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—Program-control systems
  • G05B19/02—Program-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 program data in numerical form
  • G05B19/401—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 program data in numerical form characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes
• • 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
  • G05B2219/37037—Remeasure workpiece regularly for deformation
• • 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
  • G05B2219/37194—Probe work, calculate shape independent of position, orientation, best fit
• • 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
  • G05B2219/50151—Orient, translate, align workpiece to fit position assumed in program
• • 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
  • G05B2219/50152—Align axis cylinder, tube with rotation axis machine

Definitions

• the present invention relates to a numerically controlled machine tool having at least 4-axes and preferably 5-axes for machining, in particular milling, a gear clamped on a clamping means of the machine tool by means of a recorded on a work spindle of the machine tool.
• the machine tool includes a numerical machine control device configured to control the tool received on the work spindle of the machine tool relative to the gear (e.g., spur gear, bevel gear) clamped on the chuck means of the machine tool on the basis of numerical control data.
• the present invention relates to a functional extension of standard machine tools, such as e.g. Milling machine tools, milling / boring machine tools, universal machine tools and machining centers.
• gears such.
• Spur gears, bevel gears and crown gears of any desired gearing e.g., spur, helical, serrated or helical, etc.
• any desired tooth profile e.g., involute profile, cycloid profile, etc.
• the gear is manufactured in several steps, wherein first in a soft machining a pre-milled gear on the standard CNC machine tool (in contrast to previous methods using special gearing machines) is made with a predetermined gearing from a blank. After the soft machining, the pre-milled gear is stretched out of the machine tool and subjected to a material-hardening heat treatment for hardening at least one surface layer of the pre-milled gear. After this heat treatment, the pre-milled hardened gear is again clamped to the chucking means of the CNC standard 5-axis machine tool to be subjected to final finishing or hard machining.
• This is referred to as a so-called zero offset, in which a deviation between the coordinate zero point of the machine tool coordinate system and the coordinate zero point of the workpiece coordinate system is determined, and this deviation is then numerically taken into account when processing the numerical control data for finishing or hard machining.
• rotationally symmetrical workpieces such as Pre-milled gears, in particular spur gears, bevel gears and also ring gears
• a machine tool in which the rotationally symmetrical workpiece, e.g. is clamped on a turntable, softer means of a rotary axis of the machine tool can be rotatably controlled, it is particularly necessary to determine a rotational zero offset between the zero point of the turntable controlling rotary axis and the rotational zero point of the clamped workpiece.
• the vorgefräste, hardened gear is first translated based on a position determination of the center hole and then rotationally aligned in a rotational alignment based on a scanning by means of a probe of the machine tool or by means of position determination of an off-center position hole on the front side of the gear. Subsequently, the clamped and aligned gear can be finished on the basis of the determined zero offsets, possibly translationally as well as rotationally.
• the alignment method by means of a probe conventionally two opposite tooth flanks of a tooth or a tooth gap are each scanned once to determine a rotational orientation of the clamped gear.
• gears such as e.g. Spur gears, bevel gears and crown gears with arbitrary tooth shape
• gears such as e.g. Spur gears, bevel gears and crown gears with arbitrary tooth shape
• gears such as e.g. Spur gears, bevel gears and crown gears with arbitrary tooth shape
• large 5-axis machine tools or machining centers very large, partially individually manufactured gears with diameters up to more than one meter or more in which an unusually large heat distortion on the tooth flanks may occur after the heat treatment.
• the greatest heat distortion usually occurs at the points that have the least material accumulation and the greatest distance from the gear main body, i. in the case of toothed wheels, that is, usually on the tooth head, so that the teeth are virtually bent.
• opposing tooth flanks i. left and right tooth flanks, possibly distorted or deformed completely differently by the heat treatment and possibly even distorted in different directions.
• a delay of the tooth flanks may be so large that at these points too much material is removed at these points, which may be exceeded at these locations during the removal of material hardened in the heat treatment hardening depth and thus unfavorable soft or non-hardened areas on the surface of the finished tooth flanks may occur, whereby the susceptibility to wear of the gear is significantly reduced.
• a numerically controlled machine tool according to claim 1 a method for controlling an automatic rotational alignment operation on a numerically controlled machine tool according to claim 16 and a computer program product according to claim 17 are proposed.
• Dependent claims relate to preferred embodiments of the present invention.
• According to a first aspect of the invention is a numerically controlled ⁇
• Machine tool with at least 5 axes for cutting machining, in particular milling proposed a workpiece clamped on a Einspannmittei the machine tool by means of a recorded on a work spindle of the machine tool.
• the machine tool preferably comprises a numerical machine control device which is set up to control the tool received on the work spindle of the machine tool relative to the workpiece clamped on the clamping device of the machine tool on the basis of numerical control data.
• the machine control device of the machine tool is set up to control an automatic rotational alignment process for the numerical determination of a rotational zero offset for a finishing of a gear clamped on the clamping means.
• a "rotary zero offset” is to be understood in particular to be a numerical value (preferably an angle value) of a rotary axis rotation to be determined (in particular in accordance with a rotational degree of freedom) required for subsequent finishing, about a coordinate or angular zero point of the rotary axis (n) in the machine tool coordinate system with a rotational coordinate or angle zero point of the clamped gear in the workpiece coordinate system, the workpiece coordinate system when creating or generating numerical control data such as an NC program are based, however, the rotary axis (s) by means of commands of the numerical control data such as, for example, an NC program, with reference to the machine tool coordinate system.
