the curvature of the upper side can form a spline, preferably along the entire curvature. Alternatively, the curvature of the upper side can also form conical curves, preferably along the entire curvature. According to yet another alternative embodiment, the curvature of the upper side can have several radii of curvature, in particular several radii of curvature which merge essentially tangentially into one another. In all embodiments of the pressure rail for the rotary press or a rotary tablet press equipped therewith, it is particularly advantageousif the local radius of curvature of the upper side preferably increases continuously from the first point to the second point. A single pressure rail with a curved upper side is expediently used. Alternatively, the pressure rail for the lower punches could also consist of several segments. In this configuration, either each segment could have an upper side with a constant radius of curvature, or the segments following in the direction of rotation could have a larger radius of curvature than the segments leading in the direction of rotation. In all of the aforementioned configurations of the rotary tablet press, according to one configuration, the upper punches could be assigned a control cam for the upper punches, which has a pressure rail with a pressure rail body with an at least partially horizontally extending underside along the rotation path.In this case, the counter-pressure rail for the upper punches and the pressure rail for the lower punches are advantageously arranged in the region of the printing station along the rotation path such that the curved region of the upper side of the pressure rail for the lower punches is opposite the horizontally extending region of the underside of the counter-pressure rail for the upper punches. According to an alternative embodiment, the control cam for the upper punches could comprise a pressure rail with a pressure rail body with a bottom side,wherein the underside is curved between a first point on the underside and a second point spaced therefrom in the arc direction of the pressure rail body by an arc angle. By using a pressure rail with a curved upper side for the lower punches and a pressure rail with a curved underside for the upper punches, the compression behavior of the material to be pressed can be even better influenced and thus also improved overall, for example to achieve an even higher hardness of the tablet. In a pressure rail for the upper punches with a curved underside, the curvature of the underside could form a spline, preferably along the entire curvature. Alternatively, the curvature of the underside could form conical curves, preferably along the entire curvature. According to yet another embodiment, the curvature of the underside could have several,preferably has radii of curvature that merge substantially tangentially into one another. This embodiment can also prove particularly advantageous if the local radius of curvature of the underside preferably increases continuously from the first location to the second location. In a rotary tablet press, only one control cam with a pressure rail with a curved top or bottom side could be used, which optionally also interacts with conventional pressure rollers in the main pressing station. In the particularly preferred embodiment, however, only pressure rails and no pressure rollers are used for the upper and lower punches in the main pressing station, and even more preferably in all compaction stations, of which at least one, and possibly all,have a curved sliding surface for interacting with the punches to apply the local pressing force. The above object is achieved in a generic rotary press according to a second aspect of the invention in that in the main pressing station and in each existing pre-pressing station, only pressure rails and no pressure rollers are provided for the upper punches and the lower punches, and that the pressure rail for the lower punches in the main pressing station has a continuously rising upper surface, at least partially between the first point and the second point. By dispensing with pressure rollers and compacting the material exclusively by means of pressure rails, which at least partially have a straight or curved rising upper surface, the compression pressure for the material is achieved so that it increases slowly but steadily, if necessary.The compression pressure, which gradually increases due to the rise of the upper side, can be specifically influenced by the design of the upper side of the pressure rail, even over a comparatively short rotational path. The design of the upper side of the pressure rail can be used or modified accordingly to control the pressure curve in the material to be compressed. The upper side of the pressure rail can have sections with different pitch angles or sections with a straight and curved course in order to influence the compression behavior of the material. This design of the pressure rails, especially in the main press station, also enables quick changeover when changing materials or dies. It is particularly advantageousif the upper side of at least one pressure rail of a pre-press station also has a continuously rising upper side, at least partially between a first location and a second location. According to one embodiment, the upper side of the pressure rail for the lower punches in the main press station can rise in a straight line between the first location and the second location, and / or the upper side of at least one pressure rail of a pre-press station can rise in a straight line at least partially between the first location and the second location. The upper side of the pressure rail for the lower punches in the main press station can also be curved, and / or the upper side of the pressure rail for the lower punches in at least one pre-press station can also be curved. Further features and advantages of the invention will become apparent from the following description and the drawings.wherein preferred embodiments of the invention are explained in more detail using schematically greatly simplified examples. It shows: FIG. 1 shows a schematic plan view of a rotary tablet press with the stations arranged along the rotation path; FIG. 2 shows a schematic, also