The invention relates to a lever system for force transmission for a grinding roller according to the preamble of claim 1.
Lever systems of this type are used in particular in roller mills or vertical mills for the comminution of grinding material such as cement clinker or coals.
With regard to such vertical mills reference is made to WO 2005/028112 A1 for example.
In
The lever system 50 customarily employed so far has an upward-protruding rocking lever fork 53 which is supported on a rocking lever axis 54 and in operation firmly is connected to an L-shaped central rocking lever 52. The central rocking lever 52 accommodates the axis of the grinding roller 51 which is supported at the end facing towards the grinding table.
The rocking lever fork 53 which extends in the downward direction and is slightly bent towards the center of the mill is connected on both sides at the lower end to a respective hydraulic cylinder 56, 57 by way of hinge eyelets 67. Together with the pump units 63 and the accumulator units 64 these hydraulic cylinders 56, 57 form the hydropneumatic spring system for the grinding roller 51. To increase the compressive forces of the grinding roller 51 onto the corresponding grinding material the hydraulic cylinders with their piston rods and the connection via the hinge eyelets 67 act by applying tensile forces onto the rocking lever 53 and thus onto the grinding roller, whereby, in particular, cracks and fractures can appear in the rocking lever due to the forces occurring.
In their hitherto existing design the known lever systems are integrated in mill stands 60 of steel so that in a vertical mill with four grinding rollers four mill stands 60 with corresponding lever systems 50 are arranged equidistantly around the grinding table of the vertical mill.
The drawback with this known lever system is the relatively great effort and the high costs that arise in particular due to a cast rocking lever fork and the design of the hydropneumatic spring system. Likewise, the hitherto employed principle of applying tension to the rocking lever to increase the compressive forces onto the grinding roller requires improvement. In the case of a necessary dismantling of the rocking lever fork 53 this requires a considerable amount of work as this usually necessitates drilling out of the rocking lever axis 54. In addition, accessibility and handling of the structural components integrated in the mill stand of previous lever systems also appears to be in need of improvement.
Therefore, the object of the invention is to overcome the drawbacks of previous lever systems for grinding rollers and thereby be more cost-efficient as well as easier in terms of installation and maintenance.
In accordance with the invention this object is achieved by a lever system for the force transmission onto a grinding roller having the features of claim 1.
An essential core idea can be seen in the fact that a rocking lever fork hitherto used for the force transmission onto the grinding roller is abandoned and instead provision is made on the central rocking lever for an eccentrically arranged side lever having a lever arm which extends in the opposite direction to the grinding roller and at the end of which the force coupling to the piston rod of a hydraulic cylinder is provided. In this case, the arrangement between the hydraulic cylinder and the end of the side lever is realized such that the piston rod of the hydraulic cylinder can act in a substantially perpendicular manner onto the end of the lever arm of the side lever facing away from the grinding roller.
With regard to the ability of the grinding roller to swing out from its normal operating position in the region of the grinding track of the mill into an approximately vertical position of the grinding roller axis for maintenance or repair purposes the side lever is arranged such that it can be easily uncoupled from and coupled to the central rocking lever.
Furthermore, one proceeds by placing the rocking lever axis and the hydraulic cylinder on a bearing pedestal, in particular on a stepped concrete pedestal. In this way, a relatively cost-efficient bearing block for the rocking lever axis and the hydraulic cylinder is accomplished, in which case this relatively open arrangement brings about improvements with regard to maintenance, installation and dismantling of structural components rather than integrating the lever system into a largely closed mill stand and placing essential structural components and modules externally of supporting structures for better accessibility.
The lever system according to the invention can also be referred to as tilting lever concept since a force is applied to the side lever in a largely perpendicular or vertical manner by means of the hydraulic cylinder. This also allows relatively easy modification of the grinding force which acts on the grinding material during operation and consists of a combination of the weight force of the grinding roller and the hydraulic force additionally generated by the hydraulic cylinder. The hydraulic cylinder is preferably arranged on a concrete pedestal of the lower mill part. This arrangement of the hydraulic cylinder with coupling to the side lever and the central rocking lever enables a functioning as a pressure cylinder during grinding operation, as opposed to most conventional mills, in which the cylinder is pressurized on the side of the piston rod and therefore operates as a tension cylinder.
Due to the fact that during grinding operation a force is applied to the lower piston-sided cylinder chamber of the hydraulic cylinder it is possible that according to the relation of the piston surface to the surface on the side of the piston rod the hydraulic cylinder can be of smaller and more cost-efficient construction in this corresponding arrangement.
Moreover, on account of the largely perpendicular arrangement of the hydraulic cylinder and its piston rod transverse forces onto the pistons, piston rod guides and pistons and their sealings are prevented which, in the previous conventional inclined arrangement of the hydraulic cylinder(s), could lead to damage on these elements. The design and arrangement according to the invention therefore brings about a reduced load of the piston of the hydraulic cylinder so that the hydraulic cylinder can be of simpler design and designed with less load capacity.
The concept according to the invention thereby also reduces the risk of failure of the entire mill due to a damage on the stated structural components.
Although account must also be taken of the fact that due to the eccentric arrangement of the side lever an uneven load of both bearings of the rocking lever axis in the bearing block is present, according to the invention this unevenness is compensated in that the bearing located on the side of the side lever is designed larger than the bearing which is located opposite the side lever and the design of which can in particular be of smaller, more cost-efficient dimensions than the direct bearing for the side lever. Both bearings are preferably designed as roller bearings.