• a machine control device controls or measures Measuring probe means at a plurality of tooth flanks of the gear at a plurality of predetermined Tastpdsitionen on each of the tooth flanks a respective actual position, comparing the Machine control device for each of the predetermined Tastpositionen the determined actual position with a respective predetermined target position and calculates or calculates for each Tastposition a target-actual deviation based on the comparison, and the machine control device determines or calculates based on the determined target-actual deviations at least a rotational zero offset for the finishing of the gear clamped on the chuck.
• the invention is based on the fundamental idea that different points of the tooth flanks of the toothed wheel can be distributed differently over the tooth flank due to the heat treatment in the curing process, and that different tooth flanks can also be distributed differently over the toothed wheel.
• the determination of the rotational zero offset according to the invention is carried out by a plurality of target actual position comparisons by means of a measuring probe on a plurality of tooth flanks in order to detect the effects of different distortion of different tooth flanks improved to be able to compensate, and on each of these tooth flanks each at a plurality of Tastpositionen to compensate for the effects of different delay at different points of the respective tooth flanks improved.
• the plurality of determined target-actual deviations After determining the target-actual deviations at a plurality of Tastpositionen, which are arranged according to the invention both on a plurality of tooth flanks of the gear and also on each of the tooth flanks at different locations, the plurality of determined target-actual deviations to determine a evaluated rotational zero offset.
• both the possibly different occurring distortions at different locations of a respective tooth flank as well the possibly different occurring distortions on different tooth flanks can be improved.
• the present invention improved to determine a rotational zero offset for the finishing of the gear, at the same time both the occurrence of points on tooth flanks with too much material removal and the consequent possible occurrence of soft spots on Zahnflankeh, the increased Wear susceptibility of the gear lead, as well as the occurrence of points on tooth flanks with too little or no material removal and the possible subsequent occurrence to avoid or at least significantly reduce a deteriorated rolling behavior of the gear.
• the rotational zero offset can be determined or calculated in a simple way by checking in a simulation by varying the rotational zero offset which rotational zero offset is at least required in order to obtain all the Actual deviations become greater than or equal to zero.
• the values of the individual target / actual deviations can assume both positive and negative values.
• positive values according to a selected definition mean that the tooth flank is warped away from the tooth at the respective touch position
• negative values mean that the tooth flank is warped toward the tooth at the respective touch position.
• the rotational zero offset can then be determined such that it is checked in a simulation by varying the rotational zero offset, which rotational zero offset is at least required to all Soll-Ist Deviations greater than or equal to the given minimum allowable.
• a rotational zero Zero offset in the above definition of the sign of the solvation-actual deviations reduces the target-actual deviations on right flanks, while increasing the target-actual deviations on left flanks, or increases the target-actual deviations on right flanks while reducing the target-actual deviations on left flanges. If it is not possible to set right and left tooth flanks by means of the same rotational zero shift, it is provided in further embodiments of the present invention to evaluate right and left flanks separately and to determine separate rotational zero offset displacements. This will be described later in more detail.
• the rotational Nuli Vietnamese shift can be determined or calculated, for example, according to further expedient(sbeispieien as fit value or best fit value by means of a mathematical compensation calculation.
• a distance value can preferably be calculated on the basis of the calculated desired-actual deviations, the distance value preferably describing the magnitude of the total deviation taking into account all determined target-actual deviations Represents value.
• the rotational offset, in the mathematical adjustment procedure then preferably by varying minimized automatically this distance value, and the value of the rotational offset at m inimêtm distance value is then obtained in Rah men T his mathematical regression analysis the determined rotational offset for use during subsequent finishing of the gear.
• the values of the individual target / actual deviations can assume both positive and negative values.
• preferably positive values in accordance with a selected definition mean that the tooth flank is warped away from the tooth at the respective touch position
• negative values preferably mean that the tooth flank is warped towards the tooth at the respective touch position.
• the distance value should preferably be selected as a function of the desired-actual deviations so that it can be described as a function of the amounts of the nominal-actual deviations or preferably as a function of the squares of the nominal-actual deviations.
• the distance value should preferably be selected as a function of the desired-actual deviations such that the value of the distance value increases strictly monotonically with the absolute value or preferably with the square of each individual desired-actual deviation.
• the distance value could be defined as a strictly monotonically increasing function of the sum of the amounts of all desired-actual deviations or preferably as a strictly monotonically increasing function of the sum of the squares of all desired-actual deviations.
• a further additional check is carried out as to whether, at all probe positions after a rotational zero shift, really positive values for the target / actual deviations can be achieved according to the value determined in the compensation calculation (or according to further embodiments Values greater than or equal to a given allowance). If this is not the case, the value of the determined rotary zero offset can be corrected accordingly (possibly separately for left and right tooth flanks) until, at all probe positions, positive desired-actual deviations or nominal-actual deviations are greater or equal achieved a predetermined allowance.
• the machine control device is further configured to automatically control the finish of the clamped gear on the basis of final control machining data after the auto-alignment operation, wherein the at least one detected rotary work offset is preferably automatically taken into account (in particular numerically considered) in controlling the finishing of the gear ).
• the finishing of the gear on the machine tool can be carried out much more efficiently and with greatly reduced tool life on the machine, since after the hardening heat treatment following clamping of the gear on the machine tool automatically an optimal rotational zero shift can be determined immediately which is then advantageously automatically taken into account in the directly subsequent automatically started finishing of the gear.
• a manual, controlling intervention of the operator after determining the rotational zero offset and before the start of finishing on the machine tool is advantageously not required.
• the plurality of tooth flanks comprise a group of left tooth flanks and a group of right tooth flanks
• the machine control means is preferably adapted to determine the target-actual deviations determined for the group of left flanks and those for the group of right flanks Evaluate target / actual deviations separately.