considerably simplified, development of the rotation sequence of a rotary tablet press according to FIG. 1 according to a first embodiment, having a pressure rail with a curved upper side; FIG. 3 shows a schematically simplified perspective view of the pressure rail for the control cam in the main pressing station of a rotary tablet press according to the invention, pressure rail with a curved upper side; and FIG. 4 shows a development of the rotation sequence of a rotary tablet press according to a second embodiment,having a pressure rail with a straight-line rising upper surface. Figure 1 shows, in a highly schematic plan view, a rotary tablet press, designated overall by reference numeral 1, for producing tablets from a suitable starting material, such as powder. The rotary tablet press 1 has a housing 2, within which a rotor 10 is arranged and rotatably supported, which can be driven in the direction of rotation R, as indicated by an arrow, by means of a drive (not shown). The rotor 10, in turn, has, as will be explained in more detail with reference to Figure 2 and is shown there, a die plate 11 with a plurality of die receptacles 14 for dies arranged on a pitch circle,in which the powdered starting material is compressed into tablets by means of interacting upper punches 12 and lower punches 13. During the rotation of the rotor 10 in the direction of rotation R, the upper punches 12 and lower punches 13 pass through different stations. In the illustrated embodiment, the rotary tablet press 1 forms a monopress or a press for single-shift operation. Along the rotation path of the rotor 10, there is a filling station 3, schematically indicated by a filling curve, in which the powdered material to be compressed into the tablets is filled into the dies by means of suitable filling devices, such as filling shoes, a dosing station 4, a compaction station 5, and a discharge station 6, symbolically indicated by a stripping rail. For each of these stations, the upper punches 12 and the lower punches 13 must be moved to different distances from each other.This movement in the rotary tablet press 1 is controlled by means of control cams throughout the entire rotation. Different control cams exist for the upper punches 12 and the lower punches 13, with only the control cams 20 for the lower punches 13 being symbolically indicated in Figure 1. All control cams 20 are arranged in a fixed position in the housing 2 and, according to the station or function of the rotary tablet press 1, are divided into different curve sections. The symbolic representation in Figure 1 shows a total of four curve sections for the lower punches, namely a pull-down and filling rail 21, a dosing rail 22, a pressure rail 50, and an ejection rail 24. This representation is only symbolic, because each of these rails could also be constructed in several parts. Reference is now made to Figure 2,in which the development of the rotation path of the rotary tablet press 1 from Figure 1 is shown, and in which the upper punches 12 and lower punches 13 are shown in different positions along the rotation path. The upper punches 12 are all movably guided in guides of an upper punch guide ring 15, and the lower punches 13 are movably guided in guides of a lower punch guide ring 16. The upper punch guide ring 15, the die plate 11 and the lower punch guide ring 16, together with the upper punch 12 and the lower punch 13, form the essential components of the rotor 10. At the left edge of the image begins the filling station, in which the lower punches 13 are moved downwards by means of the pull-down and filling rail 21 at the greatest possible distance from the upper punches 13, which are held in a most upwardly moved position by means of a filling station holding rail 31.whereby the powder 18 to be pressed can be moved, as indicated in Fig. 2, by means of a filling device 17 such as a filling shoe, into the dies closed downwards by the punch heads of the lower punches 13. Filling the dies takes some time, which is why the filling station extends over an extensive angular range of the rotation path. Adjoining the pull-down and filling rail 21 in the direction of rotation R is a metering rail 22 for the lower punches 13, by means of which the lower punches 13 are moved upwards so that the filling volume of the material to be pressed is filled as precisely as possible into the dies between the head of the respective lower punch 13 and the top of the die plate 11. A vibrating device can be assigned to the metering rail 22.to improve the filling of the powdered material into the dies, which are open at the top and closed at the bottom by means of the pressing heads of the lower punches. The filling element 17, in turn, can have a dosing edge to retain the (excess) powdered material in the filling station or the filling element and prevent it from rotating with the die plate 11. In the area of ​​the dosing rail 22 for the lower punches 13, the downward movement for the upper punches 12 also begins, as indicated by the guide rail 32 for the upper punches 12. The guide rail 32 provides an obliquely downward guide for the upper punches 12, which moves them downwards until the respective pressing head of the upper punch 12 dips into the dies. The dosing station 4 or the dosing rail 22 is followed in the direction of rotation R by the compression or pressure station 5, which in the rotary tablet press 1 is formed exclusively by means of pressure rails,as symbolically shown in Figure 2 with a single pressure rail 50 for the lower punches 13 and a single counterpressure rail 33 for the upper punches 12. The counterpressure rail 33 holds the upper punches 12 in a position in which the punch head of the upper punches 12 penetrates sufficiently into the die so that the entire pressing pressure within the dies can be applied to the material to be pressed. The pressing pressure itself is applied here via the lower punches 13 and the pressure rail 50 provided for moving these lower punches 13, which, as already clearly shown in Figure 2,in the direction of rotation R at least partially has a curved upper side 54. Due to the curved shape of the upper side 54 of the pressure rail 50, the pressing pressure can be applied non-linearly and gradually increased by shaping the