EP0658379A1 - Roller mill - Google Patents

Abstract

The roller mill has a grinding roller (1, 2) which revolves in a grinding ring (3, 4), the diameter of the grinding roller corresponding to at the least the inside radius of the grinding ring. The grinding roller (1, 2) is kept in motion by a tangential force from a drive (7). To this end, the drive (7) drives a drive table (20) to which two parallel stop beams (21) are fastened. Projecting between these beams is a stop body (23) which transmits the force to the grinding roller. The grinding roller (1, 2) and the grinding ring (3, 4) are each suspended on three universal shafts (6 and 5 resp.) and can be deflected laterally. This arrangement ensures that the centre of gravity of the grinding roller always revolves in the grinding ring at a constant revolving frequency. In addition, the suspension of the grinding roller by universal joints guarantees that its rotary impulse does not change during the revolving so that the torques acting on the mill housing remain small. <IMAGE>

Description

The invention relates to a roll mill according to the preamble of the first claim.

Mills of this type with a grinding roller that rolls in a cylindrical grinding ring surface and in which the diameter of the grinding roller corresponds at least to the radius of the grinding ring surface are e.g. known from WO 87/06500 and FR-349 886. Various advantages result from the use of such a large grinding roller. In particular, the rolling resistance is reduced compared to non-generic solutions with several smaller grinding rollers arranged on one level, such as those e.g. in EP-A-0 102 645 are considerable. In addition, the mechanical structure becomes simpler because e.g. less storage is required and the system becomes less sensitive to hard foreign objects such as e.g. Metal. In the previously known devices of this type, the grinding roller was generally pivotally suspended and brought to rotation about its own axis by a drive. This led to a rolling movement of the grinding roller on the cylindrical grinding ring surface.

However, these known mills could not prevail in practice because they have various disadvantages. In particular, it has been shown that the rotational frequency of the center of gravity of the grinding roller in the grinding ring surface (and thus also the centrifugal or pressing force) depends strongly on the diameter of the grinding roller for a given drive speed. This effect becomes noticeable with increasing wear of the grinding roller. However, since the pressing force of the grinding roller against the grinding ring surface should remain essentially constant during operation, very complex speed controls and gears for the drive and continuous monitoring of the rotational frequency of the grinding roller are necessary in systems of this type.

Therefore, the task is to provide a roll mill of the type mentioned, which does not show these disadvantages of the known devices. Furthermore, the roller mill should be as simple as possible to construct and be as robust as possible.

This object is achieved by the roll mill described in the first claim.

According to this solution, the drive does not directly cause the grinding roller to rotate about its own axis, but rather drives it by means of a tangential force component to circulate in the grinding ring surface so that it rolls on it. As a result, the rotation frequency of the grinding roller center of gravity can be controlled directly by the drive frequency and is no longer dependent on the grinding roller diameter. The centrifugal resp. The pressing force of the grinding roller on the grinding ring surface is therefore also much less dependent on the grinding roller diameter and changes only slightly when the grinding roller is worn.

The grinding ring surface and / or grinding roller are preferably mounted such that they can be deflected laterally. As a result, the grinding ring surface performs a lateral pendulum movement during operation, the common center of gravity of the grinding roller and grinding ring surface being practically not deflected. In this way, the load on the frame of the mill is reduced.

It is advantageous to mount the grinding roller in such a way that the direction of the grinding roller axis remains essentially constant during the rotating movement. This avoids a periodic change in the angular momentum of the grinding roller. In the known systems, where the grinding roller generally pivots during rotation, its angular momentum is constantly changed. This leads to considerable torques, which can hardly be absorbed, especially at high speeds and large grinding roll mass.

The grinding roller is preferably held by a grinding roller table which is gimbally attached to the grinding ring is. The grinding roller table is driven by the drive in a circular movement around the mill axis. Thus, the grinding roller and grinding ring form a jointly mounted unit, the focus of which remains stationary during operation. This reduces the dynamic loads to which the mill frame is subjected.

