EP3584011A1 - Cutting mill for cutting down samples - Google Patents

Abstract

The invention relates to a cutting mill for the cutting size reduction of samples, comprising: a device housing, a drive motor and a drive shaft (42), a grinding chamber (16) with a cutting rotor arranged therein for cutting size reduction of the samples in the grinding chamber (16), the cutting rotor a rotation axis (A) is defined and the grinding chamber (16) is axially limited on the motor side by a grinding chamber rear wall (24), the grinding chamber rear wall (24) having a shaft opening through which the cutting rotor can be driven by the drive shaft (42), the shaft opening is sealed in the grinding chamber rear wall (24) by a labyrinth seal (60).

Description

Field of the Invention

The invention relates to a cutting mill for cutting comminution of samples, in particular on a laboratory scale, with a cutting rotor rotating about a horizontally extending axis.

Background of the Invention

Cutting mills shred the samples by a scissor-like cutting effect, typically between a rotating cutting rotor with one or more substantially axially extending blades and one or more stationary axially extending counter blades. Laboratory cutting mills of this type are particularly suitable for comminuting tough or fibrous samples, for example biological samples such as straw but also, for example, also plastic films, to name just a few examples. Examples of such laboratory cutting mills are, for example, the Pulverisette® 19 and the Pulverisette® 25 from the applicant, to whose basic construction reference is hereby made. Corresponding product descriptions of the Pulverisette® 19 and the Pulverisette® 25 can be found, for example, at www.fritsch.de .

In these granulators, more or less free-flowing bulk goods are typically filled into the grinding chamber, where the cutting rotor rotates horizontally, possibly via a filling funnel. The cutting rotor can have different geometries, for example have so-called V-cutting edges, which have a swirl and therefore a good cutting effect, above all for comminuting tough-elastic materials and foils. This makes it clear that the definition of an essentially axially running cutting edge is not limited to the cutting edge running strictly parallel to the axis of rotation, but should also include obliquely running cutting edges with an axially parallel component. The essentially axially running cutting edges can therefore also run obliquely to the axis of rotation, which corresponds in principle to a helical line. Below the cutting rotor there is typically a sieve, for example a sieve cassette, through which the sample material that is already has been crushed sufficiently, can trickle through to be collected in an underlying collecting vessel. With regard to further design details, which are generally known to the person skilled in this field, reference is made to the applicant's product descriptions for the Pulverisette® 19 and Pulverisette® 25 cutting mills, which can be downloaded at the time of registration and their disclosure at www.fritsch.de , and which are hereby incorporated by reference with respect to the basic construction of such a cutting mill.

With such a cutting mill, the torque is transferred from the motor shaft to a rotor holder e.g. transmitted by means of a feather key. This rotor holder was typically permanently installed in previous cutting mills and could only be removed from the device with extensive disassembly of the device. The rotor holder in these laboratory granulators was typically sealed using felt rings.

The use of a separate rotor holder allows a simple manual insertion of the cutting rotor onto the rotor holder, but in some previously known cutting mills the torque transmission is accomplished relatively far outwards by means of driving pins, which in turn has resulted in sealing being carried out on a relatively large diameter. In relation to a predefined speed, a large diameter of the seal means a relatively high peripheral speed on the seal, which in turn is accompanied by a relatively large amount of heat. Furthermore, in previous cutting mills, the rotor holder was typically not easy to remove for cleaning. In addition, the felt rings used were also not easy to replace. Although the seal using the felt rings has generally proven itself, e.g. Waxes, oils or resins come into contact with the seal and may impair the sealing effect.

However, these felt seals have always proven themselves and have therefore been used for decades. Nevertheless, the sealing concept of a granulator can be improved. In particular, the accessibility of the seal can be further improved.

General description of the invention

It is therefore an object of the invention to provide a cutting mill of the type mentioned at the outset which is easy to maintain and / or which can be cleaned particularly well in the region of the rear wall of the grinding chamber and the drive shaft.

Another aspect of the object of the invention is to provide a cutting mill which, despite a possibly high peripheral speed at sealing points, has low heat development in the area of the drive shaft.

Another aspect of the object of the invention is to provide a cutting mill which has a good sealing effect between the grinding chamber and the area of the drive motor.

Another aspect of the object of the invention is to provide a cutting mill which allows improved access to the seal of the drive shaft in the rear wall of the grinding chamber.

The object of the invention is solved by the subject matter of the independent claims. Advantageous developments of the invention are the subject of the dependent claims.

The invention relates to a cutting mill for cutting samples, in particular on a laboratory scale. Cutting mills of this type for cutting specimens work on the scissors principle. The cutting edges of the cutting rotor and the counter cutting edges run essentially axially and radially offset to the axis of rotation of the cutting rotor. The grinding chamber thus preferably has axially offset and essentially axially running counter-knives which interact with the cutting knives of the cutting rotor, such that the samples between the cutting knives of the cutting rotor and the counter-knives are cut according to the scissors principle when the cutting edges of the cutting rotor and the stationary ones Slides slide past each other.

Here, essentially axially running should not be limited to cutting edges that run strictly parallel to the axis of rotation. Rather, the cutting edges can in particular also run obliquely, for example along a helical line, or have a twist. For example, cutting rotors with so-called V-cutting edges can be used, in which the cutting edges are axially offset from the axis of rotation and essentially axially, but obliquely along a helix, so that the cutting edges have a twist. Laboratory granulators of this type are generally known to the person skilled in the art, cf. e.g. www.fritsch.de .

