EP3623145B1 - Rotor for a rotary press - Google Patents

Description

The invention relates to a rotor for a rotary press for pressing a product into compacts, comprising a die plate with die bores that is driven in rotation by means of a rotary drive, an upper punch holder rotating synchronously with the die plate for axial guidance of upper punches, and a lower punch holder rotating synchronously with the die plate for axial guidance of stamping.

Such a rotor is known, for example, from DE 10 2015 105 936 B4 . In rotary presses, a product that is usually in powder form is pressed into compacts such as tablets. In the course of the pressing process, product residues are created, which collect in particular on the upper side of the die plate and the upper side of the lower punch holder. Therefore, suction lines from suction devices are positioned at several positions of the rotor, in particular several positions of the die table and the lower punch receptacle, which are intended to suck off the product residues. The product residue can contaminate the entire pressing chamber. The cleaning effort is correspondingly high and components that are sensitive to dirt or dust must be specially protected, for example with individual coverings. A high extraction capacity is required to minimize the spread of product dust. On the one hand, this impairs efficiency and, on the other hand, it can lead to undesired product losses in the area of the die table. The product residues are also whirled up, particularly in the area of the extraction systems, and can be distributed in the press chamber in an undesirable manner.

Out of CN 101612810A a rotary press is known with a rotor according to the preamble of claim 1, the outside of which is provided with a dust cover. A blade is also provided on the outside of the rotor, which during operation during the rotation of the rotor causes turbulence in the area of the rotor closed by the dust cover rotor caused. Accumulations of dust are to be avoided by the turbulence.

Proceeding from the explained state of the art, the invention is based on the object of providing a rotor of the type mentioned at the outset, with which product residues can be reliably removed in a structurally simple manner with a minimized risk of contamination of the pressing chamber.

The invention solves the problem by the subject matter of independent claim 1. Advantageous configurations can be found in the dependent claims, the description and the figures.

For a rotor of the type mentioned at the outset, the invention solves the problem in that a fixed annular discharge channel is provided which, during operation of the rotor, takes up product residues from the die table and/or from the lower punch receptacle, in that the discharge channel has a discharge area from which product residues are discharged and that a carrier element rotating synchronously with the die plate and guided in the discharge channel is provided, which scrapes off the product residues in the discharge channel from the bottom of the discharge channel in the manner of a scraper and conveys them to the discharge area.

The rotor according to the invention is used in a rotary press in which a mostly powdery product is pressed into compacts, for example into tablets. A die table with die bores is rotated by means of a rotary drive. An upper punch holder for axial guidance of upper punches and a lower punch holder for axial guidance of lower punches rotate synchronously with the die table. The rotor according to the invention can also comprise upper punches and lower punches rotating synchronously with the die plate and paired with the die bores. The lower punch holder has a large number of bores in which the lower punches are accommodated. Accordingly, the upper punch holder has a large number of bores in which the upper punches are accommodated. The upper and lower punches work together in the bores of the die table to compress the product. The lower punch receptacle can have an upper side in the shape of an annular disk. The upper punch receptacle can have an underside in the shape of an annular disk. The upper side of the lower punch holder can lie in a preferably horizontal plane. Also the underside of the punch holder can lie in a preferably horizontal plane. The upper side of the punch holder and the underside of the upper punch holder can lie in mutually parallel planes. The die table also generally has an upper side lying in a preferably horizontal plane and an underside generally lying parallel to the upper side, which is therefore likewise situated in a preferably horizontal plane. The upper side of the lower punch receptacle, the lower side of the upper punch receptacle and the upper and lower side of the die table can in particular lie in mutually parallel planes. The rotor may also include an upper cam that controls the axial movement of the upper punches passing through the upper cam, and a lower cam that controls the axial movement of the lower punches passing through the lower cam. The rotor also has a drive for rotating the die table with the upper punch holder and the lower punch holder. The upper and lower punches work together in a manner known per se in the bores of the die plate for pressing the product into compacts. The matrix disk can be a closed ring disk or can be formed from ring segments. The die bores can be formed by detachable die sleeves inserted into the die disk or by bores made directly in the die disk.

