EP3827317A1 - Procédé de surveillance d'une machine-outil, dispositif de surveillance, machine-outil et produit programme informatique - Google Patents

Procédé de surveillance d'une machine-outil, dispositif de surveillance, machine-outil et produit programme informatique

Info

Publication number
EP3827317A1
EP3827317A1 EP19749283.8A EP19749283A EP3827317A1 EP 3827317 A1 EP3827317 A1 EP 3827317A1 EP 19749283 A EP19749283 A EP 19749283A EP 3827317 A1 EP3827317 A1 EP 3827317A1
Authority
EP
European Patent Office
Prior art keywords
curve
tool
machining
movement
monitoring
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.)
Withdrawn
Application number
EP19749283.8A
Other languages
German (de)
English (en)
Inventor
Michael ZWERGER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP3827317A1 publication Critical patent/EP3827317A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/406—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by monitoring or safety
    • G05B19/4062—Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/37—Measurements
    • G05B2219/37214—Detect failed machine component, machine performance degradation
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/37—Measurements
    • G05B2219/37234—Monitor tool before, after and during machining
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/37—Measurements
    • G05B2219/37391—Null, initial load, no load torque detection or other parameter at no load
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/42—Servomotor, servo controller kind till VSS
    • G05B2219/42311—Store working torque profiles as function of time, position, compare with real torque
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/50—Machine tool, machine tool null till machine tool work handling
    • G05B2219/50197—Signature analysis, store working conditions, compare with actual

Definitions

  • the invention relates to a method for monitoring a machine tool, in which the movement of a tool is numerically controlled with the aid of a control computer.
  • the invention further relates to a device for monitoring a machine tool, a machine tool and a computer program product for performing the method.
  • a method for the production of threads in components is known.
  • a tool used to form threads is used, which has a groove production area at its end facing the component, with the aid of which at least one helical groove is formed in the wall of the core hole when the tool is introduced into a core hole.
  • Behind the groove generation area a plurality of thread generation areas twisted around the tool axis are formed on the tool, which are introduced into the groove when the groove is formed, that is to say during the groove generation movement.
  • the tool is rotated in the opposite direction for the grooving movement and at the same time slowly moved back.
  • the thread generation areas leave the groove and form a thread in the wall of the core hole next to the groove.
  • the tapping movement can be stopped.
  • the tool is used to drive the groove back into the core hole in order to shear off any chips that may have formed during thread cutting and protrude into the groove.
  • the tool is in a reset motion moved back and the thread created in a post-cutting movement.
  • the regrooving movement takes place in the opposite direction to the threading movement.
  • the regrooving movement thus takes place in the opposite direction of rotation with respect to the threading movement with a simultaneous slow forward movement.
  • the invention is therefore based on the object to provide a reliable method for monitoring a machine tool, in which the movement of a tool is numerically controlled with the aid of a control computer.
  • the invention is also based on the object to provide a device for monitoring a machine tool, a machine tool and a computer program product for executing the method.
  • a reference measurement curve of a monitoring measurement variable which is related to the movement of the tool, is recorded during a reference movement of the tool controlled by a reference setpoint curve. Furthermore, a machining measurement curve of the monitoring measured variable is recorded during a machining movement of the tool, a workpiece being machined by the tool with the machining movement.
  • the reference measurement curve and the machining measurement curve are brought into a temporal relationship on the basis of the reference setpoint curve and the machining setpoint curve.
  • a difference curve of the reference measurement curve and the machining measurement curve is then formed and the difference curve is monitored for exceeding predetermined limit values. Since the difference curve is essentially determined by the forces acting on the tool, the functionality of the tool can be reliably monitored using the difference curve.
  • the difference curve is divided into functional sections in which different functional areas of the tool are used, and different limit values are defined for different functional sections. In this way, various functional areas of the tool can be reliably monitored.
