Characterisation of a saw band of a band saw machine

Abstract

This application relates to a measuring device for characterising a saw band (11) of a band saw machine. According to one embodiment, the measuring device has the following: a first inductive distance sensor (30), which is designed to generate a sensor signal that represents a distance between a sensor position and a front side of the saw band (11), on which saw teeth (101, 102) are present; a support roller (32); and a preload mechanism, which is designed to press the roller against a rear side of the saw band (11).

Description

CHARACTERIZATION OF A SAW BAND OF A BAND SAW MACHINE TECHNICAL AREA

[0001] The present invention relates, among other things, to a concept for characterizing a saw blade of a band saw machine. BACKGROUND

[0002] Various types of band saws are known. In industrial settings, band saws with computerized numerical control (CNC) are frequently used. The machine control system requires various parameters to correctly control the sawing process, which, on many machines, must be manually entered into the control system by an operator. For this purpose, the machine control systems include suitable human-machine interfaces (HMIs).

[0003] The parameters mentioned above relate particularly to the saw blade, as its properties directly influence the sawing process. For example, when positioning the workpiece (e.g., automatically or semi-automatically), the width of the cutting channel must be taken into account. This, in turn, depends on the geometry of the saw blade and, on known machines, must be manually entered into the machine control system. Furthermore, the permissible cutting speed (and thus the blade speed and / or the feed rate) can depend on the type of saw blade, for example, on any set (setting) of the saw blade teeth or on the material of the saw teeth (e.g., high-speed steel or carbide). These parameters, too, must be communicated to the machine control system, depending on the type of machine.

[0004] As described above, while the sawing process itself is automated, correct process control depends on parameters that are manually entered into the machine control by an operator, which represents a potential source of error. There are concepts designed to help avoid such errors when configuring the machine control. For example, saw blades can be equipped with barcodes. QR codes (Quick Response Codes), RFID tags (Radio-Frequency Identification Tags), or similar physical markings can be used. Such marking / coding can be read automatically using suitable readers (optically in the case of barcodes or QR codes, or electromagnetically in the case of RFID tags). It represents a numerical code for which the corresponding parameters for machine control can be stored in a database. This concept of marking saw blades has the problem that different manufacturers use different systems for marking saw blades, leading to compatibility issues when using saw blades from different manufacturers. Furthermore, marking saw blades using barcodes, QR codes, RFID tags, etc., allows for...While the saw blade can be identified, its wear condition cannot be determined, which can also be a relevant parameter for machine control. Furthermore, markings such as laser-engraved barcodes on the saw blade are problematic because they can become unreadable due to wear and tear. Naturally, markings can only represent the properties of new saw blades.

[0005] The inventors have set themselves the task of improving the situation described above and developing an improved concept for the automatic characterization of saw blades. SUMMARY

[0006] The aforementioned problem is solved by the measuring device according to claim 1 and the system according to claim 12. Different embodiments and further developments are the subject of the dependent claims. A measuring device for characterizing a saw blade of a band saw machine is described below. According to one embodiment, the measuring device comprises: a first inductive distance sensor configured to generate a sensor signal representing a distance between a sensor position and the front surface of the saw blade where saw teeth are located; a support roller; and a pretensioning mechanism configured to press the roller against the rear surface of the saw blade.

[0007] Another embodiment relates to a system comprising a band saw machine with a saw band and a machine control system designed to... The system is designed to control the operation of the band saw, using one or more saw blade parameters stored in the machine control system. It further comprises a measuring device configured to determine at least one parameter value that characterizes the saw blade, and the machine control system further configured to receive the parameter value determined by the measuring device and store it as a saw blade parameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The invention is explained in more detail below with reference to the examples shown in the figures. The illustrations are not necessarily to scale, and the invention is not limited to the aspects shown. Rather, emphasis is placed on illustrating the principles underlying the invention. A brief description of the figures follows:

[0009] Figure 1 schematically shows an example of a CNC band saw machine that is known per se.

[0010] Figure 2 is an exemplary representation of a saw blade (band saw blade) with a broken saw tooth.

[0011] Figure 3 illustrates, using a schematic sketch, an example of a measurement setup for the automatic detection of defective saw teeth using an inductive distance or proximity sensor.

[0012] Figure 4 is a cross-sectional view corresponding to Fig. 3.