A rotary tablet press with a rotor according to the invention also comprises at least one filling device, in which the product to be pressed is filled into the bores of the matrix disk. The filling device can have a so-called filling shoe, for example, over which the product falls into the bores by gravity. In addition, the rotary press comprises at least one pressing device, which can comprise, for example, upper and lower pressure rollers, in which the stamps are pressed against one another into the bores of the die plate for pressing the product. After going through of the pressing device, the upper punches, guided by the upper control cam, are withdrawn from the bores and the lower punches, guided by the lower control cam, are moved upwards to eject the compacts produced in the bores. In a downstream stripping device of the rotary press, the compacts can be stripped from the upper side of the die table to one or more discharge channels, via which the compacts are discharged from the rotary press.

According to the invention, an annular, fixed discharge channel is provided. Non-pressed product, which can be in powder or dust form, for example, is located in particular on the upper side of the die plate and on the upper side of the lower punch holder. From there, the product preferably reaches the discharge channel at least predominantly, in particular essentially completely, by centrifugal force and gravity. In particular, due to the rotation of the rotor, the product is conveyed radially outwards away from the upper side of the die table or the lower punch receptacle by centrifugal force and then falls into the discharge channel by gravity. The discharge channel has a discharge area from which the product is discharged, in particular through a discharge opening of the discharge area. According to the invention, a driver element rotating with the die table is also provided, which is arranged in the discharge channel and is guided in it during the course of the rotation. The entrainment element takes along the product located in the discharge channel and conveys it to the discharge area, from where it is conveyed away, for example out of the pressing chamber of the rotary press into a scrap or recycling container. The entrainment element rotates together with the rotor, in particular with the die table and the upper and lower punch receptacles in the stationary, ie non-rotating, discharge channel. The entrainment element wipes the product off the bottom of the discharge channel in the manner of a scraper and conveys it to the discharge area. The entrainment element rotates through the discharge area through. For example, a thermoplastic such as polyoxymethylene (POM) can be used as the material for the driver element. According to the invention, the product is carried away partially mechanically to the removal area, from which it is then removed. Because the product is fed to the discharge channel, in particular by centrifugal force and gravity, on the one hand, and the product is conveyed mechanically in the discharge channel to the discharge area on the other hand, it is not necessary, in contrast to the prior art, to provide greater suction capacity in the vicinity of the die plate or the lower punch receptacle , especially at several points. Rather, a single removal area is sufficient, from which the product mechanically transported to this area is removed. Areas that can be contaminated in the pressing chamber by excess product, especially dusty product, are minimized in this way. Rather, a defined air flow takes place in a targeted manner in the area of the discharge area. Additional coverings of dirt-sensitive components required in the prior art are not necessary and the surfaces to be cleaned and thus the cleaning effort are reduced. On the one hand, the lower required extraction capacity increases efficiency. On the other hand, there is no whirling up of excess product, which is possible in the prior art, or there is no undesired suction and thus loss of product in the area of the die table.

According to a particularly practical embodiment, the removal area can be a suction area, with a suction device being provided that sucks product residues out of the suction area. The suction device can increase the conveyance of the product into the discharge channel. In particular, the suction device can generate a negative pressure that reaches into the area of the discharge channel, which supports the conveyance of the product residues into the discharge channel. But this is not mandatory. It is, As explained, it is particularly possible that the product is conveyed into the discharge channel exclusively by centrifugal force and gravity. The driver element rotates through the suction area; due to the suction effect of the suction device, the product carried along by the entrainment element is sucked out of the suction area.

Of course, according to the invention, the discharge channel can also have several discharge areas, in particular suction areas. These can then each be connected to a suction device. However, it is also possible for one suction device to be provided for several suction areas. Of course, several driver elements can also be provided.

According to one embodiment, at least the bottom of the discharge channel can be arranged in a plane below the upper side of the lower punch receptacle. In particular, the entire discharge channel can be arranged in an area below the upper side of the lower punch receptacle. The discharge channel or its bottom is thus also located below the die table, which is arranged above the upper side of the lower punch receptacle. In this embodiment, the product falls particularly easily and directly into the annular discharge channel. The discharge channel can be arranged, for example, on the outer edge of the die table or the lower punch receptacle. It can be located below the lower punch receptacle and in an area completely radially outside of the die table or the lower punch receptacle, or in the radial direction it can be partially overlapping the die table and/or the lower punch receptacle.

According to a particularly practical embodiment, the discharge channel can be a discharge channel. The discharge chute can, for example, have a U-shaped cross section.

According to a further embodiment, the driver element can be elastic. It can then, for example, bear against the floor and/or the walls of the discharge channel with slight elastic deformation and can thus take the product with it in a particularly reliable manner.