• Figur 1 einen Schnitt durch eine erste Ausführung der Mühle;
• Figur 2 eine vergrösserte Ansicht des mittleren Teils von Figur 1;
• Figur 3 eine Aufsicht auf die Mahlrollenhalterung;
• Figur 4 einen Schnitt durch die Mahlrollenhalterung der Figur 3;
• Figur 5 eine schematische Ansicht einer Kopplung zwischen Antrieb und Mahlrolle;
• Figur 6 eine alternative Ausführung der Kopplung zwischen Antrieb und Mahlrolle;
• Figur 7 einen Schnitt durch eine zweite Ausführung der Mühle, und
• Figur 8 einen Schnitt durch eine dritte Ausführung der Mühle.

Further advantages and applications of the roll mill according to the invention result from the following description of two exemplary embodiments with reference to the figures. Show:

• 1 shows a section through a first embodiment of the mill;
• Figure 2 is an enlarged view of the central part of Figure 1;
• Figure 3 is a plan view of the grinding roller holder;
• FIG. 4 shows a section through the grinding roller holder of FIG. 3;
• Figure 5 is a schematic view of a coupling between the drive and grinding roller;
• Figure 6 shows an alternative embodiment of the coupling between the drive and grinding roller;
• 7 shows a section through a second embodiment of the mill, and
• Figure 8 shows a section through a third embodiment of the mill.

Figure 1 shows a section through a first embodiment of the invention. This is a mill for grinding gravel and stone, for example for cement production.

The most important parts of the mill are the grinding roller 1, 2, the grinding ring 3, 4, the suspension 5 rsp. 6, the drive 7 with the coupling 8 between the drive 7 and the grinding roller 1, 2.

The grinding roller 1, 2 consists of an outer jacket 1 made of hard steel, for example manganese steel, and a core 2 made of aluminum. He is with a pivot bearing 9 a grinding roller holder 10 connected. This pivot bearing is coaxial to the axis of the grinding roller. The grinding roller 1, 2 is thus rotatable about its grinding roller axis relative to the holder 10. The grinding roller holder is suspended from three schematically shown cardan shafts 6 on the cover 11 of the frame of the mill. Each cardan shaft consists of three rigid parts that are connected by two cardan joints. The use of at least one cardan shaft prevents rotation of the grinding roller holder 10 with respect to the frame of the mill, without the pivoting out of the grinding roller holder to the side being prevented.

The grinding roller holder 10 consists of the supporting structure, as shown in Figures 3 and 4. It has three arms 12 for receiving the cardan shafts. Baffles 13 for guiding the ground material are provided on these arms. The screws for fastening the bearing 9 are inserted in six holes 14. The grinding roller holder serves on the one hand to hold the grinding roller and on the other hand as a distribution plate for the grinding stock falling through the opening 15 (FIG. 1) from above.

The grinding ring 3, 4 can be seen from FIG. 1 outside the grinding roller 1, 2. This consists of an inner layer 3 made of hard steel, the surface of which forms the grinding ring surface 16, and an outer ring 4, which can be made of a softer material. The grinding ring is connected to the cover 11 of the mill frame via three cardan shafts 5 which are offset by 120 ° and are only shown schematically. Here too, the use of at least one propeller shaft prevents the grinding ring 3, 4 from rotating against the mill without a lateral deflection of the ring being impeded.

A cylindrical guide plate 46 is provided on the grinding ring, which prevents ground material from falling laterally over the grinding ring.

A rubber ring 17 is arranged outside the grinding ring. This acts as damping in the event that the grinding ring is deflected too much. Such strong excursions can occur in a low speed range when starting up and / or running down the mill if the rotational frequency corresponds to the natural vibration frequency of the pendulum body.

The motor 7 here is a three-phase motor with 30 kW power. It is connected to the axis 19, which rotates the drive table 20, via a gear mechanism (not shown in detail) or only a coupling 18 of a known type.

As can best be seen from FIG. 2, two stop bars 21 running parallel to one another are arranged on the drive table. Between these beams, a guideway 22 runs radially on the drive table. A stop body 23 projects into this and is axially connected to the grinding roller 1, 2 via a rotary bearing 24. Seen from above, the stop body 23 used here has a rectangular cross section and has lateral slide bearings 25 (e.g. made of Teflon or nylon).