[0013] Figure 5 illustrates an example of a possible geometry of a saw tooth (diagram (a)) as well as different types of set of the saw teeth (diagrams (b) and (c)).

[0014] Figure 6 illustrates an exemplary modification of the measurement setup from Fig. 3 and Fig. 4.

[0015] Figure 7 shows an example of the signal waveform of the sensor signal from the inductive sensor in Fig. 4 and the detection of broken or worn parts based on it. Saw teeth (diagram (a)) as well as a signal profile of the additional sensor signal of the inductive sensor from Fig. 6 (diagram (b)) and the detection of the tooth types based thereon.

[0016] Figure 8 illustrates another measuring setup for measuring the cutting channel width of a saw band using capacitive sensors.

[0017] Figure 9 shows an example of the integration of the measurement setup from Figs. 3, 4 and 6 into a sensor device.

[0018] Figure 10 is a block diagram illustrating the coupling of the sensor device according to Fig. 9 with the machine control of the band saw.

[0019] Figure 11 shows another example of the integration of the measurement setup from Figs. 3, 4 and 6 into a sensor device.

[0020] Figure 12 shows, using a flowchart, an example of a procedure carried out using the system from Fig. 10. DETAILED DESCRIPTION

[0021] Before various embodiments are explained in more detail, the general structure of a band saw will first be briefly illustrated with reference to Fig. 1. It should be understood that the embodiments described here can be used with different types of band saws and their application is not limited to the type of band saw shown in Fig. 1.

[0022] As shown in Fig. 1, the band saw 1 has a saw frame (housing) and two wheels 10a and 10b mounted on it, one of which is driven by an electric motor. The saw blade 11 is held and guided by the wheels (similar to a belt). The driven wheel also drives the saw blade (with an adjustable rotational speed). The other wheel rotates alongside it. Fig. 1 also schematically shows a workpiece 30, which is to be cut with the help of the saw blade 11. In the example shown, the cutting plane is vertical. However, there are also band saws with a horizontal or inclined cutting plane.

[0023] The numbers 20 and 21 designate the positions on the saw frame (housing) of band saw 1 where the measuring device, which will be described in detail later, can be mounted. While mounting the measuring device at these positions is not strictly necessary, it is advisable in most applications because these locations, next to the wheels, are relatively well protected from coolant, dirt, chips, dust, and other contaminants.

[0024] The machine control system can be housed in a separate enclosure and is not shown in Fig. 1. For example, the machine control system can be implemented in an industrial PC using software. Various types of machine control systems are known, and these will therefore not be discussed in detail here.

[0025] Fig. 2 shows an example of a saw blade 11 with a plurality of saw teeth 101. The distance between two adjacent saw teeth is called the pitch p. Variable tooth pitch has proven effective when sawing metallic materials in high-performance industrial production. This is usually specified in teeth per inch. In the example shown in Fig. 2, the saw tooth 102 is broken. A saw tooth can break, for example, if a process parameter of the sawing process (e.g., the cutting speed or the feed rate) is incorrectly set. Wear can also cause a saw tooth to become so worn that its height is significantly less than that of an unworn tooth.

[0026] The embodiments described here relate to a concept for characterizing a saw blade (bandsaw blade), in particular to determine the wear condition of the saw blade, for which defective (broken) saw teeth are to be automatically detected. Some embodiments also allow the detection of the saw blade set and / or the measurement of the actual width of the cutting channel. The wear condition, in particular, cannot be determined using known methods such as the aforementioned marking with QR codes or similar methods.

[0027] Figure 3 illustrates a simplified example of a measurement setup for detecting worn (broken) saw teeth using an inductive sensor. Inductive sensors have proven to be particularly reliable (especially compared to optical sensor principles). Suitable sensors are commercially available as inductive position sensors or proximity sensors. (See Figure 3.) The inductive sensor 30 lies in the plane A of the saw blade (see also Fig. 4) and monitors the tooth side (narrow side) of the saw blade where the saw teeth are located. The measuring direction of the sensor (in which a distance between sensor 30 and saw blade 11 is measured) runs perpendicular to the direction of travel of the blade in the plane A.

[0028] The distance between sensor 30 and the tip of a saw tooth is denoted do in Fig. 3. Distance do is the minimum distance between sensor 30 and the saw blade 11. The sensor measures distance do when it is directly opposite the tip (main cutting edge) of an unworn saw tooth 101. If the gap between two saw teeth is opposite sensor 30, the measured distance d will be greater (d > do). Similarly, if a defective (worn or broken) saw tooth (denoted 102 in Fig. 3) is opposite sensor 30, the measured distance di will be greater than the minimum distance do (di > do).

