EP1473145B1 - Method for the trial pressing of tablets - Google Patents

Description

The invention relates to a method for the test-pressing of tablets according to claim 1.

Tablets are commonly made with rotary tablet presses or rotary tableting machines. Such machines include a rotor having a die plate having a series of dies, upper and lower dies co-operating with the dies and at least one printing station in which the dies are pressed into the dies against the charged material in the die , This happens during the rotation of the rotor, which is driven by a suitable drive device. Before pressing, the dies must be filled with the material to be pressed (powder). This happens continuously when the rotor rotates in a so-called filling shoe or a filling arrangement, which is arranged stationary.

It is known to associate such a tablet press with a measuring device which records essential data during production and processes it in an operating computer. These include the speed of the rotor, the maximum compressive forces in the printing station and possibly the Preßkraftverlauf in the printing station, namely assigned to the individual stamp pairs. By subsequently measuring the ejected tablets in terms of their weight, their thickness and hardness, it is determined whether the desired parameters have been achieved. If not, the capacity, pressing force or the like must be changed. Devices and methods for controlling tablet presses to achieve optimum results are well known in the art.

In the development of tablets, among other things, the compression characteristics of the material to be pressed are determined. Initially, only very small amounts of product are available, which are also very can be complex in the production and on material, so that the product losses must be kept low during the pressing.

It is known to carry out pressing experiments with special laboratory presses. These are mostly smaller eccentric presses with which one tablet can be produced for each pressing process. The disadvantage here is that the laboratory presses have a different pressing behavior than rotary tablet presses that are used for production. Therefore, the results of the pressing trials can not easily be transferred to a production rotary press.

Pressing tests with a production rotary press naturally have the advantage that the data determined during compression tests can be transferred directly to the production. In addition, all settings of the rotary press can be taken from the press trial for production use.

Conventional rotary presses have a filling shoe or a corresponding filling device, as described above. In order for such a filling arrangement to be able to fill the matrices constantly uniformly, their volume must be constantly filled with a basic amount of pressing material, even if only a small number of tablets are to be produced. Thus, in rotary presses is always vorzuhalten a larger amount of press material to be pressed, as is necessary for the actual Preßversuch.

document US-B-6,325,609 discloses a method according to the preamble of claim 1.

The invention has for its object to provide a method for Prüfspressung of tablets, which is on the one hand under production conditions feasible and on the other hand manages with minimal Preßmaterialaufwand.

This object is solved by the features of patent claim 1.

In the method according to the invention a conventional tabletting machine is used, as it is usually used in production. In the company employing a rotary tabletting machine, therefore, such a machine can be used according to the invention for experimental purposes. For this purpose, with at least partially removable filling arrangement and in a predetermined filling position with the rotor stationary, at least one die is filled with pressing material. The filling process normally consists of the filling process and the dosing process. During the filling process, by means of a suitable control cam segment, the lower punches which are located inside the die are moved downwards by a certain amount in order to release a volume of the die for the filling of material. If this filling has taken place, a slight lifting of the lower punches is effected with a further cam segment. The lifting takes place in an exact filling position, in which the volume specifies the exact amount. A small portion of the previously filled press material is therefore lifted out of the die and stripped off with the aid of the filling shoe or another filling arrangement. Only then does the pressing process begin, wherein usually a main printing station precedes a pre-printing station, each containing a pressure roller pair, which cooperates with the upper and lower punches.

In the method according to the invention, the rotor is stopped in a position in which a lower punch is in the filling position, ie, the lower punch specifies exactly the filling volume in the die. It is not problematic to approach this position by means of the drive control, since it has long been known to enable the rotation of the rotor by means of suitable angle detection arrangements monitor and control. Such monitoring is required when press characteristics are to be assigned to the individual pairs of punches.

The filling of the single die can z. B. by hand or with the help of a special suitable filling device. The usual Befüllanordnung is removed or driven to the side so far that the filling of the single die is possible. It is understood that even a limited number of dies can be filled with molding material. For this purpose, it is then necessary that the rotor moves step by step the associated matrices in the filling position.

