EP3450100A2 - Grinding machine calibration - Google Patents
Grinding machine calibration Download PDFInfo
- Publication number
- EP3450100A2 EP3450100A2 EP18189771.1A EP18189771A EP3450100A2 EP 3450100 A2 EP3450100 A2 EP 3450100A2 EP 18189771 A EP18189771 A EP 18189771A EP 3450100 A2 EP3450100 A2 EP 3450100A2
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- EP
- European Patent Office
- Prior art keywords
- machine
- datum
- bar
- calibration tool
- longitudinal axis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 238000000034 method Methods 0.000 claims abstract description 10
- 230000003287 optical effect Effects 0.000 claims description 19
- 238000005259 measurement Methods 0.000 claims description 18
- 239000000956 alloy Substances 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 239000010438 granite Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 230000001141 propulsive effect Effects 0.000 description 3
- 239000004575 stone Substances 0.000 description 3
- 238000003754 machining Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 238000009419 refurbishment Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Images
Classifications
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- 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
- B24B49/12—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 optical means
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- 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
- B24B19/00—Single-purpose machines or devices for particular grinding operations not covered by any other main group
- B24B19/14—Single-purpose machines or devices for particular grinding operations not covered by any other main group for grinding turbine blades, propeller blades or the like
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- 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
- B24B21/00—Machines or devices using grinding or polishing belts; Accessories therefor
- B24B21/16—Machines or devices using grinding or polishing belts; Accessories therefor for grinding other surfaces of particular shape
- B24B21/165—Machines or devices using grinding or polishing belts; Accessories therefor for grinding other surfaces of particular shape for vanes or blades of turbines, propellers, impellers, compressors and the like
Definitions
- the present disclosure concerns the set up and calibration of grinding machines. More specifically, it relates to a device and method for aligning and calibrating a Blade Tip Grinding Machine (BTG) for use on compressor rotor blades of a Gas Turbine engine.
- BCG Blade Tip Grinding Machine
- BTG machines are known, and are manufactured by several different companies. Typically, they incorporate some form of measurement system to determine the radii of rotor blade tips during and post grinding. Some of the typical measurement systems used on BTG's are not particularly accurate, temperature stable or reliable, and hence some BTG machines now incorporate an optical measurement system to improve the accuracy and reliability of measurements made during use of the machine.
- BCG Blade Tip Grinding Machines
- a machine calibration tool comprising a bar which has a longitudinal axis; a first location feature which is located on the bar and configured to engage with a first location of the machine; and, a datum having a location adjacent to the bar at a known but variable distance parallel to the longitudinal axis from the first location feature.
- the tool is intended to be used with an optical sensor such as a ZIMMER gauge or alternative measuring system or device to determine the location of machine mounted datums, for example knife-edge datums, on a grinding machine relative to machine datums, such as a rotating axis of the machine and/or a spindle face.
- an optical sensor such as a ZIMMER gauge or alternative measuring system or device to determine the location of machine mounted datums, for example knife-edge datums, on a grinding machine relative to machine datums, such as a rotating axis of the machine and/or a spindle face.
- the perpendicular distance of the datum from the longitudinal axis of the bar may be known at all distances of the datum parallel to the longitudinal axis from the first location feature.
- the datum may comprise one or more reference features.
- One or more of the reference features may be tapered along the longitudinal axis of the bar and/or parallel to the longitudinal axis of the bar, and/or perpendicular to the longitudinal axis of the bar.
- One or more of the reference features may comprise one or more knife-edges, for example provided on a knife-edge square plate.
- a thin knife-edge can be used to represent a typical blade tip which is to be ground.
- a tapered interface for example a knife-edge square plate, allows a very precise and accurate measurement.
- a plate with two perpendicular sides can be provided to form a square edge.
- the two perpendicular sides allow the accurate/precise measurement of both axial and radial positions of the cutting edge of a grinding wheel of a grinding machine with respect to the reference point, for example corresponding to the axis of rotation.
- the edge can be used to get an accurate position of the edge by a camera/Laser projecting a beam of light into/onto the edge.
- the resulting shadow of the tapered interface can be used as the measurement.
- the two faces of the plate may be tapered over a distance of around 2 mm.
- the bar may comprise a reference face which is parallel to the longitudinal axis of the bar, to which the datum is engaged.
- the bar may be comprised of one or more of a metal, alloy, ceramic, stone (such as granite) or polymer.
- the datum may be fixedly attached to the bar at any one of two or more locations parallel to the longitudinal axis of the bar.
- the datum may be slidably attached to the bar and be selectively movable parallel to the longitudinal axis of the bar.
- the datum may be fixable in any desired position parallel to the longitudinal axis of the bar, for example by a clamping arrangement comprising a T-slot provided in a face of the bar.
