Measuring arrangement having at least one mechatronic flow sensor, and a coolant lubricant system

Abstract

The invention relates to a measuring arrangement having at least one mechatronic flow sensor (12a,12b) connected to a fluid line (14), wherein the at least one flow sensor (12a, 12b) has a lifting body (16a,16b) with restoring means (18a,18b). In an initial state, the lifting body rests on a valve seat (20) in a sensor housing and is movable along a guide axis (M) in the direction of a sensor element (22) in order to determine a volume flow of a fluid in the fluid line (14). The measuring arrangement (10) has a first mechatronic flow sensor (12a) with an associated first measuring region (M1) and at least one second mechatronic flow sensor (12b) which is arranged in series along a flow direction (F) and has an associated second measuring region (M2). The invention further relates to a coolant lubricant system for a machine tool, to a method for workpiece machining and to a workpiece.

Description

[0001] Measuring arrangement with at least one mechatronic flow sensor and a coolant lubricant system

[0002] The invention relates to a measuring arrangement with at least one mechatronic flow sensor according to the preamble of claim 1, a coolant lubricant system, a method for machining a workpiece, and a workpiece.

[0003] Mechatronic flow sensors can be used to detect the volumetric flow rate through fluid lines for a wide variety of fluids, particularly water, glycol solutions, industrial oils, or cooling lubricants. The mechatronic flow sensor preferably operates on the principle of a spring-loaded piston that rests on a valve seat within a sensor housing and can be lifted by the fluid flowing in the fluid line against a restoring force or spring force. The displacement of the piston serves as an indicator of the volumetric flow rate, specifically the flow rate or volume, of the fluid. The piston displacement or position is preferably detected using a magnetic field sensor and can be output as an analog signal.The use of a return mechanism for the piston offers the advantage that the piston can be reliably returned to its starting position when the flow rate decreases, thus acting as a kind of check valve. In particular, this allows for installation of the flow sensor regardless of its orientation. The use of the piston enables operation under high pressure, high temperatures, and in harsh industrial environments. Mechatronic flow sensors have the advantage of being able to measure even the smallest flow rates with absolute reliability and are also highly responsive. Another advantage is that turbulence and air bubbles do not affect the measurement. This allows for installation at any point in a piping system, as special inlet and outlet sections are preferably not required.

[0004] DE 10 2006 006 018 A1 discloses a mechatronic flow sensor comprising a lifting element with a compression spring as a restoring means, wherein the lifting element, in an initial state, rests with a circumferential collar on a valve seat in a sensor housing and is adjustable along a guide axis in the direction of a sensor element in order to determine a volume flow through the sensor housing. The lifting element and the valve seat together form a check valve.

[0005] DE 10 2008 064 455 A1 also discloses a mechatronic flow sensor, in which several mechatronic flow sensors can be combined, particularly for plausibility checks. The two mechatronic flow sensors form a closing element and are actuated either with the same measuring range or based on pressure rather than flow rate. A pressure-dependent deflection of a closing element has the disadvantage of generating an undesirably high pressure drop within the fluid line, which can significantly influence a downstream control system.

[0006] Besides mechatronic flow sensors with reciprocating pistons, other measurement systems known in the art include MID, ultrasonic, vortex, gear, oval wheel, thermal, screw spindle, or paddle flow sensors. At least some of these measurement systems are not pressure-resistant, slower, too inaccurate, or generate an excessively high pressure drop in the fluid line.

[0007] In particular, the aforementioned alternative measuring systems may require the diameter of the fluid line to be adapted to a specific flow rate range. In other words, the cross-section of the fluid line is tailored to predefined flow rates, meaning that, for example, the diameter must be reduced accordingly for a low flow rate. Therefore, connecting multiple systems in series is not possible for hydraulic reasons, especially due to the cross-sectional variation. Simultaneous operation of the flow sensors would lead to a disproportionate pressure drop at the fluid line outlet, particularly at high flow rates. Especially with sensors located directly adjacent to or even within the fluid line, this high pressure drop can lead to damage or rapid aging of the flow sensor and / or cause turbulence within the flow.Therefore, the prior art uses complex parallel designs with switching options between sensors with different measuring ranges for volumetric flow. The object of the invention is to provide a measuring arrangement with at least one mechatronic flow sensor that, while avoiding the disadvantages known from the prior art, enables particularly easy installation and precise measurement over a large measuring range with a short measurement time.

[0008] Furthermore, the task consists of specifying a coolant lubricant system for a machine tool, a machining process for a workpiece and a workpiece.

[0009] The problem is solved with regard to the measuring arrangement with the features of claim 1, with regard to the coolant lubricant system with the features of claim 8, with regard to the machining method with the features of claim 9 and with regard to the workpiece with the features of claim 10.

