Device for monitoring the lubrication condition of a lubricant-laden circulating belt for transporting extrusion material

Abstract

The invention relates to a device and a method for monitoring the lubrication state of a lubricant-laden, circulating belt (4) for transporting extrusion material. Furthermore, the invention relates to a continuous press comprising such a monitoring device and a method for operating such a press. In this case, one or more sensors (9) are provided in the region of the belt (4), with which at least one measurement signal (M) can be generated that is dependent on the amount of lubricant on the belt (4). According to the invention, the sensors (9) are designed as capacitive sensors, each having at least one sensor plate (10) spaced apart from the belt (4), the sensor plate and the belt (4) each forming a capacitor (11), the capacitance of which is dependent on the amount of lubricant applied to the belt (4).

Description

Technical Field

[0001] The invention relates to a device for monitoring the lubrication state of a circulating belt loaded with lubricant for transporting extruded material, in particular in a continuously operating or continuously operable press, the device comprising one or more sensors arranged in the region of the belt, with which at least one measurement signal can be generated which is related to the amount of lubricant on the belt.

[0002] Furthermore, the invention relates to a method for monitoring the lubrication state of a circulating belt loaded with lubricant, in particular in a continuously operating press.

[0003] The present invention further relates to a continuous press comprising an upper, continuously circulating belt or extrusion belt and a lower, continuously circulating belt or extrusion belt, wherein the extrusion material is guided through a compression gap between the upper and lower belts and pressed into a sheet or a continuous sheet strip using pressure and / or heat. The continuously circulating belt of such a press is also referred to as an extrusion belt and is preferably designed as a steel belt.

[0004] Finally, the invention relates to a method for operating a continuously operating press. Background Art

[0005] Preferably, such a continuously operable press is a double-belt press, in which an upper (heatable) extrusion plate is provided in the upper part of the press and a lower (heatable) extrusion plate is provided in the lower part of the press, and a continuously circulating upper extrusion belt is guided in the upper part of the press, while a continuously circulating lower extrusion belt is guided in the lower part of the press. The extrusion belts are preferably supported on the extrusion plates with rolling bodies, such as rods or rollers, connected in between. The required extrusion force is applied by means of a force mechanism, in particular a hydraulic compression cylinder, with which the upper and / or lower extrusion plates are loaded, for example, and which is supported on a press frame, for example a press frame of the press frame. The rods are connected, for example, to a rod chain and are guided in a circular manner by means of such a rod chain.

[0006] Such presses, also known as continuously operating presses, are used, for example, to produce wood-based panels. Wood-based panels are in particular fiberboards, particleboards, or OSB boards. Alternatively, however, the invention also relates to such presses for producing composite panels or composite components (e.g., from fiber composite materials or the like), or for producing plastic panels or plastic mats.

[0007] In the extrusion gap of a continuously operating press, an extruded material (e.g., an extruded material mat) is pressed between the surrounding steel belts or extrusion belts under the application of pressure and heat, thereby producing a plate-shaped product, such as a wood material board, from the extruded material. In this case, the rod rolls on the extrusion plate as a rolling element assembly. Due to common manufacturing tolerances or the slightest deviation of the rod shape from a perfect cylindrical shape, a stroke or length difference may occur on the two outer ends of the rod during the rolling motion, which is compensated by micro-slipping. Against this background, in practice, it is usually necessary and technically necessary to lubricate the rod or the cylindrical surface of the rod and / or the corresponding surface of the surrounding belt with a lubricant. Such a lubricant is preferably configured as a liquid lubricant (e.g., oil) and is applied, for example, sprayed onto the rod and / or the extrusion belt, for example, by means of a nozzle or the like in the inlet area or in the circumference of the rod. The (inner) surface of the continuously circulating belt facing the rollers is thereby loaded with lubricant, either directly (eg by spraying the belt surface) or indirectly via the lubricated (eg sprayed) rollers.

