Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B33/00—Honing machines or devices; Accessories therefor
  • B24B33/04—Honing machines or devices; Accessories therefor designed for working external surfaces of revolution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B33/00—Honing machines or devices; Accessories therefor
  • B24B33/06—Honing machines or devices; Accessories therefor with controlling or gauging equipment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B33/00—Honing machines or devices; Accessories therefor
  • B24B33/08—Honing tools
  • B24B33/087—Honing tools provided with measuring equipment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
  • B24B49/08—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving liquid or pneumatic means

Definitions

• the invention relates to methods for non-contact measurement of the geometry of a workpiece surface with the aid of a fluidic measuring system according to the preamble of claim 1, a device for material-removing fine machining a workpiece surface of a workpiece according to the preamble of claim 10, and a measuring system, which in the context of the method and the Device is used.
• Preferred applications include measurement assisted finishing of internal bore inner surfaces and measurement assisted finishing of largely rotationally symmetric curved outer surfaces of workpieces by belt finishing, superfinishing or external honing, in the context of fine machining, i. before, during and / or after the fine machining, a measurement is carried out to determine the geometry of the workpiece surface.
• Honing is a machining process with geometrically indeterminate cutting, in which multi-bladed honing tools carry out a two-component cutting movement, which leads to a characteristic surface structure of the machined inner surface with crossed machining marks.
• By honing finely machined surfaces can be produced, which meet extremely high requirements in terms of dimensional and shape tolerances and in terms of the surface structure. Accordingly, for example, in engine construction - -
• Cylinder running surfaces i. Inner surfaces of cylinder bores in an engine block or in a cylinder sleeve to be installed in an engine block, and bearing surfaces for waves honing processed.
• cylinder surfaces typically several different, consecutive honing operations are performed, for example, a pre-honing to produce the desired macro-shape of the bore and a finish honing, with which the surface structure required on the finished workpiece is generated. Measuring steps can be used to check the processing success.
• DE 38 27 892 C2 shows a honing device with Nachmessstation, in which the measurement results are used to control the radial delivery of the honing stones in a honing tool with a large radial displacement.
• a pneumatic measuring system has at least one measuring nozzle, which is attached to a tool and connected via a compressed gas line with a remote from the measuring nozzle compressed gas source.
• Such pneumatic measuring systems work according to the nozzle-flapper principle.
• compressed air flows out of the measuring nozzle in the direction of the bore wall.
• the resulting back pressure in the area of the measuring nozzle serves as a measure of the distance of the measuring nozzle to the bore wall.
• a connected to the measuring nozzle via the compressed gas line transducer measures the pressure in the compressed gas line and provides for a conversion of the (pneumatic) pressure signal in an electrically quizverarbeitbares voltage signal which is fed to an evaluation and evaluated there.
• the measuring nozzle is thus brought to perform a measurement in the vicinity of the workpiece surface and a dependent of the distance between the measuring nozzle and the workpiece surface property of the compressed gas, namely the pressure at the location of measurement is measured and evaluated to determine the distance.
• the bore diameter can be determined. Measurements at different axial positions and / or in different rotational positions of the tool can be used for a shape measurement, ie a measurement of the macro-shape of the bore.
• the measuring nozzles are integrated in the honing tool in the case of in-process measurements. In the case of post-process measurements, they can be attached to a special measuring tool (measuring mandrel).
• Pneumatic measuring devices are robust and enable a non-contact, independent of the material of the test object measuring and within its measuring range high measuring accuracies in the order of a few micrometers.
• the repeat accuracy of the recorded measured values can be less than 0.5 ⁇ m (depending on the surface roughness and on static measurement).
• the recorded reading is an average of the distance of the measuring nozzle from the swept points of the workpiece surface.
• the measuring range is relatively limited.
• the measuring nozzles In order to be able to record meaningful measured values, the measuring nozzles must be arranged in a certain, relatively narrow range of distances (typically a few 100 ⁇ m, for example approximately 200 ⁇ m) from the workpiece surface, for example a bore wall.
• the width - - The then usable, linear measuring range is typically between 100 ⁇ and 200 ⁇ .