Due to the arrangement and alignment of the hydraulic cylinder on a concrete pedestal there is also the advantageous possibility to position the necessary pump and accumulator units for the corresponding spring system of the mill locally close, i.e. closely adjacent to the hydraulic cylinder on the concrete pedestal. For this respectively short hydraulic connection between the pump and accumulator units on the one hand and the hydraulic cylinder on the other hand flexible high-pressure hoses can be used due to the locally close set-up, whereby installation times as well as component costs can be reduced considerably.
The lever system according to the invention and the locally close arrangement of essential structural components, such as hydraulic cylinder, side lever and pump and accumulator units, with respect to each other is also aimed at realizing a simplified construction of a mill in its entirety by assigning to each individual roller module a lever and hydraulic system of its own so that laborious pipe connections between opposite grinding rollers can be avoided.
Compensation of the roller forces of opposite grinding rollers during operation of a roller mill and the achievement of an almost even load of slide bearings, in particular the axial slide bearing of the gear transmission positioned below a grinding table of a mill, is implemented in the present concept by means of an electronic regulation of the roller forces, thus allowing the mill's spring system of each individual roller module to be quickly regulated electronically.
In addition, the lever system according to the invention is designed such that a swinging-out of the grinding roller from an operating position in the region of the grinding track into a largely vertical, upward-tilted position can be carried out relatively easily.
For this purpose, a separate unit with hydraulic cylinder and piston rod is arranged on the concrete pedestal in the free region of the central rocking lever which is located laterally with respect to the side lever. To this end, on the free side of the lever system a hydraulic cylinder with a piston rod of greater length is provided, the upper end of which is fastened directly or indirectly on the central rocking lever while the lower base block of the hydraulic cylinder is linked to the concrete pedestal or a stepped region located slightly lower. After a fastening flange of the side lever to the central rocking lever has been released it is then possible, on actuation of the hydraulic swing cylinder, to raise the grinding roller and swing it outwards and upwards at least up to a vertical position.
In a further development of the invention the side lever is expediently designed in a triangular shape or L-shape, with its longer leg being force-coupled to the hydraulic cylinder and aligned approximately parallel to the roller axis. In this case, by an approximately parallel arrangement an angle of 10° to 15° between the longer L-leg and the longitudinal axis of the roller axis is also to be understood.
In the end region of the shorter L-leg of the side lever a force-locked and/or flange-like fastening to the central rocking lever is expediently provided. In this way, a form-locked connection between the side lever and the central rocking lever can be created. Thus, required is only a simple and one-sided release of the corresponding fastening to achieve a swinging-out of the grinding roller so that the effort of dismantling these connection elements as compared to a two-sided arrangement on the rocking lever is reduced considerably.
Furthermore, the eccentric arrangement of the side lever and of the corresponding hydraulic cylinder allow for a better accessibility for the coupling of a separate hydraulic swing cylinder to swing out the grinding roller and for maintenance works in this region.
The invention is explained in greater detail hereinafter by way of a schematic exemplary embodiment, wherein show:
In
The central rocking lever 10 is arranged via a rocking lever axis 9 in a U-shaped bearing block 12 which, in the example, is fastened on a stepped concrete pedestal 25.
In the perspective side view on the lever system 1 according to
The side lever 11 which is of approximately triangular or L-shaped design faces with its longer leg of the L-shape in the opposite direction to the grinding roller 3 or rather its grinding roller axis 6. For the application of force to the side lever 11 provision is made in the end region of the lever arm 13 for a fastening eyelet 18, via which a piston rod 16 of a hydraulic cylinder 15 is in engagement with the side lever 11.
The hydraulic cylinder 15 is fastened by way of a base block 19 on the region of the pedestal 24 of the concrete block.
Furthermore, arranged at a short distance or locally close to the hydraulic cylinder 15 is an accumulator unit 17 which is connected via corresponding high-pressure hoses to the hydraulic cylinder 15 and its cylinder chambers. A pump unit assigned to the accumulator unit 17 is not illustrated in
Since the side lever 11 is attached eccentrically and only on one side of the central rocking lever 10 a free lateral region 27 remains on the other side, in which a hydraulic swing cylinder 30 can be arranged as illustrated in
In
In
Therefore, should it become necessary to swing the grinding roller 3 from the position shown in
The concept according to the invention with the eccentric arrangement of the side lever 11 and the largely perpendicular force coupling of the hydraulic cylinder 15 with piston rod 16 enable on the one hand a relatively simple and reliable pressurization of the grinding roller 3.
On the other hand, opposite the side lever 11 a free lateral region 27 is created, in which a hydraulic swing cylinder 30 to swing out the grinding roller 3 can be arranged relatively easily and quickly, in which case the installation and dismantling of these structural components on the open concrete pedestal 25 can also be handled well because use is not made of the integration of the entire lever system into a largely closed mill stand, as it is conventionally the case.
Moreover, the abandoning of a hitherto employed rocking lever fork, specifically consisting of cast material, and, in lieu thereof, the utilization of a side lever, consisting of a steel plate where appropriate, leads to a significant cost reduction.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/058516 | 4/4/2019 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2020/200455 | 10/8/2020 | WO | A |
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Entry |
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Number | Date | Country | |
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20220032311 A1 | Feb 2022 | US |