  • the reference measurement curve and the machining measurement curve can be brought into a temporal relationship by subjecting the assigned reference setpoint curve and the machining setpoint curve to an adjustment in which the relative time interval between the reference setpoint curve and the machining setpoint curve is determined as a free parameter to be determined. ter is used and an error standard describing the deviation between the reference setpoint curve and the machining setpoint curve is minimized. Since the setpoint curves are usually executed in the same way, the temporal relation can be reliably determined using the setpoint curves.
  • the sum of the quadratic deviations between the reference setpoint curve and the machining setpoint curve is used as the error standard.
  • the transition section lies in the reference setpoint curve and in the assigned reference measurement curve and / or at least one transition section in the machining setpoint curve and in the assigned machining measurement curve, so that the different delays do not adversely affect the adaptation.
  • the reference movement can be carried out outside the workpiece.
  • the difference curve is only determined by the forces acting on the tool and the functionality of the tool can be monitored easily and reliably.
  • the reference movement can also be carried out on a workpiece with a new tool.
  • the difference curve shows the changes in the forces acting on the tool.
  • the reference movement and thus the recording of the reference setpoint curve can be repeated after a large number of machining movements have been carried out, so that gradual changes
  • the machine tool does not interfere with the monitoring and it is ensured that the difference curve is a measure of the current forces acting on the tool.
  • the reference movement and the machining movement can comprise a rotational movement and / or a translational movement of the tool.
  • the monitoring measurand can be a torque or a translational force.
  • the setpoints of the machining setpoint curve and the reference setpoint curve can each indicate the position of the tool along a predetermined path along which the tool is moved during the machining movement and the reference movement.
  • the movement performed by the tool follows a precisely defined path.
  • the tool is loaded in a certain way by external forces.
  • the respective position of the tool is therefore particularly suitable for bringing the reference measurement curve and the machining measurement curve into a temporal relationship.
  • the machine tool can convert a rotary movement generated by a drive motor into a translational movement of the tool and a torque of the drive motor can be used as the monitoring variable.
  • Difference curve can then be used to monitor the forces acting on the tool in the translation direction. This is a particularly suitable measure to monitor the functionality of the tool.
  • the values of the difference curve can be converted from torque values into force values and monitoring can be carried out using the force values.
  • an alarm that can be recognized by a user can be triggered and / or the movement of the tool can be influenced.
  • the movement of the tool can be stopped or reversed.
  • the movement of the tool for example the rotational movement of the tool or the movement of the tool along a predetermined path, can be slowed down and the energy input into the workpiece caused by the machining can be kept below a predetermined limit value.
  • the method is suitable for monitoring a wide variety of machining processes with different tools.
  • the tool can be designed for drilling, tapping, milling, turning or grinding.
  • A can be used to carry out the monitoring procedure
  • Monitoring device may be provided, the monitoring device being set up to
  • a machine tool can have a control computer which is set up to carry out the monitoring method.
  • the Computerprogrammpro product then contains commands that when executed on a Computer cause this to carry out the monitoring procedure.
  • Figure 1 is a representation of a numerically controlled machine for threading, in which the tool is moved in the direction of the tool axis with the aid of a spin del, which can be set in rotation by a spindle drive;
  • FIG. 2 is a diagram in which the time course of the
  • Target position is plotted in the direction of the tool axis and the torque of a spindle drive when machining a workpiece
  • Figure 3 is a diagram illustrating conventional methods of surveillance
  • FIG. 4 is a diagram in which the time course of the
  • Desired position the torque of the spindle drive when machining a workpiece, the torque during a reference process and a difference curve are shown;
  • Figure 5 is an enlarged view of the difference curve
  • FIG. 6 shows a representation of the adaptation of the setpoint curves of a machining process and a reference process
  • FIG. 7 shows the preparation of a setpoint curve before the adjustment.