[0010] Advantageous embodiments of the invention are specified in the dependent claims.

[0011] According to the invention, a measuring arrangement with at least one mechatronic flow sensor, in particular for a coolant lubricant system, is claimed, which is connected to a fluid line, wherein the at least one flow sensor has a lifting body with restoring means, wherein the lifting body rests on a valve seat in a sensor housing in an initial state and is displaceable along a guide axis, preferably in the direction of a sensor element, wherein a deflection of the lifting body can be detected or is detected by means of a sensor element in order to determine a volume flow of a fluid in the fluid line, in particular over a predetermined overall measuring range.The measuring arrangement comprises a first mechatronic flow sensor with an associated first measuring range and at least one second mechatronic flow sensor arranged in series along a flow direction with an associated second measuring range in order to extend the overall measuring range of the measuring arrangement and / or to improve measuring accuracy, wherein the second measuring range indicates a higher minimum volume flow and preferably a higher maximum volume flow than the first measuring range, and wherein the at least one second mechatronic flow sensor is designed to be permeable to the volume flow of the first measuring range such that the lifting element of the at least one second flow sensor can be deflected or is deflected in a flow-dependent manner by means of at least the minimum volume flow of the first measuring range or a higher volume flow.In particular, the lifting body can be deflected depending on the flow rate for a volume flow that is below the actual minimum volume flow of the flow sensor itself or for which a volume flow can be detected by means of the second flow sensor.

[0012] For example, the lifting body of the second flow sensor for the minimum volume flow of the first measuring range may be deflected so little that a deflection cannot yet be detected by the sensor element or at least not within a desired proportional detection range in order to detect the volume flow.

[0013] Mechatronic flow sensors can be used to detect the volumetric flow rate through fluid lines for a wide variety of fluids, particularly water, glycol solutions, industrial oils, or cooling lubricants. The mechatronic flow sensor preferably operates on the principle of a spring-loaded piston that rests on a valve seat within a sensor housing and can be lifted by the fluid flowing in the fluid line against a restoring force or spring force. The displacement of the piston serves as an indicator of the volumetric flow rate, specifically the flow rate or volume, of the fluid. The piston displacement or position is preferably detected using a magnetic field sensor and can preferably be output as an analog signal. The use of the piston allows for operation under high pressure, high temperatures, and in harsh industrial environments.Mechatronic flow sensors offer the advantage of being able to measure even the smallest flow rates with absolute reliability and rapid response times. Another benefit is that turbulence and air bubbles have no impact on the measurement. This allows for installation at any point within a piping system, as special inlet and outlet sections are preferably not required.

[0014] Preferably, the at least one second mechatronic flow sensor is designed to be permeable to the volume flow of the first measuring range in such a way that the lifting element of the at least one second mechatronic flow sensor can be deflected or is deflected depending on the flow rate by means of the minimum volume flow of the first measuring range.

[0015] In other words, the measuring arrangement comprises at least two mechatronic flow sensors to increase the overall measuring range of the arrangement by dividing it into a first and at least one second measuring range, and / or to measure partially with a higher resolution. The at least one second flow sensor preferably forms a kind of bypass at the valve seat to allow a volume flow in the first measuring range to pass through. In other words, the stroke element of the at least one second flow sensor preferably forms a check valve with the valve seat such that the check valve is open for the volume flow in the first and at least one second measuring range.

[0016] The invention offers the advantage that the overall measuring range for volume flows of the measuring arrangement can be extended and / or made more precise without significantly increasing flow resistance within the fluid line. In particular, pressure drops caused by the permeable at least one second flow sensor during the measuring state of the first flow sensor can be reduced or prevented. Furthermore, due to the series connection, active switching between the flow sensors is not required to change between the measuring ranges. In other words, the measuring arrangement can be connected to the fluid line analogously to a single flow sensor, without increasing the installation effort.The invention also recognizes that the pressure-resistant and robust properties of mechatronic flow sensors make it possible to connect a flow sensor with a measuring range for small volume flows in series with a flow sensor for high volume flows without damage.

[0017] The extended overall measuring range advantageously enables the highly accurate measurement of the smallest volume flows for precision engineering, while the measuring arrangement can simultaneously determine large volume flows, especially for cooling larger tools.

[0018] The use of the reciprocating piston has the additional advantage that a measurement in the first measuring range for a smaller minimum volume flow is possible even for large diameters or regardless of the diameter of the fluid line, which is why it is advantageous that the diameter of the fluid line does not have to be changed for the two measuring ranges.

[0019] Furthermore, the advantages of a particularly fast response time of the mechatronic flow sensor can be retained, especially less than 0.01 s. Additionally, the mechatronic flow sensors can preferably be operated up to a pressure of 200 bar in order to measure particularly high volume flows or sudden fluid transfer.