[0008] Proper lubrication is particularly important for the smooth operation of continuously operating presses. Generally, both underlubrication and overlubrication must be prevented. Therefore, in practice, the lubrication state or the amount of lubricant or oil applied by spraying is monitored, typically manually or visually by service personnel based on empirical values. It is important to ensure that the amount of lubricant applied to the belt surface for lubrication is evenly distributed and that no areas of insufficient lubrication, such as lack of lubricant, such as oil, are created. In principle, these simple measures have proven effective in practice. However, there is a need to optimize and, in particular, automate monitoring. Therefore, there is a particular need to design reliable and quantifiable monitoring systems to reliably prevent underlubrication and, for economic reasons, keep lubricant consumption within required limits.

[0009] Continuously operating presses including associated lubrication systems are known, for example, from DE 31 48 412 A1, DE 40 15 706 A1 and DE 41 26 717 C1.

[0010] Furthermore, DE 10 2016 102 931 B4 discloses a device for monitoring and / or regulating the lubrication state in a continuously operating press, wherein one or more sensors are provided for measuring physical phenomena related to the amount of lubricant on the belt. For this purpose, an analysis unit is provided for determining a lubrication parameter as a characteristic parameter of the amount of lubricant on the belt based on the sensor measurements. The sensor may be, for example, a light sensor for measuring light reflection values ​​of the belt and / or rollers, or a light sensor for measuring light absorption values ​​of the belt and / or rollers of the press. Alternatively, a conductivity sensor, a laser distance sensor, or an ultrasonic sensor may be used. Furthermore, pressure sensors, tension sensors, power sensors, and / or force sensors are mentioned. A controllable lubrication unit for applying lubricant is provided, the lubrication unit being designed with a regulating device for regulating the amount of lubricant applied by the lubrication unit based on the determined lubrication parameters. Summary of the Invention

[0011] Based on the previously known prior art, the object of the present invention is to provide a device and a method with which the lubrication state of a circulating belt can be monitored in a simple and particularly reliable manner, in particular in continuously operating presses.

[0012] To achieve this object, the invention teaches, in a device of the type mentioned at the outset, that the sensor or sensors are designed as capacitively operating sensors, each having at least one sensing plate (said sensing plate being made of an electrically conductive material, for example metal) arranged at a distance (parallel) from the belt, each forming a capacitor with the (electrically conductive and, for example, grounded) belt, the capacitance of which depends on the amount of lubricant applied to the belt (between the sensing plate and the belt).

[0013] The present invention is based on the recognition that the lubrication state of a press or the amount of lubricant on the belt surface can be monitored or determined particularly simply and reliably with the aid of a capacitive device, and more precisely with a belt that contains electricity, for example a steel belt. This can be a belt made entirely of a conductive material, for example steel. Alternatively, however, a belt that is (only) equipped with a conductive surface can also be used, wherein in principle it is sufficient that the belt surface (wetted by the lubricant) is of conductive construction. One or more induction plates are arranged at a predetermined fixed distance from the belt, so that the induction plates and the belt form a capacitor, the capacitance of which is sensitively influenced by the dielectric effect of the lubricant, for example oil. This is because the dielectric constant or relative dielectric constant of a lubricant, for example oil, has a value of approximately 2 and differs very significantly from the dielectric constant of air, which has a value of approximately 1. Because based on the relationship C=εxε rxA / d, this dielectric constant is linearly contained in the capacitance of the flat plate capacitor formed by the induction plate and the belt, so that the capacitance of the capacitor formed in this way with the belt (for example the extruded belt of a continuous press) is a sensitive and reliable measure of the amount of lubricant provided on the belt and therefore within the flat plate capacitor.

[0014] Although capacitive sensors operating based on the change in capacitance of a capacitor are known from the prior art, for example as pressure sensors, distance sensors, proximity switches, gap sensors, travel sensors, or even as moisture sensors, such technology has hitherto not been considered for use in continuous presses, and in particular for monitoring the lubrication state of a circulating belt loaded with lubricant.