  • Figure 8 is an illustration of a gear hobbing process
  • FIG. 9 is a diagram in which the time course of the
  • Desired position the torque when grinding the gear, the torque during a reference process and the difference curve are shown;
  • FIG. 10 shows an external cylindrical grinding process, for example a shaft
  • FIG. 11 is a diagram in which the time course of the
  • Desired position the torque when grinding the workpiece, the torque at a reference process and the difference curve are shown;
  • FIG. 12 shows an illustration of a surface grinding process
  • Figure 13 is a diagram in which the time course of the
  • the target position, the torque when grinding the workpiece, the torque during a reference operation and the difference curve are shown.
  • FIG. 1 shows a numerically controlled machine tool 1.
  • a workpiece 2 is machined.
  • the machine tool 1 has a tool 3, which can be, for example, a tool for cutting threads in the workpiece 2.
  • the tool 3 is driven by a tool motor 4, which rotates the tool 3.
  • the tool 3 can also be a drill or milling head.
  • the tool motor 4 is mounted in the embodiment shown in Figure 1 on a spindle block 5, which is for example via a ball bearing 6 on a spindle 7 in the direction of an axis of the tool 3 is slidably attached.
  • the spindle 7 is driven by a gear 8
  • Spindle motor 9 driven, which rotates the spindle 7 and in this way causes a translation of the spindle block 5 along the spindle 7.
  • Both the tool motor 4 and the spindle motor 9 are connected to a control computer 10.
  • the control computer 10 is a computer which typically comprises at least one processor, various storage units and output and input units.
  • a program for controlling the machine tool 1 is executed on the control computer 10.
  • the control computer 10 in particular sends control signals to the tool motor 4 and the spindle motor 9 and evaluates sensor signals for monitoring the tool motor 4 and the spindle motor 9.
  • the tool motor 4 can be connected to the control line 11 and a sensor line 12, for example
  • Control computer 10 may be connected.
  • a drive current used to control the tool motor 4 can be transmitted via the control line 11.
  • a measurement signal from a speed sensor 13 can be transmitted to the control computer 10 via the sensor line 12.
  • the speed sensor 13 detects the revolutions carried out by the tool motor 4 per unit of time and outputs the result as speed n (revolutions / time).
  • the spindle motor 9 is connected to the control computer 10 via a control line 14 and a sensor line 15.
  • the drive motor 9 can be supplied with drive current via the control line 14.
  • the instantaneous power drawn by the spindle motor 9 of the spindle motor 9 can also be used Known speed, the instantaneous torque of the spindle motor 9 can be determined.
  • the measured values of a revolution counter 16 can be transmitted to the control computer 10 via the sensor line 15. With such a revolution counter 16, both the speed and the position of the spindle block 5 can be determined by counting the number of revolutions starting from a starting position.
  • a monitoring computer 19 can also be connected to the control computer 10 via the data lines 17 and, like the control computer 10, typically also comprises at least one processor, various storage units and output and input units.
  • the machine tool 1 can be used to form a thread in a core hole 20 using the tool 3 in accordance with the machining method known from DE 10 2016 114 631 A1.
  • the active force 21 acting on the tool 3 is used to determine the functionality of the
  • FIG. 2 shows a diagram in which a machining setpoint curve 22 for the position of the tool 3 is plotted against time.
  • the position of the tool 3 is understood to mean the position of the tool 3 along the spindle 7.
  • the position of the tool 3 can also be expressed by the number of revolutions that the spindle motor 9 must perform in order to move the spindle block 5 and thus the tool 3 from a zero position to a specific position.
  • the position can also be expressed as a linear distance between the zero position and the determined position. For the sake of simplicity, only the z position is mentioned below.
  • the setpoint for the z position is specified by the control computer 10 and executed with the aid of a control device implemented in the control computer 10.
  • This is usually a cascade controller known to the person skilled in the art, in which the position deviation is controlled by an external control loop, the speed of the spindle motor 4 by a central control loop and the torque of the spindle motor 4 is controlled by an internal control loop.
  • a series of times ti to t 9 are also marked by dashed lines.
  • an insertion movement 23 is carried out, with which the tool 3 is inserted into the core hole 20.
