EP2573264A1 - Device for a scraper and scraper assembly with such a device - Google Patents

Abstract

The device (2) has a holding element (3) detachably connectable with a carrier element for fastening a scraper blade to a carrier element. A sensor is firmly connected with the holding element for detecting vibrations in the interior of the holding element. The sensor is inserted in a receiving space of the holding element. The sensor is encapsulated with a curable medium, particularly a resin or adhesive, in the receiving space. An independent claim is included for a scraper arrangement for moving surfaces, such as roller surfaces, particularly in a machine for producing fibrous webs.

Description

The invention relates to a device for a scraper for moving surfaces, in particular surfaces of a paper, cardboard or other fibrous web manufacturing machines.

Scraper devices of the type mentioned serve for scraping or stripping off deposits or impurities, such as fiber residues from a fibrous web, on running surfaces. Such moving surfaces are found, for example, on rotating rollers for guiding, pressing and / or drying of paper, board or other fibrous webs passing through the machine. By means of such scraper devices, in particular excess application medium is scraped off the moving surface and / or the web is lifted off the moving surface.

When used in machines for the production of fibrous webs, which often have a very large width, there is the problem to ensure a predefined contact pressure and to detect the wear of the scraper or the underlying roller in time.

From the DE 10 2008 001 624 A1 is a scraper device for moving surfaces with a doctor blade known. The doctor blade is inserted in a blade holder, which is held by a support body. The scraper device has a plurality of sensors for detecting the force acting on the doctor blade pressing force. The sensors are arranged on the surface of a measuring device, which as is formed separate component. The scraper blade and the measuring device are placed together in the blade holder.

From the DE 10 2008 001 265 A1 is a scraper device with a scraper blade for cooperation with a moving surface, a holder for the doctor blade and a device for detecting the contact pressure or the contact pressure known. The device has a plurality of piezoelectric sensors which are arranged on the top or bottom of the doctor blade.

From the DE 38 21 095 A1 For example, a method for identifying surface damage of a stone roller in the press section of a paper machine is known. For this purpose, a scraper is provided with a holder and a scraper part attached thereto. The holder is mounted on the frame of the press section so that it can rotate about its length axis. On the holder acceleration sensor are arranged to register the surface damage caused by the stone roller blows on the doctor blade.

From the DE 10 2004 018 421 B3 is a calibration device for the contact pressure of a voltage applied to the circumference of a roll doctor blade of a doctor blade. On the scraper blade a sensor holder and a pressure sensor is attached. The holding blade, the sensor holder and the pressure sensor are positioned so that the position of the pressure sensor on the circumference of the roller corresponds to the location of the blade.

Existing solutions may have the disadvantage of undesired environmental external influences on the sensors. In addition, separate manufacturing and assembly steps for mounting the sensors on the doctor blade or a connection component may be required.

The present invention has for its object to provide a device for a scraper on moving surfaces, such as roll surfaces, in particular surfaces of a paper, cardboard or other fibrous web-making machines, which allows a detection of vibrations, simple design and inexpensive to produce, and in existing scraper arrangements easy to integrate. The object is also to propose a scraper arrangement with such a device for detecting vibrations.

The solution consists in a device for a scraper blade for moving surfaces, comprising a holding element which is releasably connectable to a support member for fixing the scraper blade to the support member; and at least one first sensor for detecting vibrations; wherein the at least one first sensor is arranged in the interior of the holding element and fixedly connected to the holding element.

The advantage is that the device performs two functions as an integral component, namely on the one hand, the fixation of the doctor blade to a support member, and on the other hand, the detection of vibrations, which in turn allows conclusions about the wear of the moving surface. In particular, the moving surface may be, but is not limited to, a roll or cylinder of a paper, board, or other fibrous web making machine. Use examples for the device are the use for scrapers on Yankee cylinders, dry cylinders and / or crepe cylinders. It is also conceivable that the moving surface is a band surface, for example a rotating steel band. The scraper usually slides on a lubricating film on the moving surface. If it comes to vibrations, the scraper can strike through the lubricating film on the extremely sensitive, smooth surface of the roller or the band, which can lead to scoring here. By means of the device according to the invention, vibrations on the doctor blade can be detected in good time, so that a technically complex, time-consuming and therefore expensive revision of the moving surface can be prevented.