After filling the die, the rotor is rotated and accelerated so far that it has reached the desired production speed or rotational speed upon reaching the printing station. If the printing station has a pre-printing station, then the rotor must already have the production speed in the pre-printing station. Frequently, in larger rotary tableting machines, three printing stations are used with three filling arrangements for pressing three tablets in parallel at the same time. In this case, the rotor is only a relatively small distance to reach the production speed available. With current drives, this can be achieved.

After a single revolution, the rotor is stopped in the filling position, and it is now possible, the signals or waveforms of the individual measuring points, for. As main and form, ejection force, stamp binding, etc., which have recorded during the rotation measured values to be evaluated in a computer or to be displayed by this.

With the method according to the invention, a large number of advantages are obtained. Since only a single die or a very small number of matrices must be filled with molding material, the cost of molding material is very low. The loss of molding material is very low. Another significant advantage of the invention is that the results of the experiment can be applied to any production rotary press and that special laboratory presses are not required for pressing trials.

All process-relevant settings can be set and tried in the compression test, such as speed, compressive force, tablet thickness, tablet hardness, tablet weight, etc. To test the compressibility of new tablet forms only one pair of punches must be made. It is also possible to test a number of different punch shapes that are used in pairs in the rotor. With a single revolution of the rotor thus a plurality of different punch shapes can be examined.

Further advantages are the very short changeover times to other pressing materials and stamp types. The dust in the compression tests is extremely low because of the small amount of molding material.

It is not necessary to equip the rotor with all pairs of punches, but possibly only with a pair of punches. However, it is not necessary to use dummy matrices, as would be the case with the use of a filling shoe. The incorporation and removal of the dummy matrices is a complex process.

Fig. 1

zeigt die Draufsicht auf eine schematisch dargestellte Tablettiermaschine herkömmlichen Aufbaus.

Fig. 2

zeigt schematisch die Abwicklung der Tablettiermaschine nach Fig. 1 ohne Füllschuh.

Fig. 3

zeigt eine ähnliche Ansicht wie Fig. 1, jedoch ohne Füllschuh für die Durchführung des erfindungsgemäßen Verfahrens.

The invention will be explained in more detail with reference to drawings.

Fig. 1

shows the top view of a schematically illustrated tabletting machine of conventional construction.

Fig. 2

shows schematically the processing of the tabletting machine Fig. 1 without filling shoe.

Fig. 3

shows a similar view as Fig. 1 but without filling shoe for carrying out the method according to the invention.

In Fig. 1 there is shown a rotor 10 of a rotary tableting machine having a die plate 12 with a series of dies 14 arranged on a circle about the axis of the rotor 10 with die bores 16 for receiving material to be pressed. Each die 14 or die bore 16 is associated with an upper punch and lower punch, which in Fig. 1 are not shown.

At the periphery of the rotor 10, a pre-printing station 18 and a main printing station 20 are stationary. They have paired pressure rollers, of which 22 and 24 respectively a lower pressure roller is shown. The pressure rollers cooperate with the facing ends of the punches to press them into the die bores 16 and to press the material therein. In the direction of rotation in front of the printing station 18, a filling arrangement 26 is shown. The details of the filling arrangement should not be discussed, since they are known. With the help of the filling arrangement, which has a certain volume and is filled continuously via a hopper, the matrices are filled, each run below the filling assembly 26. During this movement, the die holes are gradually filled with pressing material. The finished in the main printing station 20 tablets are from ejected from the lower punches while the upper punches are above the dies. A scraper (not shown) ensures that they are pushed to a tablet drain 28.

