Patent Description:
The present invention relates to the increase of the production capacity of a tableting device, in particular a rotary tablet press. The production capacity depends on the attainable press speed and the number of punches that can be accommodated on the pitch circle.

Traditionally, it has been proposed to address the above mentioned problem by decreasing the tooling (e.g. punches) dimensions below the industry standards in order to accommodate more punches on the pitch circle, thereby increasing the production capacity (e.g. <CIT>). This tooling is also defined as non-standard tooling. The drawbacks associated with this approach are that the die insert becomes too small, leading to deformation and fixing difficulties.

To address these deformation/fixation issues, it has been proposed to introduce exchangeable die plates with die bores directly provided into the plate, thereby preventing the use of small exchangeable dies (e.g. <CIT>). Nevertheless, this solution has drawbacks limiting the applicability to rotary tablet presses with small pitch circle diameter. Indeed, heavy tables cannot be easily handled. Alternatively, segmented exchangeable die plates were developed as disclosed in <CIT>. However, strict tolerances are required not only to ensure that the die bores match with the top and bottom punch tips but also to guarantee correct body diameter in order to increase the number of punches on a given pitch circle.

As an alternative to the increase in the output capacity of a rotary tablet press, tooling with multiple tips on the same punch has been proposed in <CIT> disclosing the features of the preamble of claim <NUM>. This old document (<NUM>) shows that three tips are aligned with the three corresponding die bores arranged on a single exchangeable die insert. However, the impossibility to evaluate weight of individual tablets during compression process as well as an increased complexity may render this approach less interesting to increase in output capacity.

Similarly to <CIT> (<FIG>), <CIT> proposes an exchangeable die insert with at least two or more bores arranged on a single die insert. The latter document differs from the former document not only in that it defines a specific shape for the die insert, namely a circular arc and/or a substantially kidney-shaped design die insert, instead of mandrel (i.e. circular shaped), but also in that the purposes of <CIT> differs from those of <CIT>. Indeed, the rationale behind the circular arc shaped insert is to reduce fitting times, as well as to improve servicing and cleaning. <CIT> therefore seeks to solve another problem. Furthermore, the solution outlined in <CIT> requires new die insert fixing solutions involving new development and reduction in economies of scales since they cannot be shared with those of standard die inserts. <CIT> discloses a tableting device according to the preamble of claim <NUM>.

An object of the present invention is to address the above-mentioned drawbacks, in particular to obtain a high capacity and robust die table, preferably compatible with standard die insert fixing solutions.

In a first aspect of the invention, this and further objects are achieved by a tableting device according to claim <NUM> and comprising a rotary turret with a rotation axis including: an upper receptacle body provided with reciprocating upper punches, a lower receptacle body provided with reciprocating lower punches, a die table, die inserts; wherein the die table is provided with receiving recesses, in which the die inserts are arranged; wherein the die inserts and the receiving recesses have a complementary form; wherein each die insert comprises at least one circular cylindrical outer surface with a die insert outer diameter, said surface facing an inner surface of the corresponding receiving recess, wherein each die insert comprises a pair of working bores, in which a pair of directly adjacent upper punches respectively reciprocate in use, and in which a corresponding pair of directly adjacent lower punches respectively reciprocate in use.

By the provision of such a pair of working bores within each die insert, it has been made possible to increase the number of working bores while keeping the standard fixation traditionally used to fix the die inserts into the receiving die table. In this way, it is possible to directly benefit from the use of standard fixations. This is advantageous for a number of reasons, in particular as regards availability, costs, and mechanical stability.

It is noted that the term "a pair of working bores" is meant to encompass at least two working bores present in a single die insert; however, embodiments in which only two working bores are present in each die insert are preferred.

According to specific embodiments of the invention, the tableting device comprises one of more of the below technical features. It is noted that the features may be combined with each other in any manner:.

In the following description embodiments of the invention will be described with reference to the drawings, in which.

The present invention will now be described in more detail hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness.

In the below description, elements of the prior art having counterpart elements of corresponding function as in the subsequent embodiments of the invention are denoted by the same reference numerals preceded by a "P" for ease of understanding, but this is not to be construed that such elements do not differentiate from each other.