- the datum may be configured within an arm arrangement.
- the datum may be configured to pivot about a pivotable attachment feature within the arm arrangement.
- the arm arrangement may be comprised of one or more of a metal, alloy, ceramic, stone (such as granite) or polymer.
- the machine calibration tool may further comprise a clocking mandrel located on the bar and aligned with the first location feature. Providing a clocking mandrel, or a tube or other extension from a front face of the bar, provides an accessible reference point to measure the radial distance to the datum.
- the clocking mandrel may be movable relative to the bar.
- the clocking mandrel may be adjustable for alignment with the working axis of a grinding machine.
- a method of calibrating a grinding machine comprising the steps of securing the first location feature of a machine calibration tool according to any preceding claim to a grinding machine, setting a datum of the machine calibration tool at a known position relative to a fixed machine datum feature, and using a measurement device and the datum of the machine calibration tool to determine the position of one or more further datum features mounted to the grinding machine relative to the machine datum feature.
- the measurement device comprises an optical sensor, possibly associated with or mounted on the grinding machine.
- the measurement device may comprise a triangulation probe or a physical measurement device.
- the one or more further datum features mounted to the grinding machine may comprise machine mounted datum knife-edges.
- the grinding machine may be a blade tip grinding (BTG) machine, and the machine datum feature may comprise a rotational axis of the BTG machine, for example the rotational axis of a machine workhead spindle and/or spindle face.
- BTG blade tip grinding
- Other possible machine datum features such as a tailstock spindle or spindle face may alternatively, or additionally, be included in the calibration.
- the invention will be used during the installation of new gauges, following refurbishment, and for the routine calibration of optical sensors such as ZIMMER systems or similar/derivatives on BTG machines.
- a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11.
- the engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high pressure compressor 15, combustion equipment 16, a high pressure turbine 17, an intermediate pressure turbine 18, a low pressure turbine 19 and an exhaust nozzle 20.
- a nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20.
- the gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second air flow which passes through a bypass duct 22 to provide propulsive thrust.
- the intermediate pressure compressor 14 compresses the airflow directed into it before delivering that air to the high pressure compressor 15 where further compression takes place.
- the compressed air exhausted from the high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted.
- the resultant hot combustion products then expand through, and thereby drive the high, intermediate and low pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust.
- the high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14 and fan 13, each by suitable interconnecting shaft.
- gas turbine engines to which the present disclosure may be applied may have alternative configurations.
- such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines.
- the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.
- FIG. 2 shows an intermediate pressure (IP) compressor drum, generally indicated 14, in a blade tip grinding (BTG) machine, which is generally designated 24.
- IP compressor drum 14 is mounted on a central axis 26 between a headstock spindle 28 and a tailstock spindle 30 of the BTG machine 24.
- a grinding wheel 32 and an optical sensor 34 are aligned with one stage 36 of the compressor drum 14. As the compressor drum 14 is rotated about the axis 26, the grinding wheel 32 is moved into contact with the ends of individual compressor blades in a particular stage 36, while the optical sensor 34 measures the location of the blade tips, and thereby determines their radii from the axis 26.
- the optical sensor 34 in order for the BTG machine 24 to ensure that the rotor/blades are machined to the required finished size, and thus ensure the correct tip clearance when the drum 14 is received in its compressor casing, the optical sensor 34 must be aligned and positioned correctly relative to the axis of rotation 26 and other datum features of the BTG machine 24.
- Machine mounted calibration edges such as datum knife-edges 38, 40 are also provided at known radial and axial distances from the datum features forming part of the BTG machine 24 structure, such as the rotational axis 26 of the workhead spindle 28 and/or the tailstock spindle 30, and are used during machining of blades on the rotor/drum 14.
- FIG 3 shows a calibration tool 42 mounted in the BTG machine 24 of Figure 2 .
- the calibration tool 42 will be described more fully below, but briefly comprises a gauge bar 44, a gauge arm 46 extending at right angles to the gauge bar 44, and a mounting spigot 48 via which the calibration tool 42 can be mounted to the headstock spindle 28.
- the optical sensor 34 is aligned with a free end portion of the gauge arm 46, which represents the position of the tip of a machined compressor blade.
- the optical sensor 34 is capable of measuring in the plane perpendicular to its optical axis, which is into the page as shown, so can detect datum features provided on the gauge arm 46.
- the position of the machine mounted datum knife-edges 38, 40 may be reliably established relative to the datum features forming part of the BTG machine structure.
- An optical sensor such as a ZIMMER gauge, may be aligned axially and radially relative to datum features on the BTG machine using the described calibration tool.
- Some blade stages have "Hade” angles ground on their tips, and therefore any axial positioning error can affect the measured radii of individual blade stages.