[0015] The present invention offers a particularly advantageous possibility of selectively or individually analyzing or monitoring the lubrication condition of the belt across the belt width. This makes it possible to detect not only a lubrication condition averaged across the width, but also, in particular, uneven distributions across the width. This is because, in a preferred embodiment, the present invention provides for a plurality of sensor plates to be arranged side by side across the width of the belt. These sensor plates, along with the belt, form a plurality of capacitors, each assigned to a different width position of the belt. For example, it is possible to implement at least five sensor plates and, therefore, five capacitors across the width of the belt, thereby enabling monitoring of the lubrication condition in five tracks arranged side by side. The division and number of the tracks allow adaptation to the respective given conditions, and more specifically, to enable detailed or selective monitoring of the belt across the belt width using a large number of tracks.

[0016] Of interest is the fact that strips, such as the extruded strips of continuous presses, are usually made of an electrically conductive material (e.g., a steel strip) and are usually grounded, so that one or more capacitors can be easily implemented with the sensor plate for capacitive lubricant monitoring. However, it is also possible to use continuous strips or extruded strips that are not made completely of an electrically conductive material but only have an electrically conductive strip moistened with lubricant.

[0017] Optionally, one or more sensor plates can be arranged movably relative to the belt, more specifically, preferably in a direction extending transversely to the plate plane. During normal operation, the sensor plates can be in an operating position (which defines a desired distance from the belt) and, during operation—for example, when an object is located on the belt surface—shift from the operating position to a shifted position (which increases the distance from the belt). This reliably prevents interference and / or damage, for example, when an object is undesirably located on the belt and / or when a large number of interfering particles, such as wood material, are located on the belt. In such cases, the plates can be shifted from the target position, and therefore from the operating position, more specifically, in a shifting direction oriented transversely to the plate plane. Additionally, it can be advantageous for the sensor plates to be force-loaded, for example, by a spring, in the operating position and therefore in the target position, so that the plates are shifted against the force, for example, the spring force, by the interfering object and then automatically return to the operating position, thereby ensuring the desired and predetermined plate distance during normal operation, which avoids measurement errors.

[0018] In particular, in embodiments that include movable induction plates, it can be advantageous for one or more induction plates to have an angled or wedge-shaped inlet edge, more specifically, an angled or wedge-shaped inlet edge on the induction plate's inlet-side edge, which is arranged opposite the circumferential direction. This creates a wedge-shaped inlet gap between the induction plate and the belt in the region of one or more induction plates, tapering in the running direction. This can be achieved, for example, by simply chamfering the corresponding induction plate in the inlet region or on the inlet edge, thereby providing an inlet chamfer. Alternatively, angled induction plates or induction plates with a curved inlet region can also be used. Such a design including an angled or wedge-shaped inlet edge is particularly advantageous in conjunction with the movable induction plate, as this simplifies the deflection of the induction plate and thus prevents interference.

[0019] In particular, in the case of movable and therefore deflectable sensor plates, it can be advantageous if a deviation from the operating position of the sensor plate can be detected directly or indirectly by a control unit or the control unit. Thus, by means of the assignable belt position and / or by calculating the belt's rotational speed, a targeted removal of objects detected in conjunction with a deflection of the sensor plate can be initiated.

[0020] It is also advantageous to arrange the induction plate in the area of ​​the extruded strip. This way, the extruded strip experiences minimal position fluctuations, so that the capacitor gap does not change or changes only insignificantly. For this purpose, it may be advantageous to arrange the induction plate in the area of ​​the rollers within the press, for example, in the area of ​​guide rollers or in the area of ​​support rollers already present in the press for the strip. It is also possible to provide separate support rollers and arrange the induction plate in the area of ​​these support rollers. For this purpose, the induction plate can be designed with an arched shape, depending on the strip's path around the respective rollers and the desired distance from the strip. However, depending on the thickness of the strip, the preferred area may also begin or end up to 500 mm or even 1500 mm before or after the nip formed by the strip and rollers.