• the knowledge is used that although all tooth flanks may warp differently due to the curing heat treatment, the differences in the delay between two different left flanks or differences in the delay between two different right flanks are typically lower than differences in delay between a left flank and a right flank.
• the machine control device is preferably further configured to carry out a first rotary zero offset for the group of left tooth flanks and one determine second rotational zero offset for the group of right tooth flanks.
• the machine control means is arranged to automatically control the finish of the clamped gear on the basis of final control machining data after the automatic alignment operation, the first determined rotational zero shift being preferably automatically taken into account in controlling the left tooth flank finishing and the first second determined rotational zero offset is preferably automatically taken into account when controlling the finishing of the right tooth flanks.
• first and a second zero offset for the left and right tooth flanks are proposed, in which first a common evaluation of right and left tooth flanks can be carried out in principle in order to determine a common rotational zero offset. In this case, it is then checked whether a positive value or a value greater than or equal to a predetermined allowance is reached or can be reached at all probe positions on left and right tooth flanks.
• a separate evaluation of the left and right tooth flanks can be used to determine a first and a second zero offset.
• the scanning process for the individual tooth flanks can also be performed advantageously more efficiently and at a higher feed rate, since an opposite row-wise scanning, especially in the vicinity of the tooth base, in which the tooth gap typically has a smallest thickness, would have to be guided very carefully and slowly to avoid collisions, and in contrast to column-by-column scanning the scanning process can therefore advantageously be carried out more efficiently at a faster feed rate.
• the measuring probe scans the probe positions of a column in the direction of the tooth base, preferably by first sensing the next closest to the tooth tip scanning position for each column and the next closest to the tooth base scanning position is scanned.
• the machine control device controls the sensing means after scanning the next closest to the tooth root scanning position of a column at rapid traverse to the nearest tooth tip scanning position of the adjacent column.
• the plurality of tooth flanks comprises a first tooth flank and a second flank, wherein the first and second flanks are preferably either left flanks or both right flanks, and wherein the first flank is preferably disposed on a first side of the gear which is a second side of the gear, on which the second tooth flank is arranged, preferably with respect to the gear axis is substantially radially opposite.
• the plurality of tooth flanks preferably comprises a group of N tooth flanks, wherein the group N tooth flakes are preferably either all left flanks or all right flanks, and wherein the N flanks of the group are preferably circumferentially around the gear with substantially equal angular spacing between each other are arranged, ie, preferably substantially at an angular distance of 360 ° / N.
• this preferred embodiment not only provides for scanning a plurality of tooth flanks, but also for selecting the tooth flanks to be scanned as far as possible uniformly distributed as far as possible over the toothed wheel.
• tooth flanks For two (preferably either left or right) tooth flanks to be scanned, they are preferably selected substantially on opposite sides of the gear.
• substantially means particularly preferably that the tooth flanks need not necessarily be exactly opposite, i.e. at 180 °, but preferably within opposing angle segments having an angle less than or equal to 90 °, preferably less than or equal to 45 °.
• tooth flanks to be scanned are preferably selected substantially at an angular distance of 360 ° / N to each other.
• substantially means in particular preferred that the N tooth flanks need not necessarily be arranged at an angular distance of 360 ° / N, but preferably in each case within angular segments which have an angular distance of 360 ° / N to each other and preferably a respective angle of less than or equal to 180 ° / N, preferably less than or equal to 90 ° / N.
• the machine control device is set up to control the measuring means for sampling the sampling positions on the basis of sampling data, wherein the sampling data for each sampling position preferably indicate a predetermined target position, a predetermined scanning direction and / or a predetermined orientation direction for the measuring sensing means.
• the orientation direction for the measurement-sensing means designates a direction to be adopted of a longitudinal axis of the measurement-sensing means in the scanning operation at the touch position, e.g. when using a stylus with tip ball arranged on the tip of the longitudinal axis of the stylus.
• the target position indicates (preferably in the machine tool coordinate system) the position of a scan target for the scan position, and the scan direction preferably specifies a scan direction for the scan tool in scanning the scan position toward the target position.
• a scanning position based on the tactile data is then preferably scanned in such a way that the measuring probe is moved according to the predetermined orientation direction in the direction of the predetermined scanning direction to the predetermined target position until a contact contact with the tooth flank is reached at the scanning position the actual position can be measured.
• the predefined target position can in this case correspond, for example, to the predetermined setpoint position of the tooth flank (ie without delay) or else to a position which is defined by the predefined setpoint position plus a predefined allowance amount of a given allowance, for example in the direction of the surface normal of the setpoint edge form at the touch position.
• the tactile data for all probe positions of a tooth flank indicate the same predetermined orientation direction for the measuring probe, so that the machine control device preferably controls the probe probe such that the orientation direction of the probe probe remains unchanged during scanning of the probe positions of a tooth flank.
• the at least 5 axes of the machine tool in this case comprise at least two rotary axes, wherein the predetermined orientation direction of the tactile data for a probe position preferably indicates a numerical position specification for the position to be adopted of the at least two rotary axes of the machine tool during scanning of the tooth flank at the touch position.
• the machine tool further comprises an input means, by means of which a user can predefine a respective plurality of touch positions for one or more tooth flanks, and / or an interface means via which touch position data can be entered which specify a respective plurality of touch positions for one or more tooth flanks ,
• the machine control device is then configured to automatically generate the tactile data based on the predetermined probe positions.
• the interface may include, for example, an Ethernet, LAN, WLAN, and / or USB interface for inputting and outputting data to the machine tool.
