Characterization of saw bands in band saw machines

Abstract

An improved concept for the automatic characterization of saw bands is developed. [Solution] This patent application describes a measurement device for characterizing a saw band of a band saw machine. In one embodiment, the measurement device includes a first inductive distance sensor (30) configured to generate a sensor signal representative of the distance between a sensor location and a front surface of the saw band where saw teeth (101, 102) are located, a support roller (32), and a biasing mechanism configured to press the support roller (32) against a back side of the saw band (11).

Description

[Technical Field]

[0001] The present invention particularly relates to the characterization of saw bands in band saw machines. [Background technology]

[0002] There are many different types of bandsaw machines. In industrial environments, computer numerically controlled (CNC) bandsaw machines are frequently used. The machining control system requires various parameters to properly control the sawing process, and for many machines, these must be manually entered by the operator into the machine control system. The machining control system includes a human-machine interface (HMI) suitable for this purpose.

[0003] Such parameters are particularly relevant for the saw band, since the characteristics of the band saw directly affect the sawing process. For example, the width of the kerf must be taken into account when positioning the workpiece (e.g., automatically or semi-automatically). This depends on the shape of the saw band and, in known machines, must be entered manually in the machine control. Furthermore, the allowable cutting speed (and therefore the band speed and / or feed rate) may depend on the type of saw band, e.g., on a given set of teeth in the saw band, or on the material of the saw teeth (e.g., high-speed steel or cemented carbide). Depending on the type of machine, these parameters also need to be communicated to the machining control system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DE 3903133 A1 [Patent Document 2] WO 2021008714 A1 [Patent Document 3] DE 102018118369 A1 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, although the sawing process itself is automated, correct process control relies on parameters manually entered by the operator into the machine control system, which can lead to errors. Several concepts have been devised to avoid such errors when configuring machine control systems. For example, saw bands can be physically labeled with barcodes, QR codes (Quick Response Codes), or RFID tags (Radio Frequency Identification Tags). Such labeling / coding can be automatically read (optically in the case of barcodes and QR codes, or electromagnetically in the case of RFID tags) using an appropriate reading device. This labeling / coding represents a numerical code that is stored in a database for parameters related to machining control. This concept of saw band labeling has its drawbacks: different manufacturers use different systems for labeling saw bands, which can lead to compatibility issues when using saw bands from different manufacturers. Furthermore, labeling saw bands with barcodes, QR codes, or RFID tags can identify the saw bands, but they do not provide information about the wear status of the saw bands, which is an important parameter for machining control. Furthermore, markings such as bar codes laser engraved on saw bands can become illegible due to wear, and inevitably, such markings can only represent the characteristics of a new saw band.

[0006] The inventors set themselves the task of improving the situation described above and developing an improved concept for the automatic characterization of saw bands. [Means for solving the problem]

[0007] The above-mentioned problem is solved by a measuring device according to claim 1 and a system according to claim 12. Various embodiments and further developments are the subject of the dependent claims. In the following, a measuring device for evaluating the properties of a saw band of a band saw machine is described. According to one embodiment, the measuring device comprises a first inductance distance sensor configured to generate a sensor signal representative of the distance between a sensor position and a front side of the saw band on which the saw teeth are located, a support roller, and a biasing mechanism configured to press the support roller against a back side of the saw band.

[0008] A further embodiment is a system including a band saw, the system comprising a saw band and a machining control unit configured to control a sawing process performed with the saw band, using one or more saw band parameters and / or process parameters stored in the machining control unit, the system further comprising a measuring device configured to determine at least one parameter value characterizing the saw band, the machining control unit further configured to receive parameter values ​​determined by or derived from the measuring device and store them as saw band parameters or process parameters. [Effects of the Invention]

[0009] The above-described conventional situation is improved, and automatic characterization of saw bands is improved. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a schematic diagram of an example of a conventional CNC band saw machine.

[0011] [Figure 2] FIG. 1 is a diagram illustrating an example of a saw band (band saw blade) with broken saw teeth.

[0012] [Figure 3] Schematic diagram showing an example of a measurement configuration for automatic detection of sawtooth defects by inductance distance or proximity sensors.

[0013] [Figure 4] FIG. 4 is a cross-sectional view of FIG.