- the calibration tool 42 from Figure 3 is shown in greater detail in Figure 4 .
- the gauge bar 44 is flat and straight, with the sides square to each other, and is of sufficient rigidity and stability such that it does not distort under its own weight and that of the gauge arm 46.
- the gauge bar 44 is provided with a number of discrete mounting points, stops or other fixings to allow location of the gauge arm 46 at a number of discrete/defined radial distances 60 from the mounting spigot 48.
- the gauge bar 44 and arm 46 as illustrated are steel components, but it should be understood that either or both could instead be constructed from an alternative thermally and dimensionally stable material, such as a suitable metal, alloy, ceramic, stone (such as granite) or polymer, or from a combination of such materials.
- the gauge bar 44 is fastened onto the mounting spigot 48.
- the function of the mounting spigot 48 is to locate the gauge bar 44 and arm 46 onto the spindle face of the BTG machine 24 in place of the hydraulic chuck used during machining operations, and assist with stability and alignment.
- a rear engagement face 50 of the mounting spigot 48 abuts to the front face of the spindle of the BTG machine 24, and a calibrated dimension 52 between the plane of the rear face 50 of the mounting spigot 48 and the front face 54 of the gauge bar 44 can then be established via a suitable measurement method.
- the function of the gauge arm 46 is to provide datum features in known geometric alignment to the face 54 of gauge bar 44 and the rotational axis 26 of the BTG machine workhead spindle 28. For example, taking a corner 56 of the gauge arm 46 as a datum, the axial distance 58 from the face 54 is known, and the radial distance from the rotational axis 26 is the sum of the distance 60 and the radius of the mounting spigot 48, both of which are known.
- Levelling screws may be provided to set the gauge bar 44 parallel to the direction of travel of the optical sensor 34 and the base of the BTG machine. This operation may be performed using an engineer's spirit or electronic level, mounted onto the horizontal surface of the gauge bar 44.
- the centring of the mounting spigot 48 on the rotational axis 26 can be checked using a Dial Test Indicator (DTI) or similar to measure the runout on its outside diameter (OD).
- DTI Dial Test Indicator
- OD outside diameter
- a clocking mandrel 51 is provided concentrically with the mounting spigot 48 on the opposite side of the gauge arm 44.
- the alignment of the clocking mandrel 51 can be adjusted independently of the gauge arm 44, and can thus be made precisely coaxial with the rotational axis 26 of the BTG machine. This could be achieved by measuring the runout on the outside diameter of the clocking mandrel 51, for example with a Dial Test Indicator (DTI), and adjusting the alignment of the clocking mandrel 51 so that the runout is minimised.
- DTI Dial Test Indicator
- the clocking mandrel 51 gives greater certainty of the position of the datum point 56 relative to the rotational axis 26.
- the distance 61 from the outer diameter of the clocking mandrel 51 to the datum point 56 can be readily determined, either by direct measurement or by measurement to a known reference point on the gauge arm 46.
- the radius of the clocking mandrel 51 is known and, because of the possibility of fine adjustment, is known to precisely correspond to additional distance to the rotational axis 26 of the machine.
- clocking mandrel 51 additionally provides a readily accessible reference for the machine axis 26, which is an important datum of the BTG machine that is largely obscured or inaccessible once the tool 42 is attached.
- FIG. 5 shows an alternative calibration tool 42a.
- a gauge bar 44, mounting spigot 48 and clocking mandrel 51 are provided as before, but in the alternative tool 42a the gauge arm 46 has been replaced by a shaped extension 46a having a surface 47 provided at an oblique angle to the front face 54 of the gauge bar 44.
- the axial position 58 and radial position 60, 61 of any datum point 56a on the angled surface 47 can be readily determined.
- the location of the datum 56a perpendicular to the longitudinal axis of the gauge bar 44 is known at all distances of the datum 56a from the rotational axis 26 of the BTG machine 24.
- a further alternative calibration tool 42b is shown in Figure 6 .
- the tool 42b comprises a gauge bar 44, gauge arm 46, mounting spigot 48 and clocking mandrel 51 similar to the tool 42 of Figure 4 .
- the alternative calibration tool 42b of Figure 6 additionally comprises a knife-edge square plate 62, which provides a radial knife-edge 64 and an axial knife-edge 66.
- the radial knife-edge 64 and an axial knife-edge 66 provide features which, when measured by the optical sensor 34, are of the same form as the datum features 38, 40 of the BTG machine 24. Both the radial knife-edge 64 and the axial knife-edge 66 can be aligned in a plane that passes through the rotational axis 26, and is parallel to the top face of the gauge bar 44.
- the optical sensor 34 is designed to "see" knife-edges, such as the datum knife-edges 38, 40 or compressor blade tips, so the inclusion of the knife-edge square plate 62 helps to ensure that the datum(s) 56b provided on the calibration tool 42b is/are reliably detected.