• ein Gerätegehäuse,
• einen insbesondere in dem Gerätegehäuse angeordneten Antriebsmotor und eine Antriebswelle, welche die Motorwelle und ggf. weitere Wellenelemente wie z.B. ein auf die Motorwelle aufgesetztes Rotoraufnahmeelement aufweisen kann,
• eine Mahlkammer mit einem darin angeordneten Schneidrotor zum schneidenden Zerkleinern der Proben in der Mahlkammer.

The granulator includes

• a device housing,
• a drive motor arranged in particular in the device housing and a drive shaft which can have the motor shaft and possibly further shaft elements such as a rotor receiving element placed on the motor shaft,
• a grinding chamber with a cutting rotor arranged therein for cutting comminution of the samples in the grinding chamber.

The cutting rotor, which is driven by the drive shaft, rotates around an axis of rotation within the grinding chamber. The grinding chamber is axial on the motor side, i.e. axially with respect to the axis of rotation or at the motor end, limited by a grinding chamber rear wall. The cutting rotor is preferably largely cylindrical and the motor-side end face of the cylindrical cutting rotor runs parallel to the rear wall of the grinding chamber. The back wall of the grinding chamber has a shaft passage opening through which the cutting rotor can be driven by the drive shaft. In particular, the drive shaft extends through the shaft passage opening in order to rotate the cutting rotor in the grinding chamber. The drive shaft and / or the axis of rotation of the cutting rotor preferably run horizontally and / or the rear wall of the grinding chamber runs vertically.

In contrast to previous cutting mills, the shaft passage opening in the rear wall of the grinding chamber is now sealed using a labyrinth seal. Labyrinth seals are sometimes also called gap seals because they are a non-contact shaft seal. The sealing effect is based on the extension of the flow path through the sealing gap, which increases the flow resistance. This path extension can be achieved, for example, by interlocking shaped elements of the rotor and stator, a so-called intermingling.

The speed of the cutting rotor in the cutting mill can e.g. in the interval from 20 U / min to 5000 U / min, preferably between 50 and 3000 U / min. It has now been found that, in some cutting mills, the radius or circumference of the seals on the rear wall of the grinding chamber is relatively large due to the design, which causes a relatively high peripheral speed on the seal. The use of a labyrinth seal is advantageous, among other things, since it can reduce the heat generation on the rear wall of the grinding chamber.

Another advantage of using a labyrinth seal at this point is that improved access to the area inside and behind the shaft passage opening in the grinding chamber rear wall can be made possible, so that the cutting mill is maintenance-friendly and in particular simplifies cleaning in the region of the shaft passage opening in the grinding chamber rear wall and can be improved. This can e.g. be helpful when crushing oily or resinous samples, as this could, in the case of conventional cutting mills, possibly lead to oil and / or resinous residues being able to diffuse into the area of the seal of the shaft passage opening when crushing the samples.

Another advantage of using a labyrinth seal is its durability and ease of maintenance. Furthermore, the labyrinth seal can be easily installed and removed, e.g. to clean, control and / or replace them.

The grinding chamber of the cutting mill has, at least in some areas, preferably at least at the bottom, a peripheral sieve wall, which separates the grinding chamber from a collecting container, in such a way that the sieve wall directly crushes such sample particles below a particle size predefined by the sieve openings when cutting the samples passes through the sieve openings into the collecting container.

The sieve wall is preferably designed as part of a sieve cassette, the sieve cassette being insertable as a unit below the cutting rotor into the grinding chamber.

The device housing further preferably comprises a closure cover on the end face axially with respect to the axis of rotation. The sealing cover is arranged on the side of the grinding chamber opposite the grinding chamber rear wall and can be opened to open the grinding chamber. When the grinding chamber is open, the cutting rotor and / or possibly other parts such as the sieve cassette and / or the labyrinth seal can be removed from the grinding chamber. This allows the parts to be replaced, e.g. against another cutting rotor and / or another sieve cassette.

The cutting rotor is on the one hand plugged onto the drive shaft and thus mounted on the motor side via the drive shaft, and on the other hand preferably on the side opposite the motor or the labyrinth seal in the openable cover when the cover is closed. For this, the cover can be e.g. include conical counter bearing. This structure enables the components to be easily removed, e.g. for cleaning and replacement.

The cutting rotor can preferably be attached coaxially or concentrically by hand to the drive shaft and can be removed when the sealing cover or the grinding chamber is open. When the cover is opened, the counter bearing is opened and the cutting rotor can then be manually removed from the drive shaft. The cutting rotor is e.g. just plugged onto the drive axle.

The torque is preferably transmitted from the drive shaft to the cutting rotor by a positive coupling when the grinding chamber is closed. For this, e.g. Carrier elements which engage in a form-fitting manner in the cutting rotor when the cutting rotor is placed on the drive shaft in order to transmit the torque to the cutting rotor by means of the driving elements.

According to a preferred embodiment of the invention, the drive shaft is constructed in several parts and comprises at least one primary shaft, which can be directly the motor shaft, for example, and an intermediate piece, the so-called rotor receiving element, placed coaxially on the primary shaft. The rotor receiving element is then coaxial with the primary shaft attached and there are coupling means between the primary shaft and the rotor receiving element, which effect the torque transmission from the primary shaft to the rotor receiving element, for example a feather key. The cutting rotor is plugged onto the rotor receiving element and can be easily removed from the rotor receiving element manually and without tools with the grinding chamber open. The rotor receiving element can also be removed from the primary shaft, a pulling tool possibly being required, for example a central screw for pressing the rotor receiving element off the primary shaft, parts of the labyrinth seal being automatically removed from the rear wall of the grinding chamber if necessary.