In Fig. 2 two upper punches are shown at 30, while a number of sub-punches 32 are shown in phantom. It can be seen that the punches 30, 32 move from the printing station 18 to the right and occupy different positions in height relative to the die plate 12. This is achieved by a control curve 34 for the upper punch 30 and by a control cam 36 for the lower punch 32 for ejection. Following the main printing station 20, the filling takes place, wherein in Fig. 2 the filling assembly 26 after Fig. 1 not shown or is removed. The upper punches 30 have a raised position outside the die bore, with the top of the in Fig. 2 not shown Matrizenscheibe is indicated by the dashed line 36a. The oblong box 38 indicates the filling section and the box 40 indicates the metering section. As can be seen from the position of the lower punch 32, these are gradually driven by control cams, not shown, so that they release a portion of the die bore for filling with molding material. After the position taken farthest down, as indicated by the dot-dash line 32 in the dosing section 40, the punches 32 are raised again slightly. In this raised position of the lower punches 32, the filling volume is defined in the die bore. Here, a small part of the previously filled press material is lifted out of the die bore, which can then be stripped off approximately by the filling assembly 26. Following the upper punch 30 are lowered by the cam 42 and driven under the next printing station, which may be the pre-printing station 18 or another pre-printing station, if more than one pre and main printing station is provided.

In the method according to the invention, such as in Fig. 3 shown, the filling assembly 26 after Fig. 1 got out of business. Moreover, the tableting machine can after Fig. 3 have the same parts as Fig. 1 , Therefore, in Fig. 3 with Fig. 1 same parts provided with the same reference numerals.

When a compression test is performed, the rotor 10 is brought into a position in which a lower punch 32 is in the filling position, as indicated by 40 in FIG Fig. 2 indicated. Now, with the rotor 10, the die bore 16 is filled with pressing material with the aid of a suitable filling device or by hand. The control for the drive, not shown, of the rotor 10 is set via a computer so that the rotor is automatically rotated after the Stärt exactly one revolution, so that the working pair of punches is back in the filling position. The acceleration of the rotor drive is adjusted so that the production speed is reached in the pre-printing station 18 to avoid slope angle.

During the rotation data for the compression of the material are recorded by means of suitable measuring points not shown. These include the rotational speed of the rotor 10 and the pressing characteristics in the pre-and main pressure stations 18, 20, which are measured by means of suitable pressure or Kraftmeßaufnehmer. The signals of the measuring points are recorded in the computer and brought to display and evaluation. It can be pressed in this way automatically several individual tablets in succession, wherein after each revolution process and tablet parameters can be adjusted automatically due to the measurement data or by predetermined changes in the adjustment parameters to determine optimal production conditions.

During the described experiment, all other punches 30, 32 remain installed or removed. As already mentioned, a single pair of punches is sufficient to carry out pressing tests. The installation of blind matrices when removing press dies is eliminated.

The data obtained in the compression test can be easily transferred to the tableting machine under production conditions.

Claims (4)

1. A method for test pressing tablets by means of a rotary tabletting machine, a rotationally driven rotor (10) which has a series of upper and lower rams (30, 32), a die-plate (12) with dies (14) with which the rams interact, a control cam system for said rams, and a filling assembly to continuously fill said dies with said rotor rotating, further by means of at least one pressure station at which the material located in said dies is compressed into a tablet, and a measuring device having a plurality of measuring positions which measures at least the compression force applied by said rams and the number of revolutions of said rotor, characterized by the following process steps:

   a pair of rams selected for a single compression procedure is automatically moved to a filling position,

   a die or limited number of dies (14) is filled with material with said filling assembly removed at least in part and said rotor at stoppage,

   said rotor is set into rotation subsequently and is sped up such as to have the desired production speed in said pressure station,

   said rotor (10) is stopped in said filling position after a revolution and signals or signal runs of the measuring positions are recorded while the rotor is rotating and are provided to a computer for display and evaluation.
2. The method according to claim 1, characterized in that only one pair of rams or a limited number of pairs of rams are fitted in the rotor.
3. The method according to claim 1 or 2, characterized in that the pairs of rams associated with the dies to be filled are of different shapes.
4. The method according to any one of claims 1 to 3, characterized in that the tablet and/or process parameters are automatically adapted after each revolution of said rotor because of the data measured or in response to predetermined variations of the setting parameters.

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