Patent Application
20120122374
1. Field of the Invention
The present invention relates to a grinding device for grinding rollers, in particular for grinding rollers for machines for producing and/or finishing a web of fibrous materials such as, for example, a web of paper, cardboard or tissue.
2. Description of the Related Art
The rollers which are used in the paper industry are subject to unavoidable wear. The re-processing is at present usually carried out by transporting the rollers to a service center and conditioning them there. However, since the dimensions and the weight of these rollers are continuously increasing—over 100 tons (t) in weight and 12 (meters) m in length are no longer unusual—an alternative concept is both economically desirable and necessary, for example due to restrictions on goods traffic. A grinding device which is mobile and can be easily transported to a paper factory and operated there is suitable for this.
A device and a method for grinding roller surfaces which are described in WO 01/49451 A1 are already known for dry cylinders of paper machines for producing tissue paper. The dry cylinders in this type of paper machine are, on the one hand, very large and, on the other hand, difficult to disinstall due to their heatable configuration, for which reason the surface of the so-called yankee cylinders always have to be treated in situ. WO 01/49451 A1 describes a grinding device for grinding such a yankee cylinder, wherein the grinding device can be moved in a direction which is essentially parallel to the roller and can be displaced toward and away from the roller. Furthermore, a measuring system which is assigned to the grinding device and can be moved therewith is provided for measuring the roller, relative to at least one reference line which is provided outside the roller and is adjusted parallel to the axis of the roller, wherein the relative position is determined in a plane which is preferably perpendicular to the reference line. The grinding process which is carried out by the grinding device, i.e. the contact pressure force or the contact pressure, is regulated on the basis of the measured values which are obtained by the measuring system. The grinding process therefore takes place with force control on the basis of a previous measurement of the surface.
A disadvantage with this known grinding device is here, on the one hand, that the measuring system does not reach the level of accuracy which is required for treating roller surfaces with various coverings, and the force-controlled grinding is difficult with soft or elastic coverings. The yankee cylinders which are mentioned further above are made of metal or are provided with a ceramic coating or hard metal coating, but are not covered with a soft covering.
In addition the suitability of the belt grinding technology, used according to WO 01/49451 A1, for treating soft roller coverings is not provided to the desired degree.
Furthermore, the guide which is used in the device known from WO 01/49451 A1 on the scraper bar is not available, and the device would also not be suitable for grinding with geometric guidance.
Conventional grinding machines, such as are known, for example, from EP 1 584 396 A, have the disadvantage of being entirely secured to one location. This is due, in particular to the formation of the grinding beds for these grinding machines. Such grinding beds usually include in this context a concrete square of large dimensions and mass, which is arranged in a suitable recess in the substructure, for example of a hall, and is mounted on springs for decoupling oscillation. Such a grinding bed can weigh several hundred tons and therefore can be manufactured only at extreme cost. In addition, such a grinding bed runs contrary to any requirement for mobility. Grinding machines with such a grinding bed are built exclusively for stationary use and cannot be transported.
What is needed in the art is a grinding device for rollers which is mobile, does not require a costly and heavy grinding machine bed and is suitable for use with any desired roller surfaces. In this context, important criteria are the requirements for accuracy and the unsusceptibility to faults as well as the coverage of a wide application field.
The present invention provides a grinding device including stationary components and mobile components which can be separated from one another. The stationary components include guide rails which extend essentially parallel to a roller axis of the roller which is to be treated and are connected to a substructure.
The stationary components move here within a framework which is distinguished, in comparison with normal grinding beds, by ease of installation, small requirement for foundations and cost-effectiveness. The stationary components can therefore be present in any paper factory which desires them, while the mobile components can be easily distanced from the stationary components, and the mobile components can then be moved to other locations in order to be used there.
Paper factories are therefore neither forced to set up a separate, very costly stationary grinding device, nor must heavy and long rollers be sent to a service center at enormous cost. The acquisition of the mobile components is also dispensed with since they can be ordered, used and transported away again as required in the form of a service performance. The cost factor for fixed installations is therefore low.