• the user can advantageously specify only the respective target positions, wherein the further required tactile data can be automatically generated on the machine tool by the machine control device.
• the respective predetermined scanning direction for each scanning position on a tooth flank is in each case aligned parallel to a normal vector which is perpendicular to the respective scanning position on the tooth flank.
• the scanning direction can be calculated in a simple manner already on the basis of the desired edge geometry and the target positions, since the scanning direction is based on the surface normal of the desired edge at the touch position.
• the actual sensing operation can be carried out more accurately at a touch position.
• the keying operation could be achieved with vertical probing of the actual edge, with the exact perpendicular direction to the actual edge at the keying position not being accurately known due to the unknown distortion.
• the accuracy of the scan can be advantageously optimized on average over all probe positions even without knowledge of the true surface normal of the edge shape with delay.
• the machine control device is preferably set up to determine the at least one rotational zero offset of the toothed wheel clamped on the chucking device with the proviso that material is removed at each scanning position when the toothed wheel is finished. This can be made possible in a simple manner by checking the determined rotational zero offset, for example, for all determined target-actual deviations, in order to find out whether the determined zero offset is insufficient at one or more of the touch positions to be at this touch position at finishing Remove material. On the basis of this check, the determined zero offset may then be slightly corrected, if necessary, in order to be able to remove material at these probe positions, whereby preferably it should be checked again whether this correction could not lead to no material being removed at other probe positions becomes.
• determining a zero shift or corrected zero shift in which material is removed at all scanning positions during the finishing, it can be particularly improved to avoid ever occurring on tooth flanks on which no material is removed.
• specifications of a minimum material removal depth at the completion of the rotational zero offset determination can optionally be specified by a user again via an input means or in data form via a data interface.
• the machine control device is adapted to determine the at least one rotational zero offset of the gear clamped on the chuck taking into account a predetermined minimum material removal depth, with the proviso to ablate at least material up to the predetermined minimum material removal depth at finishing the gear at each scanning position.
• the machine control device comprises a storage means and is adapted to store the at least one determined rotational zero offset for the clamped gear.
• This has the advantage that the stored rotary zero offset can be taken into account numerically in a simple manner in the subsequent finishing, since even during the processing of the control data when executing the finishing always on the stored value can be accessed.
• a method of controlling an automatic rotational registration for determining a rotational zero offset for a finishing gear on a numerically controlled machine tool wherein the machine tool is preferably formed according to one or more of the above-described embodiments performed as on a machine tool according to one or more of the embodiments described above.
• the method comprises determining a respective actual position at a plurality of predetermined probe positions on each tooth flank of a plurality of tooth flanks of the gear by means of a measuring probe, comparing the determined actual position for each of the predetermined probe positions with a respective predetermined desired position, determining a soli- actual deviation Basis of the comparison for each probe position, and determining at least one rotational zero offset for the finishing of the gear clamped on the chuck, based on the determined target-actual deviations.
• the cogged gear finishing operation controlled by the machine control means automatically follows the automatic alignment operation on the basis of control data predetermined for the finishing, the at least one determined rotational zero offset is preferably taken into account automatically in controlling the finishing of the gear.
• the plurality of Zahnfianken include a group of left tooth flanks and a group of right flanks, wherein the determined for the group of left flank target-actual deviations and the determined for the group of right flanks target-actual deviations are preferably evaluated separately ,
• a first zero offset for the group of left tooth flanks and a second zero offset for the group of right tooth flanks are determined.
• the machining of the cogged gear controlled by the machine control means automatically follows the automatic alignment operation based on final control data, preferably the first detected rotational zero offset is automatically taken into account in controlling the left tooth flank finishing and the second detected rotary zero shift is preferably automatic is taken into account in controlling the finishing of the right tooth flanks.
• the measuring probe scans the probe positions of a column in the direction of the tooth base by first scanning the next closest to the tooth head scanning position for each column and the next closest to the tooth base scanning position is scanned last.
• the scanning means is controlled in this case after scanning the closest to the tooth root scanning position of a column at rapid traction to the nearest tooth tip scanning position of the adjacent column.
• the plurality of tooth flanks comprise a first tooth flank and a second flank, wherein the first and second flanks are preferably either left flanks or both right flanks, and wherein the first flank is preferably disposed on a first side of the gear which is a second side of the gear, on which the second tooth flank is arranged, with respect to the gear axis substantially radially opposite.
• the plurality of tooth flanks preferably comprise a group of N tooth flanks, wherein the N tooth flanks of the group are preferably either all left tooth flanks or all right flanks, and wherein the N tooth flanks of the group are preferably circumferentially of the gear substantially equal angular distance between each other are arranged.
• the measurement sampling means is controlled for sampling the Tastpositionen on the basis of Tast schemes, wherein the Tast flowers preferably indicate for each Tastposition a predetermined target position, a predetermined scanning direction and / or a predetermined orientation direction for the Messtaststoff.
• the tactile data for all probe positions of a tooth flank indicate the same predetermined orientation direction for the measuring probe, so that the probe probe is preferably controlled such that the orientation direction of the probe probe remains unchanged during scanning of the probe positions of a tooth flank.
• the at least 5-axes of the machine tool comprise at least two
• the predetermined orientation direction of the tactile data for a probing position preferably indicates a position specification for the at least two rotary axes of the machine tool during scanning of the tooth flank at the touch position.
• the tactile data are preferably generated automatically on the basis of predetermined probe positions, wherein the predetermined probe positions can preferably be predefined via an input means by a user and / or via an interface means for one or more tooth flanks.