[0014] [Figure 5] 5(a) and 5(c) show exemplary possible shapes of sawtooth (FIG. 5(a)) and different types of sets of sawtooth (FIG. 5(b) and FIG. 5(c)).

[0015] [Figure 6] FIG. 5 is a diagram showing an example in which the measurement configuration of FIGS. 3 and 4 is modified.

[0016] [Figure 7] 7A and 7B are diagrams illustrating exemplary signal curves of the sensor signal of the inductance sensor shown in FIG. 4 and detection of breakage or wear of sawtooth based thereon (FIG. 7A), as well as signal curves of the additional sensor signal of the inductance sensor shown in FIG. 6B and detection of tooth type based thereon.

[0017] [Figure 8] FIG. 10 shows a further measurement setup for measuring the width of the kerf of the saw band using a capacitance sensor.

[0018] [Figure 9] FIG. 7 is a diagram showing an example in which the measurement configurations shown in FIGS. 3, 4 and 6 are integrated into a sensor device.

[0019] [Figure 10] FIG. 10 is a block diagram showing the coupling of the sensor device shown in FIG. 9 with the machining control of a band saw.

[0020] [Figure 11] FIG. 7 shows a further example of the integration of the measurement configurations shown in FIGS. 3, 4 and 6 into a sensor device.

[0021] [Figure 12] 11 is a flowchart illustrating an example of a method that can be performed using the system of FIG. 10. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will now be described in more detail with reference to various illustrative embodiments, which are not necessarily to scale and are not intended to limit the invention to the illustrated embodiments, but rather to illustrate the principles underlying the invention.

[0023] Before describing the various embodiments in more detail, a brief description of the general structure of a band saw will first be provided with reference to Figure 1. The embodiments described herein can be used with different types of band saws and are not limited in their application to the type of band saw shown in Figure 1.

[0024] According to Figure 1, the band saw 1 has a saw frame (housing) and two rotating wheels 10a, 10b attached to the saw frame, one of which is driven by an electric motor. The saw band 11 is held and guided by the rotating wheels (similar to a belt). The driven rotating wheel also drives the saw band (its rotation speed is adjustable). The other rotating wheel is driven. Figure 1 also shows diagrammatically a workpiece 30 being cut by the saw band 11. In the example shown, the cutting plane is vertical. However, there are also band saws with horizontal or inclined cutting planes.

[0025] Numbers 20 and 21 indicate locations on the saw frame (housing) of the band saw 1 where measurement devices, which will be described in more detail below, can be located. While it is not absolutely necessary to mount the measurement devices in such locations, these locations adjacent to the rotating wheels make sense in most applications because they are relatively well protected from cooling lubricants, dirt, chips, dust and other hazards.

[0026] The machining control system may be located in a separate housing and is not shown in Figure 1. For example, the machining control system may be implemented in an industrial PC using software. Many different types of machining control systems are known and will not be described in further detail here.

[0027] FIG. 2 shows an example of a saw band 11 having multiple saw teeth 101. The distance between two adjacent saw teeth is called the pitch p. Variable tooth pitch has proven its value in sawing metallic materials in industrial high-performance production. It is usually specified in teeth per inch. In the example shown in FIG. 2, a saw tooth 102 is broken. A saw tooth can break, for example, if the sawing process parameters (e.g., cutting speed and feed rate) are not set correctly. A saw tooth can also become worn, causing the height of the saw tooth to become significantly smaller than the height of an unworn tooth.

[0028] The embodiments described herein relate to the concept of saw band (band saw blade) characterization, in particular to determine the wear state of the saw band and automatically detect defective (broken) saw teeth. In some embodiments, it is also possible to detect the set of saw bands and / or measure the actual width of the kerfs. In particular, known methods such as labeling with QR codes (registered trademark) as mentioned above are not capable of determining the wear state.

[0029] Figure 3 shows a simplified example of a measurement setup for detecting worn (broken) saw teeth using an inductance sensor. Inductance sensors have proven to be particularly reliable (especially in principle compared to optical sensors). Suitable sensors are available on the market as inductance position sensors or proximity sensors. As shown in Figure 3, the inductance sensor 30 is located on the band surface A of the saw band (see also Figure 4) and monitors the tooth side (narrow side) of the saw band where the saw teeth are located. The measurement direction of the sensor (in which the distance between the sensor 30 and the saw band 11 is measured) extends in the band surface A at a right angle to the running direction of the band.