Also preferably included is a driver flange which extends around the drive shaft and has a substantially larger diameter than the motor shaft. The driver elements, e.g. Driving pins engage on the one hand in the driving flange and on the other hand in the cutting rotor in order to effect the transmission of torque from the drive shaft to the cutting rotor over the largest possible radius.

The gap dimension of the labyrinth seal is preferably between 0.05 mm and 2 mm, more preferably between 0.1 mm and 0.5 mm, radially preferably in the range of 0.2 mm, axially possibly a little more due to bearing play.

The driver elements are preferably designed as axially extending driver pins, their radially outer boundary being at least 10 mm, preferably at least 15 mm, preferably at least 20 mm or preferably at least 25 mm, e.g. Is 31.5 mm radially from the axis of rotation, whereby a high torque can be transmitted.

The driver flange is preferably designed as part of the rotor receiving element and the rotor receiving element with the driver flange can be plugged onto the primary shaft as a unit. This has proven itself for the transmission of the required torques in the cutting mill.

According to a preferred embodiment of the invention, the driver flange is at least partially arranged within the shaft passage opening. This has proven to be advantageous in terms of size. A relatively large shaft passage opening is required for this, but this is easy to handle with a labyrinth seal.

The labyrinth seal preferably comprises an inner labyrinth ring rotating with the drive shaft and a labyrinth ring cover on the grinding chamber side, an axial end face of the inner labyrinth ring on the grinding chamber side being intermeshed with an axial end face of the labyrinth ring cover on the grinding chamber side.

Furthermore, the labyrinth seal preferably comprises the inner labyrinth ring rotating with the drive shaft and a labyrinth ring cover on the motor side, an axial end face of the inner labyrinth ring on the motor side being intermeshed with an axial end face of the labyrinth ring cover on the motor side.

Such an axial frontal combing is advantageous with regard to the demotability of the labyrinth seal.

The grinding chamber rear wall preferably has an annular recess on the grinding chamber side, in which the labyrinth ring cover on the grinding chamber side is fixed. It is particularly advantageous if the end surface of the labyrinth ring cover on the grinding chamber side is flush with the rear wall of the grinding chamber.

Preferably, the labyrinth ring cover on the grinding chamber side is clamped in the annular recess on the grinding chamber side, so that when the cutting rotor is removed from the drive shaft or the rotor receiving element, the labyrinth seal remains assembled. However, the inner labyrinth ring can always be removed in the direction from the motor to the grinding chamber if the clamping of the labyrinth ring cover on the grinding chamber side is overcome in the annular recess on the grinding chamber side and the labyrinth ring cover on the grinding chamber side with the inner labyrinth ring is pulled off the drive shaft. For this purpose, the rotor receiving element is preferably withdrawn from the primary shaft while overcoming a certain clamping force, the inner labyrinth ring and the labyrinth ring cover on the grinding chamber side is pulled off the drive shaft, e.g. supported on the motor side by the driver flange.

The labyrinth ring cover on the grinding chamber side can be clamped in the rear wall of the grinding chamber or in the annular recess of the rear wall of the grinding chamber on the grinding chamber side, preferably by a positive fit, and can be removed while overcoming the clamping force caused thereby.

The inner labyrinth ring is preferably arranged radially outside on the rotor receiving element, in particular radially outside on the driver flange.

According to a further exemplary embodiment, an air flow generating device is included which generates an air flow through the gap in the labyrinth seal, preferably from the motor in the direction of the grinding chamber. The effect of the labyrinth seal can thereby be improved, in that the diffusion of dirt from the grinding chamber in the direction of the motor area through the shaft passage opening can be reduced.

For this purpose, the inner labyrinth ring can have fan blades, which generate an air flow through the gap of the labyrinth seal when the inner labyrinth ring rotates. The large radius of the seal, which initially appears to be disadvantageous for the seal, proves to be advantageous, since the large peripheral speed associated therewith can have a positive effect on the generation of an air flow.

For example, the fan blades are expediently arranged on the radially outer peripheral wall of the inner labyrinth ring.

An air-supplying ventilation duct is preferably provided between the rear wall of the grinding chamber and the drive motor, e.g. in the motor side of the rear wall of the grinding chamber, through which the air flow is guided in the direction of the grinding chamber through the labyrinth seal.

Alternatively or in addition, a circumferential "open labyrinth" or so-called look-through labyrinth can also be provided. The labyrinth seal in turn includes one with the Drive shaft co-rotating inner labyrinth ring and the shaft passage opening has an inner radial ring wall, within which the inner labyrinth ring is arranged, so that the inner radial ring wall surrounds the inner labyrinth ring in a ring. The open labyrinth or see-through labyrinth is characterized in that either the inner radial ring wall or the outer radial ring wall of the inner labyrinth ring define a meandering shape in axial cross section, but the inner radial ring wall and the outer radial ring wall of the inner labyrinth ring are not intermeshed in such a way that the inner labyrinth ring can still be pulled axially out of the shaft opening.

Preferably the meandering shape of the open labyrinth or look-through labyrinth is radially tapering in axial cross section, e.g. triangular in axial cross-section, possibly triangular tapered.