[0020] The volumetric flow rate, in particular a flow rate or flow quantity, is preferably measured by the flow sensors as a fluid volume per unit of time.

[0021] Preferably, the two measuring ranges can overlap, with the minimum volumetric flow rate of the second measuring range being smaller than the maximum volumetric flow rate of the first measuring range. The second measuring range preferably indicates a larger maximum volumetric flow rate than the first measuring range in order to increase the measuring range of the measuring arrangement. Alternatively or additionally, the first measuring range can cover a sub-range of the second measuring range in order to detect the volumetric flow rate with a more precise resolution.

[0022] Preferably, the inner diameter of the fluid line for connecting the multiple mechatronic flow sensors remains unchanged to avoid a pressure drop. Preferably, it is even possible to adapt the flow sensors to existing fluid lines.

[0023] It is particularly preferred that the multiple mechatronic flow sensors of the measuring arrangement are connected by a common fluid line. It is especially preferred that the flow cross-section of the sensor housings with valve seats of the flow sensors is larger than or equal to the flow cross-section of the fluid line, in particular a flow cross-section perpendicular to a longitudinal direction of the fluid line.

[0024] According to a preferred embodiment, the lifting body of the at least one second flow sensor can be designed to be deflected from the initial state over a minimum stroke into a measuring state in order to set a higher minimum volume flow of the second measuring range, wherein the lifting body is preferably pre-tensioned and / or the spring stiffness of the restoring means is designed such that the minimum volume flow of the first measuring range lifts the lifting body of the at least one second flow sensor from the valve seat, in particular depending on the flow rate.

[0025] In other words, at least one second flow sensor has a minimum stroke for the lifting element to enter the measuring state of the second measuring range. This has the advantage that a higher maximum volume flow rate can be set for the second measuring range while maintaining high measuring accuracy. Preferably, in the measuring state, the distance between the lifting element and the sensor element along the guide axis is small enough to detect the stroke.

[0026] It may be preferable for the valve seat to form a check valve in its initial state and in conjunction with the lifting body.

[0027] The sensor element is preferably designed as a magnetic field sensor, in particular as a GMR measuring cell.

[0028] The sensor element can be arranged along the guide axis, with the lifting body moving towards and away from the sensor element. Alternatively or additionally, it is conceivable that the sensor element is arranged or mounted on a sensor housing transversely or perpendicularly to the guide axis. Preferably, for this embodiment, the sensor element is designed for multi-axis detection of a magnetic field, in particular as a multi-axis magnetoresistive sensor. Such an arrangement of the sensor element has the advantage that the lifting body can be aligned or arranged in the direction of flow or in the direction of a fluid line. It is particularly preferred that the receptacle for the restoring means is designed to be permeable to the fluid flow.

[0029] Between the initial state and the measured state, at least one second flow sensor preferably forms an intermediate state, in which the lifting element lifts off the valve seat and opens it. In particular, the lifting element lifts at least slightly to allow the volume flow in the first measuring range. Preferably, the return element is designed as a compression spring, especially a coil spring. Alternatively or additionally, the return element can also be ensured by orienting the lifting element such that gravity acts on the lifting element in the direction of the valve seat, whereby such an embodiment may be conceivable, in particular, for very low volume flows. However, a return element designed as a compression spring is preferred.

[0030] Preferably, the restoring means of the at least one second flow sensor have a higher spring stiffness than the first flow sensor in order to preferably be able to determine a higher minimum and maximum volume flow rate. Furthermore, it may be preferred that the restoring means of the at least one second flow sensor have a lower spring constant for a stroke between the initial state and the measured state, particularly in the intermediate state.

[0031] According to a preferred embodiment, the lifting elements of the mechatronic flow sensors may have a circumferential collar for bearing on the valve seat in the initial state, wherein the lifting elements form a channel radially to the guide axis and against the flow direction below the collar, with the at least one second flow sensor preferably forming a radially wider channel. A wider channel has the advantage that the effective pressure along the guide axis on the lifting element of the at least one second flow sensor, particularly in an intermediate state, can be increased. The use of the circumferential collar in conjunction with the channel has the advantage that even a small stroke allows sufficient opening of the valve seat of the at least one second flow sensor to reduce pressure loss for the measurement state of the first flow sensor.Preferably, lifting the collar into the intermediate state, particularly by a stroke of less than 1 mm, has no effect on the measurement of the at least one second flow sensor. In other words, a kind of "zero" measurement takes place for the intermediate state. A slight or gap-like lifting of the collar is sufficient to achieve a pressure loss of less than 1 bar, which is negligible compared to a preferred pressure in the overall system of over 80 bar. Preferably, the gap channel of the at least one second flow sensor can taper along the guide axis and in the flow direction by means of a conical lifting element, wherein at least one mean gap distance over a height of the valve seat along the guide axis is larger than the mean gap distance of the first flow sensor.A conical lifting body and a tapered slot channel of at least one second flow sensor also have the advantage that the effective pressure in the direction of the guide axis can be increased compared to a partially non-conical lifting body of the first flow sensor. Preferably, the tapering of the slot channel of the at least one second flow sensor can begin immediately below the collar in order to increase the effective pressure on the lifting body in the intermediate state and reduce the pressure loss.