[0030] The distance between the sensor 30 and the tip of the saw tooth is labeled d0 in FIG. 3. Distance d0 is the minimum distance between the sensor 30 and the saw band 11. The sensor measures distance d0 when it is directly facing the tip (main cutting edge) of an unworn saw tooth 101. If the gap between two saw teeth faces the sensor 30, the measured distance d will be larger (d>d0). Even if the saw tooth facing the sensor 30 (labeled 102 in FIG. 3) has a defect (worn or broken), the measured distance d1 will be larger than the minimum distance d0 (d1>d0).

[0031] A single inductance distance sensor is not sufficient to reliably detect a defective saw tooth. In practice, the saw band 11 not only moves in the direction of travel or cutting (as indicated by the arrows in FIG. 3 ), but also vibratory movements can occur transverse to the direction of travel, which prevents or at least impairs reliable measurement of distance or reliable detection of changes in distance. Such vibrations can be locally reduced, at least in the area of ​​the sensor 30, by arranging a support roller 32 on the back surface 103 of the saw band 11, on the side facing the sensor 30. The support roller 32 can be attached to the frame structure of the sensor device so that it contacts the narrow side of the back surface 102 of the band. As the saw band 11 moves, the support roller also rotates.

[0032] For example, the support roller 32 may be displaceable and coupled to a spring so that the support roller 32 is pressed against the back surface of the band with a force F (preload force). The preload force F is the only factor of interest, not how it is generated. For this reason, only the preload force F is shown in FIG. 3 , not the spring. The support roller 32 may be made of metal, but in some embodiments, it may be made of plastic. The running surface of the support roller 32 may also be coated with plastic or rubber. In particular, in conjunction with the preload force F, the support roller 32 reduces rocking motion transverse to the running direction of the saw band 11, significantly improving the reliability of saw tooth defect detection.

[0033] Figure 4 is a cross-sectional view of the example of Figure 3. Section C (see Figure 3) is perpendicular to the direction of travel of the saw band 11 and passes through the tip of the unworn tooth 101. The axis of rotation B of the support roller 32 is also shown in Figure 4. The detection of individual broken teeth will be explained in more detail later (see also, for example, Figure 7).

[0034] FIG. 5 illustrates various aspects of saw bands and their sawtooth shapes. FIG. 5(a) is a cross-sectional view showing an example of a special sawtooth shape in which the width (thickness) of the sawtooth increases toward the tip. Therefore, this type of sawtooth is also called a trapezoidal tooth. Plane A indicates the center plane of the band saw blade. The outermost edge of the sawtooth (perpendicular to center plane A) forms the main cutting edge. The edge extends diagonally to the left and right of the center plane. The diagonal portion of the cutting edge is also called the minor cutting edge. The portion of the sawtooth 101 facing the main cutting edge has the same thickness as the back surface 103 of the band. The main and minor cutting edges of the sawtooth can be made of a different material than the back surface 103 of the band. For example, the cutting edge can be made of cemented carbide or high-speed steel, while the back surface 103 of the band can be made of ordinary tool steel. Saw bands with different sawtooth shapes exist. These sawtooth shapes differ, for example, in the width of the main cutting edge. As an example, FIG. 5(a) illustrates two possible variations in tooth shape using dashed lines. In one case, the main cutting edge extends across the entire width of the tooth. In this case, there are practically no minor cutting edges. Saw bands can also have alternating saw teeth of different types. This is especially the case with unset saw bands. A specific ordered group of saw teeth can be repeated periodically on the saw band (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).

[0035] Figures 5(b) and 5(c) show different types of sets of saw teeth on a bandsaw blade. Figure 5(b) shows a standard set where of three adjacent teeth, one is straight (i.e., in the band plane A), one is curved to the left, and one is curved to the right (i.e., at an angle to the band plane A). In Figure 5(b), the straight saw teeth are labeled 101, the right-bent saw teeth are labeled 101', and the left-bent saw teeth are labeled 101".