curvature. Behind the pressure station 5, in the direction of rotation R, there is the ejection rail 24 for the lower punches 13 and a lifting rail 34 for the upper punches 12, in order to expose the completely pressed tablet and to lift it by means of the lifting movement of the lower punches 13 in such a way that the tablet can be moved radially outwards away from the die table or die disk by means of a stripping device and can be guided out of the housing 2 of the tablet press 1; here, as is known per se, a tablet outlet can also be provided, via which defective bad tablets are simultaneously sorted out. The basic structure of a rotary tablet press with upper punch 13 and lower punch 12,which are moved by means of control cams and suitable rails in the filling station 3, the dosing station 4, and the ejection station 6, are known to those skilled in the art, which is why they will not be discussed in detail here. The innovations according to the invention in the rotary tablet press 1 primarily consist in the fact that in the tablet press 1, the entire pressing pressure is applied exclusively by means of one or more pressure rails, and that the pressure rail 50 has a curved upper side 54 in the embodiment variant in Figure 2. For simplification, only a single pressure rail 50 for the lower punches 13 and a single counterpressure rail 33 for the upper punches 12 are shown.Multi-part pressure rails and / or counterpressure rails could also be used for the corresponding function. The curvature of the upper side of the pressure rail 50 can be adjusted depending on the arc length and the desired curve for the pressing force. The counterpressure rail 33 can also have a curved underside in order to influence the pressing force via the counterpressure rail. The counterpressure rail can also have an underside extending diagonally and straight in the direction of rotation in order to increase the pressing pressure in the direction of rotation via the counterpressure rail in addition to the curved curve of the pressure rail for the lower punches. In the pressure rail 50, the curved section of the upper side extends only over a partial area, since the upper side 54 of the pressure rail 50 transitions into a horizontal and straight section.and preferably runs tangentially therein. Figure 3 shows an example of the structure of a corresponding pressure rail 50. The pressure rail 50 has a curved segment-like rail body 51 that is bent around the rotation axis in a curve corresponding to the curvature of the control cam. The rail body is provided with retaining holes 52, 53, via which the pressure rail can be fixedly secured to stationary anchor rods on the housing of the tablet press. The upper side 54 of the pressure rail body 51 is curved in such a way that it rises steadily from a first point 55 to a second point 56, namely continuously and with a curvature with a preferably changing radius of curvature.e.g., according to a spline. The different thicknesses of the pressure rail body 51 clearly show this rise of the upper side 54 in Fig. 3. The curvature of the upper side 54 can also form conical curves or run logarithmically. The curvature can also extend over the entire length of this pressure rail 50, since several pressure rails can be arranged in the compaction station, whereby, if necessary, only one of these pressure rails has a correspondingly curved upper side, whereas the other pressure rails can form curved sections in the compaction station with different functions. Thus, the curved sections in the compaction station can form a pre-press station and a main press station, and if necessary, only one of these press stations in the compaction station has a pressure rail with a curved upper side, whereas the other pressure rails there have a continuously and linearly rising upper side.or a straight, horizontal profile of the upper side, depending on the desired profile for the compression pressure. Figure 4 shows an alternative embodiment of a rotary tablet press 101. As in the previous embodiment, a die plate 111 with die openings 114, an upper punch guide ring 115 for the upper punch 112, and a lower punch guide ring 113 for the lower punch 112 are provided, which together form the rotor 110 of the rotary tablet press 101. Here, too, the movement of the upper punches 112 is controlled by the rails 131, 132, 133 and 134, and the movement of the lower punches 113 is controlled by means of the hold-down and filling rail 121, the dosing rail 122, a pressure rail 150 and an ejection rail 124, while the rotor 110 rotates in the direction of rotation R. Similar to the previous embodiment, there are no pressure rollers present here either,Rather, the entire pressing pressure is applied exclusively by means of the pressure rail 150 and the counterpressure rail 134. However, here the pressure rail 150 has an upper side 154 that is not curved, but rises in a straight line to a point where the pressure rail 150 transitions to a horizontal course. Numerous modifications will become apparent to those skilled in the art from the foregoing description, which are intended to fall within the scope of the appended claims. The exemplary embodiment shown merely symbolizes the structure of a rotary tablet press according to the invention. Each curved section can consist of several subsections and correspondingly several sub-rails. Several rails can be arranged in the compression station or pressure station.of which at least one pressure rail functions as a pre-press station and another rail functions as a main press station. The dies provided for producing the tablets can also be formed integrally on the die plate. The above embodiments show a rotary tablet press for single-shift operation. The invention can also be advantageously used in a rotary tablet press as a double press or for multi-shift operation; along the rotation path there are then (at least) two filling stations, two dosing stations and two compaction stations, and in a double press there are also two ejection stations. In a multi-layer press, a multi-layer tablet or core tablet is produced during one rotation using the same punch pair; in a double press, the same punch pair is used during one complete rotation of the rotor 2, optionally even more,Tablets manufactured.,