  • the time ti is the start time and the time t 3 is the time at which the tool reaches the maximum depth.
  • the insertion movement 23 strikes 3 at time t 2 to the workpiece 2. Therefore, the insertion movement 23 can be in a movement of approach 24 between the time t and the time t ⁇ 2 and a Nutschneidebewe- dividing 25 between time t 2 and time t 3 .
  • the groove cutting movement 25 at least one helical groove is formed in the wall of the core hole 20 with the aid of the groove generating area of the tool 3.
  • the retraction movement 26 follows between the times t 3 and t 4 a tapping movement 27, in which the thread-generating regions of the tool 3 leave the respective groove and cut the thread in the wall of the core hole 20.
  • the tool is rotated in the opposite direction to the slot cutting movement 25 and is slightly withdrawn in accordance with the pitch of the thread to be formed.
  • the threading movement 27 ends as soon as the thread generation areas reach one groove or the next groove. This is the case at time t 5 .
  • Control computer 10 was recorded and read out by the monitoring computer 19.
  • Negative values of the machining torque curve 32 show an acceleration of the tool 3 towards the workpiece 2 in the z direction or a deceleration of a backward movement counter to the z direction.
  • Positive values of the machining torque curve 32 mean that a movement in the z direction is braked or a movement is accelerated against the z direction.
  • the tool 3 is strongly accelerated in the z direction, for example, from the time ti.
  • the minimum of the machining torque curve 32 that is to say the maximum of the torque, is reached shortly after the tool 3 hits the workpiece 2 at the time t 2 .
  • the machining torque curve 32 rises sharply towards positive values.
  • the sign of the machining torque curve 32 changes at the zero crossing, the movement of the tool 3 is braked in the z direction and accelerated against the z direction from time t 3 in order to carry out the retraction movement 26.
  • a machining torque curve 32 to define a lower limit curve 33 and an upper limit curve 34, between which the machining torque curve 32 must lie.
  • the distance between the lower limit curve 33 and the upper limit curve 34 is too large if the lower limit curve 33 and the upper limit curve 34 are set such that the lower limit curve 33 and the upper limit curve ve 34 form a band of constant thickness around the machining torque curve 32.
  • the distance to the machining torque curve 32 is chosen to be constant along the ordinate. Then, in the area of large gradients of the machining torque curve 32, incorrect error messages often occur, since small shifts in the machining torque curve 32 lead to the lower limit curve 33 and the upper limit curve 34 being exceeded.
  • machining torque curve 32 Monitoring the extreme values of the machining torque curve 32 by means of assigned lower limit values 35 and upper limit values 36 has also proven to be insufficiently reliable for monitoring the quality of the tool 3.
  • a number of variables are included in the machining torque curve 32: In addition to the frictional forces in the gears and bearings, inertial forces also play an important role, since 1 large masses are moved in machine tools. Variations of this size superimpose changes in the forces acting on the tool 3 and by means of which the functionality of the tool 3 can actually be monitored. Because when the tool 3 wears out, the forces acting on the tool 3 change since the machine tool 1 does
  • Tool 3 moves according to the machining setpoint curve 22. When tool 3 is worn, therefore, greater forces are required than with a new tool 3. However, the forces acting on tool 3 are considerably smaller than the inertial and frictional forces and can therefore not be determined easily on the basis of the machining torque curve 32 recorded on spindle motor 9 become.
  • FIG. 4 now shows a further diagram in which, in addition to the machining torque curve 32 already shown in FIGS. 2 and 3, a reference torque curve 38 recorded using a reference setpoint curve 37 is shown.
  • This reference torque curve 38 is preferably without
  • the tool 3 can, for example, be moved to a sufficiently large distance from the workpiece 2 and there execute a reference movement in the air corresponding to the reference setpoint curve 37.
  • the reference setpoint curve 37 corresponds to the machining setpoint curve 22, with deviations that may be explained in more detail below may occur in practice.