Experiments have shown that such an open labyrinth or viewing labyrinth or such geometries can produce vortices that can cause air cushions and can thus make it more difficult for dirt to pass through the labyrinth seal.

The invention is explained in more detail below on the basis of exemplary embodiments and with reference to the figures, wherein the same and similar elements are partially provided with the same reference numerals and the features of the different exemplary embodiments can be combined with one another.

Brief description of the figures

Fig. 1

eine dreidimensionale Ansicht einer Schneidmühle auf einem Stativ gemäß einer ersten Ausführungsform der Erfindung,

Fig. 2

eine dreidimensionale Ansicht der Schneidmühle aus Fig. 1 mit geöffneter Mahlkammer,

Fig. 3

eine dreidimensionale Ansicht der Schneidmühle aus Fig. 1 mit geöffneter Mahlkammer und entferntem Schneidrotor, entfernter Siebkassette sowie abgenommenem Mahlkammer-Verschlussdeckel,

Fig. 4

eine dreidimensionale Ansicht des Schneidrotors und der Siebkassette für die Schneidmühle aus Fig. 1,

Fig. 5

eine ausschnittsweise dreidimensionale Darstellung, teilweise geschnitten, des Wellendurchtritts durch die Mahlkammerrückwand der Schneidmühle aus Fig. 1,

Fig. 6

eine Ausschnittsvergrößerung aus Fig. 5 im Bereich der Labyrinthdichtung,

Fig. 7

eine Querschnittsdarstellung der geschlossenen Mahlkammer mit Schneidrotor der Schneidmühle aus Fig. 1,

Fig. 8

eine Querschnittsdarstellung eines vergrößerten Ausschnitts aus Fig. 7 im Bereich der Labyrinthdichtung,

Fig. 9

eine Ansicht des Antriebmotors für die Schneidmühle aus Fig. 1,

Fig. 10

eine Ansicht von unten auf das Rotoraufnahmeelement der Schneidmühle aus Fig. 1,

Fig. 11

eine Querschnittsdarstellung des Rotoraufnahmeelements aus Fig. 10 entlang der Linie 11-11,

Fig. 12

eine Querschnittsdarstellung der Labyrinthdichtung gemäß einer weiteren Ausführungsform der Erfindung,

Fig. 13

eine vergrößerte Darstellung des Ausschnitts A13 in Fig. 12.

Show it:

Fig. 1

3 shows a three-dimensional view of a cutting mill on a stand according to a first embodiment of the invention,

Fig. 2

a three-dimensional view of the cutting mill Fig. 1 with open grinding chamber,

Fig. 3

a three-dimensional view of the cutting mill Fig. 1 with opened grinding chamber and removed cutting rotor, removed sieve cassette and removed grinding chamber cover,

Fig. 4

a three-dimensional view of the cutting rotor and the sieve cassette for the cutting mill Fig. 1 .

Fig. 5

a fragmentary three-dimensional representation, partially cut, of the shaft passage through the rear wall of the milling mill Fig. 1 .

Fig. 6

an enlarged section Fig. 5 in the area of the labyrinth seal,

Fig. 7

a cross-sectional view of the closed grinding chamber with cutting rotor of the cutting mill Fig. 1 .

Fig. 8

a cross-sectional view of an enlarged detail Fig. 7 in the area of the labyrinth seal,

Fig. 9

a view of the drive motor for the cutting mill Fig. 1 .

Fig. 10

a view from below of the rotor receiving element of the cutting mill Fig. 1 .

Fig. 11

a cross-sectional view of the rotor receiving element Fig. 10 along the line 11-11,

Fig. 12

2 shows a cross-sectional illustration of the labyrinth seal according to a further embodiment of the invention,

Fig. 13

an enlarged view of section A13 in Fig. 12 ,

Detailed description of the invention

Referring to the Fig. 1-3 The cutting mill 10 has a device housing 12, from which the parts of the cutting mill are accommodated. The device housing 12 of the cutting mill on a laboratory scale can, for example, be placed on a stand 8 ( Fig. 1 ). In the right part 12a of the device housing 12 there is a commercially available electric drive motor 14 (cf. Fig. 7 . 9 ). In the present example it is in Fig. 9 shown drive motor 14 around a gear motor for a cutting mill 10 with a speed range of 50 to 700 U / min. Another embodiment of the cutting mill 10 works with a drive motor 14 without gear for a speed range from 300 to 3000 rpm (not shown). The grinding chamber is located in the left part 12b of the device housing 16, in which the samples to be comminuted or the ground material can be filled in during operation via a filling funnel 18 through a filling opening 19. The grinding chamber 16 can be opened from the side by opening the grinding chamber cover 20. Furthermore, the grinding chamber 16 can be opened further by opening a grinding chamber side wall, sometimes also referred to as the upper housing part or upper grinding chamber part, in this example the grinding chamber side wall 21, to which the filling funnel 18 is attached. It was pointed out that terms such as "front", "rear" or "side" refer to the point of view and are therefore not to be understood absolutely.

Referring to Fig. 7 the drive motor 14 is flanged with a motor flange 22 to the motor side 24a of the grinding chamber rear wall 24. The motor shaft 26 as the primary shaft runs horizontally and extends through a passage opening 28 in the rear wall 24 of the grinding chamber and extends into the grinding chamber 16. An intermediate shaft piece, which forms the rotor receiving element 30, is placed on the motor shaft 26. The torque transmission between the motor shaft 26 and the rotor receiving element 30 is accomplished by a feather key 32. In this example, the torque is therefore transmitted from the motor shaft 26 directly to the rotor receiving element 30 by means of the feather key 32.