[0036] Figure 5(c) shows a left-right set in which the teeth are bent alternately left and right. The sawtooth 101 in the band plane A is not present in this variant. There are other types of sawtooth sets, such as group sets, in which two or more consecutive teeth are bent in the same direction. In wave sets, the angle of inclination of the sawtooth changes periodically from tooth to tooth, with one period consisting of, for example, eight teeth. Saw bands with carbide blades are often not set, while bimetal saw bands with high-speed steel blades are usually set. The various types of band saw blades and the various types of sets are known per se and will not be described further here.

[0037] FIG. 6 shows an example of a modification / extension of the measurement configuration shown in FIGS. 3 and 4, in which a second inductance position or distance sensor 31 is used to determine the set type of the saw band 11. The support roller 32 and the first sensor 30 are arranged in FIG. 6 in the same way as in FIGS. 3 and 4, and the above explanations are referred to. The measurement direction of the sensor 31 is perpendicular to the band plane A. Therefore, the sensor 31 detects the saw band 11 (especially the saw teeth) from the side. The sensor signal depends on the distance a between the sensor 31 and the saw band (see FIG. 6). If the saw tooth next to the sensor 31 is curved to the left (towards the sensor) (tooth 101"), the distance a is small. If the saw tooth next to the sensor 31 is curved to the right (away from the sensor) (tooth 101'), the distance a is slightly larger. For straight teeth 101, the distance a is an intermediate value.

[0038] Figure 7(a) shows the signal curve (waveform) of the sensor signal (measurement data) of the inductance sensor in Figures 3 and 4, and an example of saw blade breakage detection based on this. The sensor signal indicates the distance d (see Figure 4). The cutting speed v of the saw band. c If is constant, the sensor signal is periodic in nature, with a period duration of p / v c , frequency is v c / p (where p denotes the pitch, as mentioned above). For example, for a band speed of 1.5 m / s and a pitch of 1.5 mm, the frequency of the sensor signal is 1 kHz. Each period therefore corresponds to a saw tooth or its tip. In the case of a variable tooth pitch, the periodic period will vary as well (e.g., fluctuate around a mean value).

[0039] As can be clearly seen in Figure 7(a), local minima in each cycle represent the distance between the sensor 30 and the corresponding sawtooth. Undamaged (unworn) and defective (broken) sawtooth can be detected by analyzing the sensor signal, i.e., the measurement data (see Figure 10, data processing unit 4), for example, by comparing it with a threshold value. If the level of the sensor signal falls below a (predefined) threshold value for a certain period (corresponding to a certain sawtooth), the respective sawtooth is detected as "not defective." If this value does not fall below the threshold value, the respective sawtooth is detected as "defective." In this way, the number of defective sawtooths on the saw band and, therefore, the wear state of the saw band can be determined. The number of defective sawtooths can be used as a quantitative measure of the wear state. In the example of Figure 7(a), two threshold values ​​are shown. The threshold value labeled "broken tooth" represents the distance d1 and is used to detect broken sawtooth. The threshold value labeled "worn" is used to detect partially worn (but not broken) teeth. In special cases, different threshold values ​​(between d0 and d1) are used, representing different degrees of wear. In some cases, the wear is quantitatively assessed directly by the measurements (in the interval between d0 and d1). Such analysis, threshold comparisons, etc. can be performed in an evaluation unit (data processing unit, see Figure 10).

[0040] In the concepts described herein, it is possible to determine not only the number of damaged saw teeth but also the degree of wear. In some embodiments, multiple thresholds can be used to recognize the degree of wear. The threshold used for detecting broken teeth may depend on the average value of the measured distance d0 (for each tooth). As described above, the value d0 represents the tooth height of each saw tooth. The change in the average value of the tooth height (compared to a new, unworn saw band) can be regarded as an indicator of (progressive) wear. Depending on the wear condition (decrease in average tooth height and / or number of broken teeth), a machining control system can adjust specific process parameters (such as cutting speed and feed rate). Depending on the current wear condition, the machining control system can also determine whether to start a new sawing process (which may take several hours) with that saw band or whether it is necessary to replace the saw band.