[0032] According to a further development, the lifting elements can be made of plastic, with the collar preferably being a metal ring, preferably made of brass. This has the advantage of a lighter lifting element that can be installed in different positions with less influence from gravity. In particular, this allows for improved measurement resolution for the first flow sensor.

[0033] Alternatively or additionally, a bypass channel, in particular a slot-like bypass channel, can be provided between the lifting element and the valve seat of at least one second flow sensor in its initial state. This has the advantage that the at least second flow sensor is permeable to the lower minimum volume flow rate of the first measuring range. The bypass channel is designed with a flow resistance such that, for a volume flow rate in the second measuring range, the lifting element of the at least one second flow sensor is brought into the measuring state.

[0034] In this context, it is preferable that at least one second flow sensor has a lifting element with an oval cross-sectional area perpendicular to the guide axis and, in its initial state, forms the bypass channel in conjunction with a circular valve seat. Preferably, the valve seat is designed as a bore along the guide axis and is therefore particularly easy to manufacture. Advantageously, the lifting element can adjust the bypass channel with minimal design modification, in particular without having to modify a sensor housing with a valve seat. Alternatively or additionally, the bypass channel can also be designed as a notch or shoulder.

[0035] Preferably, the valve seats of the multiple flow sensors are designed with the same geometry, with adaptation to the different measuring ranges achieved via the different stroke bodies. Advantageously, this allows identical flow paths to be set, both of which are optimized for low pressure drop.

[0036] Preferably, the two flow sensors are arranged in separate sensor housings to allow flexible mounting in the fluid line.

[0037] Preferably, the first and at least one second mechatronic flow sensor have different lifting elements with different restoring means and / or the lifting elements are designed with different taperities, in particular at least partially conical or conical, which are specifically adapted to measuring the different volume flow ranges, wherein preferably the first flow sensor has a restoring means with a lower spring stiffness and / or a lifting element with a lower taper for measuring a smaller minimum volume flow in the first measuring range. In other words, the at least two mechatronic flow sensors are adapted to measuring the volume flow over different measuring ranges.

[0038] The term "taper" refers in particular to the slope of a cone flank of the at least partially conical lifting body along the guide axis, where, for example, a taper of 1:100 indicates an increase of 1 mm in cone diameter for a cone length of 100 mm. Alternatively, the taper can also be specified as a cone angle. Preferably, the taper can be between 0.5° and 15°, more preferably between 1° and 10°. Preferably, a specific ratio between volume flow and displacement can be set in this way. In other words, the geometry and taper of the lifting bodies are preferably adapted to the volume flows of the preferred measuring ranges, and it is additionally or alternatively conceivable that the taper is variable along the guide axis.In particular, this allows a measurement signal to be obtained that is linearly, quadratically, logarithmically or in another suitable manner proportional to a stroke or volume flow.

[0039] The return elements of the at least two flow sensors are particularly preferably designed as compression springs, especially coil springs, wherein the spring stiffness of the compression spring of the first flow sensor is less than that of the return element of the at least one second flow sensor. In this context, it may be further preferred that the preload of the compression spring is adjustable in order to adapt the sensitivity of the flow sensor to the preferred measuring range.

[0040] According to a preferred embodiment, the volumetric flow rate of the first measuring range is 0 to 30 ml / min, preferably 0.1 to 15 l / min, and most preferably 0.05 to 15 l / min, wherein the higher flow rate for the second measuring range is 1 to 70 l / min, preferably 1 to 50 l / min. Advantageously, the overall measuring range of the measuring arrangement can thus be extended, and the measuring accuracy for the first measuring range can preferably be improved, particularly with improved resolution. The resolution of the measuring range is preferably at least 0.01 l / min. Preferably, the at least one second flow sensor is designed such that the lifting element of the at least one second flow sensor is displaceable at a minimum volumetric flow rate of the first measuring range.

[0041] Preferably, the minimum flow rate is 100 ml / min and the maximum flow rate is 501 ml / min. Alternatively or additionally, the maximum flow rate, particularly for the second measuring range, can be increased to up to 5001 ml / min.

