EP2888051A2

EP2888051A2 - Grinding device

Info

Publication number: EP2888051A2
Application number: EP13750882.6A
Authority: EP
Inventors: Ralf Haase
Original assignee: GBF Gesellschaft fur Bemessungsforschung MbH
Current assignee: GBF Gesellschaft fur Bemessungsforschung MbH
Priority date: 2012-08-22
Filing date: 2013-08-21
Publication date: 2015-07-01
Anticipated expiration: 2033-08-21
Also published as: US9844784B2; DE102012107729A1; WO2014029815A3; JP2015526285A; US20150298133A1; WO2014029815A2; CN104703703B; DK2888051T3; JP6261586B2; CN104703703A; EP2888051B1

Abstract

The invention relates to a grinding device (1, 1', 1"), in particular a vertical mill for comminuting a product to be ground, said device having: a) at least two grinding bodies (2, 3) which can be moved relative to one another, said two grinding bodies (2, 3) together forming at least one grinding region in which the product to be ground can be ground by the two grinding bodies (2, 3); and b) at least one contact pressure device (7, 7', 7") having at least one hydraulic cylinder (8) with a cylinder working chamber and having at least one gas spring (9) with a spring working chamber, the cylinder working chamber and the spring working chamber having a fluidic connection. A contact pressure can be applied to at least one of the grinding bodies (2, 3) by the at least one contact pressure device (7, 7', 7"), by means of which pressure the grinding bodies (2, 3) can be pressed towards each other. In order to produce a grinding device (1, 1', 1") that is no longer at risk from unstable vibrational conditions, according to the invention c) the smallest cross-sectional area between the cylinder working chamber and the spring working chamber through which fluid passes is at least 10 % of the cross-sectional area of the cylinder working chamber and/or d) a connecting section extending between a first transitional cross-section of a connecting component, which cross-section communicates with the cylinder working chamber, and a second transitional cross-section of the connecting component, which cross-section communicates with the spring working chamber, has a maximum length of 100 cm.

Description

grinder

description

introduction

The present invention relates to a grinding apparatus, in particular a vertical mill, for comminuting material to be ground, comprising a) at least two grinding bodies which are movable relative to one another, the two grinding bodies jointly forming at least one grinding area in which the ground material can be grinded by means of the two grinding bodies, and at least one pressing device, the at least one a

Cylinder working space having hydraulic cylinder and at least one one

Has spring working space having gas spring, wherein the cylinder working space and the spring working space are fluidly connected to each other, wherein on at least one of the grinding media by means of the at least one pressing a contact force can be applied by means of which the grinding media are pressed towards each other. In the context of the present application, the term "grinding device" is to be understood as meaning only those grinding devices which are suitable for incorporation in

Production processes are provided. In particular, such grinding devices, which are used only for experimental or research purposes, should not be included. In this context, the term "grinding body" can be used to mean both actively active bodies acting on the grinding stock (for example actively driven rolling cylinders of a rolling chair) and passive and optionally stationary bodies, for example merely as a support for the ground material and thus as a counterpart to In any case, a mutual movement of at least two grinding media must take place in order to bring about a grinding success.

With regard to the "fluidic connection" of the cylinder working space with the spring working space, it is basically irrelevant whether this connection is only of one (two-dimensional) flow cross-section, a connecting component - for example in Form of a pipeline - or even formed by a plurality of different connecting components.

The term "cylinder workspace" refers to that space within a

Hydraulic cylinder filled with hydraulic fluid. It is the space in which a piston of the hydraulic cylinder can typically be moved.

The "spring working space" refers to an entire space present in an interior of the gas spring, which is typically partially filled with the hydraulic fluid and further comprises a gas cushion of the gas spring Gas filled the gas cushion.

State of the art

Grinding devices of the type described above have been known for some time and are used in a variety of applications. By way of example, a so-called roller mill and a so-called vertical mill are mentioned here. A roll mill typically has two horizontally oriented rolling cylinders which rotate in opposite directions and form the grinding region at a narrow point where both roll cylinders have a minimal distance from each other or are in contact. The ground material to be ground in each case is passed from an upper side of the grinding area between the two roll cylinders, wherein the individual particles of the ground material flow the

Pass the grinding area and ground. Such grinding devices are used for example for grinding cereals. An exemplary embodiment can be taken from WO 2009/067828 A1, inter alia.

In contrast, vertical mills are mills in which the material to be ground is applied to a grinding plate arranged horizontally and rotating about a vertically oriented axis. In an outer peripheral edge region of the grinding plate, in which the ground material collects due to the centrifugal forces acting, typically several so-called roller mills are arranged, whose grinding bodies are formed by upright rollers whose axis of rotation is oriented horizontally. The grinding area is in this type of mills between a respective underside of the roller and the grinding table, wherein due to the rotation of the grinding table about the vertical axis continuously the material to be ground under the role ago. The roll is pressed in the direction of the grinding table, wherein both the weight of the roll and externally applied by the pressing means applied pressure forces. The material to be ground is ground under this pressure exerted by the roller on the material to be ground. Such vertical mills are typically used in the cement industry. An exemplary embodiment can be taken from DE 10 2008 046 921 A1, inter alia.