The at least one sensor is used to detect vibrations, which is why it can also be referred to as a vibration sensor. This means that the sensor is designed so that it can detect at least one measurement variable representing vibrations, for example an acceleration. With at least one Sensor is meant that the holding element can have one or more such sensors, which can sense, for example, vibrations in different directions, for example tangentially and / or normal to the moving surface.

Vibrations of the scraper or of the moving surface can be determined particularly accurately with the device according to the invention, since the sensor is arranged in the interior of the holding element, and oscillation pulses introduced on the holding element are thus registered directly and as unadulterated as possible. By interior of the holding element, it is meant that the sensor is arranged within an enveloping surface of the holding element. For example, the detected vibrations allow conclusions as to whether the scraper undesirably comes into contact with the moving surface. On the other hand vibrations can be recorded, which are generated at an already made ripple education on the cylinder surface. The device can replace an otherwise found at this point terminal and thus extends the holding or clamping function to the sensor function.

In a preferred embodiment, the at least one first sensor is inserted in a first receiving space of the holding element, which is preferably designed in the form of a bore. It is particularly advantageous if the sensor in the first bore with a curable medium, in particular with a resin or an adhesive, is shed. In this way, a secure connection of the at least one sensor to the holding element is ensured, so that vibrations introduced into the holding element are transmitted directly to the sensor. For a reliable functioning of the sensor (s), it is provided according to a favorable configuration that the receiving space, after insertion and, if appropriate, potting of the vibration sensor, be sealed by means of a lid. Due to the sealing connection between the lid and the holding element, the at least one sensor remains unscathed by external environmental influences, such as spray water or dust. It is particularly favorable when the lid is welded around after insertion of the at least one sensor with the holding element. In this way, the sensor is completely hermetically sealed off to the outside. However, other types of connection between the cover and holding element are conceivable, for example a screw connection, wherein a seal would then preferably be inserted between an outer surface of the cover and an inner surface of the holding element.

The at least one sensor is designed to detect high-frequency vibrations. It is particularly advantageous if the vibration sensor can detect vibrations of 10 kHz to 40 kHz. It is particularly preferred if the vibration sensor is designed for detecting vibrations in the ultrasonic range, that is to say vibrations starting at approximately 25 kHz. This refinement allows highly dynamic changes to be registered during the scraping process between scraper and doctor blade and moving surface. It is understood that the vibration sensor can also be designed to measure smaller frequency ranges as needed, for example, frequency ranges from 10 kHz to 1 Hz. The at least one first sensor for detecting vibrations is preferably designed in the form of a piezoelectric sensor, with other sensors for Detecting vibration-representing variables, such as an integrated circuit (IC chip) are conceivable.

The holding element has a clamping surface which is in contact with the doctor blade in contact. In this case, the vibration sensor is preferably arranged in the covering area with the clamping surface in a plan view of the retaining element. In this way it is ensured that the vibrations of the scraper blade pass directly into the holding element and can be detected here by the at least one vibration sensor. For fastening the retaining element to the carrier element, the retaining element preferably has a through-hole through which a screw can be passed for attachment to the carrier element. In particular, it is provided that the through hole has a shoulder against which the screw head or a nut for the screw can be axially supported. Preferably, the through hole for the screw and the bore for receiving the at least one vibration sensor are parallel to each other or, in other words, the bore for the vibration sensor is perpendicular to the clamping surface of the holding element. However, it is in principle also possible that the bore for the vibration sensor at an angle to the through hole, in particular this perpendicular crossing runs.

According to a preferred development, a second sensor for detecting temperatures is provided. By this is meant that this sensor can detect at least one quantity representing the temperature. Preferably, this temperature sensor is also located in the interior of the holding element, so that it is well protected from external influences and can reliably detect the temperature of the holding element. Preferably, the temperature sensor is arranged in a second receiving space of the holding element, which may be designed in the form of a bore. For fixing the temperature sensor in the holding element is provided in a favorable manner that this is in the receiving space by means of a curable medium, such as a resin or adhesive, shed.