• the patent application DE 10 2012 01 1 470 A1 describes the use of radar sensors in the measurement of finely machined workpiece surfaces. Measuring systems with radar sensors are highly dynamic and can be used, for example, for measuring diameters, measuring macro-form and measuring roughness. The usage of - -
• Radar sensors for measuring workpiece outer surfaces during fi nishing are also described.
• the invention provides a method having the features of claim 1, a measuring system having the features of claim 5, and an apparatus having the features of claim 10.
• Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated herein by reference.
• a generic method for non-contact measurement of the geometry of a workpiece surface using a fluidic measuring system is characterized in that by means of a flow sensor, a fluid flow (volume flow and / or mass flow) of the pressure fluid flowing through the pressure fluid line to the measuring nozzle measured and a sensor signal the flow sensor is evaluated to determine the distance.
• the invention is based on the recognition that the quantity of pressurized fluid which flows out through a defined measuring nozzle per unit of time has a clear relationship to the distance of the measuring nozzle from the workpiece. - -
• Piece surface stands. This relationship does not necessarily have to be linear. However, since there is a clear relationship between this distance and the fluid flow (volume flow and / or mass flow) of the pressure fluid flowing through the pressure fluid line, which can be determined quantitatively, if necessary, by flow calibration, flow sensors can be used for distance measurement.
• the sensor signal supplied by the flow sensor for example an electrical signal in the form of a measuring voltage or an electrical current, can be transmitted to an evaluation device and evaluated to determine the distance.
• Flow sensors have heretofore typically been used for leak detection or leak testing or flow control in fluidic systems (i.e., pneumatic or hydraulic systems).
• the invention now proposes u.a. the use of a flow sensor in a fluidic measuring system for non-contact measurement of the shape of a workpiece surface, for measuring the fluid flow of a pressurized fluid flowing in a pressurized fluid line, which is a pressurized fluid source of the measuring system with a remote from the pressurized fluid source on a tool attached measuring nozzle of the measuring system connects.
• Diameter difference of up to about 800 ⁇ or even more is a significant expansion of the usable measuring range compared to conventional pneumatic measuring systems.
• the enlarged measuring range allows standardization in the tool design, because tools with the same tool body can be used for a larger diameter range. This helps to save costs.
• a measuring system with a large measuring range can be used in the context of Honstin or other finishing stages, which remove a lot of material, both at the beginning of the processing (relative small distance of the workpiece surface to the measuring nozzle) and in the final phase of processing (relatively large distance the workpiece surface to the measuring nozzle) is still given a sufficient measurement accuracy.
• the measurement accuracy at large distances makes it possible to exactly reach the final dimension desired at the end of each processing stage. Investigations have shown that fluid flow measurements, especially in the range of larger distances, can have a significantly better signal-to-noise ratio than pressure measurements, so that the measurement accuracy remains adequate even at relatively large distances.
• the fluidic measuring system is designed as a pneumatic measuring system, which works with a pressurized gas, in particular compressed air, as pressurized fluid.
• the components of such a measurement system may be substantially identical or functionally similar to those of conventional air measurement systems, in contrast to these instead of a converter which converts the pressure of the pressure fluid in the pressure fluid line into a further processable electrical signal, now a flow sensor is used, with which the volume flow and / or mass flow of the at - -
• Measuring point flowing through pressure fluid can be detected quantitatively.
• the measuring method according to the invention can be provided to set the provided by the pressure fluid source operating pressure of the pressurized fluid depending on the distance to be measured according to a predetermined distance function in advance (before the measurement) to a suitable value.
• a corresponding adjusting device for changing the operating pressure can be provided.
• the adjustment is made so that the operating pressure is reduced with increasing distance. This measure takes into account that with increasing distance between measuring nozzle and workpiece surface of the pressure fluid after exiting the measuring nozzle available flow cross-section (area between measuring nozzle and workpiece wall) is greater, so that the flow resistance decreases and at the same operating pressure a larger amount of pressurized fluid per Time unit can be derived.
• the volume flow and / or the mass flow in the area of the flow sensor at larger distances could possibly fall into a range outside the optimum measuring range of the flow sensor.