In particular, the latter vertical mills are fundamentally subject to the problem in the prior art that they have a strong tendency to fall into an unstable vibration state, which is colloquially referred to in the art as "rumble." In such a state, the grinding device undergoes oscillation, which causes the roll and the grinding table to move in a vertical direction relative to one another, ie the roll is at least raised by the grinding bed formed by the grinding bed (possibly can even lift off) and then returned to this same "push-in" or " In this case, dynamic forces on the order of several Meganewton [MN] act, so that it can be particularly easy to damage the vertical mill

Roller shell, which surrounds the role circumferentially, in this unstable vibration state of a very high load.

In the context of the operation of such grinding devices exists accordingly the effort to avoid these extreme load conditions. Therefore, many are

Monitoring systems installed, which detect certain operating parameters of the mill, from which finally to infer a critical load. As a result, there is a problem that it is implied because of the fear of one

Swinging the system to frequent shutdowns and thus too economical

disadvantageous downtime of the mill comes. In addition, it sometimes happens that the described "rumble" of the mill even occurs despite these monitoring strategies.

The aforementioned DE 10 2008 046 921 A 1 deals, among other things, with precisely this problem and attempts to monitor the grinding device so that critical

Load states are reliably and early detected, the forces acting on the rollers dynamic forces to be detected in certain frequency ranges and a shutdown of the entire grinding device is made when a threshold value is reached. Another document, EP 2 408 565 B 1, also addresses the problem of rumbling mills. The document describes a vertical mill, the pressing device of which is designed as an "open system." That is to say, the pressing device, which is formed by the at least one hydraulic cylinder and the at least one gas spring, additionally has at least one hydraulic pump, by means of which it continuously injects

Oil pressure in the at least one hydraulic cylinder and / or the at least one gas spring can be adjusted. In particular, EP 2 408 565 B1 describes that by means of the action of the hydraulic pump, a lower pressure chamber of the hydraulic cylinder there can be pressurized, which leads to the corresponding roller mill "lifting", that is to say reducing at least one contact pressure of the roller mill, possibly even a contact between the roller mill and the grinding bed is completely lifted, thereby calming the vibrating mill system.

A disadvantage of the latter system, on the one hand, the complexity of the open

Pressure system that relies on the action of a hydraulic pump. On the other hand, the disclosed device as such is not free from the adverse vibration states ("rumble"), but merely provides a system by means of which in the case of Rumpeins the same can be corrected particularly easily.

Nevertheless, EP 2 408 565 B1 also provides an avoidance strategy with respect to rumpein which is based on a pressure adaptation of the roller mills by the action of the roller mills

Hydraulic pump is based, with a pressure adjustment in the opposite pressure chambers of the hydraulic cylinder used there is used. This

Control system is equally complex and sluggish, since a pressure build-up by means of the hydraulic pump as a countermeasure against an adjusting critical

Vibration state takes comparatively much time, whereby a swinging of the mill system in case of doubt can not be prevented in time.

A system, which reliably prevents the risk of Rumpeins ever occurs, is therefore not known in the prior art.

task

Accordingly, it is the object of the present invention, a just such

To cause the grinding device, the risk in the described unstable

Vibration state expires, is no longer subject. solution

The underlying object is achieved on the basis of a grinding device of the type described above according to the invention that c) a smallest durchströmbare cross-sectional area between the cylinder working space and the spring working space at least 10% of a cross-sectional area of the

Zylinderarbeitsraums is and / or d) a connecting path extending between one with the cylinder working space

corresponding first transitional cross-section of a connecting member and a corresponding to the spring working space second transitional cross-section of the connecting member, a maximum of 100 cm long.

The "smallest cross-sectional area" between the cylinder working space and the

Spring working space is always to be understood as the sum of parallel cross-sectional areas which are available to the hydraulic fluid for flowing from the cylinder working space into the spring working space. For example, would be a single spring work space by means of ten parallel connected individual lines in the form of pipes, each having a constant cross-sectional area of 5 cm ² , to the cylinder working space

For the purposes of the present application, the "smallest cross-sectional area" would be calculated as A = 10 - 5 = 50 cm ² , since this is actually the smallest cross-sectional area available to the hydraulic fluid for flow into the spring working space Cross-sectional areas of individual connecting components between a cylinder working space and several spring working spaces, provided that the gas springs are connected in parallel to the cylinder working space.