  • the recording of the reference torque curve 38 can be repeated at periodic intervals.
  • the reference torque curve 38 and the machining torque curve 32 are subtracted from one another using a method described in more detail below, and in this way a difference curve 39 is calculated.
  • the difference curve 39 depends only on the forces acting on the tool 3 and inhibiting the movement of the tool 3 in the workpiece 2 , Accordingly, the difference curve 39 deviates from zero only after the tool 3 has entered the workpiece 2 at the time t 2 .
  • the inhibiting force that inhibits the movement of the tool 3 in the material is the active force 21
  • Reference torque curve 38 has pronounced local extreme values, the size of which is determined by setting lower limit values 40 and upper limit values 41 can be monitored. If the difference curve 39 falls below one of the lower limit values 40 or exceeds one of the upper limit values 41, the monitoring computer 19 detects an error and at least writes it in an error log. If necessary, the monitoring computer 19 causes an error display on the display unit 18 or influences the movement of the tool 3 by issuing appropriate control commands from the monitoring computer 19 to the control computer 10. These control commands can correspond to the control commands that are generated with the aid of the display unit 18 and transmitted to the control computer 10, for example a control command for stopping the machine tool 1.
  • the limit values 40 and 41 can be distributed along the difference curve 39 in such a way that different functional sections of the difference curve 39 are covered.
  • the functionality of a slot cutting area of the tool 3 is decisive.
  • the thread cutting movement 27 it is also a question of the thread cutting range of the tool 3. In this way, different functional areas of the tool 3 can be monitored.
  • the monitoring of the limit values 40 and 41 presupposes that the machining torque curve 32 and the reference torque curve 38 are not shifted in time with respect to one another, since otherwise the difference curve 39 is incorrect. The initial times ti must therefore be made to coincide.
  • the machining setpoint curve 22 and the reference setpoint curve 37 can be used.
  • the machining setpoint curve 22 and the reference setpoint curve 37 can be made to coincide by the monitoring computer 19 using the method of least squares of deviation.
  • the necessary time shift DT is a measure of the relative time interval between the machining setpoint curve 22 and the reference setpoint curve 37.
  • the monitoring computer 19 can thus also determine the relative time interval between the associated machining torque curve 32 and the reference torque curve 38.
  • Figure 6 illustrates a corresponding method.
  • the processing setpoint curve 22 and the reference setpoint curve ve 37 are particularly suitable because their course is almost identical.
  • the control computer 10 is typically a computer that is able to control movements of the machine tool 1 in real time. The movements to be carried out are specified by a list of movement commands to be processed by the control computer 10, which the control computer 10 processes in succession.
  • a first movement command can trigger the execution of a guide movement 23, for example.
  • a subsequent second movement command can trigger the execution of a guide movement 23, for example.
  • Movement command can cause the retraction movement 26.
  • the movement commands are always executed in the same way: the sections of the setpoint curve generated on the basis of the individual movement commands are therefore always the same.
  • the sections of the setpoint curve for the insertion movement 23, the retraction movement 26, the threading movement 27, the shearing movement 28, the reset movement 29, the re-cutting movement 30 and the retraction movement 31 are always the same for the different setpoint curves.
  • the control computer 10 has to perform other tasks between the execution of the movement commands, and there are delays At n of different lengths between the execution of the movement commands.
  • random control deviations from the setpoint curves 22 and 37 should not lead to values of the difference curve 39 which are greater than the permissible deviations from the difference curve 39.
  • the lower limit values 40 and the upper limit values 41 are to be set as a function of the maximum control dependency so that, if possible, no random, incorrect error messages are generated. In practice, however, there are usually no noteworthy random deviations. If control deviations from the setpoint curves 22 and 37 occur, this is due to the occurrence of additional forces which are reflected in the difference curve 39, which is the desired effect.
  • an alternative reference torque curve for example using a new example of the tool 3.
  • monitoring is more difficult since the forces acting on tool 3 are also included in the reference torque curve.
