EP2061600B1 - Grinding unit having cooling device - Google Patents

Abstract

The invention relates to a grinding unit (2) for a vibration mill (1), particularly a disk vibration mill, wherein a milling chamber (3) is configured in the grinding unit (2), the chamber being delimited on the side by a grinding wall (4) and comprising a cooling device (38) surrounding the wall. In order to achieve a practical improvement, the cooling device (38) comprises two or more cooling channels (39) abutting the grinding wall (4) from the outside and disposed circumferentially along at least one common circumferential section of the grinding wall (4), wherein adjacent cooling channels (39) are spaced from each other at least circumferentially in section by a circumferentially extending support projection (41). The support projection (41) supports the grinding wall (4) against a housing (11) surrounding it from the outside. The invention further relates to a vibration mill (1), particularly a disk vibration mill, having said grinding unit incorporated.

Description

The present invention relates to a milling unit for a vibrating mill, in particular for a disc vibrating mill, wherein in the milling unit, a grinding chamber is formed, which is laterally bounded by a grinding wall, and comprising a cooling device surrounding the grinding wall. Such device is eg off US 570 2060 known.

Such grinding units or vibrating mills are used, for example, for grinding a sample of pourable, granular ground material in the course of preparation of the sample for desired analyzes, for example for X-ray-based investigations of the elements contained with suitable equipment (eg XRF). Also regrind, which is rinsed by a liquid in the grinding chamber, is conceivable. The sample, which may be, for example, a rock sample, ore, slag, etc., is mixed in the vibratory mill with excipients and ground and then pressed with addition aids to a tablet, which is fed to an analyzer for analysis of the components. The sample must be crushed in such a way that all components give a homogeneous mixture, for which a fine and uniform comminution of the material to be ground in the vibratory mill is essential. Often it is required that after the grinding process, a certain proportion of the particles (for example 90%) must fall below a certain size (for example 32 μm). For a quantitative determination of ingredients it is essential that the analysis is based on a well-defined sample size. For this purpose, a controlled automatic vibratory mill have a metering device for feeding the milling unit with regrind and tools in always exactly defined amount. After an adjustable grinding time (so-called grinding phase), the ground sample material is emptied into a sample collecting container during an adjustable discharge phase. In some compositions of the material to be ground, it may, in particular after the end of the grinding cycle in the automatic discharge to adhesions in the milling unit, in particular in the Austragsbereichen the Grinding vessel, the discharge area and the spout come. As a result, not all of the sample is available for analysis and thus the

Analysis result can be falsified. In addition, there is a risk that the adherences contaminate a subsequent sample and make it unusable for analysis. It has been found that the tendency to build up, especially during prolonged operation of the vibrating mill, may increase as a result of the frictional heat generated and the resulting increase in the temperature of components and the ground material. In this respect, an increase in temperature, in particular with the addition of certain desired grinding auxiliaries, for example on a paraffin basis, can have a disadvantageous effect due to increased adhesions. It should be added that a particularly uneven temperature distribution in the milling unit can also lead to an undesirable geometric distortion, ie to change in shape and position of components. Adhesions as well as shape and position deviations on the grinding chamber bordering the grinding wall are particularly disadvantageous in that the grinding gap formed with a grinding ring or a grinding stone can lose its original parallel boundary which is essential for achieving fine grinding material particles and uniform particle size. In order to counteract heating, a grinding unit mentioned at the outset for a vibrating mill has a cooling device surrounding the grinding wall. In such, out DE 8902514 U1 known vibratory mill, the grinding wall of the grinding chamber is surrounded by an annular flow space, which is bounded by an outer shell and by the upper and lower ends of the flow space bounding bottom and top walls. Although such, over the entire height adjacent to the grinding wall cooling gap promises immediate and uniform cooling, and thus the achievement of very fine and uniform Mahlgutpartikel depending on the material to be ground still be difficult.

On this basis, the invention has the object, advantageously further develop a grinding or vibrating mill of the type mentioned, so that in particular the suitability for the production of small Mahlgutpartikeln is improved with uniform particle size as possible.

The object is achieved according to the invention according to claims 1-12.