The present invention is fundamentally based on the finding that the oscillation problem ("rumble") already described above is known

Grinding devices is caused by a stiffening of the entire grinding device. It was further recognized that this stiffening is mainly caused by a stiffening of the pressing device, which is in particular due to the fact that in the field of high-frequency vibrations, which are sometimes subject to the grinding devices in the known according to the prior art grinding devices on the

Hydraulic cylinder connected gas spring can no longer act, that is, in the Hydraulic cylinder existing hydraulic fluid can not flow into the gas spring. In principle, the gas spring serves to provide the hydraulic fluid in the cylinder working space with a compensation chamber into which it can flow as soon as a piston of the hydraulic cylinder is deflected.

The underlying problem is discussed below using the example of a vertical mill in the form of a roller mill:

The piston of the hydraulic cylinder is in a roller mill according to the invention

typically connected directly to a bearing axis of the same and provides significantly for the contact pressure of the roller, which here forms one of the grinding media, on the material to be ground. In a deflection of the role of the roller mill in the vertical direction, as it constantly occurs when rolling over the material to be ground, rises together with the role of the roller mill and their bearing axis and consequently also the piston of the hydraulic cylinder, which consequently in the

Hydraulic cylinder is moved. As part of this movement, the hydraulic fluid is at least partially in the gas spring connected to the cylinder working space

or displaced the spring working space, which is typically permanent in the spring working space of the gas spring and in a connecting cross-section or a connecting member between the cylinder and the spring working space

Hydraulic fluid is located. By introducing additional hydraulic fluid into the gas spring, a gas cushion, which is typically made of nitrogen, compressed in the spring working space and - in addition to the already set bias - formed an additional restoring force. This ensures that the hydraulic fluid tends to flow back into the cylinder working space, the piston of the

Hydraulic cylinder and consequently the roller are pressed back down in vertical direction on the grinding bed.

If, in the course of a grinding process, a strong deflection of the roll of the vertical mill occurs very suddenly, for example when a particularly large particle is being rolled over in the material to be ground, a sudden deflection of the piston in the hydraulic cylinder and, consequently, an acceleration of the piston occur

Hydraulic fluid in the cylinder workspace.

As a result of this acceleration of the hydraulic fluid in the cylinder working space, that hydraulic fluid which has to be accelerated and displaced in the connecting cross-section between the cylinder working space and the spring working space must also be accelerated and displaced analogously located. According to the prior art, this connecting cross-section, which is typically defined by a tubular connecting component, has a considerably smaller cross-sectional area than the cylinder working space (cf., for example, FIG. 1 of DE 10 208 046 92 1 A 1). This "narrowing" of a flow-through cross section (jump from the cross section of the cylinder working space to the connecting member or

Connection cross-section), which is inevitably subject to the hydraulic fluid, has the consequence that in the connection cross-section an antiproportional to the cross-sectional constriction greater flow velocity of the hydraulic fluid must be present. In the present case, due to the high frequency of oscillation occurring, the increase in the

Flow rate directly after it, that the hydraulic fluid in the cross-section must also be correspondingly accelerated. As a result, this acceleration acting on the hydraulic fluid in the connecting section is many times higher than in the cylinder working space.

In order to produce this acceleration, correspondingly large forces are required. However, according to the prior art, only a relatively smaller

Cross-section available, so that the hydrostatic pressure of

Hydraulic fluid only a small "attack surface", namely only the

Connection cross section, available. As a result, as a result, the hydraulic fluid in the connecting cross-section is not accelerated and consequently is not moved, so the spring working chamber is not at all used as a compensation chamber for the

Hydraulic fluid can be activated. At the moment of deflection of the role of

Consequently, this deflection can not be compensated for by means of a movement of the piston, since it remains in its original position at that moment and does not allow any vertical movement of the bearing axis of the vertical mill. Instead, it comes to deformations of the entire foundation on which the

Vertical mill is founded, the extremely high rigidity of the overall system finally cause due to the deflection of the role of the above-described extreme forces that are finally able to cause the damage to be complained of in the prior art. By the invention described above, alternatively or advantageously together trainees this very disadvantageous effect of the known grinding devices is suppressed. It is possible, on the one hand, to set the minimum or minimum cross-sectional area to a minimum value that is at least 10% of the cross-sectional area of the

Work cylinder should make. By defining this "minimum size" of the smallest cross-sectional area, it is ensured that the ratio of the accelerations between the cylinder working space and the connecting cross-section is limited to a maximum value, ie, the necessary force for accelerating the hydraulic fluid in the connecting cross-section is limited to the top in that the resistance of the hydraulic fluid in the form of inertia in the smallest

Cross-sectional area increases beyond a maximum value and stiffens the entire grinding device. This solution is particularly advantageous.