  • the difference curve between the machining torque curve 32 and the alternative reference torque curve also does not show the effective force 21 as in the case of the difference curve 39, but the change in the effective force 21.
  • the alternative reference torque curve is not used only in place of the reference torque curve 38 can, but also in addition to it. In this case, not only the active force 21, but also the changes in the active force over time are recorded and monitored.
  • a monitoring method has also been described in connection with a machining method with which a thread can be formed in a core hole 20 of a workpiece 3.
  • the monitoring method described here can in principle also be applied to other machining methods in which a tool is moved in a translatory and / or rotary manner.
  • the monitoring method can also be used to monitor a drilling, turning or milling method. With these methods, active forces along the translation axes and / or effective torques about the axes of rotation of the respective machine tool as well as combinations of the active forces or effective torques can be determined and, if necessary, monitored.
  • the effective force acting along the longitudinal axis of the drilling tool and / or the effective torque acting on the drilling tool can be determined and monitored.
  • the effective force acting along the longitudinal axis of the milling head be determined in the z direction, but also the active forces can be determined which act laterally in the x or y direction on the milling head of the milling machine. Depending on the direction of movement, the force acting laterally on the milling head can occur from under different, constantly changing directions
  • the amount of this force is calculated from the force components acting along the x and y axes of the force acting laterally on the milling head and the amount of the laterally acting force is monitored for exceeding or falling below certain limit values. In certain cases, for example if only milled in a certain direction it can also make sense to monitor only one force component.
  • the active forces on the turning tool can be moved in the feed direction, i.e. in the z direction and / or the active forces in x - and y-direction or also the total force composed of these force components are determined and monitored.
  • the monitoring method described here can also be used for a grinding process.
  • Figure 8 shows the arrangement of the workpiece 2 and the tool 3 in a hobbing process.
  • the workpiece 2 is a helically toothed gear 43 which is fastened to a gear shaft 44 of the machine tool 1.
  • the gear shaft 44 can be rotated about an axis of rotation 45, which is sometimes also referred to as the B axis.
  • the tool 3 is formed by a profiled grinding wheel 46 which rotates about an axis of rotation 47, which is sometimes also referred to as the C axis. During the grinding process, the grinding wheel executes a linear movement 48 along the z axis.
  • the linear movement 48 can, as in the machine tool shown in Figure 1, with the aid of a
  • FIG. 9 shows a diagram in which the machining setpoint curve 22, the reference setpoint curve 37, the machining torque curve 32, the reference torque curve 38 and the difference curve 39 are entered.
  • the position of the grinding wheel 46 in particular the position of the axis of rotation 47 (C axis) along the z axis during the grinding process to get voted.
  • Axis of rotation 47 (C axis) of the grinding wheel 46 is moved linearly along the z axis.
  • the machining setpoint curve 22 and the reference setpoint curve ve 37 are divided into three sections. During one
  • Start-up phase 49 between times ti and t 2 grinding wheel 46 is moved at a high feed rate over a large feed distance along the z axis.
  • the first contact between the grinding wheel 46 and the gear 43 takes place at the time ti.
  • the material removal is initially low and increases continuously as the grinding wheel 46 approaches the gear 43. Accordingly, the torque with which the grinding wheel 46 has to be driven or the torque with which the linear movement of the axis of rotation 47 (C-axis) is achieved also increases.
  • a run phase 50 between times t 2 and t 3 the feed rate for the linear movement along the z axis is reduced.
  • the axis of rotation 47 (C axis) is approximately in the middle above the
  • the sequence phase 51 follows between the times t 3 and t 4 .
  • Figure 10 shows a process with external cylindrical grinding.
  • the workpiece 2 is, for example, a round shaft 52 which is clamped in a holder which allows the round shaft 52 to be rotated about a shaft axis 53 (B axis).
  • the round shaft 52 is around the
  • Figure 11 is a diagram showing the machining setpoint curve 22, reference setpoint curve 37, machining torque curve 32, reference torque curve 38, and difference curve 39.