The three-dimensional arrangement of the stop bars 21 and the stop body is schematically illustrated again in FIG. 5. In this figure, details that are insignificant in this context have been omitted. It shows a view of the drive table 20 on which the stop bars 21 run. The stop body 23, which is shown here in broken lines and without its suspension arranged above it, projects from above between the stop beams. A deflection bearing 26 is also fastened between the stop beams, which forms a radial stop for the stop body 23 and deflects it out of the mill axis 27 in the rest position. This ensures that the mill starts up safely. As soon as the drive starts to move, the stop body 23 will move outward in the guideway along arrow A and move slightly upward until the grinding roller touches the grinding ring surface.

In this version, the coupling between drive and grinding roller must be such that it is a tangential force component in the direction of rotation of the drive table is able to transfer, but does not hinder a deflection of the grinding roller to the side and upwards. Instead of the stop bar 21 and the stop body 23, a rope rope can also be used, for example, as a coupling between table 20 and grinding roller. Chain arrangement can be used. Other couplings, such as oil coupling or magnetic coupling, are conceivable. It is important that the transmission of a force component tangential to the mill axis 27 is possible.

Figure 5 also indicates the course of a compressed air line 28. This is part of an overpressure system by means of which dust is kept away from the bearings. The compressed air is for this purpose as shown in Figure 2 via a hose 29 to the gearbox. the clutch 18 out. From there it reaches openings 32 on the drive table via openings 30 and an annular channel 31. From there it is guided via the flexible hose 28 into the space 33 below the grinding roller 1, 2, from where it can reach the bearings 9 and 24. In this way, all sensitive parts of the mill are under pressure and the ingress of dust can be prevented. The mill's pressurized system is isolated by suitable seals of known type.

Figure 6 shows an alternative embodiment of the coupling between the drive and grinding roller. Instead of the stop bar 21 and the stop body 23, the grinding roller (not shown) and the drive table 20 are connected here via an articulated rod 40. At its upper end, the rod 40 is fastened to the pivot bearing 24 'via a hinge joint 41 with a horizontal tilt axis. This pivot bearing replaces the bearing 24 in FIG. 2 and allows the grinding roller to rotate relative to the rod 40. At its lower end, the rod 40 is fastened to a lower pivot bearing 43 via a second hinge joint 42. This pivot bearing 43 is connected to the drive table 20. The pivot bearing 43 allows the rod 40 to follow radial movements of the center of the grinding roller. The hinges 41 and 42 allow the rod 40 to compensate for vertical movements of the grinding roller.

In operation, the regrind is introduced through the opening 15, lands on the grinding roller holder 10 and is laterally thrown off by this. Lateral material cones 35 form and the material falls into the gap 36 between the grinding roller and grinding ring. The rotational speed of the grinding roller is chosen so high that material falling through the gap 36 is reliably grasped and ground in one circulation of the grinding roller, i.e. that the minimum fall time through the gap is greater than the round trip time of the grinding roller. The ground material then falls through a cylindrical space 37 outside the motor and leaves this space through floor openings (not shown).

A second embodiment of the mill results from FIG. 7. This mill has the same basic structure as that according to FIG. 1 with grinding roller 1, 2, grinding ring 3, 4, drive 7 and coupling 8 between drive 7 and grinding roller 1, 2. Purpose of the coupling 8 in turn lies in exerting a force on the grinding roller 1, 2 which is tangential with respect to the grinding ring surface and perpendicular to the grinding ring axis, so that it is driven to rotate in the grinding ring.

In contrast to the embodiment according to FIG. 1, however, the grinding roller 1, 2 is not suspended directly on the mill frame. Rather, it rests rotatably about a bearing 50 via an eccentric member 55 on a round eccentric plate 51. The eccentric plate 51 in turn lies on a table 52. The eccentric plate 51 is held laterally by guides 53 and can rotate about the eccentric axis 54.