The guide rails can be advantageously connected directly to the substructure with carriers which are inserted into the substructure or with a frame which is inserted into the substructure, with the result that a foundation arrangement which corresponds to the required accuracy levels can be achieved.
The roller which is to be ground can be arranged on bearing blocks which are connected to the substructure.
In order to decouple the bearing blocks and/or the guide rails, passive insulation against excitation of vibrations in the form of a damping layer and/or damping elements in the form of spring elements can be provided between the substructure and the bearing blocks and/or between the substructure and the guide rails.
The bearing blocks and/or the guide rails can also have devices in the form of actuators which can be open-loop and closed-loop controlled, for actively bringing about decoupling from the substructure. This is a costly but very reliable form of damping. Mixed forms composed of active and passive damping are also possible.
In order to permit both large and small roller diameters to be treated and to be able to set the position of the tool for surface treatment correctly with respect to the roller axis, the bearing points of the roller in the bearing blocks may be both horizontally and vertically adjustable.
Mobile components of the grinding device can include a longitudinal carriage which is movably guided on the guide rails and is arranged in such a way that it can be moved or slid along an extension direction of the roller axis of the roller which is to be treated.
The longitudinal carriage can have bearings which interact with the guide rails. Forms of bearing which are acceptable for use in this context include sliding bearings or roller bearings. According to one embodiment of the present invention, the formation of a fixed/freely moving bearing is provided with the circulating roller shoes which have a high degree of accuracy and good guidance with little susceptibility to offsets in the transverse direction with respect to the direction of movement.
A transverse carriage is, for example, arranged so as to be movable or slidable on the longitudinal carriage, wherein a movement direction of the transverse carriage is oriented essentially perpendicularly to the movement direction of the longitudinal carriage. As a result, the desired means of freedom in the movement relative to the roller can be actuated directly and in a simple way.
In order to be able to carry out specific embossing or form other surface structures in the roller surface, the transverse carriage can be horizontally and/or vertically pivoted with respect to the longitudinal carriage.
A rail bearing system can also be formed between the longitudinal carriage and the transverse carriage which can be embodied in such a way that bearings engage around guide rails since as a result it is possible to provide protection against lifting-off forces during the processing.
The transverse carriage can be arranged in such a way that it is secured on the longitudinal carriage or can be removed therefrom. A secured arrangement facilitates the expenditure on mounting since the transverse carriage does not have to be specially mounted, and on the other hand a removable transverse carriage contributes to the compactness of the device.
A tool, for example, a grinding disk, a belt grinder, a grooving device, a superfinishing device or a honing device can be arranged on the transverse carriage, which ensures a broad application spectrum for the grinding device.
The operation of the tools is, for example, carried out with geometry control since this permits a higher level of accuracy to be achieved.
According to another embodiment of the present invention, the grinding device has measuring devices which can determine a position of the grinding device relative to the roller which is to be treated. The measuring devices can have at least two sensing devices for a reference object, which measuring devices can be embodied in the form of scanners, such as laser scanners. Scanners of this type permit easy but very reliable sensing of the position of objects.
The reference object can be embodied in the form of a stretched wire, which wire is arranged essentially parallel to the roller axis of the roller which is to be treated and has a fixed, invariable geometric relationship with the roller axis. This referencing permits the spatial position of the essential components of the device to be located precisely with respect to one another, with the result that possible inaccuracies in the mechanical foundations can be compensated. The wire is, for example, arranged in such a way that it can be sensed by the scanners, which is made possible by a corresponding geometry of the scanners. The scanners can each be arranged in pairs here both on the longitudinal carriage and on the transverse carriage. The selection can be carried out in each case here according to aspects such as the protection of the scanners during transportation, simple accessibility for the operating personnel, etc.
Furthermore, the measuring devices can include at least one inclination sensor which is arranged on the transverse carriage and by which an inclination of the transverse carriage relative to the substructure can be sensed.