  • the relative distance between the axis of rotation 47 (C axis) of the grinding wheel 46 and the shaft axis 53 (B axis) of the round shaft 52 along the z axis can be used for the machining setpoint curve 22 and the reference setpoint curve 37.
  • the machining process is now divided into different phases.
  • the round shaft 52 of the grinding wheel 46 is approximated in an approximation phase between the time ti and t 2 .
  • the subsequent phase between the times t 2 and t 3 is a roughing 56 in which the round shaft 52 over a relatively large distance and with a relatively high distance Ge speed is moved to the grinding wheel 46.
  • the roughing 56 removes a lot of material from the round shaft 52.
  • a finishing 57 is carried out between the times t 3 and t 4 , with a small feed distance and a low feed speed in the direction of the grinding wheel 46. During the finishing 47, only a little material is removed from the round shaft 52.
  • FIG. 12 shows the process of surface grinding, in which the grinding wheel 46 is used to grind the workpiece 2 flat.
  • the workpiece 2 performs a linear movement 58 with respect to the grinding wheel 46.
  • FIG. 13 shows the associated diagram with the machining setpoint curve 22, the reference setpoint curve 37, the machining torque curve 32, the reference torque curve 38 and the difference curve 39.
  • Either the torque acting on the grinding wheel 46 or the torque on a spindle, not shown, with which the workpiece 2 is displaced with the linear movement 58 can be used to record the machining torque curve 32 and the reference torque curve 38.
  • machining process is divided into different phases.
  • a start-up phase 59 between the time ti and t 2 the grinding wheel 46 begins in contact with the
  • Process phase 61 the grinding wheel 46 still removes the remaining material from the workpiece 2 until there is no more contact between the grinding wheel 46 and the workpiece 2 at time t 4 .
  • the feed speed is high compared to the feed speed during the run-through phase 60. It should be noted that a significantly greater distance is covered during the throughput phase 60 than during the start-up phase 59 and the execution phase 61.
  • the special feature of the grinding processes shown in FIGS. 8 to 13 is that an oil is typically used for cooling the grinding wheel 46 and is injected into the pores of the grinding wheel 46. This oil is removed from workpiece 2 during the grinding process.
  • This effective frictional force can be eliminated by recording the reference torque curves 38 on the workpiece 2, but without removing material. The effective frictional force then occurs both when recording the machining torque curve 32 and also at the reference torque curve 38 and therefore does not enter into the difference curve 39.
  • the workpiece is thermally damaged by a so-called grinding fire. Grinding fires can lead to new hardening or softening of certain areas in workpiece 2 or to structural changes. A grinding fire cannot be seen with the naked eye in all cases and can considerably impair the function of the life of the finished workpiece 2 in its respective function. If the values of the difference curve 39 exceed certain limit values during grinding, the machining process can be stopped. In principle, it is also conceivable to slow down the movement along the z direction and / or to decrease the rotational speed of the turntable 46 when crossing or approaching certain limit values, as a result of which the energy input can be reduced and a grinding burn can be prevented. It is expedient to switch to an operating mode for which there is also a reference setpoint curve and a reference torque curve.
  • a plurality of machining torque curves 32 and reference torque curves 38 for different drives can also be recorded and monitored in parallel, for example, in the grinding processes shown in FIGS. 8 to 13, the torque of the spindle drive can be used for the movement along the z axis and the torque for driving the grinding wheel 46 are recorded in parallel and monitored for exceeding predetermined limit values.
  • control computer 10 and the monitoring computer 19 are separate physical units. This offers the advantage that existing machine tools 1 can be retrofitted with the monitoring computer 19. However, it is also possible to combine the control computer 10 and the monitoring computer 19 in one physical computing unit, for example in a display unit designed as a computer.
  • the method described here can also be implemented in a computer program product that is installed, for example, on the control computer 10 and executed there. When a processor then processes the code of the computer program product, the monitoring method described here is carried out.