According to a preferred embodiment, the retaining element has a tapered end portion, wherein it is provided that the second receiving space for receiving the temperature sensor at least partially, in particular for the most part, is disposed within this tapered end portion. This ensures that the temperature is as close as possible to the end of the holding element and thus close to the doctor blade, so that a reliable and accurate temperature detection is possible. It is particularly favorable in this context that the closed end of the second receiving space is disposed within a front half, in particular within a front third of the tapered end portion of the holding member. The tapered end portion of the retaining element is preferably wedge-shaped. For a compact construction, it is advantageous if the second receiving space for the temperature sensor opens into the first receiving space for the vibration sensor. Thus, after insertion of the sensors advantageously only one opening to close, which has a favorable effect on the production. Preferably, the main extension direction of the receiving space for the temperature sensor extends at an angle to the main extension direction of the receiving space for the vibration sensor. In this case, an included between the main directions of extension of the receiving spaces angle is preferably between 10 ° and 90 °.

According to a preferred embodiment, the holding element has an interface for connecting a data cable. Via this interface, the quantities detected by the at least one vibration sensor and optionally by the temperature sensor and / or a further sensor are forwarded to an electronic unit for evaluation. It is particularly favorable for reliable transmission of the detected variables if the connection between the sensor (s) and the interface extends within the retaining element. For this purpose, a through hole is provided between the interface for connecting the data cable and the first receiving space for the vibration sensor, through which an electrical line for transmitting the detected by the vibration sensor or the temperature sensor sizes is passed.

In principle, it is also possible to integrate additional sensors into the retaining element, for example one or more force sensors or strain gage sensors and / or one or more inclination angle sensors. By means of this additional sensor, further relevant variables can be detected, which can then be taken into account in the evaluation of the vibration behavior of the moving surface or of the doctor blade.

The solution of the above-mentioned object further consists in a scraper arrangement for moving surfaces, in particular a machine for producing fibrous webs, comprising a carrier element; a scraper blade; at least one first device having a holding element for releasably securing the doctor blade to the carrier element and having at least one first sensor for detecting vibrations, wherein the at least one first sensor is arranged inside the holding element and firmly connected thereto; and a plurality of second holding devices for releasably securing the doctor blade to the support member, wherein the second holding devices are designed sensorless. In this case, the said first devices can be designed according to one or more of the abovementioned embodiments.

The advantage of said scraper arrangement is that it is particularly easy to produce. It is also possible to convert existing scraper arrangements in a simple manner with the devices according to the invention. For this purpose, only some of the previously existing holding devices must be replaced and replaced by first devices with holding element and sensor. The first holding element and sensor devices, which may also be referred to as integrated holding element sensor devices, replace the pure functional clamps. An adaptation of the scraper bar construction is therefore not required.

According to a preferred embodiment, a plurality of first devices are provided with holding element and sensor, wherein between two first devices in each case at least one sensorless second holding device is arranged. The number of first devices with sensor is basically arbitrary and depends on the width of the doctor blade or the moving surface. For a particularly reliable detection of the vibrations a plurality of holding devices according to the invention are arranged distributed with sensors over the length of the doctor blade. In this way, high-precision vibration detection is possible with optimal technical integration.

Figur 1

eine erfindungsgemäße Vorrichtung für einen Schaber für bewegte Oberflächen in perspektivischer Ansicht;

Figur 2

die Vorrichtung aus Figur 1 im Längsschnitt;

Figur 3

das Halteelement der Vorrichtung aus Figur 1 als Einzelheit in perspektivischer Ansicht;

Figur 4

das Halteelement gemäß Figur 3 in Seitenansicht;

Figur 5

das Halteelement gemäß Figur 3 in Draufsicht;

Figur 6

das Halteelement gemäß Figur 3 in Vorderansicht und

Figur 7

eine erfindungsgemäße Schaberanordnung mit mehreren erfindungsgemä-βen Vorrichtungen gemäß Figur 1.