[0041] The detection of the left - right distinctiveness of the teeth of the saw band can be performed in a similar way to the detection of broken teeth. Assuming that the distance a = a0 for a straight tooth 101 from the sensor 31, for a tooth 101' bent to the right, the distance a1 > a0, and for a tooth 101" bent to the left, the distance a2 < a0. For example, two different thresholds b1 (a1 > b1 > a0) and b2 (a2 < b2 < a0) can be used to distinguish between curved teeth and straight teeth. If the condition a > b1 is satisfied, each saw tooth is bent to the right. If the condition a < b2 is satisfied, each saw tooth is bent to the left. When no left - right distinctiveness is detected (b2 < a < b1), for a saw band with a high - speed steel blade, in most cases, the cutting edge is set, so there is a very high possibility that the cutting edge is a saw band made of carbide. This information can be used in the machining control system, at least for a validity check. Furthermore, not only is it possible to detect whether a set exists, but in some embodiments, it is also possible to detect which type of set exists (group set, standard set, etc., see Figure 5).

[0042] FIG. 7(b) shows the detection of a series of different tooth types (saw teeth of different shapes) of unset saw teeth by sensor 31 (see FIG. 6). To do this, sensor 31 detects the saw tooth corners from the side, and the sensor signal from sensor 31 can distinguish between different tooth types. For saw teeth with narrow main cutting edges and long minor cutting edges, sensor 31 measures a larger distance than for saw teeth with wide main cutting edges and short (or missing) minor cutting edges. In the case shown in FIG. 7(b), it is possible to distinguish between five different tooth types whose sequence repeats periodically. For example, several thresholds can be used to distinguish between different tooth types. In one embodiment, the amplitude sequence of the measured local minima (each corresponding to a tooth) is compared with patterns stored in a database and classified into a specific saw band type. Depending on the detected tooth type, the sequence of detected tooth types, or the derived saw band type, a process parameter in the machining control system can be adjusted (e.g., cutting speed).

[0043] Figure 8 shows an embodiment of a further measurement arrangement that can be combined with the examples of Figures 3, 4 or 6. Both measurement arrangements can be integrated one into the other (relative to the direction of travel of the saw band) in the same sensor device / sensor unit. Depending on the application, the two measurement arrangements of Figures 6 and 8 can also be installed separately at different positions on the band saw. According to Figure 8, the measurement arrangement includes at least one capacitance sensor 41 (in the illustrated example, there are two capacitance sensors 40 and 41). Each of the sensors 40 and 41 has two electrodes 40a and 40b (sensor 40) and electrodes 41a and 41b (sensor 41) facing each other, with the saw band passing between the two electrodes 41a and 41b (and electrodes 40a and 40b).

[0044] The operation of a capacitance sensor for measuring the thickness of a conductive material arranged between two corresponding electrodes (e.g., electrodes 41a and 41b) is known per se and will not be described in further detail here. Sensor 40 is used to measure the thickness of the saw blade in the area of ​​the back side of the saw band, and sensor 41 is used to measure the thickness of the saw blade in the area of ​​the minor cutting edge of the saw tooth. The width t1 of the kerf can be determined automatically from the sensor signal of capacitance sensor 41.

[0045] FIG. 9 shows an example of how the measurement arrangements of FIGS. 3 and 4 can be integrated into a sensor device (sensor module), which can be mounted, for example, on the saw frame (on the housing of the saw machine 1). According to FIG. 9, the sensor device comprises a frame 50 with a mounting surface 55 that is attached to the saw machine 1 in the vicinity of the saw band (see FIG. 1, mounting positions 20 and 21). The frame 50 can be any support element, a structure of several support elements, or part of the housing. The frame 50 is used to mount or suspend various other components of the sensor device. The frame 50 has one or more linear guides (support position 51) on which the support rollers 32 and the sensors 30, 31 are displaceably mounted.

[0046] The positions of sensors 30 and 31 are fixed after initial adjustment. Meanwhile, support roller 32 is mounted so as to be displaceable against the spring force of spring 52. Spring 52 presses support roller 32 against the back surface of the saw band (see Figures 3 and 4). Note that Figure 9 is only an example, and the actual configuration of the sensor device will vary greatly depending on the conditions of each band saw machine.

[0047] FIG. 10 is a flow diagram illustrating the coupling of the sensor device according to FIG. 9 with the machining control of a band saw. The overall system comprises a band saw 1 with a saw band 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 machining control unit 2. The machining control unit 2 is configured to control the operation of the band saw 1. For this purpose, one or more parameters stored in the machining control unit 2 are used, which in particular characterize the saw band (saw band parameters) or depend on the properties of the saw band (process parameters, such as the rotation speed of the saw band or the feed rate of the workpiece during the sawing process). The data processing unit 4 (evaluation unit) is configured to determine at least one value of the saw band parameter and / or one value of a process parameter based on the measurement data supplied by the sensor unit 3. The machine control unit 2 is also configured to receive and store the parameter value(s) determined by the measuring device and, if necessary, update previously stored values ​​and use them as the saw band parameter or process parameter.