• the respective predetermined scanning direction is on one for each scanning position
• Tooth flank aligned in each case parallel to a normal vector, which is perpendicular to the respective touch position on the tooth flank.
• the at least one rotational zero offset of the gear clamped on the clamping means is determined under the proviso to remove material at each scanning position when finishing the gear.
• the at least one rotational zero offset of the gear clamped on the clamping means is determined taking into account a predetermined minimum material removal depth, with the proviso, at finishing the gear, to remove at least material up to the predetermined minimum material removal depth at each scanning position.
• the at least one determined rotational zero offset for the clamped gear is stored in a storage means.
• a computer program product comprising a computer-readable medium and a computer program stored therein, the computer program being stored in the form of a sequence of states corresponding to instructions established by a machine controller of a numerical control machine tool according to one or more of of the above-described embodiments, so that the machine controller controls a method according to one or more of the above-described embodiments on the machine tool based on the commands.
• the present invention makes it possible to provide an improved alignment process for soft-machined and heat-treated gears on a machine tool in which the disadvantages described above can be avoided, and in which the rotational zero shift can still provide advantageous results, in particular for very large gears with diameters of up to more than one meter or more, so that can be avoided in the finishing of that Tooth flanks occur where too much and / or too little material is removed.
• FIG. 1 shows by way of example a schematic representation of a machine tool according to an embodiment of the invention.
• FIG. 2 shows by way of example a schematic representation of two adjacent teeth of a straight-toothed spur gear in a perspective view.
• Fig. 3 shows an example of a schematic representation of a right tooth flank for
• FIG. 4 shows by way of example a schematic representation of actual positions and desired positions of a column of probe positions on tooth flanks of a tooth from FIG. 2.
• FIG. 5 shows an exemplary flowchart of an alignment process for finishing a gear according to an embodiment of the present invention.
• the machine tool 100 is a numerically controlled machine tool having at least 5 axes for machining a workpiece 200 clamped to a clamping means 130 of the machine tool 100 by means of a tool received on a work spindle III of the machine tool 100.
• the machine tool 100 comprises three linear axes X, Y, and Z (not shown) and two rotary axes, for example a first rotary axis A, B or a combination of A and B (not 1), by means of which the tool received on the work spindle 111 can be controlled relative to the workpiece 200 clamped on the clamping means 120, in particular in three translatory degrees of freedom and two rotational degrees of freedom.
• the machine tool For controlling the axis movements of the three linear axes X, Y, and Z and the two rotary axes, the machine tool comprises a numerical machine control device 150, which preferably comprises a CNC control device and a PLC control device, wherein the machine control device 150 is adapted to that on the work spindle 111 of the machine tool 100 relative to the clamped to the clamping means 130 of the machine tool 100 workpiece 200 based on numerical control data to control, in particular for example on the basis of one or more NC programs.
• a numerical machine control device 150 which preferably comprises a CNC control device and a PLC control device, wherein the machine control device 150 is adapted to that on the work spindle 111 of the machine tool 100 relative to the clamped to the clamping means 130 of the machine tool 100 workpiece 200 based on numerical control data to control, in particular for example on the basis of one or more NC programs.
• the work spindle III is held on a spindle head 110 of the machine tool, which can be rotationally driven via a rotary shaft (not shown), and is adapted to receive one or more tools at a tool receiving interface. Furthermore, the work spindle 111 is adapted to receive a tool received on the tool holder, such as a tool. a milling or drilling tool, for generating the cutting cutting motion during machining of a workpiece on the machine tool at high rotational speed to drive (tool-carrying spindle). However, in addition to cutting tools, it is also possible to receive non-cutting tools on the work spindle III and to move them by means of the at least 5 axes relative to the workpiece 200 clamped to the clamping means 130.
• the tool shown in Fig. 1 is e.g. a measuring tool 140 (e.g., stylus) by means of which the clamped workpiece 200 can be scanned at a sensing position for determining the position of the workpiece surface.
• the machine tool further comprises a turntable 120, on which the clamping means 130 is fastened for clamping a workpiece 200 and which is rotatable about the rotation axis M1 in FIG. 1 by means of the rotary axis B.
• the machine control device 150 comprises, for example, an interface 170 for inputting and outputting control data, such as, for example, NC data comprising one or more NC programs.
• the interface 170 can have a very wide variety of data interfaces, for example a LAN interface, a WLAN interface, an Ethernet interface, a Bluetooth interface, a USB interface, etc.
• the machine control device 150 comprises an operating device 160, via which an operator can operate the machine tool 100 and in particular the machine control device 150.
• the operating device 160 comprises a display unit 161 for displaying a graphical user interface (comprising means for visual information transmission, ie a monitor, touch screen, or bar displays, lamps, LEDs, etc.) and operating units 162a and 162b for manual input of operating commands ,
• the operating unit 162a may be formed with a keyboard and / or softkeys
• the operating unit 162b may be embodied, for example, as a position-indicating operating unit, eg as a computer mouse, a tracking ball, a touchpad, a joystick or the like.
• the machine tool 100 according to FIG. 1 is adapted to control an automatic rotational alignment process for determining a rotational zero offset for a finishing of a gear 200 clamped to the clamping means 130.
• the gear 200 is shown in Fig. 1 as a straight-toothed bevel gear.
• the present invention is advantageously applicable to performing an automatic rotary alignment operation for determining a rotational zero offset for finishing a variety of gears (eg, spur gears, bevel gears, ring gears, etc.) with arbitrary tooth forms (eg straight teeth, helical teeth, arc gears, spiral teeth, etc.). and also with any tooth profiles (eg involute profile, cycloid profile, etc.).