[0042] In this context, it is preferred that the measurement deviation or accuracy for a volume flow rate of 100 ml / min is less than ±20 ml and for 50 l / min less than ±2.5 l / min. The aforementioned design of the measuring arrangement has the advantage that the pressure drop can be less than 0.5 bar at 100 ml / min and less than 1 bar at 50 l / min.

[0043] According to an advantageous embodiment, a lifting body of the first flow sensor can be designed to be adjustable along the guide axis, in particular with an increased stroke, such that for a higher volume flow of the second measuring range the valve seat of the first

[0044] The flow sensor is opened in such a way that a pressure drop within the fluid line for the second measuring range is prevented or reduced. In other words, the stroke element of the first flow sensor for high volume flows can be extended or retracted so far along the flow direction from a measuring channel and from the valve seat that the stroke element only engages the valve seat with a conical section.

[0045] In this context, it may be preferable for the first and second measuring ranges to overlap, with both flow sensors simultaneously measuring the volume flow through the fluid line in an overlap area and the valve seat not being fully open at least partially.

[0046] Alternatively or additionally, the measuring arrangement can include at least one third flow sensor between the first and second flow sensors, which forms a third measuring range between the first and second measuring ranges, preferably for a mean volumetric flow rate. In particular, this allows the first and / or second measuring range to be further subdivided and / or enlarged. Preferably, the third flow sensor is a combination of the first and second flow sensors, which is permeable to the volumetric flow rate of the preceding flow sensor in the flow direction.

[0047] The invention further relates to a cooling lubricant system for a machine tool, in particular with a previously mentioned measuring arrangement, wherein at least two mechatronic flow sensors arranged in series are connected to a common fluid line for supplying a cooling lubricant in front of a machining zone of a workpiece in order to determine a volume flow of the cooling lubricant, and wherein the measuring arrangement is connected to a control electronics unit which controls the supply of the cooling lubricant by means of a fluid conveying device as a function of the measured volume flow as actual value.

[0048] The use of at least two flow sensors and the division of the volumetric flow measurement into at least two measuring ranges offers the advantage that a very low volumetric flow rate for small tools can be quickly and highly precisely controlled and measured, while simultaneously the volumetric flow rate for large tools can be reliably monitored and controlled. In other words, the measuring range can be expanded and / or refined, allowing the required volumetric flow rate to be precisely set for each tool. This, in turn, has the advantage that the pump output can be adjusted to the tool selection for energy savings. Additionally, the optimally adjusted volumetric flow rate ensures that the tool's behavior is not negatively affected by excessive volumetric flow or pressure.In particular, vibration during workpiece machining can be reduced, and the production of drilled holes can be carried out more precisely and with less tool wear. Advantageously, the pressure of the coolant lubricant in the tool can be kept as low as possible, thus preventing aerosol formation and / or tool chatter.

[0049] Preferably, the cooling lubricant system forms a cooling lubricant circuit, wherein a proportional valve and / or a speed-controlled pump unit is designed as a fluid conveying device to regulate the volume flow of the cooling lubricant through the fluid line in at least two measuring ranges and to supply it to a tool.

[0050] Particularly preferred are the at least two mechatronic flow sensors arranged directly in front of the machining zone, especially in front of the feed into an internal drill cooling system of the machine tool.

[0051] Furthermore, it may be preferable for a third mechatronic flow sensor, together with a valve and the pump unit, to form a bypass circuit, whereby the coolant is only supplied to the two mechatronic flow sensors and the tool for internal cooling when the tool is in operation. In other words, a pre-fluid circuit is formed, which includes the valve together with a preferably third flow sensor to select a predefined flow and reduce the pressure in the system. The fluid flowing through the pre-circuit can preferably be diverted into an intermediate reservoir. Once the tool is connected, the coolant is directed from the pre-circuit through the first and at least one second flow sensor to the tool.The output signals of the two flow sensors are preferably supplied to the control electronics unit, serving as an actual value for a control loop to control the volume flow.

[0052] The coolant lubricant system is preferably used for internal drill cooling in machine tools. Water, glycol solutions, and / or coolant lubricants are preferably used as fluids.