Preferred embodiments of the invention are explained below with reference to the drawing figures. Hereby shows:

FIG. 1

a device according to the invention for a scraper for moving surfaces in a perspective view;

FIG. 2

the device off FIG. 1 in longitudinal section;

FIG. 3

the holding element of the device FIG. 1 as a detail in perspective view;

FIG. 4

the holding element according to FIG. 3 in side view;

FIG. 5

the holding element according to FIG. 3 in plan view;

FIG. 6

the holding element according to FIG. 3 in front view and

FIG. 7

a scraper arrangement according to the invention with a plurality of devices according to the invention according to FIG FIG. 1 ,

The Figures 1 and 2 , which will be described together below, show a device 2 according to the invention for a moving surface scraper. In this case, the scraper, which is not shown here, is used for application to the moving surface in order to keep it free from contamination or to separate paper or other fibrous webs from the moving surface. For example, the moving surface may be the surface of a cylinder or roll of a paper, board, or other fibrous web making machine.

In the present embodiment, the device 2 according to the invention comprises a holding element 3 and a plurality of sensors 4, 5, which are arranged within the holding element 3.

The holding element 3 has on its lower side on a clamping surface 6 which is in the assembled state with a doctor blade (not shown here) in contact and clamps it to a mating surface. The holding element 3 has a through hole 7 into which a screw for fastening the holding element 3 can be inserted or screwed with a carrier element, not shown here. In this case, the screw head for bracing on a shoulder 8 of the through hole 7 can be supported axially.

The holding element 3 further has a receiving space 9, in which the first sensor 4 is received. The receiving space 9, which may also be referred to as a recess, is preferably designed in the form of a blind hole, which extends in particular parallel to the through hole 7. In this case, the recess 9 extends as far as possible over the entire height of the holding element 3, so that the lower end of the recess 9 is arranged in a lower third, in particular in a lower quarter with respect to the total height of the retaining element 3. Furthermore, it can be seen that the recess 9 or the sensor 4 arranged therein are arranged in register with the clamping surface 6. In this way, it is ensured that vibrations introduced by the doctor blade into the holding element 3 can be detected accurately and reliably by the sensor 4.

The sensor 4 is designed to detect at least one vibration representing size. Preferably, the sensor is designed for detecting high-frequency oscillations of more than 10 kHz to 40 kHz. In this way, highly dynamic changes during the scraper process between scraper blade and the moving surface can be registered reliably. The sensor 4 is designed in the present case in the form of a piezoelectric sensor which can detect vibration excitations in one or more axes. It is understood that, in principle, a plurality of vibration sensors can be provided in the holding element 3, whereby, depending on the requirements, particularly accurate conclusions can be drawn on the vibration behavior of the device or the interaction between the doctor blade and the moving surface. The variables detected by the vibration sensor 4 are forwarded via cable connections 11 or electrical lines to an interface 15 of the holding element 3. In this case, the cable connections 11 run in the interior of the holding element 3, so that they are well protected from external environmental influences.

Starting from the first recess 9, the holding element 3 has a further recess 10 in the interior. This is preferably designed in the form of a blind hole, which starts from the first recess 9 or opens into it. At the end 12 of the second recess 10, the second sensor 5 is seated; insofar as the second recess 10 may also be referred to as a second receiving space. It can be seen that the end 12 of the second recess 10, viewed in longitudinal section through the device 2, is arranged between the first recess 9 and a free end 13 of the holding element 3. Furthermore, it can be seen that the end 12 of the second recess 10 in the overlapping area with the clamping surface In relation to the height of the holding element 3, the end 12 of the bore 10 is located in a lower half portion of the holding element 3. By the thus defined arrangement of the recess 10 and whose end portion, in which the second sensor 5 is accommodated, ensures that the second sensor 5 is arranged particularly close to the end 13 of the retaining element 3, both in relation to the height and with respect to the length of the retaining element 3. Due to the fact that the temperature sensor 5 is arranged close to the tip of the holding element 3, there is at the same time a spatial proximity to the doctor blade. In this way, even small temperature increases can be detected quickly, which can be an indication that there has been an undesired contact between the doctor blade and the moving surface.