[0048] Examples of saw band parameters include, as mentioned above, the number of teeth on the saw band (e.g., teeth per inch), the number of broken teeth on the saw band, the degree of wear on the saw band, a value indicating whether the saw band 11 has sets (and in some cases the type of sets), or a value representing the width of the kerf, and / or the order of the detected tooth types (in the case of trapezoidal teeth), or the type of saw band that can be inferred therefrom. Examples of process parameters that can be obtained from measurement data (or saw tooth parameters determined from measurement data) are the band rotation speed (which can be zero in an emergency stop of the band saw) and the workpiece feed rate, depending on the sawing process.

[0049] The data processing unit 4 is configured to receive measurement data (digital or analog) from the sensor unit 3, process (evaluate) the sensor data, determine therefrom one or more saw band and / or process parameters (e.g., parameter sets), and forward these to the machining control unit 2. Data exchange between the data processing unit 4 and the machining control unit 2 can be performed using known technology (e.g., bus systems for serial digital communication) and is typically manufacturer-dependent. The data processing unit 4 can therefore operate independently from the machining control unit 2; merely the communication link between the data processing unit 4 and the machining control unit 2 is manufacturer-specific. In special cases, the data processing unit 4 can be integrated into the sensor unit 3 ("intelligent sensor").

[0050] As can be seen from Figure 10, the bandsaw, the sensor unit, the data processing unit and the machining control unit can be operated as a control loop. This means that, based on the measurement data supplied by the sensor unit 3, the data processing unit 4 can actively intervene in the ongoing sawing process, for example by sending an updated set of parameters to the machining control unit 2 or by sending a command to the machining control unit to, for example, change the saw band or process parameters (during operation) or cause an emergency stop of the bandsaw. Furthermore, the measurement results and the parameters derived therefrom can be visualized using the HMI of the machine control unit 2. The HMI also allows for manual intervention in the sawing process by a service person.

[0051] The data processing unit 4 also enables (optional) vertical integration into the automation network (see Figure 10), so that the system data can be used to optimize the process at the process control level (e.g. supervisor control and data acquisition SCADA systems). Cloud connectivity is also possible. Based on the system architecture (the data processing unit 2 is separated from the machining control unit 2), it is also possible to integrate machines with older generation control units into the automation network.

[0052] The data processing unit 4 may include a processor and a memory for storing software instructions that, when executed by the processor, cause the data processing unit 4 to perform the functions described herein for analyzing the sensor signals / measurement data. To this end, the data processing unit 4 may include peripheral devices (e.g., communication interfaces, analog-to-digital converters) that enable connection with the sensor unit 3 and the machining control unit 4. The data processing unit 4 may be, for example, a personal computer (PC), an industrial PC, or an embedded system. Parts of the data processing unit 4 may also be implemented using electronic circuits (hardware) that do not require software to function. The data processing unit 4 is understood to be any entity consisting of hardware and software suitable for providing the functions described herein (e.g., analyzing the sensor signals / measurement data and determining one or more parameters or commands for the machining control system based thereon).

[0053] FIG. 11, like FIG. 9, shows a further example of integrating the measurement arrangements of FIGS. 3, 4, and 6 into a sensor device. FIG. 11(a) is a perspective view, and FIG. 11(b) is the corresponding side view. FIG. 11(c) shows the device without the guide elements, which will be explained in more detail later. The embodiment of FIG. 11 differs from the embodiment of FIG. 9 essentially in the element that serves to move the sensor device, which is attached to the band saw, away from the saw band by a pivoting movement, in order to make it easier to replace the saw band. The axis of rotation of said pivoting movement is marked "C" in FIG. 11.