<FIG> discloses a transversal view of a tableting device P2 according to the state of the art. The device comprises an upper receptacle body P10 provided with reciprocating upper punches P12, a lower receptacle body P20 provided with reciprocating lower punches P22, a die table P30 provided with a plurality of exchangeable die inserts P40. The die insert P40 shown comprises a working bore P42. The die insert P40 is disposed in its receiving recess P32 in a form-fitting manner. In operation, the upper receptacle body P10, the lower receptacle body P20 and the die table P30 rotate synchronously about a rotation axis extending vertically. The upper receptacle body P10, the lower receptacle body P20 and the die table P30 form the rotary turret of the tableting device P2. A stator element of the tableting device is not shown in <FIG>. Typically, the stator element comprises an upper and a lower cam profile guide or roller actuating respectively the upper P12 and lower P22 punches, when the punches P12, P22 rotate with their respective upper P10 and lower P20 receptacle body. The upper P12 and lower P22 punches can comprise an end surface P18, P28 that slides on a corresponding cam profile guide surface or rolls on a roller surface. The opposite end (tip) P14, P24 of the upper P12 or lower P22 punches can reciprocate in the corresponding working bore P42. In operation, a powder composition, for instance, is fed by a feeder assembly (not shown). The powder composition is then confined in a variable volume defined by the ends (tips) of the corresponding upper P12 and lower P22 punch, as well as the inner lateral surface of the corresponding working bore P42. During at least one rotation cycle, two opposed upper P12 and lower P22 punch ends (tips) get closer to each other and compress the powder composition so as to form a tablet, for example. The formed tablet is then ejected from the working bore. For instance, the corresponding upper punch tip end is extracted from its working bore, leaving a free opening, while the corresponding lower punch end moves upwards and preferably beyond the upper surface of the corresponding die so that the formed tablet is pushed out of the working bore P42. Then, the tablet can be transferred to another location, for instance an outlet. Once the working bore P42 is free, it can be filled again with a powder composition.

<FIG> discloses an alternative to the tableting device of <FIG>. In the tableting device of <FIG>, the upper P12 and lower P22 punches are adapted to receive three tips so as to increase the capacity. The free ends of the three tips can reciprocate in three corresponding working bores P42. This design does not allow the evaluation of the weight of individual tablets during the compression process well as increases complexity, thereby rendering this approach less interesting to increase in output capacity.

<FIG> discloses a schematic representation comparing a tableting device according to the another example of the state of the art (without stationary pin f as shown in <FIG>) and that of the present invention. The prior art tableting device in <FIG> and the invention device have in common the outer lateral surface of the die insert. The invention differs from the state of the art in that it combines two upper/lower punches with one single tip <NUM>, <NUM> aligned, respectively with two working bores <NUM> arranged in the same insert <NUM>. The present invention makes it possible to increase the number of working bores <NUM> while keeping the standard fixation traditionally used to fix the die inserts <NUM> into the receiving die table <NUM>. The solution of the invention can therefore directly benefit from the use of standard fixations, especially from their mechanical stability. In other words, no additional screw or assembly web are needed to fix the die insert as suggested in the prior art (e.g. <CIT>).