[0021] According to another alternative concept of the present invention, multiple induction plates can be arranged one after the other in the belt running direction and staggered relative to one another in the width direction, so as to overlap with respect to the width position. Thus, at least two induction plates are arranged so as to overlap one another as viewed across the width of the belt. To this end, one induction plate can be arranged forward or backward relative to the other induction plate in the belt's circumferential direction. Advantageously, the induction plates have triangular or trapezoidal surfaces on their sides facing the belt.

[0022] From the relationships described above, it can be deduced that a small d and a large A can be advantageous for measuring thin lubricant film thicknesses in order to obtain the most accurate possible measurement results. Experiments have shown that the ratio of area to distance as dimensionless values ​​lies between 100 and 10,000, in particular between 500 and 5,000, and preferably between 1,000 and 4,000.

[0023] In principle, it is advantageous if the distance d between the strip and the sensor plate is not more than 50 mm and, depending on the application, is preferably designed in the range between 2 mm and 30 mm, in particular in the range between 5 mm and 25 mm.

[0024] In a preferred further development, the sensor or sensors each comprise an (electronic) circuit arrangement that is connected to the corresponding sensor plate or integrated into the circuit arrangement and that can generate a measurement signal related to the lubricant quantity. The sensor components are therefore not only the capacitor itself, but also an electronic circuit arrangement, in which, however, known methods can be used to wire the capacitor or capacitor plate during capacitive measurement. Thus, the circuit arrangement can be, for example, an electronic resonant circuit and thus an LC oscillator, formed on one side by at least the capacitor (including the sensor plate and the strip) and on the other side by an additional coil, wherein the frequency of the resonant circuit or oscillator as a measurement signal is related to the capacitance of the capacitor and, therefore, the amount of lubricant present in the capacitor. Thus, the capacitance change caused by the electrical effect of the oil can be detected as a change in the frequency of the LC oscillator, wherein the frequency of the oscillator changes when the amount of oil between the plate and the strip decreases or increases, for example, when it becomes less than or more than the expected amount of oil. The lubricant- or oil-related capacitor according to the invention thus serves as a frequency-influencing element in an LC oscillator and thus as a frequency-determining component. As long as the oil quantity changes, the frequency also changes.

[0025] The one or more sensors can be connected to or equipped with a (common) or multiple (separate) evaluation device, which can generate an information signal related to the measurement signal and representative of the lubrication condition by analyzing the measurement signal. To this end, the measurement signal can be compared, for example, with one or more comparison values ​​or with one or more comparison intervals in the one or more evaluation devices. The information signal can be generated by comparing the measurement signal with the one or more comparison values ​​or comparison intervals, for example, if the comparison value or comparison interval is exceeded or fallen below. Such an evaluation device can be implemented very simply in terms of circuitry, for example, by means of a filter circuit known in principle, which generates an information signal when a corresponding deviation occurs, which can be transmitted, for example, to a reporting device.

[0026] It goes without saying that, on the one hand, the sensor circuit arrangement (with the capacitor integrated into it) and the evaluation device connected to it (e.g., a filter circuit) can be combined in terms of circuit technology in a common device or a common circuit. However, it is also possible to provide a common evaluation device for multiple sensors, each equipped with a circuit arrangement, which can also be integrated into a computer, for example. The same applies to the optionally provided reporting device, which can be designed jointly with the evaluation device in terms of component technology or can be formed by a separate unit or, if necessary, also by a computer, such as a central computer.

[0027] As an alternative to the described circuit arrangement in the form of an LC oscillator, other circuit arrangements known in principle, such as, for example, a PLL (phase locked loop) circuit, can also be used.

[0028] There is the possibility of transmitting the measurement signal (e.g., frequency) or, in particular, the information signal generated thereby (e.g., undershooting of the lubrication specification) to at least one reporting device or system. This reporting system can, for example, be used to visually and / or acoustically indicate faulty lubrication by, for example, generating a warning message based on the information signal indicating over-lubrication or under-lubrication. Based on this warning message, an operator can, for example, intervene in the process. Alternatively, however, there is also the possibility of an automated response in the sense of control or regulation. In this case, for example, it is possible to connect the circuit arrangement and / or the analysis device preferably connected thereto to a (common) control device, by means of which the lubrication process can be automatically influenced, preferably in the sense of control or regulation, based on the measurement signal or information signal.