- the radial and axial knife-edges 64, 66 provide a good approximation to compressor blade tips.
- the optical sensor 34 is capable of measuring in the plane perpendicular to its optical axis, i.e. along axes perpendicular to the radial and axial knife-edges 64, 66, and also of the machine mounted calibration edges 38, 40.
- a further alternative calibration tool 42c is shown in Figure 7 .
- the tool 42c comprises a gauge bar 44, mounting spigot 48 and clocking mandrel 51 as before.
- the gauge arm 46c in the tool 42c of Figure 7 extends at an oblique angle to the gauge bar 44 and is provided, at its free end, with a knife-edge square plate 62 as described in relation to Figure 6 .
- the axial knife-edge 66 of the knife-edge square plate 62 is aligned to be parallel with the gauge bar 44.
- the radial distance 60c, 61c from the mounting spigot 48 to a datum point is made continuously variable.
- the front face 54 of gauge bar 44 is provided with a T-slot, and the gauge arm 46c has two ground surfaces which abut to the gauge bar 44. Screws from the gauge arm 46c are received in T-nuts fitted into the T-slot, allowing the gauge bar 46c to slide along the gauge bar 44 as shown at 68. Once in the desired radial position, the ground surfaces of the gauge arm 46c are clamped against the ground surfaces of the gauge bar 44 by tightening the screws into the T-nuts. The sliding adjustment described allows stepless, continuous, adjustment of the gauge arm 46c in the radial direction.
- the radial distance 60c may be set and measured using any suitable measurement system and method.
- FIG 8 shows a further alternative calibration tool 42d.
- the gauge arm 46d in this alternative has a first portion 70 extending from the gauge arm 44, and a second portion 72 mounted to the first portion 70 by a pivot 74, and movable between positions indicated in broken lines.
- a knife-edge square plate 62 is provided on the end of the second portion 72 remote from the pivot 74.
- the axial and radial positions 58d, 60d, 61d of the datum can both be varied using the pivot 74.
- the gauge arm 46, 46a, 46b, 46c, 46d may be provided with one of more measurement faces and/or levelling pads for mounting an engineer's spirit or electronic level to ensure that the gauge arm 46, 46a, 46b, 46c, 46d is level relative to the base of the BTG machine 24.
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Abstract
Description
- The present disclosure concerns the set up and calibration of grinding machines. More specifically, it relates to a device and method for aligning and calibrating a Blade Tip Grinding Machine (BTG) for use on compressor rotor blades of a Gas Turbine engine.
- In order to obtain optimum performance from a Gas Turbine engine, it is necessary to control the tip clearance between the tips of both intermediate pressure (IP) and high pressure (HP) compressor rotor blades and their corresponding rotor paths in their respective casings. Optimum tip clearance can be achieved by grinding the blades of the IP and HP rotors on a purpose-built Blade Tip Grinding Machine (BTG) following their assembly into the rotor drum.
- BTG machines are known, and are manufactured by several different companies. Typically, they incorporate some form of measurement system to determine the radii of rotor blade tips during and post grinding. Some of the typical measurement systems used on BTG's are not particularly accurate, temperature stable or reliable, and hence some BTG machines now incorporate an optical measurement system to improve the accuracy and reliability of measurements made during use of the machine.
- Blade Tip Grinding Machines (BTG) grind rotors to a finished size in a manually or automatically controlled closed loop grinding cycle, where the tip radii determined by the optical gauge "in process" controls the in-feed of the grinding wheel on the machine as part of the control system.
- However, in order for rotors to be ground to the correct size it is essential that the measurement plane and direction of travel of the optical gauge and the slide system on which it is mounted are aligned and positioned correctly to the axis of rotation and the datum features of the grinding machine. This can be difficult to achieve with conventional measurement and alignment equipment.
- It is an aim of the present invention to address, mitigate, or overcome some or all of these difficulties.
- According to a first aspect there is provided a machine calibration tool, the tool comprising a bar which has a longitudinal axis; a first location feature which is located on the bar and configured to engage with a first location of the machine; and, a datum having a location adjacent to the bar at a known but variable distance parallel to the longitudinal axis from the first location feature.
- The tool is intended to be used with an optical sensor such as a ZIMMER gauge or alternative measuring system or device to determine the location of machine mounted datums, for example knife-edge datums, on a grinding machine relative to machine datums, such as a rotating axis of the machine and/or a spindle face.
- The perpendicular distance of the datum from the longitudinal axis of the bar may be known at all distances of the datum parallel to the longitudinal axis from the first location feature.
- The datum may comprise one or more reference features.
- One or more of the reference features may be tapered along the longitudinal axis of the bar and/or parallel to the longitudinal axis of the bar, and/or perpendicular to the longitudinal axis of the bar.