[0054] During operation, the support roller 32 is pressed against the back surface of the saw band 11 by, for example, a spring (not shown in FIG. 11 ). To pivot the sensor device (i.e., the housing or frame 50) away from the saw band 11, a locking mechanism is provided to lock the support roller 32 at a fixed distance from the back surface of the band. As shown in FIG. 9 , in this embodiment, the support roller 32 is mounted on a slide element 54, which is displaceably mounted along a linear guide 53 (part of the frame 50). The slide element 54 is provided with a stopper 58 that can be engaged by a latch 59. In the illustrated example, the slide element 54 (sliding platform) can be pushed away from the back surface of the belt against the biasing force of the spring until the latch 59 engages the stopper 58 and locks the slide element 54 in place. This state is shown in FIG. 11( c ), where the spring presses the stopper 58 of the slide element 54 against the latch 59. The locking mechanism can be manually released by actuating lever 60, which tilts latch 59 away from stop 58. The illustrated locking mechanism for support roller 32 (i.e., the locking mechanism for slide element 54 to which support roller 32 is attached) is only an example; other locking mechanism configurations can be used.

[0055] The sensors 30 and 31 are mounted on a second sliding element 54' so that they can be displaced on a linear guide. During operation, the sliding element 54' can be clamped on the linear guide. In the illustrated case, the clamp can be activated and released by a rotating knob 61. When the clamp is released, the sliding element 54' can be displaced so that the sensors 30 and 31 move away from the saw blade, as shown in FIG. 11(c). The sensor arrangement can be easily pivoted (about the rotation axis C) away from the saw blade. In the state shown in FIG. 11(b), the two sliding elements 54, 54' are coupled, i.e., are 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'.

[0056] FIG. 12 is a flowchart illustrating an example of a method that can be performed using the system of FIG. 10. Accordingly, the method includes acquiring measurement data characterizing the saw band of the band saw by a sensor unit that can be incorporated into the band saw (FIG. 12, step S1). The method also includes generating a command for the band saw's machining control unit based on the measurement data (FIG. 12, step S2) and transmitting the command to the band saw's machining control unit (FIG. 12, step S3). The command can be an update command for updating one or more saw band or process parameters. The command can also be an emergency stop command to interrupt the sawing process.

[0057] In one embodiment, generating the command includes determining at least one saw band parameter characterizing a characteristic of the saw band based on the measurement data. In this case, the command is an update command for updating the saw band parameter in the machining control unit. For example, if the saw band parameter indicates excessive wear of the saw band, the command can also be an emergency stop command. Examples of saw band parameters include wear (loss of tooth height due to wear), kerf width, total number of broken teeth, number of consecutive broken teeth, and sets, as previously mentioned. If the wear becomes too severe, for example, if a certain number of adjacent teeth are broken, an emergency stop command can be generated to interrupt the sawing process.

[0058] Generating the commands may also involve determining (based on the measurement data) process parameters that affect the sawing process carried out on the band saw. In this case, the commands are also update commands for updating the process parameters of the machining control unit (2). Examples of process parameters are, as already mentioned, the workpiece feed rate and the belt rotation speed, which can be reduced, for example, in response to wear of the saw band.

[0059] In particular, commands can be transmitted to the machining control system during an ongoing sawing process with the bandsaw in order to actively intervene in the sawing process, such as to modify or stop the sawing process. [Explanation of symbols]

[0060] 1...Band saw 2...Machining control unit 3...Sensor unit 4...Data processing unit 11...Sawband 30, 31...Inductance distance sensor 32...Support roller 41...Capacitance sensor 50...frame 54, 54'...slide element 101, 102...Sawtooth

Claims

1. A measuring device for characterizing a saw band (11) of a band saw, comprising: a first inductance distance sensor (30) configured to generate a sensor signal representative of the distance between a sensor position and a front surface of the saw band on which the saw teeth (101, 102) are located; a support roller (32); a bias mechanism configured to press the support roller (32) against the back side of the saw band (11); A measuring device having:

2. Further comprising a frame (50) for mounting the measuring device to the band saw; The first inductance distance sensor (30) is attached to the frame (50) so that the measurement direction of the first inductance distance sensor (30) is located within the band plane of the saw band (11); The support roller (32) is displaceably mounted on the frame (50), 2. The measuring device according to claim 1, wherein the bias mechanism includes a spring that generates a bias force between the frame and the support roller, and the bias force presses the support roller against the back side of the saw band.