[0029] The device for monitoring the lubrication state according to the present invention preferably includes not only the monitoring device but also at least one application device, with which lubricant can be applied to the belt, specifically either directly or indirectly (e.g., via a rotating roller). Such an application device can be, for example, a spray device known in principle for liquid lubricants (e.g., oil). Particularly preferably, such an application device is designed for width-selective application of the belt, so that specific width areas can be targeted with different amounts of lubricant using the application device. It is therefore possible to connect the control device to the application device so that the application of lubricant can be controlled or regulated using the application device based on specific measurement signals or information signals. This is particularly preferably also achieved in a width-selective manner. If, for example, sensors detect the presence of under- or over-lubrication in a specific width area (i.e., the track) of the belt, the application device and the lubricant profile over the width can be automatically influenced using the control device.

[0030] Furthermore, the present invention relates not only to a device for monitoring the lubrication state, but also to a corresponding method for monitoring the lubrication state, which is preferably implemented using a device of the type described. The method is characterized in that a measurement signal related to the lubricant quantity is generated using the one or more capacitive sensors, and the lubrication state or its deviation from one or more comparison values ​​is determined from this. From the measurement signal, an information signal containing information representing the lubrication state can be generated using the analysis device, for example, in the manner described, and this information can be transmitted, for example, to a reporting device and / or a control device. This makes it possible to control or regulate an application device for applying lubricant to a belt using the control device as a function of the measurement signal or the information signal. In this manner, the lubrication state of the belt can be selectively monitored for a plurality of individual width positions of the belt using a plurality of sensors distributed side by side across the width of the belt.

[0031] Furthermore, the technical solution of the present invention is a continuously operating press having at least one upper continuously encircling belt (extrusion belt) and a lower continuously encircling belt (extrusion belt), wherein the extrusion material is guided through an extrusion gap between the upper belt and the lower belt. Preferably, it relates to an extrusion device in which the extrusion material is pressed into a plate or a continuous plate strip using pressure and / or heat. Alternatively, such a press can also be a preheating device, which is used, for example, to preheat the extrusion material during a continuous extrusion process, and then the extrusion material is introduced into the continuously operating press for the production of the actual plate. Preferably, such a continuously operating press is tested in the manner of a double-belt press, in which the extrusion belt is supported on the corresponding extrusion plate with rolling bodies, such as rollers or rods, connected in the middle. However, the present invention alternatively also relates to another structural type of press including an encircling extrusion belt, such as a calendering press. Such presses are always equipped with a device for monitoring the lubrication state of the type described above. In other words, the description of lubricating and monitoring the belt in the press preferably relates to the respective upper and / or lower press belt. The technical solution of such presses is usually also an application device, with which lubricant can be applied (directly or indirectly) to the upper and / or lower belt. Therefore, the press according to the invention is characterized in that it is equipped with a device for monitoring the lubrication state of the type described above.

[0032] In a corresponding manner, the present invention finally also relates to a method for operating such a press, wherein the method is characterized in that the lubrication state is monitored by means of one or more capacitive sensors of the described type. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is explained in more detail below with the aid of the accompanying drawings which show only one exemplary embodiment.

[0034] Figure 1 A schematically simplified illustration of a continuously operating press including a device for monitoring the lubrication state of the extrusion strip,

[0035] Figure 2 Schematically simplified diagram for monitoring in accordance with Figure 1 The lubrication status of the equipment within the press, and

[0036] Figure 3 Shown in accordance with Figure 2 The circuit arrangement structure of the device. DETAILED DESCRIPTION