On the other hand, it is alternatively (or additionally) according to the invention equally possible (albeit cumbersome) to limit the link according to the above explanation to the specified maximum length. This happens against the background that with such a short connection route, only a relatively small amount of hydraulic fluid can be present in the connection cross section due to the design. Analogously to the amount of hydraulic fluid is logically also in the

Connection cross-section existing mass thus limited to a small maximum extent. The force [F] that is necessary to move a mass [m] to a specific one

To accelerate acceleration [a], one can determine F = m ^■ a. That is, the necessary force to accelerate the low-mass hydraulic fluid may be applied even if the above-described aspect ratio of the cylinder workspace cross-sectional area to the smallest cross-sectional area between the cylinder working space and the spring work space is below 10%. Line lengths shown in the prior art exceed the values claimed here considerably and do not suggest an understanding of the problem identified here.

Advantageously, said minimum ratio of the invention

Cross-sectional area and the maximum connecting distance between cylinder working space and spring working space combined. A "blockade" or "deactivation" of the gas spring, as occurs in the prior art, as described above by means of the invention

Permanently inhibited grinding device and thus solved the task. In a particularly advantageous embodiment of the grinding device according to the invention, the smallest flow-through cross-sectional area between the cylinder working space and spring working space is at least 20%, preferably at least 50%, more preferably at least 80% of a cross-sectional area of the cylinder working space. These further larger ratios are particularly advantageous for efficient operation of the grinding device according to the invention. In particular, the inertial force occurring at the connection cross-section can be further reduced, which can lead to a far-reaching slimming of the entire grinding device, especially the foundation masses.

In a further advantageous embodiment of the device according to the invention, it is proposed to limit the connection distance to a maximum length of 60 cm, preferably a maximum of 30 cm, more preferably a maximum of 10 cm. Analogous to

As a result of this argument, a further lowering of the inertia forces can be achieved and thus a far-reaching streamlining of the entire grinding device can be achieved. In a further advantageous embodiment of the grinding device according to the invention, it is proposed to form the at least one gas spring from a bladder accumulator. Such memories are particularly easily available and can be installed in retrofit solutions for existing grinding devices at a rational expense.

Particularly advantageous in this context is the provision of a plurality of parallel connected to the hydraulic cylinder gas springs, wherein the parallel connection cross-sections between the cylinder working space and the individual

Working spaces of the individual gas springs to a "cross-sectional area" in the sense of

Claim 1, which is the hydraulic fluid available and on the basis of which the ratio is calculated according to the characterizing part of claim 1. In a particularly advantageous embodiment of the grinding device according to the invention a damper device is provided, by means of which a flow velocity of the flowing between the cylinder working space and the spring working space

Hydraulic fluid can be reduced, preferably a degree of damping of the

Damper device is different in different flow directions of the hydraulic fluid, further preferably the degree of damping in a flow of hydraulic fluid in a direction away from a piston of the hydraulic cylinder direction is greater than in a flow of hydraulic fluid in the reverse direction. The Provision of a damper device is fundamentally advantageous, as caused by the grinding bed or the material to be ground excitation of the role and thus the

Hydraulic fluid are damped and unfavorable vibrations or unfavorable restoring forces can be reduced. Particularly advantageous in this context is the different expression of the rebound and the pressure stage of the damper, so a different expression of the degree of damping achieved by the damper device, which should advantageously be lower in an increase of the role, ie a flow direction of the hydraulic fluid in the direction of the spring working space, than in the opposite direction. In this way, it is relatively "easy" to lift the roll from the grinding bed, but in the return of the roll it is "braked", so that an unnecessarily hard impact of the roll is avoided on the grinding bed. This is particularly useful for minimizing the wear on the vertical mill roll while not unduly deforming the bed as is often the case in the art ("washboard"), and moreover, for maximum flexibility of the mill It is advantageous for the user to be able to configure the damper device, for example, for different millbases or different characteristics of the same millbase this is formed by a breakthrough throttle plate, wherein the damper device

preferably further comprises at least one blocking device which is relative to the

Throttle plate is movable and by means of which the openings of the throttle plate are at least partially closed. Such a damper device is particularly easy to manufacture and particularly easy to adjust by means of the blocking device.

In a particularly advantageous embodiment of the grinding device according to the invention, the hydraulic cylinder and the gas spring are integrated

Running pressing device, wherein the cylinder working space and the spring working space flow into each other, wherein in particular the hydraulic fluid between a piston of the pressing device and a gas cushion of the pressing device is arranged. In this embodiment, the cylinder working space and the spring working space are

geometrically, the same working space, where functionally a subdivision in cylinder working space and spring working space within the meaning of the preamble of claim 1 is still possible. The "smallest cross-sectional area" in the sense of claim 1 is accordingly formed in this embodiment by the cross-section of the cylinder working space or the spring working space itself, so that the ratio of the smallest cross-sectional area to the cross-sectional area of the cylinder working space here is 100%.