<FIG> on the right hand side discloses a partial transversal view of the tableting device <NUM> according to the invention. The device <NUM> comprises an upper receptacle body <NUM> (not show) provided with reciprocating upper punches <NUM>, a lower receptacle body <NUM> (not shown) provided with reciprocating lower punches <NUM>, a die table <NUM> provided with a plurality of exchangeable die inserts <NUM>. The die insert <NUM> shown comprises two working bores <NUM>. The die insert <NUM> is disposed in its receiving recess <NUM> in a form-fitting manner. In operation, the upper receptacle body <NUM> (not shown), the lower receptacle body <NUM> (not shown) and the die table <NUM> rotate synchronously about a rotation axis extending vertically. The upper receptacle body <NUM> (not shown), the lower receptacle body <NUM> (not shown) and the die table <NUM> form the rotary turret of the tableting device <NUM>. A stator element of the tableting device is not shown in <FIG>. Typically, the stator element comprises an upper and a lower cam profile guide or roller actuating respectively the upper <NUM> and lower <NUM> punches, when the punches <NUM>, <NUM> rotate with their respective upper <NUM> (not shown) and lower <NUM> receptacle body (not shown). The upper <NUM> and lower <NUM> punches can comprise an end surface <NUM>, <NUM> that slides on a corresponding cam profile guide surface or rolls on a roller surface (not shown). The opposite end (tip) <NUM>, <NUM> of the upper <NUM> or lower <NUM> punches can reciprocate in the corresponding working bore <NUM>. In operation, a powder composition, for instance, is fed by a feeder assembly (not shown). The powder composition is then confined in a variable volume defined by the ends (tips) of the corresponding upper <NUM> and lower <NUM> punch, as well as the inner lateral surface of the corresponding working bore <NUM>. During at least one rotation cycle, two opposed upper <NUM> and lower <NUM> punch ends (tips) get closer to each other and compress the powder composition so as to form a tablet, for example. The formed tablet is then ejected from the working bore. For instance, the corresponding upper punch tip end is extracted from its working bore, leaving a free opening, while the corresponding lower punch end moves upwards and preferably beyond the upper surface of the corresponding die so that the formed tablet is pushed out of the working bore <NUM>. Then, the tablet can be transferred to another location, for instance an outlet. Once the working bore <NUM> is free, it can be filled again with a powder composition.

Furthermore the punches of the invention are thinner than those of the prior art (e.g. punches defined according to ISO <NUM>:<NUM>(E)) so that at larger number can be accommodated on a pitch. The punches of the invention are therefore less bulky, reducing the inertial forces. Advantageously, the selected punches <NUM>, <NUM> have a barrel diameter (referenced as D1 in table <NUM>) smaller than the lower D1 value encountered in ISO <NUM>:<NUM>(E), namely <NUM>, preferably less than <NUM>, more preferably less than <NUM>.

<FIG> shows a lower punch according to standard ISO <NUM>:<NUM>(E). Some reference diameters such as D1 are shown in the table <NUM> below. It should be noted that that the diameter of the tip of the lower punch is to be selected by the user and is therefore not defined in this standard.

Typically, the diameter of the lower or upper punch tip is smaller than or equal to the barrel diameter D1.

It is not compulsory that a lower/upper punch fulfils the requirement of ISO <NUM>:<NUM>(E). For instance, European patent <CIT>, the content of which should be incorporated in the present demand, shows an example of punches that do not comply with ISO <NUM>:<NUM>(E). These punches are also known as non-standard tooling.

Advantageously, the outer contour of the die insert (a. a "die") according to the invention, meets the requirement of ISO <NUM>:<NUM>(E). It should be noted that ISO <NUM>:<NUM>(E) defines a single working bore die insert <NUM> while the present invention relates to a two working bore solution.

<FIG> shows a typical die insert <NUM> with one bore according to ISO <NUM>:<NUM>(E) and table <NUM> shows reference values, such as the outer diameter of the die insert (N).

<FIG> show a die insert <NUM> with only two bores <NUM> according to the invention.

<FIG> shows a top view of the die insert <NUM>. The two through bores <NUM> are positioned on both sides of a symmetric plane. Preferably, the two through bores <NUM> are disposed symmetrically along a circular arc passing by the center of the die insert <NUM>.

<FIG> represents a sectional view of the die insert <NUM>, while <FIG> discloses a side view. As discussed above, the outer contour can meet the requirements of ISO <NUM>:<NUM>(E). The inner contour of both bores can also follow the requirements of this standard, that defines a single bore die insert.

<FIG> represents a partial view of the upper receptacle body <NUM>, the die table <NUM> and the lower receptacle body <NUM> according to the invention, when the die inserts <NUM> are not disposed on said table <NUM>.

<FIG> only differs from <FIG> in that the die inserts are arranged in their recesses <NUM>. Locking pins can be screwed into radial bores <NUM> opening on a lateral (outer) surface of the die table <NUM>. The die table upper face <NUM> is flush with the die insert upper faces <NUM>. The die table lower face <NUM> can also flush with the die insert lower faces.