[0037] exist Figure 1, a continuously operating press 1 is shown, which is suitable and designed, for example, for pressing a mat of extruded material into an extruded material board during the production of particleboard, fiberboard or other wood-based boards. In its basic construction, the continuous press 1 comprises an upper press part with an upper, heatable extrusion plate 2 and a lower press part with a lower, heatable extrusion plate 3. The heatable extrusion plates 2, 3 are also referred to as heating plates. A continuously circulating belt 4, also referred to as an extrusion belt 4 (or simply belt 4) and made, for example, of steel, is guided in the upper press part and in the lower press part. An extrusion gap P is formed between the extrusion belts 4, through which the extruded material is guided. The extrusion belt 4 is supported on the extrusion plates 2, 3 with a rod or roller 5 connected in between. The rod 5 is guided, for example, on a rod chain (not shown in detail). Within the press, the extruded material is pressed into a sheet strip that is discharged from the press using pressure and heat. The extrusion force required for this is applied by means of a force mechanism, in particular by means of a hydraulic compression cylinder 7, to which the upper extrusion plate 2 or the lower extrusion plate 3 is loaded, for example. This compression cylinder 7 is supported on a press frame, for example a press frame 6 of the press frame. Figure 1 Here, an upper piston press is shown merely by way of example, in which the upper press plate 2 is acted upon by means of a compression cylinder 7 .

[0038] The squeeze belt is loaded with a lubricant, in particular a liquid lubricant, such as oil. Figure 1 The following possibility is shown, that is, for example, by a suitable coating device 8 to directly load the corresponding extruded belt with lubricant, which coating device can be designed, for example, as a spray device extending transversely to the belt running direction over the belt width. However, alternatively or in addition, there can be provided Figure 1 The coating device 8 'shown in FIG, loads the surrounding roller 5 so that the squeeze band is indirectly loaded with lubricant via the roller. Figure 1 Only the lubrication of the upper belt is shown. It goes without saying that corresponding measures are also provided in the area of ​​the lower belt. The "inner" surface of the corresponding extrusion belt 4, which faces away from the extruded material, is always loaded.

[0039] The press 1 is equipped with a device for monitoring the lubrication state of the circulating belt loaded with lubricant. Figure 2 The device is shown in FIG. The device comprises a plurality of sensors 9 arranged in the region of the belt and distributed over the belt width, with which at least one measurement signal M is generated, which is related to the respective amount of lubricant on the belt. According to the invention, these sensors 9 are designed as capacitive sensors, each having at least one sensor plate 10 arranged at a distance from the belt 4, which together with the belt 4 form a capacitor 11, the capacitance of which is related to the amount of lubricant applied to the belt. Figure 2As can be seen in the figure, a plurality of sensor plates 10 are arranged side by side across the width of the belt 4. Together with the belt, these plates form a plurality of capacitors 11 arranged side by side, which are assigned to different positions along the belt's width. In the exemplary embodiment, five sensor plates 10 and, therefore, five sensors arranged side by side are shown, allowing the lubrication condition on the belt to be monitored in five separate tracks. The sensor plates 10 are spaced a distance d from the belt 4.

[0040] The sensors 9 each have a circuit arrangement 12 which is connected to the corresponding sensor plate 10 or into which the corresponding sensor plate 10 is integrated (see, for example, Figure 3 ). With this circuit arrangement 12, a measurement signal M which is dependent on the lubricant quantity can be generated (for the respective width position). In the exemplary embodiment shown, the circuit arrangement 12 is designed as a resonant circuit and thus as an LC oscillator, which has a capacitor 11 on the one hand and a coil 13 on the other hand. Figure 3 1 shows a variant in which a basic resonant circuit is first provided, comprising a coil 13 and a directly connected capacitor 11 ′, which is connected in parallel with the capacitor 11 formed by the induction plate 10 and the strip 4 , so that the capacitances of the capacitors 11 and 11 ′ are added. Furthermore, an amplifier 14 with an input E and an output A, as well as an impedance R, is shown. Figure 3 The output of circuit arrangement 12 provides a frequency signal as the measurement signal. Specifically, the frequency of the resonant circuit is related to the capacitance of capacitor 11 and, therefore, to the amount of lubricant present on belt 4 within capacitor 11. As the amount of oil between plate and belt decreases or increases, the frequency of the oscillator changes. Thus, capacitor 11, which is associated with the lubricant, serves as a frequency-determining component in the LC oscillator, which serves as measurement signal M.