[0029] An inductive distance sensor alone is insufficient for the reliable detection of defective saw teeth. In practice, the saw band 11 not only moves in the direction of travel or cutting (indicated by the arrow in Fig. 3), but oscillating movements (flutter) can also occur perpendicular to the direction of travel, preventing or at least impairing reliable distance measurement or reliable detection of a change in position. These oscillations can be reduced, at least locally in the area of ​​the sensor 30, by arranging a support roller 32 on the back of the saw band 11 opposite the sensor 30. The support roller 32 can be mounted on a frame structure of the sensor device such that it contacts the narrow side of the back of the saw band 11. As soon as the saw band 11 moves, the support roller rotates with it.

[0030] The bearing point of the support roller 32 can, for example, be displaceable and coupled to a spring such that the support roller 32 is pressed against the belt back with a force F (preload force). Only the preload force F is important, not the method of its generation. Therefore, only the preload force F is shown in Fig. 3, not the spring. The support roller 32 can be made of metal, but in some embodiments it can also be made of plastic. The running surface of the support roller 32 can also have a coating of plastic or rubber. Particularly in combination- The preload force F reduces the oscillating movements of the saw band 11 perpendicular to the direction of travel of the saw band by the support roller 32 and significantly increases the reliability of the detection of defective saw teeth.

[0031] Fig. 4 shows a cross-sectional view of the example from Fig. 3. The section plane C (see Fig. 3) is at a right angle to the direction of travel of the saw band 11 and passes through the tip of an unworn tooth 101. The axis of rotation B of the support roller 32 is also shown in Fig. 4. The detection of individual broken teeth will be described in more detail later (see, for example, Fig. 7).

[0032] Fig. 5 relates to various aspects of the geometry of a saw blade and its saw teeth. Fig. 5, diagram (a), shows an example of a special saw tooth geometry in a cross-sectional view, where the width (thickness) of the saw tooth increases towards the tip. Such a saw tooth is therefore also called a trapezoidal tooth. The plane A denotes the median plane of the band saw blade. The outermost edge of a saw tooth (perpendicular to the median plane A) forms the main cutting edge. The edge runs obliquely to the left and right of the median plane. The oblique parts of the cutting edge are also called secondary cutting edges. The part of the saw tooth 101 opposite the main cutting edge has the same thickness as the blade back 103. The main and secondary cutting edges of the saw tooth can be made of a different material than the blade back.For example, the cutting edges can be made of carbide or high-speed steel, while the band back can be made of standard tool steel. Some saw blades have teeth with different geometries. These teeth differ, for example, in the width of the main cutting edge. Figure 5, (a), shows two possible modifications of the tooth geometry with dashed lines. In one case, the main cutting edge extends across the entire width of the tooth. In this case, there is practically no secondary cutting edge. Saw teeth of different types can follow one another in a single saw blade. This is particularly common in non-set saw blades. Groups with a specific sequence of saw teeth can repeat periodically in a saw blade (e.g., tooth 1 with a narrow main cutting edge, tooth 2 with a medium main cutting edge, tooth 3 with a wide main cutting edge).

[0033] Diagrams (b) and (c) of Fig. 5 show different types of tooth set on a band saw blade. Fig. 5, diagram (b), shows a standard set where of three adjacent teeth, one is straight (i.e., in the plane of the blade A), one is angled to the side. The left and right-handed saw teeth are shown, one curved to the left and the other to the right (i.e., oblique to the plane of the band A). In Fig. 5, diagram (b), the straight saw tooth is labelled 101, the right-handed saw tooth 101', and the left-handed saw tooth 101".

[0034] Fig. 5, diagram (c), shows a right-left set, in which the teeth are alternately bent to the right and left. Saw teeth 101, which lie in the plane of the band Ä, are not present in this variant. There are other types of set, such as group set, in which groups of two or more consecutive teeth are bent in the same direction. In wave set, the angle of the saw teeth varies periodically from tooth to tooth, with one period encompassing, for example, eight teeth. Saw bands with carbide cutting edges often do not have a set, whereas bimetallic bands with high-speed steel cutting edges almost always do. Various types of band saw blades and various types of sets are well known and are therefore not discussed further here.