This proposed integrated embodiment is particularly easy to implement and is recommended accordingly for newly designed grinding devices.

Furthermore, such an embodiment of the grinding device according to the invention is particularly advantageous, in which the contact force which can be applied by means of the pressing device is variable. This allows a maximum adaptability of the grinding device to each grinding material to be ground.

Furthermore, it is particularly advantageous if the at least one hydraulic cylinder and the at least one gas spring form a closed hydraulic system. A "closed hydraulic system" is understood to mean that an externally applied to the system of the hydraulic cylinder and the gas spring pressure ("bias") is kept constant by the system is closed. A possibility of one

Escape of hydraulic fluid or any other component present in the system is just as impossible as adding one of them. In particular, a closed hydraulic system has no permanently connected to the hydraulic system hydraulic pump, by means of which a constant pressure in the

Adjusting pressing device that is continuously increased or decreased. Although a hydraulic pump is typically present to make a pressure correction if necessary. However, this is decoupled from the hydraulic system, which

usually achieved by means of blocked pressure lines, which are opened only when needed.

In a further advantageous embodiment of the grinding device according to the invention, the at least one hydraulic cylinder has exactly one cylinder working space. Such a hydraulic cylinder is relatively simple and fulfills all the necessary tasks as part of the pressing device. In particular, it is in the inventive

Grinding device not necessary to provide a "lower pressure space" below the piston of the hydraulic cylinder, by means of which the piston by an externally applied Pumping power could be raised in the hydraulic cylinder, whereby at the same time the grinding media would be raised in the form of the role. In the prior art, such constructions are used to avoid the risk of a critical

To take account of vibration state and raise the role of the doubt in their grinding bed. Since the risk of a vibrating grinding device according to the invention is no longer given, therefore, a hydraulic cylinder with two cylinder working spaces is not necessary.

embodiments

The invention described above is explained in more detail with reference to exemplary embodiments which are illustrated in the figures. It shows:

1: a grinding device according to the prior art,

2 shows a first grinding device according to the invention with a plurality of individual

Gas springs,

3 shows a detail of a pressing device of the grinding device according to FIG. 2 FIG. 4 shows another grinding device according to the invention with a plurality of individual ones

Gas springs in the form of bubble stores,

5 shows a detail of a pressing device of the grinding device according to FIG. 4, FIG.

Fig. 6: Another grinding device according to the invention with an integral

Embodiment of a cylinder working space and a spring working space, and FIG. 7: a section through a pressing device of the grinding device according to FIG

FIG. 6.

A first example, which is shown in FIG. 1, shows a grinding device 100 according to the prior art, wherein the illustration according to FIG. 1 is reduced to essential components of the grinding device 100. The grinding apparatus 100 shown here is a so-called vertical mill. This has a total of five grinding bodies 2, 3, wherein four grinding bodies 2 in the form of rollers 4 with the grinding body 3 in the form of a grinding plate 5 cooperate. On the grinding table 5 is to be ground grinding, which is not shown here. The grinding table 5 is driven by means of a drive device, not shown, so that it rotates about a vertical axis. As a result of this movement of the grinding plate 5, the grinding material located thereon is moved in the same way and guided thereby under the rollers 4, whereby they are dragged, that is to rotate solely around the rotation axis of the grinding plate 5 about a horizontal axis of rotation 6. An active drive for the rollers 4 is not

provided, but readily conceivable.

The rollers 4 are by means of a pressing device 101 in a vertical direction

"Prestressed", that is to say they are pressed in the direction of the grinding table 5 or a grinding bed formed by the grinding stock by means of the pressing device 101. Under the pressure of the pressing device 101 and a weight of the rollers 4, the material to be ground is ground on the grinding table 5, wherein the rollers 4 and the grinding table 5, so the

Grinding bodies 2, 3 move relative to each other.

The pressing device 101 has a hydraulic cylinder s, not visible in FIG. 1, and a gas spring 9. Both parts are by means of a connecting member 102nd

fluidically interconnected, which is formed here by a pipe. A spring working space of the gas spring 9 has a gas cushion, which is formed from nitrogen. A cylinder working space of the hydraulic cylinder 8, the connecting member 102, and a part of the spring working space of the gas spring 9 arranged outside the gas cushion are filled with a hydraulic fluid.