Likewise, the measuring devices can have at least one measuring probe which is arranged on the transverse carriage and by which the roller surface which is to be treated can be sensed and/or the distance between the grinding device and the roller axis can be measured. The measuring probe can be embodied as an inductive measuring probe or as a laser probe.
According to an embodiment of the present invention at least one further measuring probe is provided which is arranged opposite the first measuring probe with respect to the roller axis, on a rear side of the roller, which further measuring probe senses untrue running errors at the support points of the roller.
The measured values of the scanners, of the inclination sensor, and of the at least one measuring probe of the measuring devices can be fed in for the purpose of performing open-loop and closed-loop control of the position of the tool by means of actuating devices. The actuating devices may be embodied here, for example, in the form of piezo-actuators.
The tool can be pivoted in a plurality of planes with respect to the roller axis by means of at least one actuating device.
In addition, the tool can be adjustable in the direction of the roller axis by means of at least one actuating device. In this way, any desired position can be adopted and any desired presettable surface shape, such as, for example, embossing, can be fabricated.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to
Roller 2 which is to be ground is set up at the selected location on bearing blocks 3 with suitable foundations (not visible in
In order to be able to achieve the necessary stiffness during the grinding process when grinding device 1 according to the present invention is used and in order to be able to compensate disruptive environmental influences in the form of the excitation of vibrations, there is therefore a need for a connection between bearing blocks 3 of roller 2 and guide rails 5 for grinding device 1 which is as rigid as possible. Furthermore, despite the omission of a conventional grinding bed, a basic geometric relationship must be created and maintained between grinding device 1 and roller 2.
In order to damp vibrations, various concepts are possible, and therefore, for example, a passive isolating device can be used which is illustrated in a highly schematic form in
However, as an alternative to this, it is also possible to use actively compensating installation elements 8. Frame 4, which is, however, rigidly connected to substructure 6 in order to achieve a greater degree of basic rigidity, is also provided here. For the purpose of compensating travel excitations from substructure 6, grinding device 1 then has its own active compensation elements 8 or actuators, as is apparent from
Bearing blocks 3 of roller 2 must ensure a position of the roller axis in the vertical and horizontal directions which can be used as a reference. Depending on the size of roller 2 which is to be treated and/or in the case of fluctuating dimensions thereof, bearing blocks 3 can be adjusted in at least one direction. The position of bearing blocks 3 can be adjusted by virtue of the possibility of sliding bearing blocks 3 relative to one another in the axial direction and/or relative to substructure 6 for rollers 2 of different lengths, wherein a rail system (not shown in more detail in the Figs.) which is parallel to guide rails 5 of grinding device 1 can be used. Furthermore, continuously adjustable bearing point 9 of roller 2 can be provided in bearing block 3 for different roller diameters, or at least two discrete bearing points 9a, 9b have to be provided for two groups of roller diameters. In both cases, the roller axis can be slid parallel to substructure 6 in the horizontal direction, as is illustrated schematically in a lateral view in
Furthermore, it is necessary to ensure that the axes of roller 2 and of tool 17 which treats the roller surface are at the same height. This can be made possible by virtue of an adjustment possibility of the tool height and by virtue of an adjustment possibility of bearing points 9a, 9b of roller 2 in bearing blocks 3 in the vertical direction. A roller drive (not illustrated in more detail in the Figs.) and the structural integration thereof can be arranged in a known fashion as in conventional grinding machines.
As a result of the fact that guide rails 5 require a high degree of accuracy during their laying in order to ensure the accuracy required for the grinding process in the treatment of the roller surface, it is recommended to attach guide rails 5 permanently to substructure 6. Various possibilities, as are respectively illustrated in lateral highly schematic views in
It is basically possible to screw guide rails 5 directly to substructure 6, as is illustrated schematically in
Frame 4 which is let into substructure 6 therefore serves for guide rails 5 as a type of simple machine bed. It defines the geometric position of guide rails 5 and can also serve to increase the rigidity in accordance with its configuration.