Claims

Claims:

1. Rotary tablet press with a housing (2), with a rotor (10) arranged in the housing (2) so as to be drivable, which has an upper punch guide ring (15) with guides for the upper punch (12), a lower punch guide ring (16) with guides for the lower punch (13) and a die plate (11) arranged between the punch guide rings (15; 16) with dies for producing tablets in the dies by means of the upper punches (12) and lower punches (13), with at least one filling station (3), a compaction station (5) and an ejection station (6) distributed over the rotation path of the rotor (10), and with stationary control cams (20; 31-34) for the upper punches (12) and the lower punches (12) for controlling the movement of the upper punches and the lower punches along the rotation path,wherein the control cams have a plurality of curve sections distributed over the rotation path, and at least one curve section for the lower punches in the region of the compression station forms a pressure rail with a pressure rail body (51) having an upper side (54) which is designed to rise in the direction of rotation at least partially between a first point on the upper side and a second point spaced therefrom in the arc direction of the pressure rail body by an arc angle, characterized in that the pressure rail (50) for the lower punches in the compression station (6) has a curved upper side (54) at least partially between the first point and the second point.

2. Pressure rail as a curve section of a control cam for the punches of a rotor of a rotary tablet press, in particular according to claim 1, with a pressure rail body (51) having an upper side (54),which preferably rises continuously between a first point (55) of the upper side and a second point (56) spaced therefrom in the arc direction of the pressure rail body by an arc angle, characterized in that the upper side (54) is curved between the first point and the second point.

3. Rotary tablet press according to claim 1 or pressure rail according to claim 2, characterized in that the curvature of the upper side, preferably along the entire curvature, forms a spline, or in that the curvature of the upper side, preferably along the entire curvature, forms conical curves.