- One or more of the reference features may comprise one or more knife-edges, for example provided on a knife-edge square plate.
- A thin knife-edge can be used to represent a typical blade tip which is to be ground. A tapered interface, for example a knife-edge square plate, allows a very precise and accurate measurement.
- A plate with two perpendicular sides can be provided to form a square edge. The two perpendicular sides allow the accurate/precise measurement of both axial and radial positions of the cutting edge of a grinding wheel of a grinding machine with respect to the reference point, for example corresponding to the axis of rotation.
- The edge can be used to get an accurate position of the edge by a camera/Laser projecting a beam of light into/onto the edge. The resulting shadow of the tapered interface can be used as the measurement. The two faces of the plate may be tapered over a distance of around 2 mm.
- The bar may comprise a reference face which is parallel to the longitudinal axis of the bar, to which the datum is engaged.
- The bar may be comprised of one or more of a metal, alloy, ceramic, stone (such as granite) or polymer.
- The datum may be fixedly attached to the bar at any one of two or more locations parallel to the longitudinal axis of the bar.
- Alternatively, the datum may be slidably attached to the bar and be selectively movable parallel to the longitudinal axis of the bar. The datum may be fixable in any desired position parallel to the longitudinal axis of the bar, for example by a clamping arrangement comprising a T-slot provided in a face of the bar.
- The datum may be configured within an arm arrangement.
- The datum may be configured to pivot about a pivotable attachment feature within the arm arrangement.
- The arm arrangement may be comprised of one or more of a metal, alloy, ceramic, stone (such as granite) or polymer.
- The machine calibration tool may further comprise a clocking mandrel located on the bar and aligned with the first location feature. Providing a clocking mandrel, or a tube or other extension from a front face of the bar, provides an accessible reference point to measure the radial distance to the datum.
- The clocking mandrel may be movable relative to the bar. In particular, the clocking mandrel may be adjustable for alignment with the working axis of a grinding machine.
- A method of calibrating a grinding machine is also provided, comprising the steps of securing the first location feature of a machine calibration tool according to any preceding claim to a grinding machine, setting a datum of the machine calibration tool at a known position relative to a fixed machine datum feature, and using a measurement device and the datum of the machine calibration tool to determine the position of one or more further datum features mounted to the grinding machine relative to the machine datum feature.
- The measurement device comprises an optical sensor, possibly associated with or mounted on the grinding machine. Alternatively, the measurement device may comprise a triangulation probe or a physical measurement device.
- The one or more further datum features mounted to the grinding machine may comprise machine mounted datum knife-edges.
- The grinding machine may be a blade tip grinding (BTG) machine, and the machine datum feature may comprise a rotational axis of the BTG machine, for example the rotational axis of a machine workhead spindle and/or spindle face. Other possible machine datum features such as a tailstock spindle or spindle face may alternatively, or additionally, be included in the calibration.
- It is envisaged that the invention will be used during the installation of new gauges, following refurbishment, and for the routine calibration of optical sensors such as ZIMMER systems or similar/derivatives on BTG machines.
- The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore, except where mutually exclusive any feature described herein may be applied to any aspect and/or combined with any other feature described herein.
- Embodiments will now be described by way of example only, with reference to the Figures, in which:
-
Figure 1 is a sectional side view of a gas turbine engine; -
Figure 2 is a schematic view of a compressor drum in a BTG machine; -
Figure 3 is a schematic view of a calibration tool held in the chuck of a BTG machine; -
Figure 4 is a schematic view of the calibration tool ofFigure 3 in isolation; -
Figure 5 is a schematic view of an alternative calibration tool; -
Figure 6 is a schematic view of a further alternative calibration tool; -
Figure 7 is a schematic view of a further alternative calibration tool; and -
Figure 8 is a schematic view of a further alternative calibration tool. - With reference to
Figure 1 , a gas turbine engine is generally indicated at 10, having a principal androtational axis 11. Theengine 10 comprises, in axial flow series, anair intake 12, apropulsive fan 13, anintermediate pressure compressor 14, ahigh pressure compressor 15, combustion equipment 16, a high pressure turbine 17, anintermediate pressure turbine 18, alow pressure turbine 19 and anexhaust nozzle 20. Anacelle 21 generally surrounds theengine 10 and defines both theintake 12 and theexhaust nozzle 20. - The
gas turbine engine 10 works in the conventional manner so that air entering theintake 12 is accelerated by thefan 13 to produce two air flows: a first air flow into theintermediate pressure compressor 14 and a second air flow which passes through abypass duct 22 to provide propulsive thrust. Theintermediate pressure compressor 14 compresses the airflow directed into it before delivering that air to thehigh pressure compressor 15 where further compression takes place. - The compressed air exhausted from the
high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate andlow pressure turbines nozzle 20 to provide additional propulsive thrust. The high 17, intermediate 18 and low 19 pressure turbines drive respectively thehigh pressure compressor 15,intermediate pressure compressor 14 andfan 13, each by suitable interconnecting shaft. - Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.