[0035] Fig. 6 illustrates an example of a modification / extension of the measuring setup from Figs. 3 and 4, in which a second inductive position or distance sensor 31 is used to determine the type of set of the saw band 11. The support roller 32 and the first sensor 30 are arranged identically in Fig. 6 as in Figs. 3 and 4, and reference is made to the description above. The sensor 31 has a measuring direction that is perpendicular to the band plane A. The sensor 31 therefore detects the saw band 11 (especially the saw teeth) from the side. The sensor signal depends on the distance a between sensor 31 and the saw blade (see Fig. 6), where the distance a is smaller when the saw tooth next to sensor 31 is bent to the left (towards the sensor) (tooth 101"), and slightly larger when the saw tooth next to sensor 31 is bent to the right (away from the sensor) (tooth 101'). For a straight tooth 101, the distance a is an intermediate value.

[0036] Fig. 7, diagram (a), shows an example of the waveform of the sensor signal (measurement data) from the inductive sensor shown in Figs. 3 and 4 and the resulting detection of broken saw teeth. The sensor signal represents the distance d (see Fig. 4). At a constant cutting speed v c The sensor signal of the saw blade is essentially periodic, with a period of p / v. c and the frequency w / p be- The frequency is represented by the (p, as mentioned, denotes the pitch). For example, a belt speed of 1.5 m / s and a pitch of 1.5 mm result in a sensor signal frequency of 1 kHz. Each period can therefore be assigned to a saw tooth or its tooth tip. With a variable tooth pitch, the period will also vary (and, for example, fluctuate around an average value).

[0037] As can be clearly seen in Fig. 7, diagram (a), the local minimum in each period represents the distance between sensor 30 and the corresponding saw tooth. Undamaged (unworn) and defective (broken) saw teeth can be detected by evaluating the sensor signal or the measurement data (see Fig. 10, data processing unit 4), for example, by comparing it with a threshold value. If the level of the sensor signal falls below the (predefined) threshold value in a specific period (corresponding to a specific saw tooth), then the respective saw tooth is detected as "not defective". If the threshold value is not reached, then the respective saw tooth is detected as "defective". In this way, the number of defective saw teeth and thus the wear condition of the saw band can also be determined. The number of defective saw teeth can be a quantitative measure of the wear condition. In the diagram shown in Fig.Figure 7, Diagram (a), shows two threshold values. The threshold labeled "Tooth Breakage" represents the distance di and is used to detect broken saw teeth, while the threshold labeled "Wear" is used to detect partially worn (but not broken) teeth. In a specific example, several different threshold values ​​are used (between do and di), representing different degrees of wear. In some examples, wear is quantitatively assessed directly via the measured value (in the interval between do and di). Such evaluations, threshold comparisons, and the like can be performed in an evaluation unit (data processing unit, see Fig. 10).

[0038] With the concept described here, it is possible not only to determine the number of broken saw teeth, but also the extent of wear. In some embodiments, several threshold values ​​can be used to detect the extent of wear. The threshold used for detecting broken teeth can also depend on an average of the measured distances do (for each tooth). As described above, the value do represents the tooth height of a Each saw tooth. The change in the average tooth height (compared to a new, unworn saw blade) can be considered a measure of (gradual) wear. Depending on the wear condition (reduction in average tooth height and / or number of broken teeth), certain process parameters (e.g., cutting speed or feed rate) can be adjusted in the machine control system. Depending on the current wear condition, the machine control system can also decide whether a new sawing process (which can last several hours) can be started with the saw blade or whether a blade change is necessary.

[0039] The detection of saw blade twist can be performed in a similar manner to the detection of broken teeth. Assume that a straight tooth 101 has a distance a=ao to sensor 31, a right-bent tooth 101' has a distance ai>ao, and a left-bent tooth 101" has a distance a2<ao. Beispielsweise können zwei verschiedene Schwellenwerte bi (mit ai> bi>ao) and b2 (with a2 <b2<ao) verwendet werden, um gebogene Zähne von geraden Zähnen zu unterscheiden. Wenn die Bedingung a> If condition bi is fulfilled, then the respective sawtooth is bent to the right. If condition a <b2 erfüllt ist, dann ist der jeweilige Sägezahn nach links gebogen. Wird keine Verschränkung detektiert (b2<a<bi), dann handelt es sich auch mit großer Wahrscheinlichkeit um ein Sägeband mit Hartmetall schneiden, da Sägebänder mit Schneiden aus Schnellarbeitsstahl fast immer eine Schränkung aufweisen. Diese Information kann von der Maschinensteuerung zumindest für eine Plausibilitätsprüfung verwendet werden.Furthermore, it is not only possible to detect whether a constraint exists, but in some embodiments it is also possible to detect what type of constraint exists (group constraint, standard constraint, etc., see Fig. 5).