• the distance-dependent reduction of the operating pressure in the proposed manner it can be achieved that the volume flow and / or mass flow of the pressurized fluid remain within the measuring range of the flow sensor even at large distances, so that accurate measured values can be achieved.
• the critical measurements at particularly large distances, i. in the final stage of machining operations to be particularly accurate, without leakage problems in the feed lines and interfaces adversely affecting the measurement.
• flow sensors can be used. Particularly suitable flow sensors operate on the thermal principle of anemometry, that is to say according to a method in which the flow is determined by means of heat losses in the range of the throughput. - - Flow sensor is determined (Heat Loss method). It has been found that thus particularly favorable signal-to-noise ratios or useful signals which can be evaluated particularly well can be achieved. Flow sensors that use other measurement principles, such as Pitot tube flow sensors, Venturi nozzle flow sensors, vortex flow sensors, ultrasonic flow sensors, or electromagnetic flow sensors, may also be suitable if designed appropriately ,
• the measuring system is designed as a hydraulic measuring system which works with a suitable liquid as the pressurized fluid.
• a pressurized fluid for example, a cooling lubricant of the type can be used, which is used anyway in the material-removing fine machining for cooling, lubrication and chip removal.
• an incompressible fluid as a pressurized fluid, particularly accurate measurements are possible even if the transducer (flow sensor) has a greater distance from the measuring nozzle.
• higher sampling rates (number of measurements per unit of time) than in the air measurement are possible because changes in distance in the area of the measuring nozzle become noticeable more quickly at the measuring location (away from the measuring nozzle) due to the incompressibility of the pressure fluid. This improves the suitability for more complex shape measurements, possibly also in several levels.
• the invention also relates to a measuring system suitable for carrying out the method described in this application for measuring a finely machined workpiece surface of a workpiece.
• the invention also relates to a fine machining device, which is associated with at least one measuring system according to the invention.
• the measuring system can be used, for example, in a honing machine or in a finishing machine. - be integrated. It is also possible to design the measuring system as a measuring station separate from a processing machine.
• the measuring system is designed as an in-process measuring system.
• at least one measuring nozzle is attached to the finishing tool of the device, so that the fine machining tool serves as a support for the measuring nozzle.
• at least one measuring nozzle can be attached to a honing tool.
• a measuring nozzle may be attached to a finishing arm designed to press abrasive abrasive (e.g., abrasive belt or honing stone) against the outer surface of a workpiece portion to be machined by means of a pressing means.
• abrasive abrasive e.g., abrasive belt or honing stone
• the measuring system may e.g. be configured as a diameter measuring system or form measuring system. Depending on the measuring task, the measuring system can have one or more measuring nozzles. Their spatial arrangement and the evaluation of the sensor signals of the flow sensor determine which surface measured values are detected and which information about the measured workpiece surface is derived therefrom.
• An evaluation device of the measuring system can be signal-transmitting connected to a control device of the fine-machining machine or be part of this control device and together with it form a control device for controlling the processing on the basis of measurement data obtained with the measuring system.
• the processing time and / or the contact pressure of cutting material eg, honing stones or grinding belt
• the contact pressure of cutting material can be controlled on the basis of measured values of the measuring system in order to be able to maintain tight production tolerances even for larger series of workpieces to be machined.
• Fig. 1 shows a schematic view of an embodiment of a
• Fig. 2 shows schematically the functional relationship between the fluid flow through the flow sensor and the distance between the measuring nozzle and the bore wall at a constant pressure of the compressed gas source;
• Fig. 3 shows schematically examples of a reduction of the operating pressure of the compressed air source with increasing measuring distance.
• Fig. 1 is a schematic representation of an embodiment of a designed as a vertical honing honing machine 100 is shown, the - - For example, can be used for honing essentially cylindrical inner surfaces of holes in workpieces for engine construction.
• the honing machine 100 has a plurality of honing units, of which only one honing unit 110 is shown in FIG.
• the honing unit 110 includes a stationary assembly and a movable assembly relative to the stationary assembly.
• the movable assembly includes a honing spindle 132 mounted with a vertical spindle axis 133 and a drive rod 135 which is coupled to the lower, free end of the honing spindle 132 by means of a spindle-side hinge 136.