In this way, adhesions of the ground grind and temperature-related shape and position deviations in the discharge channel are counteracted. Surprisingly, it has been found that such a supporting projection of the outer housing, which supports the grinding wall from the outside between the cooling channels, has an advantageous effect on the achievable fineness and uniformity of the ground particles. This is attributed to the fact that the cooling effect, also depending on the cross-sectional shape and size of the cooling channels, virtually unchanged remains good, while additionally a - despite cooling - remaining remaining, yet significant distortion tendency of the grinding wall is met. In addition, the back support according to the invention of the grinding wall between adjacent cooling channels, which preferably acts at about half the height of the grinding wall, allow a comparatively short grinding operation without cooling, in which there is no support by the heating otherwise quickly to an approximately barrel-like bulge of the grinding wall would come to the outside. It is preferred that the cooling channels are introduced as cooling grooves in an outer wall surface of a housing part of the milling unit adjoining the grinding wall and the support projection adjoining the grinding wall with its free end is an integral part of the housing part. Such an embodiment is useful when the grinding wall of an abrasion resistant hard and inasmuch as brittle material should exist, while the outer housing part of a cheaper to work on and less notch sensitive material, for example. Steel or light metal, may exist. An expedient embodiment may be that the grinding wall is cylindrical and the cooling grooves are introduced into a cylindrical wall surface of a housing ring of the milling unit adjoining it on the outside. It is also preferred that the housing ring is thermally shrunk onto the grinding wall. Preferably, the outer housing part can be heated prior to assembly and then the grinding wall are inserted into the opening provided for it in the housing part. In the subsequent cooling, the housing part contracts, whereby it comes to an interference fit between the spaced sections of the wall surface, in which the cooling grooves are introduced, and the outside of the grinding wall. Alternatively or in combination, there is the possibility that the grinding wall is glued into the outer housing part. In order to achieve a cooling effect that is as uniform as possible over the circumference, it is preferable for the cooling grooves to extend along a predominant peripheral section, preferably over a circumferential angle of approximately 350 degrees. For example, starting from a common feed section, the cooling grooves may extend to a common, continuous passage section, preferably by means of a radial wall projection of the housing part surrounding the grinding wall, separate drain section. If a cooled liquid, for example water, is supplied through the feed section, it flows in a clear direction through the cooling channels to the discharge section. At the inlet and outlet section can preferably be connected to a cooling unit, which allows circulation of the coolant at a controlled coolant temperature. To achieve favorable flow conditions, the support projection may be interrupted in the region of the inlet section and / or the outlet section. An expedient development is possible in that spaced above in the adjacent from the outside of the vertical grinding wall wall surface of the housing part a circumferential groove with an annular seal, for example, with an O-ring, is provided in each case from the uppermost cooling groove and below the lowest cooling groove. A uniform support of the grinding wall is achieved when the housing part, in which the cooling grooves are introduced, above the uppermost cooling groove and below the lowermost cooling groove preferably on both sides of the annular seals wall portions adjacent to the grinding wall supporting the outside. According to a still further aspect, which may also be independently important, there is the possibility that the grinding unit has a connection for a blowing medium for purifying the discharge channel, preferably for compressed air, which opens for distribution in an annular channel, which from the housing part , in which the cooling grooves are introduced, and is bounded by an adjacent housing portion, so that a narrow annular gap remains as a passage to the discharge channel. The narrow annular gap may have a width of preferably a few or a few millimeter fractions up to possibly a few millimeters in a cross-sectional plane oriented transversely to the circumferential direction. If compressed air is blown into the annular channel, it flows through the narrow annular gap, whereby due to the defined gap width in the discharge channel a desired specific air flow is established, which is advantageous for the blowing out of milling residue. If the small gap width reduced by thermal distortion, the blowing would be difficult or possibly prevented, on the other hand would in a gap widening to blow out favorable flow conditions not reached. The milling unit can be equipped with temperature sensors, which may preferably be arranged in the region of the grinding wall. The sensors can send measurement signals to a control unit of a connected cooling unit in order to keep the temperature of the grinding wall as constant as possible in the course of a regulation by means of an adaptation of the inlet temperature as required. The invention also encompasses a vibrating mill, in particular a disk vibrating mill, comprising a grinding unit that can be excited to vibrate by means of a vibrating drive, wherein the grinding unit realizes one or more of the features described above according to the invention.