-
Figure 2 shows an intermediate pressure (IP) compressor drum, generally indicated 14, in a blade tip grinding (BTG) machine, which is generally designated 24. TheIP compressor drum 14 is mounted on acentral axis 26 between aheadstock spindle 28 and atailstock spindle 30 of theBTG machine 24. A grindingwheel 32 and anoptical sensor 34 are aligned with onestage 36 of thecompressor drum 14. As thecompressor drum 14 is rotated about theaxis 26, the grindingwheel 32 is moved into contact with the ends of individual compressor blades in aparticular stage 36, while theoptical sensor 34 measures the location of the blade tips, and thereby determines their radii from theaxis 26. - It will be understood that in order for the
BTG machine 24 to ensure that the rotor/blades are machined to the required finished size, and thus ensure the correct tip clearance when thedrum 14 is received in its compressor casing, theoptical sensor 34 must be aligned and positioned correctly relative to the axis ofrotation 26 and other datum features of theBTG machine 24. - Machine mounted calibration edges such as datum knife-
edges BTG machine 24 structure, such as therotational axis 26 of theworkhead spindle 28 and/or thetailstock spindle 30, and are used during machining of blades on the rotor/drum 14. -
Figure 3 shows acalibration tool 42 mounted in theBTG machine 24 ofFigure 2 . Thecalibration tool 42 will be described more fully below, but briefly comprises agauge bar 44, agauge arm 46 extending at right angles to thegauge bar 44, and a mountingspigot 48 via which thecalibration tool 42 can be mounted to theheadstock spindle 28. Theoptical sensor 34 is aligned with a free end portion of thegauge arm 46, which represents the position of the tip of a machined compressor blade. - The
optical sensor 34 is capable of measuring in the plane perpendicular to its optical axis, which is into the page as shown, so can detect datum features provided on thegauge arm 46. Through use of thecalibration tool 42, the position of the machine mounted datum knife-edges - An optical sensor, such as a ZIMMER gauge, may be aligned axially and radially relative to datum features on the BTG machine using the described calibration tool. Some blade stages have "Hade" angles ground on their tips, and therefore any axial positioning error can affect the measured radii of individual blade stages.
- The
calibration tool 42 fromFigure 3 is shown in greater detail inFigure 4 . - The
gauge bar 44 is flat and straight, with the sides square to each other, and is of sufficient rigidity and stability such that it does not distort under its own weight and that of thegauge arm 46. Thegauge bar 44 is provided with a number of discrete mounting points, stops or other fixings to allow location of thegauge arm 46 at a number of discrete/defined radial distances 60 from the mountingspigot 48. Thegauge bar 44 andarm 46 as illustrated are steel components, but it should be understood that either or both could instead be constructed from an alternative thermally and dimensionally stable material, such as a suitable metal, alloy, ceramic, stone (such as granite) or polymer, or from a combination of such materials. - The
gauge bar 44 is fastened onto the mountingspigot 48. The function of the mountingspigot 48 is to locate thegauge bar 44 andarm 46 onto the spindle face of theBTG machine 24 in place of the hydraulic chuck used during machining operations, and assist with stability and alignment. However, it would be possible instead to provide thegauge bar 44 with suitable features to allow it to be mounted into a chuck, collet or similar work holding feature, or for the mountingspigot 48 to be integrally formed with thegauge bar 44. - A rear engagement face 50 of the mounting
spigot 48 abuts to the front face of the spindle of theBTG machine 24, and a calibrateddimension 52 between the plane of therear face 50 of the mountingspigot 48 and thefront face 54 of thegauge bar 44 can then be established via a suitable measurement method. - The function of the
gauge arm 46 is to provide datum features in known geometric alignment to theface 54 ofgauge bar 44 and therotational axis 26 of the BTGmachine workhead spindle 28. For example, taking acorner 56 of thegauge arm 46 as a datum, theaxial distance 58 from theface 54 is known, and the radial distance from therotational axis 26 is the sum of thedistance 60 and the radius of the mountingspigot 48, both of which are known. - Levelling screws may be provided to set the
gauge bar 44 parallel to the direction of travel of theoptical sensor 34 and the base of the BTG machine. This operation may be performed using an engineer's spirit or electronic level, mounted onto the horizontal surface of thegauge bar 44. The centring of the mountingspigot 48 on therotational axis 26 can be checked using a Dial Test Indicator (DTI) or similar to measure the runout on its outside diameter (OD). - In order to account for possible misalignment of the