• the processing, in particular milling, as well as the control of the scanning process in the context of the invention in bevel gears 5-axis ie via control of at least three linear axes and at least two rotary axes
• the processing, in particular milling, as well as the control of Tasting in the context of the invention in spur gears also 4-axis done (ie via control of at least three linear axes and at least one rotary axis).
• the measuring probe 140 which is controlled by the machine control device 150 and is recorded on the work spindle 111, determines or measures a respective actual position at a plurality of predetermined tooth flanks of the gear 200 at a plurality of predetermined probe positions on each of the predetermined tooth flanks.
• the machine control device 150 compares the determined actual position with a respective predefined setpoint position for each of the predetermined probe positions and determines or calculates a setpoint-actual deviation for each probe position on the basis of this comparison.
• the engine controller 150 automatically determines, based on the determined target / actual deviations, at least one rotational zero offset for the finishing of the gear 200 clamped to the chuck 130. This will be explained in more detail later described.
• the determined actual positions are stored together with the desired positions and the associated desired-actual deviations in a storage means of the machine control device 150.
• the determined rotational zero offset for the finishing is preferably also stored in the storage means in order to be taken into account in the subsequent finishing.
• FIG. 2 shows, by way of example, a schematic illustration of two adjacent teeth 201 and 202 of a straight-toothed spur gear in a perspective view.
• the direction arrows ZH, ZB, and ZD in Fig. 2 indicate the directions ZH in the direction of tooth height (tooth height direction), ZB in the direction of the tooth width (Zahnbreitenrichturig) and ZD in the direction of the tooth thickness (tooth thickness direction).
• the tooth 201 has a left tooth flank 201a and a right tooth flank 201b
• the tooth 202 also has a left tooth flank 202a and a right tooth flank 202b.
• the gear has a tooth gap with the tooth base 203.
• FIG. 3 shows, by way of example, a schematic illustration of the right tooth flank 201b for illustrating a scanning process on the tooth flank 201b according to an exemplary embodiment of the invention.
• the scanning operation according to this embodiment is controlled based on tactile data from the engine controller 150.
• the present invention provides that a plurality of tooth flanks is scanned. 3 illustrates the scanning process on only one tooth flank, and it is provided to carry out such a scanning process according to FIG. 3 successively on a plurality of tooth flanks of the toothed wheel.
• the plurality of tooth flanks to be scanned comprises a group of left tooth flanks and a group of right tooth flanks.
• the number of left tooth flanks to be scanned and the number of right scraps to be scanned are preferably the same.
• each of the left and the right tooth flank of the same tooth can be scanned or even more expedient the left and the right tooth flank of the same tooth gap.
• the tactile data preferably initially indicate the tooth flanks to be scanned, or at least the teeth or tooth gaps to be scanned, wherein then preferably the left and right tooth flanks are scanned per given tooth or per given tooth gap.
• the tactile data continue to indicate a plurality of predetermined probe positions for the scanning process.
• the machine control device 150 is configured to receive the measuring probe 140, which is received on the work spindle 111, for the purpose of. Scanning a plurality of tooth positions arranged on the tooth edge based on the tactile data, wherein the tactile data for each probe position x (i, j) indicate a predetermined target position, a predetermined scanning direction and a predetermined orientation direction TO for the probe 140.
• probe positions x (i, j) are in a grid on the tooth flank 201b to be scanned at the respective intersections of grid lines LI, L2, L3 and L4 which lie on the tooth flank in tooth width direction ZB, and grid columns S1, S2, S3, S4, S5 and S6, which extend in the tooth height direction ZH on the tooth flank arranged.
• the index i exemplarily describes the line number and the index j exemplifies the column number. Consequently, in this example in FIG. 3, touch positions x (1, 1), x (1, 2),..., X (4, 5), x (4, 6) are arranged on the tooth flank 24, wherein the respective Actual position is to be sampled at the 24 probe positions by means of the probe 140.
• the number of rows and columns or the number of predetermined probe positions is chosen merely by way of example.
• the probe positions are preferably arranged such that all probe positions are arranged on the later tooth-active tooth flank surface.
• this arrangement of the probe positions on a tooth flank in a grid in rows and columns represents only a particularly expedient embodiment of the invention.
• sampling data TO orientation direction for the probe 140 designates a default one to be occupied along a longitudinal axis of the probe 140 in the scanning operation of the scanning positions • 24 of the tooth flank 201b.
• 3 shows, by way of example, a tip of the probe 140 with a stylus 140b, at the end of which a stylus ball 140a is mounted, which contacts the tooth flank surface for scanning the surface of the tooth flank 201b to determine an actual position at the probe positions x (i, j) to bring is.
• the target positions for each of the key positions further specified in the key data indicate (preferably in the machine tool coordinate system) the respective position of a scanning target for the respective scanning position, and the scanning directions further specified in the key data to a respective feed direction for the probe 140 when scanning the respective scanning position respective target position.
• the probe 140 is scanned at a certain scanning position in such a way that the probe 140 is oriented in an orientation according to the predetermined orientation direction TO (ie longitudinal axis of the stylus 140b in FIG.
• FIG. 3 A particularly useful embodiment of the scanning movement is shown by the dashed arrows in Fig. 3.
• the scanning positions are scanned in columns, beginning at one of the two outer columns, towards the tooth base (ie opposite to the tooth height direction ZH), ie the probe positions of a column j are consecutively arranged in the sequence x (lj), x (2, j) , x (3, j) and x (4, j) are scanned.