Bearings 11 which communicate with guide rails 5 on longitudinal carriage 15, described in more detail below, of grinding device 1 serve as an interface between the mobile and the stationary components of grinding device 1. Possible embodiment variants for bearings 11 are both sliding guides and rolling guides, are defined by a high degree of rigidity and accuracy as well as a low degree of operational expenditure.
Two different embodiments can likewise be considered for guide rails 5. On the one hand, an open guide system, also known as a fixed/freely moving bearing system, as illustrated in a schematic lateral view in
The advantage of such an open guide system is the possibility of being able to easily fit on mobile grinding device 1 to guide rails 5 without expenditure on mounting. Furthermore, the sensitivity with respect to geometric faults in the transverse direction with respect to the movement direction is low as a result of the freely moving side. The illustrated open guide is also conceivable with respect to the lifting-off forces which do not occur or which occur only to a small degree, and it is not absolutely necessary for engagement on multiple sides.
On the other hand, the use of bearings 11 which lead to a closed system and engagement on multiple sides is however also conceivable and possible. As a result, support against relatively strong lifting-off forces is also possible. With respect to the suitability as an interface between stationary and mobile components of grinding device 1, this embodiment has, however, the disadvantage that closed bearings 11 cannot be lifted off. They could, for example, be fitted permanently on guide rails 5 by mounting on a base plate. For this purpose, bearings 11 and base plate have to be provided separately at each location of use. This is, at least a cost factor, but in addition stringent requirements are made of the parallelism of guide rails 5 due to the overdeterminedness of the system, and this results in increased requirements of frame structure 4.
The lack of a conventional machine bed for receiving all the components of grinding device 1 inevitably also results in a lower degree of geometric accuracy of guide rails 5. This can be compensated by using a corresponding direct measuring method. In addition to the errors in the horizontal direction which occur directly, deviations in the vertical position between roller 2 which is to be treated and tool 17 also lead to differences in the engagement depth and therefore to treatment errors. Depending on the foundations of grinding device 1 and therefore on the achievable geometric accuracy of guide rails 5, relative movements occur between tool 17 and roller 2 in the horizontal direction. The vertical errors also have to be compensated as soon as they have a relevant influence on the working accuracy. The sensitivity with respect to errors in the vertical direction increases as the axle spacing between roller 2 and tool 17 becomes smaller.
Suitable stationary reference object 14, whose position relative to global coordinate system K defined by the roller axis is known and is invariable, serves as a reference for the measurement of roller 2 before the treatment. In the illustrated exemplary embodiment, reference object 14 is embodied in the form of stretched wire 14, but other reference objects 14, such as for example a measuring rail in a defined position, are also possible. The position of wire 14 is determined by calibration using at least suitable measuring devices, as explained below in more detail.
Wire 14 serves as a reference for the roller axis. Consequently, its position with respect to roller 2 or the roller axis must be invariable. Wire 14 is held in the exemplary embodiment on both sides by vertically and/or radially adjustable rollers, and on one side it is rigidly attached and on the other stretched by a weight with a known mass. This arrangement is in principle known and is used according to the prior art in the grinding method described above. The mounts of wire 14 have to be rigidly connected to bearing blocks 3 of roller 2 or to foundation 4. However, it is also conceivable to assign the mounts to the mobile components of grinding device 1.
Longitudinal carriage 15, already mentioned further above, of grinding device 1 is the carrier of measuring devices 16 and of tools 17 which are described below. Both measuring devices 16 and tools 17 are, for example, arranged here on transverse carriage 18 which, for its part, is arranged on longitudinal carriage 15. As is apparent from
In order to be able to manufacture specific embossing or surface shapes during the treatment of the roller, transverse carriage 18 is additionally also mounted in a pivotable fashion with respect to longitudinal carriage 15. A pivotable bearing arrangement of tool 17 with respect to transverse carriage 18 is also possible in order to achieve this objective. Technical grinding limits are placed on the pivotings to ensure, for example, that the grinding disk does not engage with its edge on roller 2 and therefore a pivoting range of approximately ±10° is sufficient.