According to a further embodiment, the maximum width of the entrainment element can essentially correspond to the width of the discharge channel. According to a further embodiment, an underside of the entrainment element can rest on the bottom of the discharge channel, in particular during the rotation. The shape of the entrainment element can be adapted to the cross section of the discharge channel in order to further optimize the entrainment effect. In particular, the entrainment element can lie against the floor and the walls of the discharge channel, as already explained.

According to a further embodiment, the driver element can be attached to the lower punch receptacle. The entrainment element is thus also rotated in a particularly simple structural manner.

Furthermore, a cladding can be provided which encloses at least the die table, the lower punch receptacle and the discharge channel, in particular encloses it in a ring shape. The cladding can seal off the die table, the lower punch receptacle and the discharge channel, in particular tightly against the escape of powder or dust. Such a covering, which is arranged at a distance, preferably a small distance, from the enclosed components, prevents product residues from spreading in the pressing chamber in a particularly reliable manner.

According to a further embodiment, a vacuum device can be provided which within the area enclosed by the paneling Negative pressure generated compared to the environment of the panel. Such a negative pressure prevents product residues, in particular dusty product residues, from escaping. According to a further particularly practical embodiment, the vacuum device can be formed by the suction device.

Figur 1

einen erfindungsgemäßen Rotor in einer teilgeschnittenen perspektivischen Ansicht,

Figur 2

einen vergrößerten Ausschnitt der Darstellung aus Figur 1,

Figur 3

eine Schnittansicht der Darstellung aus Figur 2, und

Figur 4

die Darstellung aus Figur 3 mit veranschaulichter Produktförderung.

An embodiment of the invention is explained in more detail below with reference to figures. They show schematically:

figure 1

a rotor according to the invention in a partially sectioned perspective view,

figure 2

an enlarged section of the display figure 1 ,

figure 3

a sectional view of the illustration figure 2 , and

figure 4

the representation figure 3 with illustrated product promotion.

Unless otherwise stated, the same reference symbols designate the same objects in the figures.

The rotor according to the invention shown in the figures is a rotor of a rotary press, in particular a rotary tablet press, for compressing a product, for example in powder form, into compacts such as tablets. The rotor includes a drive section 10, which is connected to a rotary drive for rotating the rotor, not shown in detail in the figures for reasons of simplicity. A die plate 12 is connected to the drive section 10 . The die plate 12 has a large number of sleeve receptacles 14 into which, in the example shown, die sleeves are inserted, which then form die bores of the die plate 12 . The die sleeves are again not shown in the figures for reasons of simplicity. The die plate 12 has a plurality of radial bores 16 on the circumference, into which clamping screws can be inserted for clampingly holding the die sleeves in the sleeve receptacles 14 . This is known per se. In the example shown, the die plate 12 is designed as a closed annular plate. However, it could also be made up of individual ring segments. It would also be conceivable for the die bores to be formed directly in the die plate 12 instead of by the detachable die sleeves. This is also known per se.

Also connected to the drive section 10 is a lower punch receptacle 18 with a large number of through bores 20 and an upper punch receptacle 22, also with a large number of through bores 24. During operation of the rotor, lower punches are guided axially in the through bores 20 of the lower punch receptacle 18 and in the through bores 24 the upper punch holder 22 upper punch guided axially. The axial movement of the upper and lower punches is controlled in a manner known per se via upper and lower cams of the rotary press, so that they interact in a manner also known per se for pressing the product in the die bores. The die table 12, the lower punch holder 18 and the upper punch holder 22 are rotated synchronously during operation via the rotary drive.

In reference numerals 26 and 28, an in figure 1 For reasons of clarity, the rotor cladding, which has been partially cut away and consists of two sections, can be seen, which in the example shown encloses the die table 12 and the lower punch receptacle 18 as well as an annular, circumferential discharge channel 30 . The discharge channel 30 is designed in the example shown as a discharge channel and is located in the area of the outer edge of the Lower stamp recording 18 below this. As in particular in the sectional view of figure 3 clearly recognizable, there is a distance between the outer edge of the die table 12 and the lower punch receptacle 18 and the upper section 26 of the casing 26, 28 in each case. As already explained, the discharge channel 30 delimited by the lower section 28 of the casing 26, 28 runs around in the form of a ring. The casing 26, 28 and thus the discharge channel 30 are fixed, so they do not rotate when the rotor rotates.