If, in the course of an operation of the grinding device 100, a vertical deflection of one of the rollers 4 occurs, a piston of the hydraulic cylinder 8 of the pressing device 101 connected to a bearing axis 1 1 of the roller 4 is moved in the vertical direction. In this case, the piston displaces the hydraulic fluid in the cylinder working space, which then flows at least partially through the connecting component 102 into the spring working space of the gas spring 9. In this case, the gas cushion is compressed in the gas spring 9 and it arises in addition to the aforementioned bias an additional restoring force, which is stored at the moment of compression of the gas cushion as potential energy in the gas. As soon as the roller 4 can move back in the direction of the grinding bed or the grinding plate 5, the hydraulic fluid from the spring working space of the gas spring 9 is pushed back into the cylinder working space of the hydraulic cylinder 8 and the piston of the hydraulic cylinder 8 moves back into its previous position. A smallest durchströmbare cross-sectional area of the connecting member 102 of

Milling apparatus 100 is particularly small in proportion to a cross-sectional area of the cylinder working space and accounts for only a few percent of the same (here about 2%). This conventional implementation of the prior art leads to the problems already described in detail above.

In addition, a connection path extending between the cylinder working space of the hydraulic cylinder 8 and the spring working space of the gas spring 9 within the

Connecting member 102 extends in the example shown in about 200 cm long. As a result, a total of such an amount of hydraulic fluid is collected in the connecting member 102, that for a sudden acceleration of the same a significant

Force would be necessary, which can not be applied due to the only very small available cross-sectional area of the connecting member 102.

As a result, the connection member 102 acts according to the prior art

in a sense like a "plug", which is a flow of hydraulic fluid from the

Hydraulic cylinder 8 to the gas spring 9 in the range of high load frequencies quasi suppressed.

This problem is by means of a first possible embodiment of a

grinding device 1 according to the invention, which is shown in Figure 2, fixed. The grinding apparatus 1 shown here has a pressing device 7, which is mounted on a so-called force frame 1 2, by means of which the forces caused by the pressing device 7 are anchored back in a foundation 22. As in the grinding device 100, the piston of the hydraulic cylinder 8 is mounted on the bearing axis 1 1 of the roller 4 to "depress" the roller 4 by means of the bearing axis 1 1, so to press on the grinding bed.

In the embodiment shown, the hydraulic cylinder 8 extends with a

constant cross-section above the power frame 1 2. At each hydraulic cylinder 8 a total of six gas springs 8 are connected here, each by means of its own

Connecting member 10 with the cylinder working space of the hydraulic cylinder eighth

are fluidically connected. The connection components 10 can be seen particularly well in a detailed illustration according to FIG. The individual connecting components 10 are approximately similar in terms of their smallest cross-sectional area to the connecting member 102 of the grinding device 100. However, here, in contrast to the known in the prior art grinding device 100 a plurality of connecting components 10 are connected in parallel, so that the hydraulic fluid in the course of a Piston movement out of the Hydraulic cylinder 8 is displaced, a total of a cross-sectional area is available, through which it can escape from the cylinder working space, which corresponds six times a single cross-sectional area of each connecting member 10. In this way, in the embodiment shown, an area ratio of the smallest cross-sectional area (equal to six times the smallest cross-sectional area of the six individual connecting members 10) between the cylinder working space and the spring working space to the

Cross-sectional area of the cylinder working space of about 40% achieved.

As a result of this considerable enlargement of the flow-through cross section according to the invention, the above-described "blockage effect" or the

Stiffening effect of the connection component eliminated.

In a detail of the pressing device 7, which is illustrated in FIG. 3, in particular a single hydraulic cylinder 8, the six connecting components 10 connected thereto and respectively associated gas springs 9 are particularly easily recognizable. A cylinder working space of the hydraulic cylinder 8 is completely filled with the hydraulic fluid, so that the

Connecting members 10 without further height offset on an outer jacket 23 of the

Hydraulic cylinder 8 can be connected. A shown "upright" arrangement of the gas springs 9, in which the respective connecting member is connected from an underside of the respective gas spring 9 forth to the same and the gas cushion in an upper

Section of the gas spring 9 is arranged, is particularly advantageous in order to avoid that the gas cushion "enveloped" or "enclosed" by the hydraulic fluid, as it may occur in a reverse arrangement of connecting member 10 and gas cushion.

In a further exemplary embodiment, which is shown in FIG. 4, the gas springs 8 of a pressing device 7 'of a grinding device 1' are formed by bubble stores 13 which, analogously to the grinding device 1 shown in FIGS. 2 and 3, are each individually separated by means of a separate connecting component 10 '. are connected to the hydraulic cylinder 8. In the embodiment shown, a total of seven gas springs 9 or bladder 13 are provided. Such bladder accumulators 13 are particularly good and available in a variety of forms, so that the grinder Γ represents a particularly quick and inexpensive design possibility to already installed

To modernize grinders. For the purpose of better understanding, FIG. 5 shows a detail of FIG

Cylinder working space of the hydraulic cylinder 8 arranged bladder accumulator 13 shown. The connecting components 10 'here in total have a cross-sectional area which corresponds approximately to 60% of the cross-sectional area of the hydraulic cylinder 8. Furthermore, the

Connecting components each have a throttle element.