• a honing tool 140 is limitedly coupled movable.
• the honing spindle is rotatable about its spindle axis 133 and can also be displaced in an axial reciprocating motion to produce the typical for honing superimposition of a rotational movement with an axially oscillating movement.
• the honing stones 142 arranged on the honing tool 140 can be delivered or withdrawn in the radial direction in order to set the effective diameter of the honing tool desired for processing.
• the spindle drive 122 and the delivery system are controlled by means of a control unit 125 of the honing machine.
• a workpiece 160 which may be, for example, an engine block (cylinder crankcase) for an internal combustion engine or a cylinder liner to be installed in an engine block.
• the workpiece is clamped in a clamping device 126 of the honing machine and is in the processing position.
• the honing tool is inserted into a substantially cylindrical bore 161 of the workpiece in order, with the aid of a suitably designed honing process, to adjust the macro-shape of the hole of predetermined diameter and a desired upper surface.
• - - surface structure of the substantially concave cylindrical curved bore inner surface 165 to achieve. This is in this example, the workpiece surface to be machined by the finishing process réellehonen.
• the honing machine has for each of its honing units an integrated measuring system 150, which allows before, during and / or after honing by "in-process measurement" to determine the actual diameter of the bore, to transmit corresponding signals to the control system 125 honing system and
• an in-process measurement for example, the current diameter dimension of the bore can be constantly monitored during honing
• the processing can be ended via the control unit 125 of the honing machine (shut-off regulation).
• the measuring system 150 is a pneumatic measuring system operating by means of compressed air. It comprises a pair of measuring nozzles 152, 153, which are arranged diametrically opposite the honing tool 140 between the honing beads 142, which are spaced apart in the circumferential direction, in the axial working region of the honing stones.
• a compressed air source 151 equipped with a compressor is attached, from which compressed air is passed via a system of communicating compressed air lines to the measuring nozzles 152, 153 attached to the honing tool.
• the operating pressure provided by the compressed air source can be adjusted continuously or in stages via the control device.
• the compressed air line system includes a stationary compressed air line section 154, a pneumatic rotary transformer 155, which is often referred to as an air distributor, between the stationary assembly and the movable assembly, and for each - -
• Measuring nozzle a compressed air line 156, 157, the spindle side of the air distributor leads to the respective measuring nozzle.
• a flow sensor 170 is mounted, with which the fluid flow flowing from the compressed air source 151 in the direction of the measuring nozzles 152, 153, i. the volume flow and / or mass flow of the compressed air, can be measured permanently.
• the pneumatic flow sensor 170 generates an electrical sensor signal which directly depends on the volume of compressed air flowing through the associated line section per unit time and / or on the mass of compressed air flowing through this line section per unit time.
• the flow sensor is signal-transmitting connected to the control unit 125, in which an evaluation device for the sensor signals of the flow sensor is integrated.
• the flow sensor 170 of the embodiment operates on the thermal principle of anemometry, ie, a heat loss method.
• Flow sensors type SFAB from Festo AG & Co. KG, Esslingen have proven to be particularly suitable for this purpose. With a very broad measuring range, ranging from 0.1 l / min to 1000 l / min, volume flows occurring in such a pneumatic measuring system (typically between 5 l / min to 1000 l / m) with high accuracy and reproducibility in electrical sensor signals are converted.
• the measuring principle used here of the pneumatic measuring system makes use of the fact that the amount of air exiting through the measuring nozzles 152, 153 per unit time stands in an unambiguous and quantitatively detectable relationship to the distance A of the respective measuring nozzle from an opposite bore wall. As can be seen directly from the detail in FIG. 1, this distance A (measuring distance) depends directly on the flow cross section. - - Together, which is the outflowing compressed air (arrows) after exiting the measuring nozzle 152 available. If the distance is small, then the flow cross-section available for the air outlet port is small, so that at a given operating pressure P of the compressed-air source 151 only a specific amount per unit time can flow through the compressed-air line system and thus also through the flow-through sensor 170.