The rotor receiving element 30 has a driver flange 34 on the motor side, the diameter of which is considerably larger than the diameter of the motor shaft 26. Eccentrically arranged driver pins 36 are fastened in the driver flange 34, by means of which the torque transmission to the cutting rotor 38 is accomplished. Due to the relatively large distance of the driving pins 36 from the axis of rotation A, a large torque can be transmitted to the cutting rotor 38. The cutting rotor 38 has corresponding receiving bores 40 for the positive engagement of the driving pins 36 in the cutting rotor 38. In this example, the rotor receiving element 30 and the motor shaft 26 (which can also be referred to as the primary shaft) together form the drive shaft 42 for the cutting rotor 38.

The driver flange 34 of the rotor receiving element 30 or the drive shaft 42 extends at least partially within the rear wall 24 of the grinding chamber or within the passage opening 28. In this example, therefore, the diameter d of the passage opening 28 is also relative large, which in turn requires a relatively large diameter of the seal of the passage opening 28.

In the present embodiment, the grinding chamber rear wall 24 is formed in two parts and consists of a fuselage part 44 made of aluminum and a plate 46 made of stainless steel on or inserted on the grinding chamber side. Weight can be saved on the one hand and aluminum abrasion in the grinding chamber 16 can be largely avoided on the other hand.

The cutting rotor 38 has a cutting rotor core 48 which is plugged onto the drive shaft 42 and has rotor blades 50 running axially on the circumference of the cutting rotor core 48. In the present example, the rotor blades 50 are molded in one piece. The rotor blades 50 can, however, also be produced as separate cutting strips, possibly made of a different material than the cutting rotor core 48, and connected to the cutting rotor core 48. The cutting rotor core 48 can also be formed in two or more parts (not shown). The cutting rotor 38 can also be designed as a disk rotor, optionally with indexable inserts (not shown). The cutting rotor 38 rotates horizontally, that is to say about a horizontal axis A. On the motor side, the cutting rotor 38 is mounted on the drive shaft 42 and is supported on the opposite side by a conical bearing 54, which in turn is rotatably mounted in the grinding chamber sealing cover 20 via ball bearings 56. The cutting rotor 38 can comprise a cone bearing receptacle 55, which can be fastened to the cutting rotor 38 with a central screw 57.

Referring back to the Fig. 2-4 The cutting mill comminutes the ground material or the sample by means of a cutting action between the essentially axially extending cutting edges 50 of the cutting rotor 38 and the likewise substantially axially extending stationary counter cutting edges 52. The cutting mill 10 thus works according to the scissors principle, in which the sample is between a pair of cutting edges 50 , 52 is cut. Here, "substantially axially extending" cutting edge or "axially extending" cutting edge does not necessarily mean that the cutting edges 50, 52 must run exactly parallel to the axis of rotation A, the cutting edges 50, 52 can also run axially obliquely (with twist), as in the case of the in the Fig. 2 . 4 illustrated example of a cutting rotor 38. That in the Fig. 2 . 4 The example shown shows a cutting rotor 38 with so-called V-shaped cutting edges 50. In the sense of a cutting mill Although these cutting edges 50 also run obliquely (with a twist), they still run axially or essentially axially, that is to say in any case not transversely or perpendicularly to the axis of rotation A. The V-shaped cutting edges 50 of the cutting rotor 38 basically run along an acute-angled helical line, but they do on the whole it can still be defined as an axial or essentially axial course. Below the cutting rotor 38 there is a sieve cassette 92, through which the correspondingly sufficiently finely ground material can trickle out into the collecting container 94.

The grinding chamber cover 20 can be opened, which means that the grinding chamber 16 is accessible from the front for removing the cutting rotor 38 when the grinding chamber cover 20 is open. Folding away the milling chamber side wall or milling chamber upper part 21 additionally improves the accessibility of the opened milling chamber 16. When the milling chamber 16 is open, the cutting rotor 38 can be manually removed horizontally from the drive shaft 42. For this purpose, the cutting rotor 38 is only axially attached to the drive shaft 42 and, except for the axial fixation by means of the conical bearing 54, is not axially fixed when the grinding chamber cover 20 is closed. The cutting rotor 38 is only rotationally coupled to the drive shaft 42 via the drive pins 36, but can be removed from the drive shaft 42 without tools after opening the grinding chamber cover 20.

Since a simple manual joining of the cutting rotor 38 to its receptacle is favored with the rotor receiving element 30, the torque transmission by means of the driving pins 36 is relatively far out in this exemplary construction, which means that sealing is carried out on a quite large diameter (cf. Fig. 3 . 5 . 7 . 8th . 10-11 ). The diameter d of the circular ring on which the driver pins 36 are arranged is d = 55 mm in this example, and therefore the external torque-transmitting outer diameter D = 63 mm for a driver pin diameter of 8 mm. In other words, the radially outer boundary of the driving pins 36 is 31.5 mm radially from the axis of rotation (A).

At constant speed, a large diameter for the seal disadvantageously means a relatively high peripheral speed of the seal compared to a seal that would hypothetically be closer to the axis of rotation A. With previous granulators could furthermore, the rotor holder can only be removed with great effort, and typically not for regular cleaning. The seal used to be made with felt rings, for example, which were cumbersome to replace. With these felt rings, it could happen that they could lead to sticking, for example through waxes, oils or resins that can be separated from the regrind.