[0040] Fig. 7, diagram (b), shows the detection of a sequence of different tooth types (saw teeth of different geometries) of an unset saw blade using sensor 31 (see Fig. 6). Sensor 31 detects the corners of the saw teeth from the side, and different tooth types can be distinguished based on the sensor signal from sensor 31. For saw teeth with a narrow main cutting edge and a long secondary cutting edge, sensor 31 will measure a greater distance than for saw teeth with a wide main cutting edge and a short (or missing) secondary cutting edge. In the case shown in diagram (b) of Fig. 7, even five different tooth types can be distinguished, the sequence of which repeats periodically. Several threshold values ​​can be used, for example, to distinguish between different tooth types. In one embodiment... The measured sequence of amplitudes of the local minima (each local minimum corresponds to a tooth) is compared with patterns stored in a database and assigned to a specific saw blade type. Depending on the detected tooth types, the detected sequence of tooth types, or the resulting saw blade type, a process parameter can be adjusted in the machine control (e.g., the cutting speed).

[0041] Fig. 8 illustrates an embodiment of another measuring setup that can be combined with the example from Fig. 3, 4, or 6. Both measuring setups can be integrated one after the other (with respect to the direction of travel of the saw blade) in the same sensor device / sensor unit. Depending on the application, the two measuring setups from Fig. 6 and 8 can also be installed separately at different locations on the band saw. According to Fig. 8, the measuring setup has at least one capacitive sensor 41 (in the illustrated example, there are two capacitive sensors 40 and 41). The sensors 40 and 41 each have two opposing electrodes 40a and 40b (sensor 40) and 41a and 41b (sensor 41), with the saw blade passing between two electrodes 41a and 41b (as well as 40a and 40b).

[0042] The operating principle of capacitive sensors for measuring the thickness of an electrically conductive material positioned between two corresponding electrodes (e.g., 41a and 41b) is known per se and therefore will not be explained in detail here. Sensor 40 measures the thickness of the saw blade in the area of ​​the blade back, and sensor 41 measures the thickness of the saw blade in the area of ​​the secondary cutting edges of the saw teeth. The width ti of the cutting channel can thus be automatically determined from the sensor signal of the capacitive sensor 41.

[0043] Fig. 9 shows an example of how the measurement setup from Figs. 3 and 4 can be integrated into a sensor device (a sensor module) that can be mounted, for example, on the saw frame (on the housing of the sawing machine 1). According to Fig. 9, the sensor device has a frame 50 with a mounting surface 55, on which the device can be mounted on the sawing machine 1 near the saw blade (see Fig. 1, mounting positions 20 and 21). The frame 50 can be any support element, a structure of several support elements, or even part of a housing. It serves to support or suspend various other components of the sensor device. 50 has one or more linear guides on which the support roller 32 and the sensors 30 and 31 are slidably mounted (bearing points 51).

[0044] The position of sensors 30 and 31 is fixed after an initial adjustment. The support roller 32, however, is mounted to slide against the spring force of spring 52. Spring 52 presses the support roller 32 against the back of the saw blade (see Figs. 3 and 4). It should be noted that Fig. 9 is merely an example and the actual design of the sensor device depends heavily on the specific conditions of the band saw machine.

[0045] Fig. 10 is a flowchart illustrating the coupling of the sensor device according to Fig. 9 with the machine control of the band saw. The overall system comprises the band saw 1 with a saw blade 11 (see Fig. 1) and a measuring device (sensor unit or sensor module 3) integrated into the band saw, as well as a data processing unit 4 and the aforementioned machine control 2. The machine control 2 is configured to control the operation of the band saw 1, for which one or more parameters stored in the machine control 2 are used. These parameters characterize the saw blade (saw blade parameters) or depend on properties of the saw blade (process parameters, such as the rotational speed of the blade or the feed rate of the workpiece during the sawing process).The data processing unit 4 (evaluation unit) is designed to determine at least one value of a saw blade parameter and / or a value of a process parameter based on the measurement data supplied by the sensor unit 3. The machine control unit 2 is further designed to receive the parameter value (or multiple parameter values) determined with the aid of the measuring device, to store it, to update previously stored values ​​if necessary, and to use it as a saw blade parameter or process parameter.