tool 42 when secured to the BTG machine, a clockingmandrel 51 is provided concentrically with the mountingspigot 48 on the opposite side of thegauge arm 44. The alignment of the clockingmandrel 51 can be adjusted independently of thegauge arm 44, and can thus be made precisely coaxial with therotational axis 26 of the BTG machine. This could be achieved by measuring the runout on the outside diameter of the clockingmandrel 51, for example with a Dial Test Indicator (DTI), and adjusting the alignment of the clockingmandrel 51 so that the runout is minimised. A Total Indicated Runout (TIR) of less than 5µm, for example, would indicate that the outside diameter of the clockingmandrel 51 is concentric to therotational axis 26 of the machine. - The clocking
mandrel 51 gives greater certainty of the position of thedatum point 56 relative to therotational axis 26. Thedistance 61 from the outer diameter of the clockingmandrel 51 to thedatum point 56 can be readily determined, either by direct measurement or by measurement to a known reference point on thegauge arm 46. The radius of the clockingmandrel 51 is known and, because of the possibility of fine adjustment, is known to precisely correspond to additional distance to therotational axis 26 of the machine. - The inclusion of the clocking
mandrel 51 additionally provides a readily accessible reference for themachine axis 26, which is an important datum of the BTG machine that is largely obscured or inaccessible once thetool 42 is attached. -
Figure 5 shows analternative calibration tool 42a. Agauge bar 44, mountingspigot 48 and clockingmandrel 51 are provided as before, but in thealternative tool 42a thegauge arm 46 has been replaced by ashaped extension 46a having asurface 47 provided at an oblique angle to thefront face 54 of thegauge bar 44. It will be understood that so long as the position and geometry of the shapedextension 46a and its position relative to thegauge bar 44 are known, theaxial position 58 andradial position datum point 56a on theangled surface 47 can be readily determined. In other words, the location of thedatum 56a perpendicular to the longitudinal axis of thegauge bar 44 is known at all distances of thedatum 56a from therotational axis 26 of theBTG machine 24. - A further
alternative calibration tool 42b is shown inFigure 6 . Thetool 42b comprises agauge bar 44,gauge arm 46, mountingspigot 48 and clockingmandrel 51 similar to thetool 42 ofFigure 4 . However, thealternative calibration tool 42b ofFigure 6 additionally comprises a knife-edgesquare plate 62, which provides a radial knife-edge 64 and an axial knife-edge 66. - The radial knife-
edge 64 and an axial knife-edge 66 provide features which, when measured by theoptical sensor 34, are of the same form as the datum features 38, 40 of theBTG machine 24. Both the radial knife-edge 64 and the axial knife-edge 66 can be aligned in a plane that passes through therotational axis 26, and is parallel to the top face of thegauge bar 44. Theoptical sensor 34 is designed to "see" knife-edges, such as the datum knife-edges square plate 62 helps to ensure that the datum(s) 56b provided on thecalibration tool 42b is/are reliably detected. The radial and axial knife-edges - As noted above, the
optical sensor 34 is capable of measuring in the plane perpendicular to its optical axis, i.e. along axes perpendicular to the radial and axial knife-edges - A further
alternative calibration tool 42c is shown inFigure 7 . Thetool 42c comprises agauge bar 44, mountingspigot 48 and clockingmandrel 51 as before. Thegauge arm 46c in thetool 42c ofFigure 7 extends at an oblique angle to thegauge bar 44 and is provided, at its free end, with a knife-edgesquare plate 62 as described in relation toFigure 6 . The axial knife-edge 66 of the knife-edgesquare plate 62 is aligned to be parallel with thegauge bar 44. - In this alternative, the
radial distance spigot 48 to a datum point is made continuously variable. Thefront face 54 ofgauge bar 44 is provided with a T-slot, and thegauge arm 46c has two ground surfaces which abut to thegauge bar 44. Screws from thegauge arm 46c are received in T-nuts fitted into the T-slot, allowing thegauge bar 46c to slide along thegauge bar 44 as shown at 68. Once in the desired radial position, the ground surfaces of thegauge arm 46c are clamped against the ground surfaces of thegauge bar 44 by tightening the screws into the T-nuts. The sliding adjustment described allows stepless, continuous, adjustment of thegauge arm 46c in the radial direction. Theradial distance 60c may be set and measured using any suitable measurement system and method. -
Figure 8 shows a furtheralternative calibration tool 42d. Thegauge arm 46d in this alternative has afirst portion 70 extending from thegauge arm 44, and asecond portion 72 mounted to thefirst portion 70 by apivot 74, and movable between positions indicated in broken lines. A knife-edgesquare plate 62, as previously described, is provided on the end of thesecond portion 72 remote from thepivot 74. The axial andradial positions pivot 74. - It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.