A guide which permits bearings to engage around guide rails is advantageous for transverse carriage 18 (not illustrated in more detail in the figure for reasons of clarity), since transverse carriage 18 has to be protected against lifting-off forces because of its comparatively low weight. Transverse carriage 18 can be fitted permanently on longitudinal carriage 15 here or be capable of being removed for transportation.
In the exemplary embodiment illustrated in the figures, for example a grinding disk is illustrated as tool 17. In this context, the grinding devices which are used at present, for example grinding stones of 300-900 millimeters (mm) in diameter can be used. The latter have the advantage of known sufficient technological properties. The large span width of the diameters requires, however, a large adjustment range of transverse carriage 18. Furthermore, ceramically bound disks (carbon or diamond) can be used. These only have small wear ranges (5 mm) and a significantly smaller range would therefore be sufficient for advancing.
Furthermore, transverse carriage 18 can also be prepared to receive devices for performing superfinishing or honing (not illustrated in more detail in the exemplary embodiment). A drive for respective tool 17 can be provided on longitudinal carriage 15, transverse carriage 18 or else externally.
In order to improve the mechanical properties, in particular in order to increase the stability and to reduce the possibility of vibrations being excited, longitudinal carriage 15 must be embodied with as high a mass as possible. This can be done, for example, by means of free volumes of cast mineral, filling with sand or water, insertion of weight-increasing plates or the like.
Referring now to
However, grinding devices 1 are illustrated by way of example and represent the order of magnitude of the respective components, since, for example, the freedom of collision of longitudinal carriage 15 with the roller surface has to be ensured for all the workpiece diameters and the freedom of collision of tools 17 with longitudinal carriage 15 has to be ensured. Here, corresponding pockets or recesses 20 can be provided (see for example
The drive of grinding device 1, which drive is not illustrated in the figures for the sake of clarity, can, with suitable adaptation of the components, make use of various possible drive concepts. Owing to the long displacement travel, a toothed rack/pinion drive is possible for the longitudinal advancing along roller 2 which is to be treated. However, other drive concepts such as ball screw drives or linear direct drives are also possible. Such drives and their arrangement on the object which is to be driven are known in principle, and a description will therefore not be given at this point. Likewise desired drive concepts which are known in principle and which provide the required accuracy and resolution of movement in the advancing movement can be applied to drive transverse carriage 18.
Regulated movement axes are required for the positioning of transverse carriage 18 and for the adjustment during operation. The movement axes implementing axial movement (advancing in the z direction) and radial forward movement in the x direction include compensation of guide path deviations as well as for a movement axis, necessary for calibration, for the pivoting of measuring devices 16.
Transverse carriage 18 is, as is, for example, clearly visible in
The following terminology is used for the coordinate systems K and K′ in
Two sensing devices 22 or scanners 22, for example laser scanners, in the exemplary embodiment detect reference wire 14 and permit, in conjunction with inclination sensor 23, the position and direction of local coordinate system K′ on transverse carriage 18 to be determined. Scanners 22 can be embodied here, as illustrated in
For the sensing of the surface of roller 2 by means of measuring probe 24, it is necessary to be able to adjust measuring probe 24 in order to maintain the measuring range depending on the current size of tool 17 (in the exemplary embodiment of the grinding disk). This can be implemented in discrete steps since no change is necessary during the measuring process. The spatial position of measuring devices 16 with respect to local system (K′) either has to be known or can be determined from the current position of the movement axes. It is absolutely necessary to measure longitudinal carriage 15 of grinding device 1 in this respect.
In the illustrated exemplary embodiment, measuring devices 16 include, as described, two scanners 22 and inclination sensor 23, which are arranged on transverse carriage 18 of grinding device 1. This makes it possible to determine the position and orientation of local coordinate system K′ on longitudinal carriage 15 in which the position of measuring devices 16 and of tool 17 are known. During the treatment of roller 2, the setpoint values for the forward movement are adapted on the basis of the determined deviations between global coordinate systems K and local coordinate system K′.