Referring to Fig. 5-8 The cutting mill 10 according to the invention now has a labyrinth seal 60 which can be easily removed by the user, for example for cleaning. In the example shown, the labyrinth seal 60 has an inner labyrinth ring 62, which in this example is placed as a separate part on the drive shaft 42, more precisely on the driving flange 34. The inner labyrinth ring 62 extends circumferentially completely around the drive shaft 42 or the driving flange 34 and has a projection on its motor-side rear side 62a as the simplest type of meandering shape 64a. Furthermore, the inner labyrinth ring 62 likewise has a meandering shape 64b on its front 62b on the grinding chamber side. The inner labyrinth ring 62 lies radially outside of the torque-transmitting driver pins 36.

However, it is also possible to design the rotor receiving element 30 or the driving flange 34 directly with corresponding labyrinth shapes or meandering on the grinding chamber and / or motor side, i.e. to manufacture the rotor receiving element 30 and the inner labyrinth ring 62 in one piece.

On the motor-side rear side 24a of the grinding chamber rear wall 24 there is a motor-side labyrinth ring cover 66 which is intermeshed with the motor-side rear side 62a or meandering shape 64a of the inner labyrinth ring 62 in order to form a corresponding labyrinth. In the present example, the labyrinth ring cover 66 on the motor side is formed in one piece with the rear wall 24 of the grinding chamber (cf. Fig. 7 . 8th ). However, the labyrinth ring cover 66 on the motor side can also be designed as a part separate from the rear wall 24 of the grinding chamber.

On the front 24b of the grinding chamber rear wall 24, more precisely on the stainless steel facing plate 46, there is a labyrinth ring cover 67 on the grinding chamber side in a corresponding recess 68 in the grinding chamber rear wall 24 or the stainless steel facing plate 46 admitted. In the example shown, the labyrinth ring cover 67 on the grinding chamber side and the grinding chamber rear wall 24 or the stainless steel plate 46 run flush, in order to jointly form an essentially flat inside of the grinding chamber rear wall 24b in the area of the cutting rotor 38.

In the present exemplary embodiment, the rotor receiving element 30 is fastened on the motor shaft 26 by means of a central screw 31, although this is not absolutely necessary depending on the embodiment. Although the rotor receiving element 30 is seated on the motor shaft or primary shaft 26 with a typical transition fit, that is to say clamping tightly, it can still be withdrawn from the primary shaft 26 axially in the direction of the opened grinding chamber sealing cover 20 while overcoming the clamping force, if the the existing screw 31 has been loosened. In the in Fig. 7 . 8th cuts shown, the rotor receiving element 30 has a central bore 33 for the central fastening screw 31. In order to overcome the clamping force of the transition fit for pulling off the rotor receiving element 30, the bore 33 can be designed as a threaded bore with a larger thread diameter. Then, for example, a corresponding threaded screw can be used in the threaded bore 33 for pulling off (not shown).

The inner labyrinth ring 62 and with it on the grinding chamber-side labyrinth ring cover 67 are also pulled off with the rotor receiving element 30, so that thereafter the passage opening 28 in the rear wall 24 of the grinding chamber is relatively easily accessible in a ring around the primary shaft 26, for example in order to clean it. In other words, the rotor receiving element 30 automatically takes the labyrinth ring cover 67 on the grinding chamber side when it is removed from the primary shaft 26. The rotor receiving element 30, the inner labyrinth ring 62 and / or the labyrinth ring cover 67 on the grinding chamber side can then be cleaned, for example in an ultrasonic bath. The labyrinth ring groove 66a on the grinding chamber side in the labyrinth ring cover 66 on the motor side is also easily accessible from the open grinding chamber 16 after the rotor receiving element 30 with the inner labyrinth ring 62 and the labyrinth ring cover 67 on the grinding chamber side has been removed and can also be cleaned.

The labyrinth seal 60 designed in this way is therefore advantageously easy to maintain, since on the one hand it is easy to clean and on the other hand it is very durable because the mutually rotating parts of the labyrinth seal - the inner labyrinth ring 62 rotating with the cutting rotor and the stationary labyrinth ring cover 66 on the motor and grinding chamber side , 67 do not touch, but work on the principle of gap sealing, ie there is an air gap between the interlocked structures. Therefore, the heat development at the labyrinth seal is low despite the relatively large seal diameter at this point, since the labyrinth seal is a non-contacting gap seal and, as long as the gaps remain clean, no increased friction is generated here. Nevertheless, the seal that runs on the rotor receiving element 30 or the driving flange 34, as in previous seals, can run far outside, so that compatibility with previous cutting mills can be maintained. In addition, the parts of the rear wall 24 of the grinding chamber 24 directly facing the grinding chamber 16, that is to say at least the plate 46 and the labyrinth ring cover 67 embedded therein, can be made of stainless steel, so that FDA compatibility is possible.

The sealing effect of the labyrinth seal 60 can now be further improved by further measures.

Referring to the Fig. 5 . 6 A first possible measure for further improving the sealing effect of the labyrinth seal 60 is to generate an air flow from the motor side in the direction of the grinding chamber 16. For example, 62 fan blades 72 can be provided on the circumferential outer side 62c of the inner labyrinth ring. These fan blades 72 can be milled out relatively easily, for example. The air flow or a dynamic pressure is thus generated by the rotor receiving element 30 or the inner labyrinth ring 62 placed thereon. In this regard, the large diameter of the labyrinth seal 60, which is rather problematic because of the high peripheral speeds with regard to the seal, can be used synergistically in a positive manner.