In figure 2 a driver element 32 can also be seen, the shape of which is adapted to the cross section of the discharge channel 30 . In the example shown, the driver element 32 is fastened to the lower punch holder 18 so that it rotates with it. During this rotation, the entrainment element 32 is guided in the discharge channel 30 . In the example shown, the entrainment element 32 is elastic and rests at least on the bottom of the discharge channel 30 , preferably also on the side walls of the discharge channel 30 . In figure 1 A suction opening 34 can also be seen in the lower section 28 of the casing 26, 28, which forms a suction area. In figure 2 it can be seen that a suction nozzle 36 is attached to this suction opening 34, which in figure 1 is not shown for reasons of illustration. A suction device, not shown in detail in the figures for reasons of simplicity, is connected to this suction connection piece 36 .

During operation of the rotor, the product, which is in particular in powder form, is pressed into pellets in the matrix beans, as explained. This inevitably leads to an accumulation of dusty or powdery product residues on the upper side of the die plate 12 and on the upper side of the lower punch receptacle 18. Due to the rotation of the die plate 12 and the lower punch receptacle 18, these product residues initially reach radially outwards due to the centrifugal force and then fall by the explained distance between the outer edges of Die table 12 and lower punch holder 18 and the casing 26, 28 due to the force of gravity downwards into the discharge channel 30. The movement of the product residues is in figure 4 illustrated by arrows 38. A collection of product residues at the bottom of the discharge channel 30 is shown schematically enlarged at reference number 40 . The product residues located in the discharge channel 30 are carried along by the entraining element 32, which rotates with the rotor during operation, and in particular are transported into the suction area defined by the suction opening 34, where the product residues are suctioned off via the suction nozzle 36 by the suction device, for example to a reject or recycling bin. The suction device can also generate a slight negative pressure inside the cladding 26, 28, which prevents product residues from being able to escape from the area enclosed by the cladding 26, 28 to the outside. However, this is not mandatory.

Reference List

10

drive section

12

die plate

14

sleeve shots

16

radial bores

18

Lower punch holder

20

through holes

22

Upper punch holder

24

through holes

26

disguise

28

disguise

30

discharge channel

32

take away element

34

Extraction opening/extraction area

36

exhaust nozzle

38

arrows

40

collection

Claims (11)

1. A rotor for a rotary press for pressing a product into pellets, comprising a die plate (12) with die holes that is rotationally driven by means of a rotary drive, an upper punch seat (22) that rotates in sync with the die plate (12) to axially guide upper punches, as well as a lower punch seat (18) that rotates in sync with the die plate (12) to axially guide lower punches, wherein an annular discharge channel (30) is provided that, during the operation of the rotor, collects product residue from the die plate (12) and/or from the lower punch seat (18), wherein the discharge channel (30) has a removal region from which product residue is removed, and wherein a catch element (32) is provided which rotates in sync with the die plate (12), is guided in the discharge channel (30), and conveys the product residue located in the discharge channel (30) to the removal region (34), characterized in that the annular discharge channel (30) is fixed; and the catch element (32) scrapes product residue located in the discharge channel (30) like a scraper off the floor of the discharge channel (30).
2. The rotor according to Claim 1, characterized in that the removal region is a suction region (34), wherein a suction apparatus is provided that sucks the product residue out of the removal region (34).
3. The rotor according to one of the preceding claims, characterized in that at least the floor of the discharge channel (30) is arranged in a plane below the top side of the lower punch seat (18).
4. The rotor according to one of the preceding claims, characterized in that the discharge channel (30) is a discharge groove.
5. The rotor according to one of the preceding claims, characterized in that the catch element (32) is elastic.
6. The rotor according to one of the preceding claims, characterized in that the maximum width of the catch element (32) substantially corresponds to the width of the discharge channel (30).
7. The rotor according to one of the preceding claims, characterized in that a bottom side of the catch element (32) rests on the floor of the discharge channel (30).
8. The rotor according to one of the preceding claims, characterized in that the catch element (32) is fastened to the lower punch seat (18).
9. The rotor according to one of the preceding claims, characterized in that a covering (26, 28) is moreover provided that at least encloses the die plate (12), the lower punch seat (18) and the discharge channel (30).
10. The rotor according to Claim 9, characterized in that a vacuum apparatus is provided that generates a vacuum relative to the surroundings of the covering (26, 28) within the region enclosed by the covering (26, 28).
11. The rotor according to Claims 2 and 10, characterized in that the vacuum apparatus is formed by the suction apparatus.

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