• the key data are particularly suitably generated or specified such that the predetermined Orientation direction TO is maintained when scanning all 24 probe positions of the tooth flank by the stylus 140, ie that the Rotary axes of the machine tool during the traversing movements during the scanning process of the entire tooth flank 201b are held.
• the orientation direction TO is to be specified on the proviso that no collisions occur during the scanning process (possibly by means of a preceding virtual collision simulation).
• the scanning operation according to FIG. 3 is repeated for all given left and right tooth flanks until the actual positions at each of the predetermined probe positions of the plurality of predetermined tooth flanks have been determined by means of the probe 140.
• a soli-actual comparison for each scanning position. Such a desired-actual comparison is illustrated by way of example for probe positions of a column of a left and a right tooth flank of a tooth in FIG. 4.
• the indications of the tactile data relate to a coordinate system in which one of the main axes of the machine tool (usually the Z axis) lies exactly on the central axis of the workpiece or in which the center axis of the workpiece is aligned exactly with the rotation axis M1 of the turntable 120 ,
• the workpiece 200 may also be clamped arbitrarily in the clamping means 130, e.g. in that the center axis of the workpiece 200 is oriented, if appropriate, axially parallel but displaced relative to the rotation axis M1 of the turntable 120.
• such Einspannabweichung between the center of rotation of the rotary axis B of the machine tool and the central axis of the workpiece 200 automatically by the machine control means 150 by means of a coordinate conversion or coordinate transformation can be compensated, ie the Tast flowers or the position and direction information in the Tast flowers a be subjected to automatic coordinate transformation to automatically compensate for a clamping deviation between the center of rotation of the rotary axis B of the machine tool and the central axis of the workpiece 200.
• the setpoint positions can be subjected to an automatic coordinate transformation and / or the actual positions determined in the keying process can be subjected to an inverse transformation.
• FIG. 4 shows, by way of example, a schematic representation of actual positions and desired positions of a column of probe positions on tooth flanks 201a (left tooth flank) and 201b (right tooth flank) of tooth 201 from FIG. 2 and tooth flank 201b from FIG. 3 in column S6 (in FIG Essentially in profile section through the tooth 201).
• the dashed lines in Fig. 4 correspond to the desired course of the tooth flanks 201a and 201b, denoted 201aso and 201DSOLL along the column S6 of Fig. 3.
• the desired course of the tooth flanks and the required set positions of the tooth flank at the touch positions can e.g. determined based on a numerical virtual model of the gear geometry after a previously performed soft machining on the machine tool, e.g. based on a CAD model of the soft-machined gear, wherein the virtual model of the gear may possibly have been based on the generation of the numerical control data for the soft machining.
• an allowance specified by the operator can additionally be taken into account for the desired course of the tooth flanks.
• the course of the columns S6 in FIG. 4 exactly follows the profile section, so that by way of example the columns S6 of the left and the right flank both lie in a profile section plane.
• this is for illustrative purposes only, and generally it is not necessary for a column of probe positions on a tooth flank to be exactly in a profile section of the respective tooth.
• the columns of a left and a right tooth flank are each in a common plane.
• the arrangement of the tactile data of the left and right tooth flanks can also be completely independent of each other.
• the respective touch positions of the left flank 201aso are x (1,6, L) to x (4,6, L) and the respective touch positions of the right flank 201bsou_ are x (1, 6, R) to x (FIG. 4,6, R).
• the actual actual positions are determined by means of the probe 140 at the respective probe positions.
• the respective determined actual positions at the respective probe positions are identified by way of example by y (ij, k), whereby the indices i, j and k denote the line number i and the column number j analogously to the indices of the setpoint positions x (i, j, k).
• the actual positions y (i, j, k) are executed, for example, in a scanning direction corresponding to the respective normal vector on the respective tooth flank (according to desired course 201asou or 201bsoa) at the touch position, the determined actual positions y (i, j, k) are positioned substantially in respective normal direction of the desired positions x (i, j, k).
• target-actual deviation parameters A are preferably calculated as the amount of the distance between the respective desired and actual positions x (i, j, k) and y (i, j, k) with a prime, the indicates whether the tooth flank is warped towards the tooth or away from the tooth (direction of distortion).
• the target-actual deviation parameters A can assume both positive and negative values, wherein a positive sign indicates, for example, that the tooth flank is warped away from the tooth at the respective touch position, and indicates a negative sign, for example in that the tooth flank is warped towards the tooth at the respective scanning position.
• the parameter values for ⁇ (1,6, ⁇ _) to ⁇ (4,6, ⁇ _) and A (3,6, R) and A (4,6, R) in Fig. 4 would be positive and A (1,6, R) would be negative;
• N pairs of right and left tooth flanks can be scanned at different points of the toothed wheel.
• the right and left tooth flanks are scanned as described above.
• "essentially” means in particular preferred that the teeth or tooth spaces do not necessarily have to be arranged exactly opposite, ie at 180 °, but preferably within opposing angle segments which have an angle smaller than or equal to 90 °, preferably smaller than or equal to 45 °
• the N teeth or tooth gaps do not necessarily have to be arranged at an angular distance of 360 ° / N, but preferably in each case within angular segments which have an angular spacing of 360 ° / N to one another and preferably a respective angle of less than or equal to 180 ° / N, preferably less than or equal to 90 ° / N.
• a rotational zero offset is determined on the basis of the determined target-actual deviations A (m, i, j, k) .
• the determined target-actual deviations A (m, i, j, k) can be regarded as a function of the one-parametric rotational zero offset, wherein the zero offset of a positive or negative rotation of the gear can be considered around the axis of rotation of the gear, wherein the determined target-actual deviations A (m, i, j, k) correspond to the function values at a zero shift equal to zero.