The table 52 rests with an axle piece 56 in a pivot bearing 57, via which it is connected to a holder 58. This holder 58 comprises radial struts 59 and a cylindrical jacket 60. The cylindrical jacket 60 is fixedly attached to the grinding ring 3, 4.

The axis piece 56 of the table 52 is also connected to the drive 7 via a cardan shaft 70. Alternatively, the drive 7 can be flanged directly to the holder 58.

A distribution table 62 is provided above the grinding roller 1, 2 and is connected via radial plates 63 to a frustoconical holder 64 which also carries the filler neck 65. Bracket 64 forms a wall that prevents material from falling over the outer edge of ring 3, 4.

In operation, the motor 7 drives the drive table 52 via the cardan shaft 70. As a result, it rotates about the central axis of the grinding ring 3, 4. The eccentric plate 51 thus runs eccentrically around the central axis. It will orient itself in its guides 53 in such a way that the eccentric member 55 is guided so far away from the central axis that the grinding roller 1, 2 comes into contact with the grinding ring 3, 4. Due to the centrifugal action, the grinding roller 1, 2 is pressed against the grinding ring 3, 4 and rolls on it.

A third and currently preferred embodiment of the mill is shown schematically in FIG. This mill also has the same basic structure as that according to FIGS. 1 and 7 with grinding roller 1, 2, grinding ring 3, 4, drive 7 and coupling 8 between drive 7 and grinding roller 1, 2. The purpose of the coupling 8 is, in turn, one with respect to the The grinding ring surface exerts tangential force on the grinding roller 1, 2 so that it is driven to rotate in the grinding ring.

As in the embodiment according to FIG. 7, the grinding roller 1, 2 is attached to the grinding ring 3, 4 here. For this purpose, the grinding roller has a central rotary bearing 50, via which it is connected to the roller table 52 '. Roller table 52 'and grinding roller 1, 2 can be rotated coaxially against one another. The roller table 52 'rests on three or four cardan shafts 75, of which only two are indicated in a schematic manner in FIG. 8. The cardan shafts 75 are mounted on support elements 76 which are firmly connected to the outer part 4 of the grinding ring. So make up Grinding roller 1, 2 and grinding ring again a dynamic unit with a common gimbal 5.

The motor 7 is firmly connected to the mill frame. A motor table 76 rests on the motor axis 19. Between the motor table 76 and the roller table 52 'there is a cable coupling 77-79. This comprises a first anchoring pin 77, which is eccentrically attached to the motor table, a second anchoring pin 78, which is attached to the roller table, and a movable one Rope 79 connected to both anchoring pins. The mutual position of the anchoring pins and the length of the rope are dimensioned such that the roller table 52 'is pulled along a circular path around the mill axis by the rotary movement of the motor table 76. The radius of this circular path is so large that the grinding roller 1, 2 comes into safe contact with the grinding ring 3, 4 and can roll on it.

Instead of the cable coupling 77-79, one of the couplings according to FIG. 5 or 6 can also be used.

Furthermore, the motor 7 can also be arranged outside the axis of the mill by moving the motor 7 and the coupling 77-79 in parallel. The radius r of the grinding roller is 35 cm when new, the inner radius R of the grinding ring is 40 cm. The roller and ring wear during operation, so that in extreme cases r = 30 cm and R = 45 cm.

Thanks to the drive, which acts directly on the orbital movement of the grinding roller center of gravity in the grinding ring, the rotational frequency of the grinding roller center of gravity in the grinding ring remains constant, since it corresponds to the rotational frequency of the drive table. Thus, the pressure of the roller on the ring changes only slightly depending on the wear of the roller and ring. In the present example, the speed of the drive is 750 revolutions per minute.