[0053] Furthermore, the invention relates to a method for machining a workpiece using a machine tool and a cooling lubricant system, in particular a cooling lubricant system mentioned above, for supplying the machine tool with a cooling lubricant, comprising the following steps in a preferred sequence, in particular with a measuring arrangement described above:

[0054] Selection of a predetermined volume flow rate for the cooling lubricant in a first measuring range or at least a second measuring range depending on the selection of a tool, particularly an internally cooled one, by a machine control,

[0055] Setting the predetermined volume flow rate using a fluid conveying device,

[0056] Guiding the coolant lubricant, in particular into a fluid line immediately in front of a machining zone of the workpiece, through a first mechatronic flow sensor with an associated first measuring range and through at least a second mechatronic flow sensor with an associated second measuring range, which is connected in series with the fluid line,

[0057] Measuring the actual value of the volume flow in the fluid line,

[0058] Rules of predetermined volume flow depending on the measured actual value,

[0059] Changing the tool, whereby the specified volume flow rate changes from the first measuring range to the at least one second measuring range or vice versa. Preferably, the preceding steps are then repeated for the newly inserted tool. In other words, the workpiece is preferably machined with a first tool to which a volume flow rate in the first measuring range is assigned, and for further machining, a tool change to a second tool to which a volume flow rate in the second measuring range is assigned takes place. Alternatively, a change from the second to the first tool can also be carried out. In particular, it can be provided that boreholes with different drill diameters are to be produced, with different volume flow rates provided for internal cooling of the drilling tools.

[0060] Furthermore, the invention also relates to a workpiece produced according to the aforementioned method using several different tools with internal cooling. In particular, the workpiece is produced using tools to which different flow rates of a cooling lubricant are assigned in the first measuring range and in the second measuring range. For example, a workpiece with boreholes of different diameters can be produced, wherein a first borehole is produced with a flow rate in the first measuring range and a second borehole with a flow rate in the second measuring range. This allows for a more precise borehole tolerance compared to workpieces for which cooling lubricant control is not regulated over at least two measuring ranges.In addition to improved tolerance of a drill diameter, improved precision can also be observed in a preferably smoother drill hole surface, with the improvement being particularly noticeable for the smaller diameter.

[0061] The invention will now be explained in more detail using exemplary embodiments and with reference to the drawings.

[0062] They show schematically:

[0063] Fig. 1: Side view of a sensor arrangement with a first and a second mechatronic flow sensor and a cross-sectional view of a sensor housing for a volume flow in a first measuring range,

[0064] Fig. 2a: Detail view of a lifting body of the second flow sensor in a section Z according to Fig. 1, Fig. 2b: Detail view of a lifting body of the first flow sensor in a section X according to Fig. 1 ,

[0065] Fig. 3: Side view of the first flow sensor according to Fig. 1 with a lifting body in a deflected position in a second measuring area.

[0066] In the following description of preferred embodiments, identical reference numerals denote identical or comparable components.

[0067] Fig. 1 shows a measuring arrangement 10 with a first mechatronic flow sensor 12a and a second mechatronic flow sensor 12b, which are connected in series along a flow direction F via a common fluid line 14. In other words, the two flow sensors 12a, 12b are connected in series to detect the volumetric flow rate of a fluid through the fluid line 14 over different measuring ranges. Alternatively or additionally, the measuring accuracy over a predetermined measuring range can also be improved by using several flow sensors 12a, 12b. The two flow sensors 12a, 12b are preferably arranged in two different sensor housings 26a, 26b, which are connected to the fluid line 14 and preferably form part of a coolant lubricant system of a machine tool.The flow sensors 12a, 12b each have a lifting element 16a, 16b with restoring means 18a, 18b, preferably a compression spring, which rests on a valve seat 20 within the sensor housings 26a, 26b and is displaceable along a guide axis S opposite a sensor element 22. As soon as a sufficiently high volume flow is present, the lifting elements 16a, 16b are lifted from the valve seat 20 along the guide axis S and displaced opposite the restoring means 18a, 18b. The deflection of the lifting elements 16a, 16b, in particular a stroke h, is preferably detected by a sensor element 22 designed as a magnetic field sensor within the flow sensors 12a, 12b for proportional evaluation of the volume flow.

[0068] Advantageously, the valve seat 20 has a cross-section orthogonal to the guide axis S that is equal to or larger than the flow cross-section of the fluid line 14, preferably to reduce pressure loss through the multiple flow sensors 12a, 12b. An exemplary flow condition of the measuring arrangement 10 for the volume flow in a first measuring range M1 of the first flow sensor 12a can be seen in detail in Figs. 2a and 2b. Fig. 2a shows the valve seat 20 with the stroke element 16b of the second flow sensor 12b, and Fig. 2b shows the valve seat 20 with the stroke element 16a of the first flow sensor 12a, wherein the stroke h of the first flow sensor 12a is preferably larger than the stroke h of the second flow sensor 12b. Preferably, the first flow sensor 12a has a measuring range M1 with a smaller minimum volume flow rate than a second measuring range M2 of the second flow sensor 12b.Preferably, the second flow sensor 12b with lifting element 16b is configured such that, in the first measuring range M1, the lifting element 16b is raised according to Fig. 2a in order to reduce or prevent a pressure drop within the fluid line 14 for the volume flow in the first measuring range M1. A gap channel d2 is particularly preferred between the lifting element 16b and the valve seat 20 of the second flow sensor 12b, so that even with a small deflection and a small stroke h, the valve seat 20 is opened for the volume flow of the first measuring range M1. Preferably, the gap channel d2 is radially larger to the guide axis S between a lifting element 16b of the second flow sensor 12b than a gap channel d1 of the first flow sensor 12a.