4. Rotary tablet press according to claim 1 or pressure rail according to claim 2, characterized in that the curvature of the upper side has several, preferably substantially tangentially merging, radii of curvature.

5. Rotary tablet press according to one of claims 1, 3, or 4 or pressure rail according to one of claims 2 to 4, characterized in that the local radius of curvature of the upper side preferably increases continuously from the first location to the second location. 6.Rotary tablet press according to one of the preceding claims, characterized in that the pressure rail for the lower punches consists of several segments, wherein preferably each segment has an upper side with a constant radius of curvature and / or wherein the segments following in the direction of rotation have a larger radius of curvature than the segments leading in the direction of rotation.Rotary tablet press according to one of the preceding claims, characterized in that the control cam for the upper punches has a pressure rail (34) with a pressure rail body with an at least partially horizontally running underside, wherein the pressure rail (34) for the upper punches and the pressure rail (50) for the lower punches are arranged in the region of the pressure station (6) along the rotation path such that the curved region of the upper side of the pressure rail (50) for the lower punches (13) is opposite the horizontally running region of the underside of the counter-pressure rail (34) for the upper punches.

8. Rotary tablet press according to one of the preceding claims 1 or 3 to 6, characterized in that the control cam for the upper punches has a pressure rail with a pressure rail body with a bottom side, wherein the bottom side extends in a curved manner between a first point on the bottom side and a second point spaced therefrom in the arc direction of the pressure rail body by an arc angle.

9. Rotary tablet press according to claim 8, characterized in that the curvature of the bottom side forms a spline, preferably along the entire curvature, or that the curvature of the bottom side forms conical curves, preferably along the entire curvature. 10.Rotary tablet press according to claim 8, characterized in that the curvature of the underside has several, preferably substantially tangentially merging, radii of curvature, wherein the local radius of curvature of the underside preferably increases continuously from the first location to the second location.

11. Rotary tablet press according to one of the preceding claims, characterized in that the compression station has a main compression station and preferably at least one pre-compression station, wherein in all compression stations, only pressure rails and no pressure rollers are provided for the upper and lower punches. 12.Rotary tablet press with a housing, with a rotor (10; 110) which is arranged in the housing and can be driven, which rotor has an upper punch guide ring (15; 115) with guides for the upper punch (12; 112), a lower punch guide ring (16; 116) with guides for the lower punch (13; 113) and a die plate (11; 111) arranged between the punch guide rings with dies for producing tablets in the dies by means of the upper punch and lower punch, with the. Rotation path of the rotor distributed at least one filling station (3), a compaction station (5) and an ejection station (6), and with stationary control cams (20) for the upper punches and the lower punches for controlling the movement of the upper punches and the lower punches along the rotation path, wherein the compaction station has a main pressing station and preferably at least one pre-pressing station and the control cams have several curve sections distributed over the rotation path and at least one curve section for the lower punches in the area of ​​the compaction station has a pressure rail (50; 150) with a pressure rail body with an upper side (54;154) which is designed to rise in the direction of rotation at least partially between a first point on the upper side and a second point spaced therefrom in the arc direction of the pressure rail body by an arc angle, characterized in that in the main pressing station and in each existing pre-pressing station for the upper punches and the lower punches, only pressure rails (50, 34; 134, 150) and no pressure rollers are provided, and the pressure rail for the lower punches in the main pressing station at least partially between the first point and the second point has a continuously rising upper side (54;154).

13. Rotary tablet press according to claim 12, characterized in that the upper side of at least one pressure rail of a pre-pressing station has a continuously rising upper side at least partially between a first location and a second location.

14. Rotary tablet press according to claim 12 or 13, characterized in that the upper side of the pressure rail for the lower punches in the main pressing station runs in a straight line between the first location and the second location, and / or the upper side of at least one pressure rail of a pre-pressing station runs in a straight line at least partially between the first location and the second location.; 15. Rotary tablet press according to one of claims 12 to 14, characterized in that the upper side of the pressure rail for the lower punches in the main pressing station is curved.

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