In the present design, the rotational frequency F of the grinding roller center of gravity in the grinding ring is equal to the rotational frequency of the drive table, respectively. Drive. The rotational frequency W of the grinding roller around itself is however not the same as F resp. f, but strongly depends on the ratio r / R. If r / R goes towards one, F / W becomes very big. However, this does not interfere with practical operation.

gegeben, wobei f die Drehzahl des Motors und der Rolle ist. Hier ist also bei grossem Radius r der Rolle (r ungefähr gleich R) die Umlauffrequenz F des Rollenschwerpunkts stark von der Abnutzung der Rolle und des Rings abhängig und sehr viel grösser als die Antriebsfrequenz f. Um gleichmässige Mahlbedingungen zu erreichen, müssen deshalb diese bekannten Mühlen mit einem regelbaren Antrieb und einer grossen Untersetzung versehen werden, was bei grösseren Anlagen, wie sie z.B. bei der Zementherstellung verwendet werden, erhebliche Probleme und Kosten mit sich bringt. Diese Probleme treten bei der erfindungsgemässen Mühle nicht auf.In contrast, in the known arrangements according to the prior art, as described, for example, in WO 87/06500, the rotational frequency F of the center of gravity of the grinding rollers in the grinding ring is given by the formula $\text{F = fxr / (R - r)}$

given, where f is the speed of the motor and the roller. Here, with a large radius r of the roller (r approximately equal to R), the rotational frequency F of the roller center of gravity is strongly dependent on the wear of the roller and the ring and is much larger than the drive frequency f. In order to achieve uniform grinding conditions, these known mills must therefore be provided with a controllable drive and a large reduction, which brings considerable problems and costs with larger plants, such as those used in cement production. These problems do not occur in the mill according to the invention.

Claims (11)

Roll mill with a grinding roller (1, 2), an essentially cylindrical grinding ring surface (16) and a drive (7, 8), the grinding roller (1, 2) having a diameter which is approximately the same size as or greater than the radius of the Milling ring surface (16), and wherein for grinding, the grinding roller (1,2) rotates about a grinding roller axis and rolls on the grinding ring surface (16), characterized in that the grinding roller (1,2) is freely rotatable about the grinding roller axis and that a force component that is tangential with respect to the grinding ring surface (16) can be exerted on the grinding roller (1, 2) by means of the drive (7, 8). Rolling mill according to claim 1, characterized in that the grinding roller (1,2) and the cylindrical grinding surface (16) are laterally deflectable. Roll mill according to claim 2, characterized in that the grinding roller is mounted in such a way that the direction of the grinding roller axis remains essentially the same during grinding. Roll mill according to one of the preceding claims, characterized in that the grinding roller (1, 2) is held by a grinding roller table (52; 52 '), the grinding roller table (52) being rotatably arranged on a grinding roller table holder (58; 75, 76) and the grinding roller table holder (58) being stationary with respect to the grinding ring surface (16). Rolling mill according to claim 4, characterized in that the grinding roller table (52 ') can be driven for a circular movement about the central axis of the grinding ring (3, 4). Rolling mill according to one of the preceding claims, characterized in that it has a fixed has standing frame (11) and that the grinding ring surface (16) is formed by the inside of a grinding ring body (3, 4), the grinding ring body (3, 4) essentially not being rotatable against the frame (11). Roll mill according to one of the preceding claims, characterized in that the grinding roller (1, 2) is connected to a rotating drive shaft (19, 20) via a coupling means (8), the grinding roller (1, 2) being opposite the coupling means (8) is rotatable. Roll mill according to claim 7, characterized in that the coupling means (8) has at least two stop bodies (21, 23), of which a first one (21) with the drive shaft (19, 20) and a second one with the grinding roller (1, 2) is connected, the tangential force component being transferable via the stop body (21, 23). Roll mill according to claim 7, characterized in that the coupling means has a coupling member (40) which, via a first joint arrangement (24 ', 41) with the grinding roller (1, 2) and via a second joint arrangement (42, 43) with the drive axis (19, 20) is connected. Roll mill according to claim 7, characterized in that the coupling means (8) has a grinding roller table (52) which is connected to the grinding ring in a rotationally fixed but laterally deflectable manner and which can be driven on a circular path around the central axis of the grinding ring (3, 4). Roll mill according to one of the preceding claims, characterized in that in a rest position of the roll mill, the grinding roller (1, 2) is deflected from the center of the grinding ring surface.

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