[0069] Figure 3 shows the lifting element 16a of the first flow sensor 12a in a deflected position along the guide axis S for a volume flow in the second measuring range M2 of the second flow sensor 12b. Preferably, the second measuring range M2 develops a higher maximum volume flow in order to increase the overall measuring range of the measuring arrangement. The lifting element 16a can preferably be deflected up to a mechanical stop, with the valve seat 20 preferably being exposed to a front portion of the lifting element 16a of the first flow sensor 12a. This advantageously reduces or prevents a pressure loss in the second measuring range M2 caused by the first flow sensor 12a.

[0070] To set the two different measuring ranges M1, M2, the lifting elements 16a, 16b according to Fig. 1 preferably have different restoring means 18a, 18b, which are preferably designed as compression springs. In particular, the restoring means 18a of the first flow sensor 12a has a lower spring stiffness, especially with a lower number of turns, than the restoring means 18b of the second flow sensor 12b, in order to detect a volume flow in the first measuring range M1 with a smaller minimum and / or maximum volume flow.

[0071] Furthermore, to adapt the flow sensors 12a, 12b to different measuring ranges M1, M2, it may be preferred that the lifting bodies 16a, 16b are conically shaped along the guide axis S with different tapers a1, a2, wherein a first taper a1 of the first flow sensor 12a is smaller for a lower volume flow than a second taper a2 of the second flow sensor 12b. Preferably, the tapers a1, a2 vary along the guide axis S such that a predefined ratio between deflection and volume flow can be set. The tapers are preferably designed to vary along the guide axis S as shown in Fig. 1.

[0072] The lifting bodies 16a, 16b particularly preferably have a circumferential collar 30 which, in an initial state not shown, rests on the valve seat 20 and preferably forms a check valve. More preferably, the lifting body 16b of the second flow sensor 12b is designed with a taper a2 directly below the circumferential collar 30 in order to allow for the largest possible gap channel d2 when the lifting body 16b is raised and thereby increase the effective pressure on the lifting body 16b along the guide axis S. This has the advantage that a pressure loss can be prevented in the first measuring range M1 and below a predefined minimum volume flow rate of the second flow sensor 12b. In other words, the second flow sensor 12b is in an intermediate state or performs a zero measurement, whereby a measuring state of the second flow sensor 12b is only reached with an increasing volume flow rate and a larger stroke h.

[0073] Furthermore, according to Fig. 3, it may be preferred that the sensor housing 26a of the first flow sensor 12a has a connection opening 28, in particular with a screw plug, to add or divert a fluid flow.

[0074] Preferably, the two mechatronic flow sensors 12a, 12b according to Fig. 1 are connected to a control electronics unit 24 to provide a measured value for the volume flow within the fluid line 14 of a coolant lubricant system.

[0075] Figure 1 further shows that the guide axis S of the flow sensors 12a, 12b is preferably designed perpendicular to a longitudinal axis of a connected fluid line 14 in order to ensure a particularly uniform flow around the lifting bodies 16a, 16b. It is preferable that the second flow sensor 12b has a flow straightener 32 to enable the second measuring range M2 with a high maximum volume flow and a uniform flow towards the lifting body 16b of the second flow sensor 12b.

[0076] Reference symbol list

[0077] 10 Measuring setup

[0078] 12a, b first and second mechatronic flow sensor

[0079] 14 Fluid line

[0080] 16a, b Lifting body of the first and second flow sensor

[0081] 18a, b Restoring means of the first and second flow sensors

[0082] 20 Valve seat

[0083] 22 Sensor element

[0084] 24 Control electronics unit

[0085] 26a, b Sensor housing of the first and second flow sensors

[0086] 28 connection openings

[0087] 30 circumferential band

[0088] 32 Flow straighteners

[0089] S guide axis

[0090] M1, M2 first and second measuring range

[0091] F Flow direction of the volume flow a1 , a2 Conicity of the first and second flow sensors d1 , d2 Gap channel of the first and second flow sensors h Stroke distance