Fig. 1

eine Schnittansicht durch die erfindungsgemäße Mahleinheit einer Scheibenschwingmühle in einer bevorzugten Ausführungsform, in ei- ner ersten Betriebsstellung für den Mahlvorgang;

Fig. 2

die in Figur 1 dargestellte Mahleinheit, in einer zweiten Betriebsstellung für den Austragsvorgang;

Fig. 3

eine Seitenansicht der Schwingmühle mit der in den Figuren 1 und 2 gezeigten Mahleinheit;

Fig. 4

perspektivisch als Einzelteil einen im eingebauten Zustand die Mahl- wand umschließenden Gehäusering, in den Kühlkanäle mit einem Stützvorsprung eingebracht sind und

Fig. 5

eine Vergrößerung des Detailausschnitts V aus Fig. 1.

The invention will be described in more detail below with reference to the attached figures, which show a preferred embodiment. It shows:

Fig. 1

a sectional view through the grinding unit according to the invention a disc vibrating mill in a preferred embodiment, in a first operating position for the grinding process;

Fig. 2

in the FIG. 1 shown mowing unit, in a second operating position for the discharge process;

Fig. 3

a side view of the vibratory mill with in the FIGS. 1 and 2 shown milling unit;

Fig. 4

in perspective as an individual part, a housing ring enclosing the grinding wall in the installed state, into which cooling channels are introduced with a supporting projection, and

Fig. 5

an enlargement of the detail V from Fig. 1 ,

FIG. 1 shows in a cross section the upper portion of a vibrating mill 1 according to the invention or a grinding unit 2 according to the invention according to a preferred embodiment. An overall view of the vibratory mill, partly schematically shows FIG. 3 , This is a so-called disc vibratory mill. Theirs in FIG. 1 shown mowing unit 2 represents one of a separate, connected to the milling unit vibratory drive vibratable assembly which includes a grinding chamber 3, which is externally bounded by a cylindrical grinding wall 4. At this bottom side during the grinding operation includes a substantially circular grinding soil 5 at. In this embodiment, a grinding ring 6 and a grinding stone 7, which is a round solid body not cut in the illustration, are located in the embodiment shown. The outer diameter of the Mahlringes 6 is smaller than the inner diameter of the grinding wall 4, and the outer diameter of the grinding stone 7 is smaller than the inner diameter of the Mahlringes 6. The thus formed between the grinding wall 4 and Mahlring 6 Mahlspalt 8 and the Mahlspalt formed between Mahlring 6 and Mahlstein 7 9 allow a lateral relative movement of Mahlring 6 and millstone 7 both to each other and with respect to the grinding wall 4. At the latter includes sealed on the top side a Mahldeckel 10 at. In FIG. 1 , in which the grinding soil 5 is during the so-called. Mahlphase in its upper possible position, the vertical distance between the grinding floor 5 and Mahldeckel 10 is only slightly larger than the height of grinding ring 6 and millstone 7, so just the desired game for the lateral movement arises. To the grinding wall 4 includes radially outside a housing ring 11, which is bolted to the underside with a housing base 12 and thereby connected to a drive flange 13. On the upper side, the housing ring 11 is screwed to a housing cover 14. Its underside has a recess 15, in which edge of a seal 16, in the example chosen an O-ring, and therein a grinder lid 17 are used. By the clamping force of circumferentially distributed cover screws 18, the underside of the housing cover 14, the Seal 16 and the Mahldeckels 17 pressed against the upper end face of the grinding wall 4. The housing cover 14 and the grinding lid 17 have off-center passage openings for forming an entry opening 19. Through this, the grinding stock (not shown) to be comminuted can be filled into the grinding chamber 3 from above, where it is distributed in the grinding gaps 8, 9. If, as described below, lateral oscillatory movements of the grinding elements 6, 7 relative to one another and to the grinding wall 4, the grinding plate 8, 9 change their width locally, whereby the material to be ground between the grinding elements 6, 7 and the grinding wall 4 is ground , The grinding wall 4, the grinding ring 6 and the grinding stone 7 can be made of a particularly suitable, in particular made of an abrasion-resistant hard material, while can be used for the housing ring 11 and the other housing parts and a conventional construction material, eg. Steel or light metal. On the housing base 12, a bracket 20 is screwed on the underside, which carries with its free end a cylinder 21 shown in simplified form, whose upper side protruding piston 22 is fastened by screwing to the grinding base 5 on the underside. The cylinder 21 has two ports 23, 24 for supplying a pressurized fluid, such as air or hydraulic fluid. In the in FIG. 1 shown operating position is supplied through the lower port 24, a pressure medium, which acts on the interior of the cylinder 21, a pressure surface of the piston 22, not shown from below and presses it with the grinding soil 5 up until the grinding soil 5 with a step 25 in limiting positive engagement with the grinding wall 4 occurs. By being in this, in FIG. 1 shown operating position, the stage 25 occurs against a lower chamfer 26 of the grinding wall 4 and a subsequent step 25 adjacent portion of the grinding tray 5 fits into the enclosed by the grinding wall 4 cross-section, the grinding chamber 3 is sealed during the grinding operation along the outer periphery of its grinding floor. FIG. 2 shows comparatively a second operating position in which the upper port 23 is acted upon by a pressurized fluid. In the interior of the cylinder 21, a pressure application surface of the piston 22 is acted upon from above in a manner not shown, so that the piston 22 pulls the grinding base 5 down until it enters a defined positive stop with a collar 27 of the housing base 12. In the lowered operating position shown, between the grinding floor 5 and the grinding wall 4 there is a gap 28 running along the circumference, through which the grinding material crushed during grinding moves into an annular discharge channel 29 and, as a result, vibration excitation up to an outlet opening, as a result of the centrifugal forces occurring in a further vibration excitation 30 reaches an outlet 31. In cross section, the discharge channel 29 is bounded radially inwardly by the grinding base 5, the underside by a resiliently supported thereon seal 32 and the housing base 12 and radially outside of the housing base 12, while at the top of the housing ring 11 and the grinding wall 4 connect. The thus formed cross-section of the discharge channel 29 is offset with respect to the grinding chamber obliquely downward / radially outside.

