Not applicable.
Not applicable.
The typical rotor for a rotary press is composed of a die plate and an upper and a lower punch guiding for upper and lower punches, which co-operate with bores in the die plate. The rotor is driven around a vertical axis by a suitable driving motor, and the powder-shaped material filled into the die bores by a filling device is pressed together by the punches. The pressing together takes place in the so-called pressing stations, in which are arranged at least one upper and one lower pressing roller at a time, which act on the punch heads. In the remaining rotation phases, the punches are guided by suitable punch cams, amongst others for ejecting the pressed articles by cams controlling the lower punches. Such rotors have become known from U.S. Pat. No. 5,004,413, DE 101 59 114 A1 or DE 10 2004 040 163 B3, the entire contents of each of these references are incorporated herein by reference.
Usually, the upper and lower punches consist of a shaft, a head co-operating with the pressing rollers and a tool portion, which sinks into the die bores. The mostly cylindrical shaft is guided in corresponding bores of the punch guidings. For the purpose that the punches do not rotate in the bores, it is also known to provide a parallel key which co-operates with a parallel key groove in order to prevent a rotation of the punches.
In order not to affect the guiding property, it is also known to provide sealings which prevent that pressing material arrives between the guiding bores and the punch shaft and lubricant leaks out. The sealing is not possible in the region of a parallel key groove. Thus, the punch shaft must not be moved through a sealing in the region of the parallel key groove.
The present invention is based on the objective to provide a rotor for a rotary tablet press in which a simple, sealed guiding of the pressing punches is made possible.
In the present invention, the shafts of the pressing punches are provided with an out of round profile in their cross section, and the cross section of the guiding bores is complementary. For instance, the cross section may be a rectangle, a triangle or a polygon rounded in any way. Thus, the pressing punch shaft has smooth surfaces across its perimeter, which can be sealed easily.
According to one embodiment of the present invention, it is provided that the guiding bores are formed by guiding sleeves, which are arranged in accommodation bores of the punch guidings. The accommodation bores may be cylindrically, for instance, while the inner cross section of the guiding sleeves is complementary to the cross section of the pressing punches. The inner profile of guiding sleeves can be produced with a high accuracy, without that a scoring action worth to be mentioned must be feared on the punch shaft. Parallel keys and associated screws can be omitted. Preferably, the guiding sleeves are made of ceramic material. Through this, any lubrication of the punch shaft does not apply. So-called black spots and punch blocking do not occur also.
According to a further embodiment of the present invention, at least one sealing ring is provided, which is arranged at the upper and/or the lower end of the guiding bores and which has an inner perimeter which is complementary to the shaft profile. Such a sealing ring can serve as a strip-off member at the same time.
According to a further embodiment of the present invention, the sealing ring has an out of round outer contour and sits in a complementary recess of the punch guiding. Through this, rotation of the sealing ring is prevented.
The sealing ring can sit in a recess of the punch guiding at the end of the guiding bores which faces the die plate. For this purpose, it may be provided according to a further embodiment of the present invention that the sealing ring has a ring rib on its outer perimeter, which is positively received by a complementary groove in the recess. The ring rib can be arranged on a radially resilient portion of the sealing ring. Preferably, one sealing ring at a time is arranged on both ends of the guiding bores.
According to a further embodiment of the present invention, the guiding sleeves extend somewhat over the guiding bores on the end turned away from the die plate. For this case, one embodiment of the present invention provides that the sealing ring has a pot-shaped portion, which is put over the guiding sleeve.
Preferably, the sealing ring has two cone-ring shaped sealing lips, spaced apart in the axis direction, which extend divergently to the axis of the sealing ring.
Finally, a further embodiment of the present invention provides that the punch heads have one truncation at a time on the side facing the neighbouring punch heads. Through the out of round contour, the rotational position of the pressing punches is fixed. When the heads of the pressing punches are provided with truncations on sides opposing each other, it can taken care with respect to the orientation by the cross section of the punch shaft that the truncations point into the rotational direction of the rotor or towards the neighbouring punch head, respectively. Through this, it is possible to bring the punch heads very close together. As a consequence, the number of pressing punches which can be arranged on a partial circle can increased.
The present invention will be explained in more detail by means of examples of its realisation in the following.
While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated
A rotor 10, from which only a cut-out is shown in
The upper punch guiding 12 has accommodation bores 18, and the lower punch guiding 14 has accommodation bores 20. The punch guidings 12, 14 guide in a pairwise fashion upper punches 22 and lower punches 24, which co-operate with die bores 26 of the die plate 16 in order to press powder-shaped material in the die bores 26 together.
As can be recognised in
As can be recognised further in
The out of round shape of the sealing ring 40 on the outer perimeter, to which corresponds a corresponding shape of the accommodation groove 46, prevents a rotation of the sealing 40 in the recess in which it sits at the end of the accommodation bore 18 in the punch guiding 12.
An additional sealing 52 is pot-like at the side facing the guiding sleeve 28 and it grasps over the guiding sleeve 28, which projects about a certain degree over the upper end of the accommodation bore 18. As the outer perimeter of the guiding sleeve 28 is out of round also, the profile prevents that the sealing 52 can rotate.
In
Finally, as becomes clear from some of the figures, the punches 22, 24 have facing truncations 56 on the heads 32. As results from
The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.
Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim 1 should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.
This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.
Number | Date | Country | Kind |
---|---|---|---|
10 2007 043 584 | Sep 2007 | DE | national |
Number | Name | Date | Kind |
---|---|---|---|
2068619 | Bailey | Jan 1937 | A |
4298563 | DeSantis et al. | Nov 1981 | A |
5004413 | Stopforth | Apr 1991 | A |
7462023 | Harada et al. | Dec 2008 | B2 |
Number | Date | Country |
---|---|---|
199 63 263 | May 2002 | DE |
10159114 | Feb 2004 | DE |
102004040163 | Apr 2006 | DE |
03084738 | Oct 2003 | WO |
Number | Date | Country | |
---|---|---|---|
20090074901 A1 | Mar 2009 | US |