[0046] Examples of saw blade parameters include, as mentioned, the number of saw teeth on the saw blade (e.g., teeth per inch), the number of broken saw teeth, the degree of wear on the saw teeth, a value indicating whether the saw blade has a set (and possibly the set type), a value representing the width of the cutting channel, and / or a detected sequence of tooth types (in the case of trapezoidal teeth) or a saw blade type derived from it. Examples of process parameters derived from the measurement data (or a saw tooth parameter determined from it) include the blade's rotational speed (which, in the event of an emergency shutdown, band saw (which can also be zero) and - depending on the sawing process - the feed rate of the workpiece.

[0047] The data processing unit 4 receives the (digital or analog) measurement data from the sensor unit 3 and is designed to process (evaluate) the sensor data in order to determine one or more saw blade and / or process parameters (e.g., a parameter set) and transmit these to the machine control 2. Data exchange between the data processing unit 4 and the machine control 2 can be carried out using known technologies (e.g., a bus system for serial digital communication) and is generally dependent on the band saw manufacturer. The data processing unit 4 can therefore operate independently of the machine control 2. Only the communication link between the data processing unit 4 and the machine control 2 is manufacturer-specific. In a specific example, the data processing unit 4 can be integrated into the sensor unit 3 ("intelligent sensor").

[0048] As can be seen in Fig. 10, the band saw, sensor unit, data processing unit, and machine control can be operated as a control loop. This means that the data processing unit 4 can actively intervene in an ongoing sawing process based on the measurement data supplied by the sensor unit 3. For example, it can do this by transmitting an updated parameter set to the machine control 2 or by sending a command to the machine control that, for instance, changes a saw blade or process parameter (during operation) or triggers an emergency shutdown of the band saw. Additionally, the measurement results or the parameters derived from them can be visualized using the HMI of the machine control 2. The HMI also allows an operator to manually intervene in the sawing process.

[0049] Data processing unit 4 additionally enables (optional) vertical integration into automation networks (see Fig. 10). This allows the system data to be used for process optimization at the process control level (e.g., Supervisory Control and Data Acquisition, SCAD A, systems). Cloud connectivity is also possible. Furthermore, due to the system architecture (data processing unit 2 is separate from machine control 2), it is also possible to integrate machines with older generation controllers into an automation network.

[0050] The data processing unit 4 can include a processor and memory for storing software instructions. When executed by the processor, these instructions cause the data processing unit 4 to perform the functions described here for evaluating the sensor signals / measurement data. For this purpose, the data processing unit 4 includes peripheral devices (e.g., communication interfaces, analog-to-digital converters, etc.) to enable a connection with the sensor unit 3 and the machine control 4. The data processing unit 4 can be, for example, a personal computer (PC), an industrial PC, or an embedded system. Parts of the data processing unit 4 can also be implemented using electronic circuits (hardware) that do not require software to function. The term "data processing unit 4" encompasses any entity, including hardware and software, that is capable of performing the functions described here (e.g.,To provide evaluation of the sensor signals / measurement data and, based on this, the determination of one or more parameters or commands for machine control.

[0051] Fig. 11 shows – similar to Fig. 9 – another example of integrating the measurement setup from Figs. 3, 4, and 6 into a sensor device. Diagram (a) of Fig. 11 shows a perspective view, and Diagram (b) shows the corresponding side view. Diagram (c) of Fig. 11 shows the device with decoupled sliding elements, which will be discussed in more detail later. The example in Fig. 11 differs from the example in Fig. 9 primarily in the elements used to move the sensor device mounted on the band saw away from the saw blade by means of a pivoting motion, thus enabling easy blade changes. The axis of rotation of this pivoting motion is labeled "C" in Fig. 11.