The second sensor 5 is designed to detect at least one measured variable representing the temperature, and can therefore also be referred to as a temperature sensor. The variables detected by the temperature sensor are forwarded via cable connections 14 or electrical lines to the interface 15 of the holding element 3. The cable connections 14 for the temperature sensor 5 likewise run in the interior of the retaining element 3.

The first sensor 4 and the second sensor 5 are preferably fixed in the respective recesses 9, 10. This can be done, for example, by means of a curable medium, in particular a resin or an adhesive, with which the sensors 4, 5 are cast. After insertion of the sensors 4, 5 and the connecting lines 11, 14, the opening 16 of the holding member 3 is hermetically sealed by means of a lid 17. For this purpose, it is provided in the present embodiment that the cover 17 is integrally connected to the holding element 3 by means of a circumferential weld 21. In this way, the sensor element 4, 5 arranged in the holding element 3 is optimally protected against external environmental influences. As an alternative to the welded connection between cover 17 and retaining element 16, other connections are also conceivable in principle. For example, the lid 17 could also be screwed to the holding element via a corresponding thread be, in which case between the cover 17 and the holding member 16 would preferably provide a seal.

At the rear end 18 of the retaining element 3, a further through hole 19 is also provided. This serves to receive adjusting means, not shown here, with which the holding element 3 can be adjusted relative to the support element.

In the FIGS. 3 to 6 the retaining element 3 is shown as a detail. Here are the holes lying inside 7, 9, 10, 19 and recesses each shown in dashed lines. In addition to the recess 9 for receiving the first sensor 4 and the recess 10 for receiving the second sensor 5, a passage 20 is further provided, one end of which opens into the recess 9 and the second end opens at the interface 15 of the holding member 3. Thus, the connection cables for the sensors 4, 5 can be guided through the connection channel 20 in the interior of the holding element 3 to the interface 15. The interface 15 preferably comprises a mechanical and electrical connection for passing the data to an electronic control unit.

In FIG. 7 a scraper assembly 22 according to the invention for a moving surface 23 is shown. The moving surface 23 is the surface of a rotating roller or cylinder used for guiding, pressing or drying machine-laid fibrous webs. With the scraper arrangement 22, the moving surface 23 is kept free of contamination or a fiber web can be creped from the surface 23.

The scraper assembly 22 comprises a scraper blade 24, a support element 25, which may also be referred to as a scraper bar or scraper holder, and a plurality of first devices 2 and second devices 27 for clamping the scraper blade 24 to the carrier element 25.

The first devices 2 are after the FIGS. 1 to 6 designed. To clamp the doctor blade 24 screws 26 are in the through holes 7 of Retaining elements 3 inserted and screwed into a corresponding mating thread in the support member 25. It can be seen that a plurality of devices 2 according to the invention are provided over the length of the moving surface 23 or the doctor blade 24. In this way, it is ensured that changes in the vibration behavior between the moving surface 23 and doctor blade 24 can be detected at different points, so that, if necessary, intervention in the production process can take place in good time before greater damage occurs.

In addition to the first devices 2 according to the invention, the second holding devices 27 are provided, which are designed sensorless. In other words, the second holding devices 27 only have a clamping function. It can be seen that the second holding devices 27 likewise have a bore into which corresponding screws can be inserted and screwed to the carrier element 25.

Overall, the advantage of the devices 2 according to the invention is that they combine two functions in one component, namely, on the one hand, the holding function of the doctor blade 24 on the carrier element 25 and, on the other hand, the sensing of various physical variables, such as vibrations or temperatures. The arranged in the device 2 according to the invention sensors 4, 5 are hermetically protected from external influences, so that they are subject to only a small wear and have a long life. Another particular advantage is that the inventive devices 2 can be easily integrated into existing scraper systems. For this purpose, only some of the formally designed as a pure functional parts holding devices must be exchanged and replaced by the devices 2 according to the invention. An adaptation of the scraper bar construction is therefore not required, so that a particularly good technical integration of the sensor is given.