3. 3. The measuring device according to claim 1, further comprising an evaluation device configured to detect whether the height of each saw tooth (101, 102) of the saw band (11) is below a threshold value based on the sensor signal for each saw tooth (101, 102).

4. 4. The measuring device of claim 3, wherein the evaluation device is configured to evaluate each of the sawtooths (102) as defective if the height of each of the sawtooths (102) is below the threshold value.

5. the evaluation device is configured to count the saw teeth (102) of the saw band (11) that are evaluated as defective; and / or 5. Measuring device according to claim 3 or 4, wherein the evaluation device is configured to determine a value representative of the number of sawtooth teeth (101, 102) per unit length.

6. 6. A measuring device according to any one of claims 3 to 5, wherein the evaluation device is adapted to determine a value representative of the degree of wear of the saw band.

7. 7. The measuring device of claim 6, wherein the degree of wear of the saw band is based on an average value of the measured saw tooth heights.

8. 8. The measuring device of claim 1, further comprising a second inductance distance sensor (31) configured to generate a second sensor signal indicative of whether the saw teeth (101, 102) are in the band plane of the saw band (11) or are inclined relative to the band plane.

9. The width (t １ 9. The measuring device according to any one of claims 1 to 8, further comprising a sensor (41) configured to measure a value representative of (a) the temperature of the object being measured.

10. The support roller (32) is supported on a displaceable slide element (54), 10. The measuring device of claim 1, further comprising a locking mechanism configured to lock the biasing mechanism and hold the support roller (32) in a spaced position from the back side of the saw band.

11. 11. The measuring device according to any one of claims 1 to 10, wherein the first inductance distance sensor (30) is mounted on a further displaceable sliding element (54'), the further sliding element (54') being fixable by a clamping mechanism.

12. a band saw (1) comprising a saw band (11) and a machining control unit (2), the machining control unit (2) being adapted to control a sawing process carried out with the saw band (1) and to use one or more saw band parameters and / or process parameters stored in the machining control unit (2); a measuring device configured to determine the value of at least one parameter characterizing said saw band (11); Equipped with The machining control unit (2) is further configured to receive parameter values ​​determined by the measuring device or derived therefrom and store them as saw band parameters or process parameters. system.

13. At least one parameter value characterizing the saw band (11) is: a value representing the number of saw teeth on the saw band; a value representing the number of broken saw teeth on the saw band; A value indicating whether the saw band (11) has a set; and a value representing the width of the kerf; 11. The system of claim 10, wherein the value is one of:

14. 12. A system according to claim 10 or claim 11, wherein the measuring device is connected to the band saw so as to be pivotable relative to the saw band (11).

15. The measuring device comprises a sensor unit (3) integrated into the band saw (1) and a data processing unit (4), The sensor unit (3) provides measurement data characterizing the saw band (11), and the data processing unit (4) is configured to determine the parameter values ​​from the measurement data.

15. A system according to any one of claims 12 to 14.

16. 16. The system according to claim 15, wherein the data processing unit (4) is configured to determine from the parameter values ​​process parameters for the sawing process performed by the band saw (1).

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

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

19. detecting measurement data characterizing a saw band (11) of the band saw (3) by means of a sensor unit (3); generating commands for a machining control unit (2) of the band saw (1) based on the measurement data; transmitting said command to the machining control unit (2) of said band saw (1); A method having the following.

20. The step of generating the command includes: determining at least one saw band parameter characterizing a property of the saw band (11) based on the measurement data; 20. The method according to claim 19, wherein said command is a command to update said at least one saw band parameter in said machining control unit (2).

21. The step of generating the command includes: determining, based on the measurement data, process parameters that influence the sawing process performed with the saw band (11); A method according to claim 19 or claim 20, wherein said command is a command to update said process parameters in said machining control unit (2).

22. 22. The method of claim 21, wherein updating the process parameters in the machining control unit causes the sawing process to be stopped.

23. 23. The method according to any one of claims 19 to 22, wherein the sending of commands to the machining control unit (2) is performed during a sawing process performed using the band saw so as to modify or stop the sawing process.

24. Band saw (1) and a machining control unit (2) for the band saw (1); a sensor unit (3) incorporated in the band saw for detecting measurement data characterizing a saw band (11) of the band saw (3); a data processing unit (4) configured to carry out the method according to claim 19 using the sensor unit (2); A system comprising:

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