[0052] During operation, the support roller 32 is pressed against the back of the saw blade 11 by a spring (not shown in Fig. 11). To allow the sensor device (i.e., the housing or frame 50) to pivot away from the saw blade 11, a locking mechanism is provided, which enables the support roller 32 to be locked at a specific distance from the back of the blade. As in Fig. 9, in the present example, the support roller 32 is mounted on a sliding element 54, which is slidably mounted along the linear guide 53 (part of the frame 50). The sliding element 54 has a stop 58 against which a latch 59 can engage. In the illustrated example, the sliding element 54 (sliding carriage) can be moved away from the back of the blade against the force of the spring. The locking mechanism is pressed until the latch 59 engages the stop 58 and locks the sliding element 54. This state is illustrated in diagram (c) of Fig. 11, where the spring presses the stop 58 of the sliding element 54 against the latch 59. The locking mechanism can be released manually by actuating the lever 60, which tilts the latch 59 away from the stop 58. It should be understood that the locking mechanism shown for the support roller 32 (i.e., for the sliding element 54 on which the support roller 32 is mounted) is only one example. Other locking options are also available.

[0053] Sensors 30 and 31 are slidably mounted on the second sliding element 54' on the linear guide. During operation, the sliding element 54' can be clamped to the linear guide. In the illustrated case, the clamping can be activated and released via the rotary knob 61. When the clamp is released, the sliding element 54' can be moved so that sensors 30 and 31 are moved away from the saw teeth, as shown in diagram (c) of Fig. 11. The sensor device can then be easily pivoted away from the saw blade (about the axis of rotation C). In the state shown in diagram (b) of Fig. 11, the two sliding elements 54 and 54' are coupled, i.e., arranged at a defined distance from each other. This distance can be predetermined, for example, by a spacer between the two sliding elements 54 and 54'.

[0054] Figure 12 shows an example of a process carried out using the system from Figure 10, illustrated by a flowchart. The process includes acquiring measurement data characterizing a band saw blade using a sensor unit that can be integrated into the band saw (Figure 12, step S1). The process further includes generating a command for the band saw's machine control based on the measurement data (Figure 12, step S2) and transmitting the command to the machine control (Figure 12, step S3). The command can be an update command to update one or more saw blade or process parameters. The command can also be an emergency stop command to abort the sawing process.

[0055] In one example, generating the command involves determining at least one saw blade parameter that characterizes a property of the saw blade, based on the measurement data. In this case, the command is an update command for updating the saw blade parameter in the machine control. The command can It can also be an emergency stop command, for example, if the saw blade parameter indicates excessive wear. Examples of saw blade parameters include, as already mentioned, wear (reduction of tooth height due to abrasion), the width of the kerf, the total number of broken teeth, the number of consecutive broken teeth, set, etc. In case of excessive wear, for example, if a certain number of adjacent teeth have broken, an emergency stop command can be generated to terminate the sawing process.

[0056] Generating the command can also include determining (based on the measurement data) a process parameter that influences the sawing process performed with the band saw. In this case, the command is also an update command for updating the process parameter in the machine control (2). Examples of process parameters are, as already mentioned, the workpiece feed rate and the band rotation speed. These can be reduced, for example, depending on the wear of the saw band.

[0057] The transfer of command to the machine control can occur particularly during an ongoing sawing process carried out with the help of the band saw, in order to actively intervene in the sawing process, to change it or to stop it.

Claims

CLAIMS 1. A measuring device for characterizing a saw blade (11) of a band saw, the measuring device comprising: a first inductive distance sensor (30) configured to generate a sensor signal representing a distance between a sensor position and a front side of the saw blade, on which saw teeth (101, 102) are located; a support roller (32), and a pretensioning mechanism configured to press the roller (32) against a rear side of the saw blade (11).

2. The measuring device according to claim 1, further comprising: a frame (50) for mounting the measuring device on the band saw, wherein the first distance sensor (30) is mounted on the frame (50) such that a measuring direction of the first distance sensor (30) lies in a band plane of the saw band (11); wherein the support roller (32) is slidably mounted on the frame (50); and wherein the pretensioning mechanism comprises a spring which generates a pretensioning force between the frame (50) and the support roller (32), such that the pretensioning force presses the support roller (32) against the back of the saw band (11).

3. The measuring device according to claim 1 or 2, further comprising: an evaluation device which is designed to detect, based on the sensor signal and for each sawtooth (101, 102) of the saw band (11), whether a height of the respective sawtooth (101, 102) falls below a threshold value.

4. The measuring device according to claim 3, wherein the evaluation device is designed to evaluate a sawtooth (102) as defective if the height of the respective sawtooth (102) falls below the threshold value.