LIST OF REFERENCE NUMBERS

2

contraption

3

retaining element

4

first sensor

5

second sensor

6

clamping surface

7

Through Hole

8th

shoulder

9

first recording room

10

second recording room

11

electric wire

12

The End

13

front end

14

electric wire

15

interface

16

opening

17

cover

18

rear end

19

Through Hole

20

Through channel

21

Weld

22

A scraper assembly

23

moving surface

24

scraper blade

25

support element

26

screw

27

second holding device

Claims (15)

Device for a scraper blade for moving surfaces, comprising
a holding element (3) which is detachably connectable to a carrier element (25) for fastening the scraper blade (24) to the carrier element (25); and at least one first sensor (4) for detecting vibrations;
wherein the at least one first sensor (4) is arranged in the interior of the holding element (3) and firmly connected to the holding element (3). Device according to claim 1,
characterized,
in that the at least one first sensor (4) is inserted in a first receiving space (9) of the holding element (3) and encapsulated therein with a curable medium, in particular a resin or adhesive. Device according to one of claims 1 or 2,
characterized,
in that the at least one first sensor (4) is designed to detect high-frequency vibrations, in particular vibrations between 10 kHz and 40 kHz. Device according to one of claims 1 to 3,
characterized,
in that the first receiving space (9) for the at least one first sensor (4), after insertion of the at least one first sensor (4), is sealed with a lid (17) which is in particular welded to the holding element (3). Device according to one of claims 1 to 4,
characterized,
in that the holding element (3) has a clamping surface (6) which in the assembled state is in contact with the doctor blade (24), wherein the at least one first sensor (4) in plan view of the holding element (3) in the covering area with the clamping surface (24). 6) is arranged. Device according to claim 5,
characterized,
that a main extension direction of the first receiving space (9) perpendicular to the clamping surface (6). Device according to one of claims 1 to 6,
characterized,
that a second sensor (5) is provided for detecting temperatures which is in the interior of the holding element (3), in particular in a second receiving space (10) of the holding element (3), and connected to this fixed. Device according to one of claims 1 to 7,
characterized,
in that the retaining element (3) has a tapering end section, wherein the second receiving space (10) for the second sensor (5) is arranged at least partially, in particular for the most part, within the tapering end section. Device according to one of claims 1 to 8,
characterized,
that the second receiving space (10) for the second sensor (5) in the first receiving space (9) opens for the at least one first sensor (4), wherein a main extension direction of the second receptacle (10), in particular at an angle (to a main extension direction of the first receptacle 9) runs. Device according to one of claims 1 to 9,
characterized,
that the holding element (3) has a through hole may be through the inserted a screw for fastening the retaining element (3) to the carrier element (25) or screwed. Device according to one of claims 1 to 10,
characterized,
in that the holding element (3) has an interface (15) for connecting a data cable, a passage opening (20) being provided between the interface (15) for connecting a data cable and the first receiving space (9) for the at least one first sensor (4) is, is passed through which an electrical line (11, 14) for the transmission of the at least one sensor (4, 5) detected variables. Device according to one of claims 1 to 11,
characterized,
in that at least one further sensor is arranged in the holding element (3), in particular a force sensor and / or a tilt angle sensor. Scraper arrangement (22) for moving surfaces (23), in particular a machine for producing fibrous webs, comprising a carrier element (25),
a scraper blade (24),
at least one first device (2) having a holding element (3) for releasably securing the scraper blade (24) to the carrier element (25) and having at least one first sensor (4) for detecting vibrations, wherein the at least one first sensor (4) is arranged in the interior of the holding element (3) and firmly connected thereto,
a plurality of second holding devices (27) for releasably securing the scraper blade (24) to the carrier element (25), wherein the second holding devices (27) are designed sensorless. Scraper arrangement according to claim 13,
characterized,
in that a plurality of first devices (2) with holding element (3) and sensor (4, 5) are provided, wherein in each case at least one sensorless second holding device (27) is arranged between two first devices (2). Scraper arrangement according to claim 13 or 14,
characterized,
in that the at least one first device (2) is designed according to one of claims 1 to 14.

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