• the flow cross-section available for the outflow of compressed air increases so that more compressed air per unit time can flow through the compressed gas line system from the compressed gas source 151 through the measuring nozzles into the space between the honing tool and the bore inner wall.
• FIG. 2 schematically shows the functional relationship between the fluid flow F (volume flow and / or mass flow) of the compressed air and the distance A (measuring distance) at a constant pressure P of the compressed gas source 151.
• the fluid flow tends to increase with increasing distance A, whereby the relationship can be linear or non-linear, but in any case can be characterized by a continuous function without jumps.
• the fluid flow F is therefore fundamentally suitable as a measured variable for the distance A.
• such a measuring system can also be used in honing stages, in which a great deal of material is removed and in which the currently possible measuring ranges would be exceeded when using conventional pneumatic measuring systems.
• certain pre-honing operations may be mentioned, or so-called "roughing", in which chip rates comparable to those of conventional fine boring methods can be achieved
• so-called high-performance fine machining which is described in the applicant's European patent application EP 1 932 620 A1
• pneumatic measuring systems with a flow sensor can be used with particular advantage.
• FIG. 2 Another advantage of fluidic measuring systems according to the invention in comparison with conventional pneumatic measuring systems will be explained with reference to FIG.
• the fluid flow detectable by the flow measurement increases continuously (with constant operating pressure) as the distance A increases.
• This tendency is in opposition to the tendency of conventional pneumatic metering systems to work with pressure measurement.
• the back pressure decreases at constant operating pressure of the compressed gas source with increasing distance.
• the operating pressure of the compressed gas source is usually set to larger values before the measurement, if it is necessary to measure with larger absolute values of the distance. This can lead to the falsification of measured values, especially in older air measuring systems due to leaks within the compressed gas line system.
• Fig. 3 is shown schematically with the solid line, a possible functional relationship between the operating pressure P and the measuring distance A when using a fluidic measuring system with flow sensor.
• the operating pressure may be reduced intermittently in increments of increasing distance.
• an operating pressure Pi is set in advance. If the expected distance values lie in the range Ai ⁇ A ⁇ A 2 , then a lower operating pressure P 2 is preset. At even higher measuring distances beyond A 2 , P 3 is measured with a further reduced operating pressure, etc.
• a changeover of the measuring range at the flow sensor can thereby possibly be avoided. Since it is possible to work with reduced operating pressure in the end phase of the final machining phase, ie in the case of the largest distance values, the risk of fluid loss at leakage points is lower and the measurement accuracy remains largely constant over the entire measuring range.
• the flow sensor is seated between air distributor 155 and compressed gas source 151, so that the sum of the partial fluid flows flowing from the compressed gas source 151 to the two measuring nozzles 152, 153 is detected. It is also possible to arrange a separate flow sensor in each of the compressed gas lines 156, 157, so that the fluid flows flowing to the individual measuring nozzles can be detected separately Flow sensors can then be electrically averaged if necessary or evaluated separately. - -
• the flow sensor 170 is fixedly attached to a fixed component of the honing machine. It is also possible to attach one or more flow sensors to a component of the honing machine which is movable during machining, for example on or in the honing spindle 132 or the drive rod 135. Optionally, additional balancing weights may be provided to compensate for possible imbalances in the rotation of the honing spindle prevent.
• a fluidic geometry measurement using one or more flow sensors is also possible with other finishing methods, e.g. Finishing (Superfinishing).
• Finishing e.g. Finishing (Superfinishing).
• the measuring nozzles of such a fluidic measuring system could be mounted at the points where radar sensors are mounted there.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)
• Measuring Arrangements Characterized By The Use Of Fluids (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

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• 2013
  • 2013-02-28 DE DE102013203340.0A patent/DE102013203340A1/de not_active Withdrawn
• 2014
  • 2014-02-12 CN CN201480011289.5A patent/CN105228796A/zh active Pending
  • 2014-02-12 WO PCT/EP2014/052741 patent/WO2014131621A1/de active Application Filing
  • 2014-02-12 EP EP14703889.7A patent/EP2961568A1/de not_active Withdrawn
  • 2014-02-12 JP JP2015559457A patent/JP2016513265A/ja active Pending

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