• the respective function values of the target-actual deviations can be varied as a function of the zero offset in order to be able to determine an optimal rotational zero offset by determining a fit value or best fit value by means of a mathematical compensation calculation.
• a distance value D (0) can preferably be calculated on the basis of the determined target actual deviations, wherein the distance value (.theta.) Is preferably the size of the total deviation taking into account all determined Describes target / actual deviations descriptive value.
• the mathematical compensation method is then preferably by variation of the rotational Zero point shift ⁇ automatically minimizes this distance value, and the value of the rotational zero offset with minimized distance value then yields the determined optimized rotational zero offset for use in the subsequent finishing of the gear wheel in the context of this mathematical compensation calculation.
• this defined distance value D (8) can be regarded as a function of the zero shift ⁇ and minimized by simulated variation of the zero shift, to the optimized rotational zero offset which is then to be used to finish the cogged gear on the basis of the final finishing numerical control data.
• the values of the individual target / actual deviations can assume both positive and negative values.
• the distance value should preferably be selected on the basis of the target / actual deviations such that it can be described as a function of the amounts of the nominal-actual deviations or preferably as a function of the squares of the nominal-actual deviations.
• the distance value may be selected, for example, based on the target-actual deviations preferably such that the value of the distance value increases strictly monotonically with the amount of each individual desired-actual deviation or preferably with the square of each individual desired-actual deviation.
• the distance values D1 and D2 can then be minimized separately so
• the determined zero offset or the rotational zero offsets for the left and right tooth flanks are checked again automatically in the machine control device 150.
• it is preferably checked for each probe position in a simulation process on the basis of the control data for finishing and / or on the basis of a virtual model of the gear after finishing, if and / or how much material at the touch position taking into account the determined zero offset or the rotational zero offsets for the left and right tooth flanks is removed during finishing.
• the determined zero offset can be corrected again (possibly separated for the left and right tooth flanks) and checked again.
• the machine control device 150 is adapted to determine the at least one rotational zero offset of the gear clamped on the clamping means with the proviso to remove material at finishing of the gear at each scanning position. This can be made possible in a simple manner by checking the determined rotational zero offset, for example, for all determined target-actual deviations, to find out whether at one or more of the touch positions the determined zero offset is not sufficient to remove material at this touch position during finishing. On the basis of this check, the determined zero offset may then be slightly corrected, if necessary, in order to be able to remove material at these probe positions, whereby preferably it should be checked again whether this correction could not lead to no material being removed at other probe positions becomes. By determining a zero shift or corrected zero shift, in which material is removed at all scanning positions during the finishing, it can be particularly improved to avoid ever occurring on tooth flanks on which no material is removed.
• the machine control device is adapted to determine the at least one rotational zero offset of the gear clamped on the chuck taking into account a predetermined minimum material removal depth, with the proviso to ablate at least material up to the predetermined minimum material removal depth at finishing the gear at each scanning position.
• the rotational zero shift can for example be determined or calculated in a simple manner such that it is checked in a simulation by varying the rotational zero shift, which rotational zero shift ⁇ is at least required to all Soll -Ist deviations A (m, i, j, k) (9) become greater than or equal to zero or which rotational zero offsets ⁇ and ⁇ 2 are required in order to obtain all desired-actual deviations A (m, i, j, L) (9i) and A (m, i, j, R) (92) become greater than or equal to zero (the latter with separate evaluation of the left and right tooth flanks).
• the rotational zero offset can then be determined such that it is checked in a simulation by varying the rotational zero offset, which rotational zero offset is at least required to all Soll-Ist Deviations greater than or equal to the given minimum allowable.
• a rotational zero offset in the abovementioned definition of the signs of the target / actual deviations reduces the target actual deviations on right flanks, while the desired actual values Deviations on the left flanks are increased or the setpoint-actual deviations on right flanks are increased, while they reduce the target-actual deviations on the left flanks. If it is not possible to set right and left tooth flanks by means of the same rotational zero offset, it is provided in further embodiments of the present invention to evaluate right and left edges separately and to determine separate rotational zero offsets.
• step S1 the previously soft-worked and hardened heat treatment gear 200 is clamped to the clamping means 130 of the machine tool.
• step S2 tactile data for a scanning process of the gear 200 are specified. These can be specified either via the interface 170 or manually via the operating device 160 or it can be specified via the interface 170 or manually via the operating device 160 tactile positions, the further tactile data based on the Tastpositionen and a virtual model of the gear 200th automatically generated.
• the scanning operation is performed in which all scanning positions of the gear 200 are scanned by means of the probe 140 in order at the respective Tastpositionen the to determine the corresponding actual items.
• step S4 After determining the respective actual positions at all predetermined probe positions, in the next step S4 respective target-actual deviations are calculated for all probe positions on the basis of predetermined desired positions and the determined actual positions, and in the following step S5 a zero offset or two zero offsets by means of a mathematical compensation calculation determined separately for the right and left tooth flanks.
• step S5 the finishing of the gear 200 on the machine tool 100 is automatically performed on the basis of numerical control data for finishing, taking into account the rotational zero offsets determined in step S5.
• the present invention makes it possible to provide an improved alignment operation for soft-machined and heat-treated gears on a machine tool. in which the disadvantages described above can be avoided, and in which the rotational zero offset can still provide advantageous results, especially for very large gears with diameters of up to over one meter, so that it can be avoided in the finishing that occur at tooth flanks locations where too much and / or too little material is removed.

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• 2012
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