FIG. 3 schematically illustrates that in the FIGS. 1 and 2 shown mowing unit 2 on the drive flange 13 is supported on the underside by means of spring-damper elements 33 on a solid surface. On the flange 13, which merges into a sleeve 13 'on the upper side, an oscillating drive 34 is flange-mounted on the underside by means of screw connections. In the example chosen, this has a drive motor 35, here an electric motor, on whose shaft 36 rotates in an overlying housing 37 to the shaft 36 off-center, known per se and therefore not graphically illustrated with imbalance or an eccentric. The torsional vibration generated in this way in the drive device is transmitted via the drive flange 13 to the connected entire milling unit 2, including all involved in the grinding process and the discharge of the ground material walls.

Again with respect to the FIGS. 1 and 2 It is shown that the vibrating mill 1 or its milling unit 2 is equipped with a cooling device 38 for the rear or outer cooling of the grinding wall 4. In the example shown, this cooling device has two cooling channels 39, which are directly adjacent to the grinding wall 4 and are spaced apart from each other in parallel. As also shown in perspective in FIG. 4, these are two cooling grooves 39, which are introduced into the wall surface 40 of the housing ring 11 of the milling unit 2 that adjoins the grinding wall 4 on the outside. The cooling grooves 39, which in the example chosen but not necessarily extend parallel to each other over a circumferential angle of about 350 degrees, are spaced apart from each other by means of a likewise circumferentially extending support projection 41 which is rib-shaped. As the FIGS. 1 . 2 show this ring-segment-like support projection 41 in the assembled state in a supporting abutment against the outside of the outer wall 4. Here, the support projection 41 is integral, ie integral part of the housing ring eleventh FIG. 4 also shows that the cooling grooves 39, starting from a common inlet section 42, extend to a likewise common outlet section 44 separated therefrom by a radial wall projection 43 of the housing ring 11. As a result, the inlet and outlet are separated by flow, so that a targeted circulation of sensing means, which is provided, for example. By a equipped with a control or regulation cooling unit, can be forced. FIG. 1 shows that in the feed section 42 (and in the in Fig. 1 concealed drain section) a radial through hole is provided in the thread of a connection for a fluid line or a closure element 45 (as shown) can be screwed. FIG. 4 further shows that the support projection 41 is interrupted in the region of the inlet and outlet sections 42, 44, or ends before these sections. In the FIGS. 1 and 2 It can be seen that in the wall surface adjoining the vertical grinding wall 4 from the outside 40 of the housing ring 11 above the upper cooling groove 39 and below the lower cooling groove 39 per a circumferential groove 46 is provided with a ring seal 47. The housing ring 11, in which the cooling grooves 39 are introduced, has above the upper cooling groove 39 to both sides of the ring seals 47 still wall areas, which abut the outside of the grinding wall 4 from the outside. The FIGS. 1 and 2 show, moreover, that the housing ring 11, in which the cooling grooves 39 are introduced, directly adjoins the discharge channel 29 surrounding the grinding base 5. Combined with FIG. 5 It is clear that the vibrating mill 1 has a connection 48 for a blowing medium, in the selected example compressed air, which opens into an annular channel 49, which of the housing ring 11, in which the cooling grooves 39 are introduced, and bounded by the adjacent housing base 12 is, so that a narrow annular gap 50 is formed as a passage to the discharge channel 29.