[0041] The sensor 9 (or its circuit 12) is connected to one or more evaluation devices 15, which in this embodiment are designed as filter circuits. The filter circuits are schematically simplified in the figure as separate components, but can naturally also be combined with one another and / or with the circuit 12 in terms of circuit technology. The evaluation devices 15 analyze the measurement signals to generate information signals S that are related to the measurement signal M and represent the lubrication state. To this end, the evaluation devices 15 can compare the measurement signal M with one or more comparison values ​​or a comparison interval, and generate information signals S based on the results of the comparisons, for example, if the comparison values ​​or comparison intervals are exceeded or fallen below. For example, it is possible to generate information signals S and transmit them to the reporting device 16 when underlubrication or overlubrication is detected for the respective width position. These information signals can be implemented in terms of circuit technology, for example, by filter circuits, i.e., when the measured frequency deviates from a predetermined frequency or leaves a predetermined frequency range. In this case, the figure shows a simple variant in which, for example, a notification or a visual and / or acoustic warning signal is generated by the notification device 16 , to which the operator can react, for example, while operating the press.

[0042] However, it is also possible to combine the device with a control device or to supply the measurement signal M or information signal S to the control device, which can be used to control or regulate, for example, the application device 8, 8' for applying lubricant to the extruded web 4. If necessary, a closed-loop control circuit can be implemented. It is always possible to automatically control or regulate the lubricant application based on the monitoring results generated by the measuring device.

[0043] Furthermore, it is advantageous to arrange the induction plate 10 in an area of ​​the extruded strip where the extruded strip experiences minimal positional fluctuations, so that the capacitor gap does not change or changes insignificantly. For this purpose, it can be expedient to arrange the induction plate in the area of ​​a roller within the press, for example, in the area of ​​a guide roller or in the area of ​​a support roller that is already present in the press for the strip. It is also possible to provide separate support rollers and arrange the induction plate in the area of ​​these support rollers. Details are not shown.

[0044] Furthermore, in the exemplary embodiment, the induction plates 10 are arranged at a fixed predetermined or defined distance d from the strip 4. Alternatively, the defined distance d relates to the desired or operating position of the induction plates, and the induction plates can be moved from this operating position in a transverse direction oriented transversely to the plate or strip plane and thus deflected. For example, in the presence of interfering objects, foreign matter, or the like, the plates can be deflected, for example, against the force of a spring or the like, to increase the gap, so that the induction plates then automatically return to the operating position with the defined gap d. Details are not shown in the figures.

Claims

1. A device for monitoring the lubrication state of a lubricant-loaded, circulating, electrically conductive belt (4) for transporting extrusion material, The device comprises one or more sensors (9) arranged in the region of the belt, with which at least one measurement signal (M) can be generated which is related to the amount of lubricant on the belt (4), It is characterized by: The sensor (9) is designed as a capacitive sensor, each having at least one sensing plate (10) arranged at a distance from the belt (4), each forming a capacitor (11) with the electrically conductive belt (4), the capacitance of the capacitor being dependent on the amount of lubricant applied to the belt (4). One or more induction plates (10) are arranged movably relative to the belt (4) in a direction oriented transversely to the plate plane, so that the induction plates (10) can be deflected from a working position to a deflected position with an increased distance from the belt by an interfering body against a spring force.

2. The device according to claim 1, characterized in that A plurality of induction plates (10) are arranged side by side across the width of the strip (4), and the induction plates and the strip form a plurality of capacitors (11) arranged side by side, which are assigned to different width positions of the strip (4).

3. The device according to claim 1 or 2, characterized in that One or more induction plates (10) have an angled or wedge-shaped inlet edge.