Referring now briefly to <FIG>, which represents a top view of a possible embodiment of a die table <NUM>, the position of the radial bores <NUM> is shown. <FIG> represents a cross-sectional view along the plane Y-Y without a die insert, and <FIG> represents the cross-section including a die insert <NUM>. A die plate <NUM> is mounted onto the die table lower face <NUM> which defines the vertical position of the die insert in the radial bore opening by aligning the lower face <NUM> to the die table lower face <NUM>. While the die plate <NUM> in the position shown is positioned such that the lower face <NUM> of the die insert <NUM> is at the same level as the die table lower face <NUM>, other configurations are conceivable as long as the die plate <NUM> ensures that the die inserts are positioned at a well-defined vertical position. Additional positioning means may be present, including an additional recess in the die plate <NUM>, or the die plate <NUM> may protrude into the receiving recess <NUM>.

Also visible in <FIG> are inner surfaces <NUM>, <NUM> of the receiving recess <NUM>, of which inner surface <NUM> constitutes an upper or first circular cylindrical inner surface and inner surface <NUM> constitutes a lower or second circular cylindrical inner surface.

<FIG> represents a sectional view of a circumferential row of punches <NUM>, <NUM> reciprocating in their working bores <NUM>.

<FIG> shows a side view of an upper <NUM> and a lower punch <NUM>. The upper/lower punch <NUM>, <NUM> comprises a single tip <NUM>, <NUM> adapted to reciprocate in one of the corresponding working bores <NUM> (not shown in <FIG>). The upper/lower <NUM>, <NUM> punch comprises barrel portion <NUM>, <NUM> adapted to reciprocated in the complementary bores formed respectively in the upper <NUM> or lower <NUM> respectable body (not shown in <FIG>). The barrel portion <NUM>, <NUM> comprises a cylindrical outer surface with a barrel diameter "D1". The designation "D1" is used so that the non-standard punches <NUM>, <NUM> according to the invention can be compared with the standard punches. The use of the designation "D1" should not be interpreted as if ISO <NUM>:<NUM>(E) defined the entire shape of the punches <NUM>, <NUM>. It has been found that the barrel <NUM>, <NUM> can advantageously have a barrel diameter D1 lower than <NUM>% of the diameter of the die insert outer diameter, namely diameter N. As for the designation "D1", the designation "N" is used so that the non-standard die insert <NUM> according to the invention (with two bores) can be compared with the standard insert with one bore. The use of the designation "N" should not be interpreted as if ISO <NUM>:<NUM>(E) defined the entire shape of the die insert. With an upper value of <NUM>%, two through bores <NUM> can be foreseen without significant reduction of the mechanical resistance. Furthermore, there is just enough material between the two through working bores <NUM>. Equally, there is also enough material between a through bore and the lateral (outer) surface <NUM>, <NUM> of the die insert <NUM>.

The number of working bores is preferably limited to two. However, a die insert with three, more, even four working bores can be foreseen.

Claim 1:
Tableting device (<NUM>) comprising a rotary turret with a rotation axis including:
- an upper receptacle body (<NUM>) provided with reciprocating upper punches (<NUM>),
- a lower receptacle body (<NUM>) provided with reciprocating lower punches (<NUM>),
- a die table (<NUM>),
- die inserts (<NUM>);
wherein the die table (<NUM>) is provided with receiving recesses (<NUM>), in which the die inserts (<NUM>) are arranged;
wherein the die inserts (<NUM>) and the receiving recesses (<NUM>) have a complementary form;
wherein each die insert (<NUM>) comprises at least one circular cylindrical outer surface (<NUM>, <NUM>) with a die insert outer diameter (N), said surface (<NUM>, <NUM>) facing an inner surface (<NUM>, <NUM>) of the corresponding receiving recess (<NUM>),
characterized in that each die insert (<NUM>) comprises a pair of working bores (<NUM>), in which a pair of directly adjacent upper punches (<NUM>) respectively reciprocate in use, and in which a corresponding pair of directly adjacent lower punches (<NUM>) respectively reciprocate in use.