  • the code can be stored on a data carrier that can be read out by a computer, such as a floppy disk, a compact disc (CD) or a digital versatile disc (DVD) or the like.
  • the computer program product may also include code stored on a server or group of data storage devices
  • the carrier may also be an electrical carrier signal that is used to transfer the code from a server to a computer by downloading it.
  • Embodiment have been described, can also be combined with another embodiment, unless this is excluded for reasons of compatibility.

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  • Engineering & Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Numerical Control (AREA)
  • Machine Tool Sensing Apparatuses (AREA)

Abstract

L'invention concerne un procédé de surveillance d'une machine-outil dans laquelle le mouvement d'un outil est commandé numériquement à l'aide d'un ordinateur de commande. Le procédé comprend les étapes suivantes : - une courbe de mesure de référence (38) d'une grandeur de mesure de surveillance, qui est liée au mouvement de l'outil, est enregistrée pendant un mouvement de référence de l'outil commandé par une courbe de valeurs de consigne de référence (37), - une courbe de mesure d'usinage (32) de la grandeur de mesure de surveillance est enregistrée lors d'un mouvement d'usinage de l'outil (3) commandé par une courbe de valeurs de consigne d'usinage (22), une pièce étant usinée par l'outil avec le mouvement d'usinage, - la courbe de mesure de référence (38) et la courbe de mesure d'usinage (32) sont amenées dans une relation temporelle sur la base de la courbe de valeurs de consigne de référence (37) et de la courbe de consigne d'usinage (22), - une courbe de différence (39) est formée entre la courbe de mesure de référence (38) et la courbe de mesure d'usinage (32) et la courbe de différence (39) est surveillée pour rechercher le dépassement de valeurs limites prédéterminées. Le procédé peut être mis en œuvre à l'aide d'un dispositif de surveillance correctement configuré ou d'une machine-outil et peut être implémenté sous la forme d'un produit programme informatique.
EP19749283.8A 2018-07-25 2019-07-25 Procédé de surveillance d'une machine-outil, dispositif de surveillance, machine-outil et produit programme informatique Withdrawn EP3827317A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102018118001.2A DE102018118001A1 (de) 2018-07-25 2018-07-25 Verfahren zur Überwachung einer Werkzeugmaschine, Überwachungsvorrichtung und Computerprogrammprodukt
PCT/EP2019/070124 WO2020021044A1 (fr) 2018-07-25 2019-07-25 Procédé de surveillance d'une machine-outil, dispositif de surveillance, machine-outil et produit programme informatique

Publications (1)

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EP3827317A1 true EP3827317A1 (fr) 2021-06-02

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Country Link
EP (1) EP3827317A1 (fr)
JP (1) JP2021531992A (fr)
CN (1) CN112602027A (fr)
BR (1) BR112021001264A2 (fr)
DE (1) DE102018118001A1 (fr)
WO (1) WO2020021044A1 (fr)

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WO2021192071A1 (fr) * 2020-03-25 2021-09-30 株式会社Ｆｕｊｉ Appareil de traitement de pièces à travailler
DE102020205088A1 (de) 2020-04-22 2021-10-28 Volkswagen Aktiengesellschaft Verfahren und Auswertesystem zur Überwachung eines Werkzeugverschleißes von Werkzeugkomponenten bei zerspanenden Fertigungsanlagen
JP7393545B2 (ja) 2020-05-30 2023-12-06 株式会社Fuji ワーク加工装置
DE102021132300B3 (de) 2021-12-08 2023-04-27 Röders Gmbh Verfahren zum Betreiben einer Werkzeugmaschine mit Achsüberwachung und Werkzeugmaschine eingerichtet zur Durchführung des Verfahrens

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BR112021001264A2 (pt) 2021-04-20
JP2021531992A (ja) 2021-11-25
DE102018118001A1 (de) 2020-01-30
WO2020021044A1 (fr) 2020-01-30
CN112602027A (zh) 2021-04-02

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