Conventionally already known measuring probes 24 are possible for the surface treatment. Inductive measuring probes 24, which have a high degree of accuracy (approximately 0.1 (micrometer (μm)) and are suitable for all surfaces in question are usually already in use for this purpose. A disadvantage is their limited dynamics, for which reason under circumstances the rotational speed of the roller has to be limited during measurement. Complete, uninterrupted measurement then takes a correspondingly long time. Alternatively, laser measurement systems can be applied which nowadays also permit mirrored surfaces to be measured. These operate in a contactless fashion and have now also achieved accuracy levels of approximately 0.2 μm. Mechanical systems for moving measuring probe 24 can be dispensed with here because measuring probe 24 does not have to be moved back during grinding, in contrast to inductive measuring probe 24.
The measured value of the system with the results of the referencing and the fixed and known positions of measuring devices 16 provide a measuring point on the roller surface expressed in a radius with respect to the roller axis. When roller 2 is rotating, the measuring points can be set either during continuous axial movement of longitudinal carriage 15 along roller 2 longitudinally with respect to a helical line, or multiple rotations can be used to acquire measuring points during incremental movement. A permanently available signal for the current angular position of roller 2 is a prerequisite. After complete measurement of the roller surface, the results are combined to form a 3-D topographic surface description.
An additional task when treating rollers 2 is to detect untrue running errors in the region of the journal on which roller 2 is mounted. If all the untrue running errors are eliminated on the grinding disk side, fluctuations which are caused by the bearing points of roller 2 in the journal can theoretically also occur on the rear side. For such investigations it is possible to provide a further measuring system (which can be installed on the rear side of the roller) or direct measurement of the journal can be provided (not illustrated in more detail in the Figs).
In the geometrically conducted grinding method of grinding device 1 according to the present invention, the forward movement occurs on the basis of the referencing, in contrast to the force-controlled grinding method according to the prior art which is described above. For this purpose, at the start of a grinding step, wireless contact is carried out with roller 2. The reference value which is defined in this way determines the grinding profile.
After the desired contour (true running/profile/embossing) has been reached, further processing steps such as polishing can take place by means of the grinding treatment. Here, the treatment is generally force-controlled. This applies specifically to additional components such as superfinishing devices. The known dynamic drives are in principle suitable for this.
The required high level of accuracy requires that the geometric conditions on longitudinal carriage 15 be known precisely. This applies specifically to the position of the zero points of measuring devices 16 and the orientation of the grinding axis in local coordinate system K′. These values can be determined in advance, but precise determination of the position of reference wire 14 is necessary in all cases before each new grinding process, the determination requiring external determination of the roller diameter at two axial positions which have to be defined.
This also applies to the case in which the wire attachments have actually not been changed since, for example, when roller 2 was inserted into bearing blocks 3, changes can take place to the geometry which can subsequently effect the grinding accuracy.
If, in particular,
The radial forward movement in the x direction for tool 17, which is regulated by measuring probe 24, is carried out by further actuating device 26 (see
The entire sequence is guided, monitored and evaluated in a program-controlled fashion. The regulation of the drives, the evaluation of the various sensors and safety precautions can be performed by a conventional NC controller which is known in principle or a motion controller.
With respect to the accuracy levels which can be achieved and which in conventional stationary grinding devices are determined exclusively by the geometric accuracy of the grinding bed, it is to be expected that the technical measuring assistance by referencing and scanning allows an equally high level of accuracy to be achieved in the treatment of rollers 2 even though the foundations can be produced easily and simply.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 003 140.5 | May 2009 | DE | national |
This is a continuation of PCT application No. PCT/EP2010/055156, entitled “GRINDING DEVICE FOR ROLLS HAVING STATIONARY GUIDE RAILS AND MOBILE GRINDING UNIT”, filed Apr. 20, 2010, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2010/055156 | Apr 2010 | US |
| Child | 13296954 | US |