5. The measuring device according to claim 3 or 4, wherein the evaluation device is designed to count the saw teeth (102) of the saw band (11) that are assessed as defective; and / or wherein the evaluation device is designed to determine a value which represents the number of saw teeth (101, 102) per unit length.

6. The measuring device according to one of claims 3 to 5, wherein the evaluation device is designed to determine a value that represents the extent of wear of the saw blade.

7. The measuring device according to claim 6, wherein the extent of wear of the saw band depends on an average value of the measured heights of the saw teeth 8. The measuring device according to one of claims 1 to 7, further comprising: a second inductive distance sensor (31) which is designed to generate a second sensor signal which indicates whether the saw teeth (101, 102) lie in a band plane of the saw band (11) or are inclined to the band plane.

9. The measuring device according to one of claims 1 to 8, further comprising: a further sensor (41) which is designed to measure a value which represents the width of the cutting channel (ti) of the saw band (11).

10. The measuring device according to one of claims 1 to 9, wherein the support roller (32) is mounted on a displaceable sliding element (54), and wherein the measuring device has a locking mechanism which is designed to block the pretensioning mechanism and to hold the support roller (32) in a position in which it is spaced from the back of the saw band.

11. The measuring device according to one of claims 1 to 10, wherein the first inductive distance sensor (30) is mounted on a further displaceable sliding element (54'), wherein the further sliding element (54') can be locked via a clamping mechanism.

12. A system that has the following: a band saw (1) with a saw blade (11) and a machine control system (2) designed to control a sawing process carried out with the aid of the band saw (1), for which purpose one or more saw blade parameters and / or process parameters stored in the machine control system (2) are used; a measuring device designed to determine at least one parameter value that characterizes the saw blade (11), wherein the machine control system (2) is further designed to receive the parameter value determined with the aid of the measuring device or a parameter value derived therefrom and to store it as a saw blade parameter or process parameter.

13. The system according to claim 10, wherein the at least one parameter value characterizing the saw blade (11) comprises one of the following values: a value representing the number of saw teeth of the saw blade; a value representing the number of broken saw teeth of the saw blade; a value indicating whether the saw blade (11) has a set; a value representing the width of the cutting channel.

14. The system according to claim 10 or 11, wherein the measuring device is connected to the band saw in such a way that it is pivotable relative to the saw blade (11).

15. The system according to one of claims 12 to 14, wherein the measuring device comprises a sensor unit (3) integrated into the band saw (1) and a data processing unit (4), wherein the sensor unit (3) supplies measurement data that characterize the saw band (11), and wherein the data processing unit (4) is designed to determine the parameter value from the measurement data.

16. The system according to claim 15, wherein the data processing unit (4) is designed to determine from the parameter value a process parameter relating to the sawing process carried out by the band saw (1).

17. The system according to claim 15 or 16, wherein the data processing unit (4) is designed to update the at least one parameter based on the measurement data and to transmit it to the machine control (2).

18. The system according to claim 16, wherein the data processing unit (4) is designed to update the process parameter based on the measurement data and to transmit it to the machine control (2).

19. A method comprising: Acquiring measurement data characterizing a saw blade (11) of a band saw (3) by means of a sensor unit (3); Generating a command for a machine control (2) of the band saw (1) based on the measurement data; and Transferring the command to the machine control (2) of the band saw (1).

20. The method of claim 19, wherein generating the command comprises: Determining at least one saw band parameter that characterizes a property of the saw band (11) based on the measurement data, wherein the command is a command for updating the at least one saw band parameter in the machine control (2).

21. The method according to claim 19 or 20, wherein generating the command comprises: Determining a process parameter that influences the sawing process carried out with the band saw (11) based on the measured data; wherein the command is a command for updating the process parameter in the machine control (2).

22. The method according to claim 21, where updating the process parameter in the machine control causes the sawing process to be aborted.

23. The method according to one of claims 19 to 22, wherein the transmission of the command to the machine control (2) takes place during an ongoing sawing process carried out with the aid of the band saw in order to change or stop the sawing process.

24. A system comprising: a band saw (1); a machine control (2) for the band saw (1); a sensor unit (3) integrated into the band saw for acquiring measurement data characterizing a saw blade (11) of the band saw (3); and a data processing unit (4) configured to carry out the method according to claim 19 with the aid of the sensor unit (2).

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