When the inner labyrinth ring 62 rotates, the fan blades 72 therefore generate an air flow and therefore form an air flow generating device 73. However, an external pump would also be conceivable as an air flow generating device 73.

Referring to Fig. 7 the air supply is ensured by an air duct 74 in the motor side 24a of the grinding chamber rear wall 24. The air flow is visualized by arrow 76. As a result, the relatively large motor flange 22 of a commercially available drive motor 14 can still be flanged to the rear wall 24 of the grinding chamber.

The air flow 76 enters through the ventilation duct 74 and through the labyrinth seal 60 from the space surrounding the drive motor 14 outside the grinding chamber 16 into the grinding chamber 16. The “sealing effect” of the labyrinth or gap seal 60 can be further improved by this air flow 76, which is forced by means of the air flow generating device 73.

Referring to Fig. 12, 13 A further possibility for improving the labyrinth seal 60 is proposed below, the basic structure being the same as in FIGS Fig. 1-11 , so that reference can be made to the description here in order to avoid repetitions.

The difference to the embodiment in the Fig. 1-11 with the air flow generating device 73 is based on the fact that the embodiment of FIG Fig. 12, 13 contains additional labyrinth elements 82 (instead of fan blades 72 for generating a forced air flow 76). The inner labyrinth ring 62 used here has meandering shapes 82 on its radially outer circumference 62c. In the present example, the meandering formations 82 are formed by two rings 84, 86 which are triangular in axial cross section. As in the sectional view of the Fig. 12 can be seen, the cylindrical outer surface 62c of the inner labyrinth ring 62 is provided with sharp-edged tips. Due to the rotation of the inner labyrinth ring 62, this geometry can form vortices that can cause air cushions and thus can make it more difficult or prevent the passage of particles from the grinding chamber 16 in the direction of the area surrounding the motor 14. An advantage of this inner labyrinth ring 62 is that it can be manufactured as a pure turned part and does not need to be milled. In the present example, the inner labyrinth ring 62 has meandering projections on its radial outer circumferential side 62c, for example in the form of two axially offset rings 84, 86 tapering radially outward. The inner ring wall 28d of the passage opening 28 surrounding the inner labyrinth ring 62 does not point into the spaces between the projections 84, 86 engaging counter labyrinth rings, so that one can speak of an open labyrinth on the circumferential side or a look-through labyrinth. In other words, the radially outwardly extending annular projections 84, 86 are not intermeshed with corresponding counter-labyrinth elements. Advantageously, the inner labyrinth ring 62 remains axially extractable from the passage opening 28.

Referring to the Fig. 7 . 8th . 12 the labyrinth ring cover 67 on the grinding chamber side is inserted in a form-fitting manner with an O-ring 88 in the recess 68 in the plate 46. The elastic O-ring 88 on the one hand ensures good clamping retention of the labyrinth ring cover 67 in the grinding chamber rear wall 24, but also allows the axial removal of the rotor receiving element 30 together with the inner labyrinth ring 62 and the labyrinth ring cover 67 on the grinding chamber side while overcoming the through the O-ring 88 clamping force caused. The user can pull the parts 30, 62 and 67 out of the passage opening 28 with corresponding axial force to overcome the clamping force of the clamping, so that the passage opening 28 and the motor-side labyrinth ring cover 66 are at least partially accessible from the front for cleaning. In other words, the labyrinth seal 60 can be pulled apart axially relatively easily, in particular by hand, in order to be accessible for cleaning.

In summary, the sealing concept presented here fulfills a number of advantages e.g. compared to previously used felt seals.

The sealing concept is easy to maintain and, on the other hand, hardly requires any maintenance. Nevertheless, the sealing concept keeps dust well in the grinding chamber and allows only a little dust to pass through the labyrinth seal in the area of the drive motor 14. Furthermore, the sealing concept has a low heat development. Nevertheless, the labyrinth seal 60 can run relatively far outside on an existing rotor receiving element 30, which can maintain compatibility with cutting mills of the earlier types.

A particular advantage is the avoidance of material abrasion (with a clean labyrinth) and the possibility of FDA approval, especially if, for example, the parts 62, 66, 67 of the labyrinth seal 60 and the plate 46 are made of stainless steel. The manufacture of such In spite of the relatively large diameter, labyrinth seal 60 has proven to be technologically feasible and in some cases even has surprising advantages. For example, efforts are currently underway in some regions of the world to approve cannabis products for various uses. This has led to increased demand for granulators in cannabis processing. Especially when crushing the oil-containing cannabis flowers, but sometimes also the cannabis leaves, it has been shown that the labyrinth seal proposed here can effectively prevent oiling or resinification of the seal, or at least significantly improve the cleaning options.

It is apparent to the person skilled in the art that the above-described embodiments are to be understood as examples and the invention is not restricted to them, but can be varied in many ways without leaving the scope of the claims. Furthermore, it can be seen that the features, regardless of whether they are disclosed in the description, the claims, the figures or otherwise, also individually define essential components of the invention, even if they are described together with other features.