Another embodiment, shown in FIG. 6, includes another one

Grinding device 1 "according to the invention, whose pressing device 7" differs from that of the remaining exemplary embodiments. The hydraulic cylinder 8 and the gas spring 9 of the pressing device 7 "are designed as an integral component, that is the

The cylinder work space and the spring work space merge seamlessly and maintain a constant cross-section and are no longer separated from each other with a sharp separation. This means that in the case of the pressing device 7 "shown, the piston protrudes from the bearing axis 1 1 (from below) into the hydraulic cylinder 8 and is mounted in an axially movable manner on this side of the piston facing away from the bearing axis 1 1. typically a hydraulic oil - arranged. "As far as corresponds to the structure of the pressing device 7" of those of the pressing devices 7 and 101st

However, in the pressing device 7 ", the gas spring 9 is no longer designed separately, but integrated directly on an" upper side "of the hydraulic cylinder 8, wherein a selective distinction of the cylinder working space and the spring working space in the pressing device 7" is no longer possible Top 14 of the

Pressing device 7 "arranged the gas spring associated with the gas spring 9, which is biased.The hydraulic fluid is applied directly to the gas cushion, so that the cylinder working space and the spring working space are arranged in a sense together in a continuous space.

6 is particularly advantageous In particular, by definition, the ratio of the smallest cross-sectional area between the hydraulic cylinder 8 and the gas spring 9 relative to the cross-sectional area of the cylinder working space is one, while the connecting distance between the cylinder

Cylinder working space and the spring working space is by definition equal to zero. Thus, this embodiment includes the best possible combination of hydraulic cylinder 8 and gas spring 9, which is also particularly easy and inexpensive to produce. In Figure 7, finally, a detail of the pressing device 7 "is shown, wherein the

The hydraulic cylinder 8 is here designed as a so-called "plunger cylinder", wherein in a lower region of the

A central region 25 of the pressing device 7 "is filled with the hydraulic fluid, the central region 25 being arranged by a region 2 1 of the pressing device 7", the gas cushion formed of nitrogen sealing from the

Hydraulic fluid separated, the separating piston 20 "floating" in the

Pressing device 7 "is mounted, so it can move freely in the axial direction of the pressing 7".

Noteworthy here is in particular a damper device 15 in the form of a throttle plate 16. This throttle plate 16 has a plurality of openings 17, which form a constriction of a flow cross-section of the hydraulic fluid in the pressing device 7 "The damper device 15 is here designed as a purely damping component and not understood as a connection component in the sense of the connection components 10, 10 'of the embodiments described above.

Such a view of the damper device shown 1 5 is nevertheless possible: In the sense of claim 1, the throttle plate 16 would represent the connecting member between the cylinder working space and the spring working space, wherein the

Cylinder working space on a plunger 24 facing side of the throttle plate 16 would be arranged and the spring working space would be located on an upper side of the throttle plate accordingly. The "transition cross-sections" would be in the sense of claim 1 corresponding formed by the transitions from the respective working spaces (cylinder and spring) to the openings 17, wherein the "connecting distance of a" length ", that is, an expansion of the throttle plate 16 in the axial direction the thrust plate 16 has a thickness of 1 cm, so that a risk of stiffening of the pressing device 7 ", as occurs in the prior art, due to the low to be accelerated Mass is not given. The damper device 15 exerts by means of the openings 17 in a flow through the same by means of the hydraulic fluid of a flow direction of the same opposite frictional resistance, which leads to a deceleration of the hydraulic fluid or to a reduction of the flow velocity. A resistance of the Damper device 1 5 is proportional to the flow velocity of the hydraulic fluid.

The damper device 15 furthermore has a blocking device 18. This is rotatable about a vertical longitudinal axis of the pressing device 7 "relative to the throttle plate 16, wherein massive - here triangular-shaped - blocking elements 19 of the blocking device 18 are adapted to" drive "through the openings 17 of the throttle plate 16 and to close it. At the same time a not visible in Figure 7 outdoor area is released below the blocking elements 19, in which a

Flow cross section between an upper side and a lower side of the damper device 15 is designed without installation. Accordingly, the damper device 1 5 is in the position shown in Figure 7 in its maximum damping position, since all free areas are closed and only those areas are released in which the hydraulic fluid must be "pushed" through the openings 17 of the throttle plate 16, wherein the desired By the rotation of the blocking device 18, finally, a degree of damping of the damper device 1 5 can be flexibly adjusted.