4. The device according to claim 2, characterized in that A plurality of induction plates (10) are arranged successively along the belt running direction and staggered with respect to each other along the width direction so as to form an overlap of two adjacent induction plates in the width direction.

5. The device according to claim 1 or 2, characterized in that The distance between the one or more sensing plates and the belt is less than 50 mm.

6. The device according to claim 1 or 2, characterized in that The one or more sensors (9) each have a circuit arrangement (12) which is connected to the sensor plate (10) or is integrated into the sensor plate (10) and by means of which a measurement signal (M) which is related to the lubricant quantity can be generated.

7. The device according to claim 6, characterized in that The circuit arrangement (12) is designed as an electrical circuit arrangement, with the aid of which a displacement current and / or charge carrier compensation between the induction plate and the strip can be measured.

8. The device according to claim 7, characterized in that The circuit arrangement (12) is designed as a resonant circuit having a capacitor (11) and additionally a coil (13), the frequency of which as a measurement signal (M) is dependent on the capacitance of the capacitor (11) and therefore on the amount of lubricant arranged in the capacitor (11).

9. The device according to claim 1 or 2, characterized in that The one or more sensors (9) are connected to one or more analysis devices (15) or are equipped with one or more analysis devices, which can generate an information signal (S) related to the measurement signal (M) and representing the lubrication state by analyzing the measurement signal (M).

10. The device according to claim 9, characterized in that In the one or more analysis devices (15), the measurement signal (M) is compared with one or more comparison values ​​or with comparison intervals, and an information signal (S) can be generated depending on the comparison result.

11. The device according to claim 9, characterized in that The at least one measurement signal (M) or the information signal (S) can be transmitted to at least one reporting device (16) or a control device.

12. The device according to claim 11, characterized in that Deviations from a predetermined lubrication state can be displayed using the reporting device (16), or a lubricant application device can be controlled using the control device.

13. The device according to claim 9, characterized in that The belt is equipped with an application device (8, 8') by means of which lubricant can be applied to the belt (4), and which can be controlled as a function of one or more measurement signals (M) or one or more information signals (S).

14. The device according to claim 1 or 2, characterized in that The belt (4) is guided around one or more guide rollers (17), the induction plate (10) being arranged in the region of the guide rollers (17) or in the region of support rollers supporting the belt.

15. Method for monitoring the lubrication state of a circulating electrically conductive belt (4) loaded with lubricant, using a device according to one of claims 1 to 14, generating at least one measurement signal (M) related to the amount of lubricant on the belt (4) by means of one or more sensors (9) arranged in the region of the belt, It is characterized by: A measurement signal (M) is generated by means of one or more capacitive sensors (9) which is related to the lubricant quantity and from which the lubrication state or its deviation from one or more comparison values ​​or comparison intervals is determined.

16. The method according to claim 15, characterized in that An information signal (S) containing information representative of the lubrication state is generated from the measurement signal (M) by means of an evaluation device (15).

17. The method according to claim 15, characterized in that The lubrication state of the belt (4) is selectively monitored for a plurality of individual width positions of the belt (4) by means of a plurality of sensors (9) distributed side by side across the width of the belt (4).

18. The method according to claim 15, characterized in that An application device (8, 8') for applying lubricant to the belt (4) is controlled or regulated by means of a control device based on the measurement signal (M) or the information signal (S).

19. A continuously operating press (1) comprising an upper continuously circulating belt (4) and a lower continuously circulating belt (4), The extrudate is guided through the extrusion gap between the upper and lower belts (4) and pressed into a sheet or a continuous sheet strip using pressure and / or heat. and the press comprises at least one application device (8, 8') with which a lubricant can be applied directly or indirectly to the upper belt (4) and / or the lower belt (4), It is characterized by: The press (1) is equipped with a device according to one of claims 1 to 14 for monitoring the lubrication state of a circulating, electrically conductive belt (4) loaded with lubricant for transporting the extrusion material.

20. Method for operating a continuously operating press according to claim 19, characterized in that The method according to one of claims 15 to 18 is used to monitor the lubrication condition of a press.

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