Claims (15)

Cutting mill (10) for cutting comminution of samples, comprising: a device housing (12), a drive motor (14) and a drive shaft (42), a grinding chamber (16) with a cutting rotor (38) arranged therein for cutting comminution of the samples in the grinding chamber (16), the cutting rotor (38) defining an axis of rotation (A) and the grinding chamber (16) axially on the motor side from a grinding chamber rear wall (24 ) is limited, the grinding chamber rear wall (24) having a shaft passage opening (28) through which the cutting rotor (38) can be driven by the drive shaft (42), the shaft passage opening (28) in the grinding chamber rear wall (24) being sealed by a labyrinth seal (60). Cutting mill (10) according to claim 1,
wherein the device housing (12) comprises an axially end-side closure cover (20) which can be opened in order to open the grinding chamber (16) and in which the cutting rotor (38) is rotatably mounted (54, 54) on the axial side opposite the drive motor (14). 56) is when the closure cover (20) is closed. Cutting mill (10) according to one of the preceding claims,
the cutting rotor (38) being coaxially manually attachable and detachable to the drive shaft (42) when the grinding chamber (16) is open. Cutting mill (10) according to one of the preceding claims,
driver elements (36) are included, which positively engage the cutting rotor (38) when the cutting rotor (38) is placed on the drive shaft (42) in order to transmit the torque by means of the driving elements (36) to the cutting rotor (38) , Cutting mill (10) according to one of the preceding claims,
wherein the drive shaft (42) is constructed in several parts and at least one Primary shaft (26) and a rotor receiving element (30) placed coaxially on the primary shaft (26), and wherein coupling means (32) between the primary shaft (26) and the rotor receiving element (30) are included, which transmit the torque from the primary shaft (26) effect on the rotor receiving element (30). Cutting mill (10) according to one of the preceding claims,
wherein the drive shaft (42) comprises a driver flange (34) which extends around the drive shaft (42) and wherein the driver elements (36) engage on the one hand in the driver flange (34) and on the other hand in the cutting rotor (38). Cutting mill (10) according to one of the preceding claims,
the driver elements (36) being designed as axially extending driver pins, the radially outer boundary of which is at least 15 mm radially from the axis of rotation (A). Cutting mill (10) according to claim 6 or 7,
wherein the driver flange (34) is designed as part of the rotor receiving element (30) and the rotor receiving element (30) with the driver flange (34) as a unit can be plugged onto the primary shaft (26). Cutting mill (10) according to one of claims 6-8,
wherein the driver flange (34) is at least partially arranged within the shaft passage opening (28). Cutting mill (10) according to one of the preceding claims, wherein the labyrinth seal (60) comprises an inner labyrinth ring (62) and a labyrinth ring cover (67) on the grinding chamber side, and wherein an axial end face (62b) of the inner labyrinth ring (62) on the grinding chamber side is intermeshed with an axial end face of the labyrinth ring cover (67) on the grinding chamber side and / or the labyrinth seal (60) having an inner labyrinth ring (62) and one comprises a labyrinth ring cover (66) on the motor side, and wherein an axial end face (62a) of the inner labyrinth ring (62) on the engine side is intermeshed with an axial end face of the labyrinth ring cover (66) on the motor side and wherein the grinding chamber rear wall (24) preferably has an annular recess (68) on the grinding chamber side in which the labyrinth ring cover (67) on the grinding chamber side is fixed and the inner labyrinth ring (62) can preferably be pulled off in the direction from the motor (14) to the grinding chamber (16) and the labyrinth ring cover (67) on the grinding chamber side is clamped in the rear wall (24) of the grinding chamber and when the inner labyrinth ring (62) is removed the labyrinth ring cover on the grinding chamber side ( 67) is released from the clamping in the grinding chamber rear wall (24) and can be removed from the drive shaft (42) with the inner labyrinth ring (62) and wherein the labyrinth ring cover (68) on the grinding chamber side is preferably clamped in the annular recess (68) on the grinding chamber side by means of an O-ring (88) inserted in a form-fitting manner. Cutting mill (10) according to claim 10,
wherein the inner labyrinth ring (62) is arranged radially outside on the rotor receiving element (30), in particular radially outside on the driver flange (34). Cutting mill (10) according to one of the preceding claims,
an air flow generating device (73) is included, which generates an air flow (76) through the gap of the labyrinth seal (60). Cutting mill (10) according to one of claims 10-12, wherein the inner labyrinth ring (62) has fan blades (72) which, when the inner labyrinth ring (62) rotates, generate an air flow through the gap in the labyrinth seal (60) and wherein the fan blades (72) are preferably arranged on a radially outer peripheral wall (62c) of the inner labyrinth ring (62). Cutting mill (10) according to one of the preceding claims,
A ventilation duct (74) is provided between the rear wall of the grinding chamber (24) and the drive motor (14), through which an air stream (76) is guided through the labyrinth seal (60). Cutting mill (10) according to one of the preceding claims, wherein the labyrinth seal (60) comprises an inner labyrinth ring (62), the shaft passage opening (28) having an inner radial ring wall (28d) within which the inner labyrinth ring (62) is arranged, so that the inner radial ring wall (28d) the inner Encloses labyrinth ring (62) in a ring shape, with either the inner radial ring wall (28d) or the outer radial ring wall (62c) of the inner labyrinth ring (62) in axial cross section defining a meandering shape (82, 84, 86), but the inner radial ring wall ( 28d) and the outer radial ring wall (62c) of the inner labyrinth ring (62) are not intermeshed with one another, such that the inner labyrinth ring (62) can nevertheless be pulled axially out of the shaft passage opening (28) and wherein the meandering shape (82, 84, 86) is preferably designed to taper radially in the axial cross section and the meander shape preferably being triangular in axial cross section, possibly triangularly tapering (84, 86).

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