LIST OF REFERENCE NUMBERS

1, Γ, 1 "grinder

2 grinding media

3 grinding media

4 roll

5 grinding plates

6 axis of rotation

7, T, 7 "pressing device

8 hydraulic cylinders

9 gas spring

10, 10 'connecting component

1 1 bearing axis

12 power frames

13 bubble memory

14 top

15 damper device

16 throttle plate

17 breakthrough

18 blocking device

19 blocking element

20 separating piston

21 area

22 foundation

23 coat

24 plungers coat

grinder

Anpresseinnchtung

connecting member

Claims

claims

1. Mahlvornchtung (1, 1 ', 1 "), in particular a vertical mill, for comminution of regrind, comprising a) at least two grinding media (2, 3) which are movable relative to each other, wherein the two grinding bodies (2, 3) together Form at least one grinding area in which the ground material can be grinded by means of the two grinding bodies (2, 3), and b) at least one pressing device (7, 7 ', 7 "), which has at least one hydraulic cylinder (8) having a cylinder working space and at least one a spring chamber having gas spring (9), wherein the cylinder working space and the spring working space are fluidically connected to each other, wherein at least one of the grinding bodies (2, 3) by means of the at least one pressing device (7, 7 ', 7 "), a contact force can be applied, by means of which the grinding bodies (2, 3) can be pressed towards each other, characterized in that c) a smallest flow-through cross-sectional area between the

Zylinderarbeitsraum and the spring working space is at least 10% of a cross-sectional area of the cylinder working space and / or d) a connecting path extending between a with the

Cylinder working space corresponding first transitional cross-section of a connecting member and one with the spring working space

corresponding second transitional cross-section of the connecting member extends, a maximum of 100 cm long.

2. grinding device (1, Γ, 1 ") according to claim 1, characterized in that the smallest flow-through cross-sectional area between the cylinder working space and spring working space at least 20%, preferably at least 50%, on

preferably at least 80%, is a cross-sectional area of the cylinder working space.

3. grinding device (1, 1 ', 1 ") according to claim 1 or 2, characterized in that the connecting path is a maximum of 60 cm, preferably at most 30 cm, more preferably at most 10 cm long.

4. grinding device (1, Γ) according to one of claims 1 to 3, characterized in that the at least one gas spring (9) by a bladder accumulator (13) is formed.

5. Grinding device (1 ") according to one of claims 1 to 4, characterized by a damper device (15), by means of which a flow velocity of the hydraulic fluid flowing between the cylinder working space and the spring working space can be reduced, wherein preferably a degree of damping of the damper device (1 5) at Different flow directions of the hydraulic fluid is different in size, further preferably the degree of damping at a flow of

Hydraulic fluid in a direction away from a piston of the hydraulic cylinder (8) direction is greater than in a flow of the hydraulic fluid in the reverse direction.

6. Grinding device (1 ") according to claim 5, characterized in that the

Damping degree of the damper device (1 5), preferably in dependence on the flow direction of the hydraulic fluid, is variable.

Grinding device (1 ") according to claim 5 or 6, characterized in that the

Damper device (15) of a breakthroughs (17) having throttle plate (16) is formed, wherein the damper device (1 5) preferably further at least one

Blocking device (18) which is movable relative to the throttle plate (16) and by means of which the openings (17) of the throttle plate (16) are at least partially closed.

8. grinding device (1 ") according to one of claims 5 to 7, characterized in that the damper device (1 5) has a throttle cross-section which in

Depending on the flow direction of the hydraulic fluid is formed differently large, preferably in the flow of the hydraulic fluid in the direction away from the piston of the hydraulic cylinder direction is greater than in the flow of hydraulic fluid in the reverse direction.

9. grinding device (1, Γ, 1 ") according to one of claims 1 to 8, characterized

characterized in that the hydraulic cylinder (8) and the gas spring (9) as an integrated Pressing device (7 ") are executed, wherein the cylinder working space and the spring working space with constant cross section into each other, wherein in particular the hydraulic fluid between a piston of the pressing device (7") and a gas cushion of the pressing device (7 ") is arranged.

Grinding device (1, Γ, 1 ") according to one of claims 1 to 9, characterized

in that the pressing force which can be applied by means of the pressing device (7, 7 ', 7 ") can be changed.

Grinding device (1, Γ, 1 ") according to one of claims 1 to 10, characterized

characterized in that a drive power of the grinding device (1, 1 ', 1 ") is at least 0.2 MW and / or a mass flow rate of ground grinding material of the grinding device (1, Γ, 1") is at least 5 tons per hour.

Grinding device (1, Γ, 1 ") according to one of claims 1 to 1 1, characterized

characterized in that the at least one hydraulic cylinder (8) and the at least one gas spring (9) form a closed hydraulic system. 13. grinding device (1, Γ, 1 ") according to one of claims 1 to 1 2, characterized

characterized in that the at least one hydraulic cylinder (8) exactly

Has cylinder working space.