- For example, the
gauge arm gauge arm BTG machine 24.
Claims (15)
- A machine calibration tool (42), the tool comprising:a bar (44) which has a longitudinal axis;a first location feature (48) which is located on the bar (44) and configured to engage with a first location of the machine; and,a datum (56) having a location adjacent to the bar (44) at a known but variable distance parallel to the longitudinal axis from the first location feature.
- A machine calibration tool (42) according to claim 1, wherein the perpendicular distance of the datum from the longitudinal axis of the bar (44) is known at all distances of the datum parallel to the longitudinal axis from the first location feature (48).
- A machine calibration tool (42) according to claim 1 or 2, wherein the datum comprises one or more reference features.
- A machine calibration tool (42) according to claim 3, wherein one or more of the reference features are tapered along the longitudinal axis of the bar (44) and/or are parallel to the longitudinal axis of the bar (44) and/or are perpendicular to the longitudinal axis of the bar (44).
- A machine calibration tool (42) according to claim 3 or 4, wherein one or more of the reference features comprise one or more knife-edges.
- A machine calibration tool (42) according to any preceding claim, wherein the bar (44) comprises a reference face which is parallel to the longitudinal axis of the bar (44), to which the datum is engaged.
- A machine calibration tool (42) according to any preceding claim, wherein the datum is fixedly attached to the bar (44) at any one of two or more locations parallel to the longitudinal axis of the bar (44).
- A machine calibration tool (42) according to claims 1 to 7, wherein the datum is slidably attached to the bar (44) and is selectively movable parallel to the longitudinal axis of the bar (44).
- A machine calibration tool (42) according to any preceding claim, wherein the datum is configured to pivot about a pivotable attachment feature within an arm arrangement.
- A machine calibration tool (42) according to any of the preceding claims, further comprising a clocking mandrel (51) located on the bar (44) and aligned with the first location feature (48).
- A machine calibration tool (42) according to claim 10, wherein the clocking mandrel (51) is movable relative to the bar (44).
- A method of calibrating a grinding machine (24) comprising the steps of:securing the first location feature (48) of a machine calibration tool (42) according to any preceding claim to a grinding machine (24),setting the datum of the machine calibration tool (42) at a known position relative to a fixed machine datum feature, andusing a measurement device and the datum of the machine calibration tool (42) to determine the position of one or more further datum features mounted to the grinding machine relative to the machine datum feature.
- A method according to claim 12, wherein the measurement device comprises an optical sensor associated with the grinding machine.
- A method according to claim 11 or 12, wherein the one or more further datum features comprise machine mounted datum knife-edges.
- A method according to any of claims 12 to 14, wherein the grinding machine is a blade tip grinding (BTG) machine (24), and wherein the machine datum feature comprises a rotational axis of the BTG machine.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB1714185.4A GB201714185D0 (en) | 2017-09-05 | 2017-09-05 | Grinding machine calibration |
Publications (2)
Publication Number | Publication Date |
---|---|
EP3450100A2 true EP3450100A2 (en) | 2019-03-06 |
EP3450100A3 EP3450100A3 (en) | 2019-05-01 |
Family
ID=60050750
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP18189771.1A Withdrawn EP3450100A3 (en) | 2017-09-05 | 2018-08-20 | Grinding machine calibration |
Country Status (3)
Country | Link |
---|---|
US (1) | US20190070708A1 (en) |
EP (1) | EP3450100A3 (en) |
GB (1) | GB201714185D0 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112247741B (en) * | 2020-09-25 | 2022-04-08 | 深圳市裕展精密科技有限公司 | Calibration system, calibration method and calibration device |
CN113814794B (en) * | 2021-09-18 | 2022-09-30 | 中国航发哈尔滨东安发动机有限公司 | Coaxial processing method for pump products |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3775857A (en) * | 1971-08-30 | 1973-12-04 | H Handy | Set-up tool |
US4501095A (en) * | 1983-06-07 | 1985-02-26 | United Technologies Corporation | Method and apparatus for grinding turbine engine rotor assemblies using dynamic optical measurement system |
GB2463270A (en) * | 2008-09-05 | 2010-03-10 | Renishaw Plc | Scale alignment tool |
-
2017
- 2017-09-05 GB GBGB1714185.4A patent/GB201714185D0/en not_active Ceased
-
2018
- 2018-08-17 US US16/104,268 patent/US20190070708A1/en not_active Abandoned
- 2018-08-20 EP EP18189771.1A patent/EP3450100A3/en not_active Withdrawn
Also Published As
Publication number | Publication date |
---|---|
EP3450100A3 (en) | 2019-05-01 |
GB201714185D0 (en) | 2017-10-18 |
US20190070708A1 (en) | 2019-03-07 |
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