All disclosed features are essential to the invention. The disclosure of the associated / attached priority documents (copy of the prior application) is hereby also incorporated in full in the disclosure of the application, also for the purpose of including features of these documents in claims of the present application.

Claims (12)

1. Grinding unit for a vibration mill, in particular for a disk vibration mill, a grinding chamber which is laterally bordered by a grinding wall being formed in the grinding unit, and having a cooling arrangement surrounding the grinding wall, whereby the cooling arrangement (38) has two or more cooling channels (39) bordering the grinding wall (4) from the outside and extending circumferentially along at least one common circumferential portion of the grinding wall (4), adjacent cooling channels (39) being spaced apart from one another, at least over a portion of the circumference, by means of a circumferentially extending supporting projection (41), by means of which the grinding wall (4) is supported against a housing (11) surrounding it on the outside, characterized in that a discharge channel (29), in particular running in an annular manner around the grinding base (5), is provided for the discharge of ground material from the vibration mill (1) and in that the cooling grooves (39) are provided in a housing part, in particular in a housing ring (11), of the grinding unit (2) that is adjacent to the discharge channel (29).
2. Grinding unit according to Claim 1, characterized in that the cooling channels (39) are provided as cooling grooves (39) in a wall surface (40) of a housing part of the grinding unit (2) that abuts against the grinding wall (4) on the outside and in that the supporting projection (41) that abuts against the grinding wall (4) from the outside with its free end is an integral part of the housing part.
3. Grinding unit according to one or more of the preceding claims, characterized in that the grinding wall (4) is cylindrically formed and the cooling grooves (39) are provided in a cylindrical wall surface (40) of a housing ring (11) of the grinding unit (2) that abuts against said grinding wall on the outside.
4. Grinding unit according to one or more of the preceding claims, characterized in that the housing ring (11) is thermally shrink-fitted onto the grinding wall (4).
5. Grinding unit according to one or more of the preceding claims, characterized in that the grinding wall (4) is adhesively bonded into the housing ring (11).
6. Grinding unit according to one or more of the preceding claims, characterized in that the cooling grooves (39) extend along a substantial circumferential portion, in particular over a circumferential angle of approximately 350 degrees.
7. Grinding unit according to one or more of the preceding claims, characterized in that the cooling grooves (39) extend from a common inflow portion (42) to a common outflow portion (44), which is separated from said inflow portion in terms of throughflow, in particular by means of a radial wall projection (43) of the housing part surrounding the grinding wall (4).
8. Grinding unit according to one or more of the preceding claims, characterized in that the supporting projection (41) is interrupted in the region of the inflow portion (42) and/or the outflow portion (44).
9. Grinding unit according to one or more of the preceding claims, characterized in that a circumferential groove (46) with a ring seal (47) is respectively provided in the wall surface (40) of the housing part that abuts against the grinding wall (4) from the outside, above the uppermost cooling groove (39) and below the lowermost cooling groove (39).
10. Grinding unit according to one or more of the preceding claims, characterized in that the housing part in which the cooling grooves (39) are provided, has above the uppermost cooling groove (39) and below the lowermost cooling groove (39), wall regions which abut against the grinding wall (4) from the outside.
11. Grinding unit according to one or more of the preceding claims, characterized in that the grinding unit (2) has a connection (48) for a blowing medium, in particular compressed air, for blowing out the discharge channel, which connection opens out into an annular channel (49), which is bordered by the housing part in which the cooling grooves are provided and by an adjacent housing portion, so that a narrow annular gap (50) remains as a passage to the discharge channel.
12. Vibration mill, in particular a disk vibration mill, having a grinding unit that can be made to vibrate by means of a vibratory drive, characterized in that a grinding unit according to one or more of the preceding claims is provided.

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