Claims

Patent claims 1. Measuring arrangement with at least one mechatronic flow sensor (12a, 12b) connected or connectable to a fluid line (14) and comprising a lifting body (16a, 16b) with restoring means (18a, 18b), wherein the lifting body (16a, 16b) rests on a valve seat (20) in a sensor housing (26a, 26b) in an initial state and is displaceable along a guide axis (S), wherein a deflection of the lifting body (16a, 16b) can be detected by means of a sensor element (22) in order to determine a volume flow of a fluid in the fluid line (14), characterized in that the measuring arrangement (10) comprises a first mechatronic flow sensor (12a) with an associated first measuring range (M1) and at least one second mechatronic flow sensor (12b) arranged in series along a flow direction (F) with an associated has a second measuring range (M2),to extend the overall measuring range of the measuring arrangement (10) and / or to improve measuring accuracy, wherein the second measuring range (M2) specifies a higher minimum volume flow rate than the first measuring range (M1), and wherein the at least one second mechatronic flow sensor (12b) is designed to be permeable to the volume flow rate of the first measuring range (M1) such that the lifting element (16b) of the at least one second mechatronic flow sensor (12b) can be deflected in a flow-dependent manner by means of the minimum volume flow rate of the first measuring range (M1).

2. Measuring arrangement according to claim 1, characterized in that the multiple mechatronic flow sensors (12a, 12b) of the measuring arrangement (10) are connected to a common fluid line (14) and wherein a flow cross-section of the sensor housing (26a, 26b) with valve seat (20) is greater than or equal to a flow cross-section of the fluid line (14).

3. Measuring arrangement according to claim 1 or 2, characterized in that the lifting body (16b) of the at least one second flow sensor (12b) can be deflected from an initial state via a minimum stroke into a measuring state in order to adjust the higher minimum volume flow of the second measuring range (M2), wherein the lifting body (16b) is pre-tensioned and / or the spring stiffness of the restoring means (18b) is / are designed such that the minimum volume flow of the first measuring range (M1) lifts the lifting body (16b) of the at least one second flow sensor (12b) from the valve seat (20) depending on the flow rate.

4. Measuring arrangement according to one of claims 1 to 3, characterized in that the lifting bodies (16a, 16b) of the mechatronic flow sensors (12a, 12b) have a circumferential collar (30) for support on the valve seat (20) in the initial state, wherein the lifting bodies (16a, 16b) form a gap channel (d1 ,d2) radially to the guide axis (S) and in the flow direction (F) below the collar (30), wherein the at least one second flow sensor (12b) forms a radially wider gap channel (d2).

5. Measuring arrangement according to claims 1 to 4, characterized in that a bypass channel, in particular a slit-like bypass channel, is formed between the lifting body (16b) and the valve seat (20) of the at least one second flow sensor (12b) in the initial state.

6. Measuring arrangement according to claim 5, characterized in that the at least one second flow sensor (12b) has a lifting body (16b) with an oval cross-sectional area perpendicular to the guide axis (S) and in the initial state forms the bypass channel in conjunction with a circular valve seat (20).

7. Measuring arrangement according to one of claims 1 to 6, characterized in that the at least two mechatronic flow sensors (12a, 12b) have different lifting bodies (16a, 16b) with different restoring means (18a, 18b) and / or that the lifting bodies (16) are designed with different conicities (a1 ,a2), wherein the first flow sensor (12a) has a restoring means (18a) with a lower spring stiffness and / or a lifting body (16a) with a lower conicity for measuring the lower minimum volume flow in the first measuring range (M1).

8. Cooling lubricant system for a machine tool with a measuring arrangement (10) according to one of claims 1 to 7, wherein at least two mechatronic flow sensors (12a, 12b) arranged in series are connected to a common fluid line (14) for the supply of a cooling lubricant in order to determine a volume flow rate of the cooling lubricant upstream of a machining zone of a workpiece, and wherein the measuring arrangement (10) is connected to a control electronics unit (24) which controls the supply of the cooling lubricant by means of a fluid conveying device as a function of the measured volume flow rate as the actual value.

9. Method for machining a workpiece using a machine tool and a cooling lubricant system, in particular according to claim 8, for supplying the machine tool with a cooling lubricant, comprising the following steps, - Selection of a predetermined volume flow rate for the cooling lubricant in a first measuring range (M1) or at least a second measuring range (M2) depending on the selection of a tool, in particular an internally cooled tool, by a machine control, - Setting the predetermined volume flow rate using a fluid conveying device, - Guiding the coolant lubricant through a first mechatronic flow sensor (12a) with an associated first measuring range (M1) and through at least a second mechatronic flow sensor (12b) with an associated second measuring range (M2), which is connected in series with the fluid line (14), - Measuring an actual value of the volume flow in the fluid line (14), - Rules for predetermined volume flow depending on the measured actual value, - Changing the tool, whereby the specified volume flow rate changes from the first measuring range (M1) to the second measuring range (M2) or vice versa.

10. Workpiece produced according to a method according to claim 9 using several different tools with internal cooling.

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