DE102018001505A1 - Method for machining a workpiece by means of an articulated robot - Google Patents

Abstract

The invention relates to a method for processing a workpiece by means of the articulated robot (1). The articulated robot (1) comprises: a base (2), a working head receptacle (7), a plurality of lever arms (3) which are arranged between the base (2) and the working head receptacle (7), wherein the lever arms (3) by means of hinges ( 4) are coupled together, a working head (8), which is arranged on the working head receptacle (7), wherein the working head (8) in a spindle housing (13) arranged working spindle (9), which at least at a first bearing point (14 ) and a second bearing (15) in the spindle housing (13) is mounted. By means of a vibration sensor, the natural frequencies of the workpiece to be machined are determined.

Description

The invention relates to a method for processing a workpiece by means of a articulated robot.

Knickarmroboter are known from the prior art, which have a working head with a recorded in a spindle housing work spindle. A machining tool is clamped in the work spindle. By pressing the machining tool to the workpiece to be machined, a force is exerted on the articulated robot by which the articulated robot is slightly deformed. The deformation of the articulated robot causes inaccuracies in the machining of the workpiece.

The object of the present invention was to overcome the disadvantages of the prior art and to provide an improved articulated robot, as well as an improved method for machining a workpiece.

This object is achieved by an apparatus and a method according to the claims.

In particular, an articulated robot is formed. The articulated robot comprises: a base, a working head receptacle, a plurality of lever arms which are arranged between the base and the working head receptacle, wherein the lever arms are coupled to each other by means of pivot joints and wherein at least one servomotor is formed per hinge, which means for adjusting the angle between the two means The working head, which is arranged on the working head receptacle, wherein the working head comprises a work spindle arranged in a spindle housing, which is mounted at least at a first bearing point and a second bearing point in the spindle housing, a computing unit, which for controlling the Servomotors used.

Furthermore, it can be provided that at least one sensor for detecting a radial force is respectively formed at the first bearing point and at the second bearing point. At least one of the two bearing points at least one sensor for detecting an axial force is formed.

An advantage of this design of the articulated robot is that by the arrangement of the sensors directly in the bearings, acting on the machine tool axial loads, radial loads and bending moments can be detected. In addition, sensors which are arranged at the bearing points, a high detection accuracy, as occurring forces can be measured as directly as possible. The mass and thus also the inertia of the between the force application point (Toolcenterpoint) and the sensors intermediate parts is very low, since this is only the machining tool itself and the work spindle. Since these have a low mass and the mass inertia to be considered is low and can optionally be taken into account.

Furthermore, it may be expedient if the two bearing points are formed by a magnetic bearing and the sensors are realized by a measuring device for determining the field strength in the magnetic bearing and for detecting the deflection of the work spindle relative to the spindle housing. The advantage here is that by means of a magnetic bearing a high speed of the machining tool can be realized. In addition, the applied forces can be precisely determined in the magnetic bearing.

Furthermore, it can be provided that the work spindle is adjustable by means of the magnetic bearing relative to the spindle housing. The advantage here is that by this measure, the work spindle can be moved to compensate for deformations relative to the spindle housing, whereby small deformations occurring in the articulated robot can be compensated. Of particular advantage here is that by means of magnetic bearing small deformations can be compensated with only a very short reaction time. In addition, it is also conceivable, for example, that by means of the magnetic bearing the work spindle is set into oscillation relative to the spindle housing and thus, for example, high-frequency axial vibrations are performed. For example, this axial vibration can result in improved chip formation.

In an alternative variant it can be provided that the sensors are designed in the form of piezo elements. Such sensors in the form of piezo elements can be combined, for example, with conventional rolling bearings or sliding bearings.

In yet another alternative variant can be provided that the two bearings are formed by a hydrodynamic sliding bearing and the sensors are realized by a measuring device for determining the hydraulic pressure in the bearing points and for detecting the deflection of the work spindle relative to the spindle housing, wherein by means of the hydrodynamic sliding bearing the work spindle is adjustable relative to the spindle housing. A hydrodynamic slide bearing has a possibility for adjusting the work spindle relative to the spindle housing. The hydrodynamic Slide bearing can be operated, for example, using an oil. Moreover, it is also conceivable that the hydrodynamic sliding bearing is operated using a gas.

According to a development, it is possible that the spindle housing is accommodated by means of a linear guide axially displaceable on the working head. The advantage here is that, for example, when performing a drilling operation by means of a tensioned in the work spindle drill, the feed movement of the drill does not have to be done by means of the robot arms, but that the spindle housing can be moved linearly. This can increase the accuracy of the bore. In addition, such delivery movements can be detected directly on the sensors of the bearings.

Furthermore, it may be expedient if an investment sleeve is formed on the working head, which is provided for application to a workpiece to be machined and that in the plant cuff, a further sensor for detecting the contact force of the plant cuff is formed on the workpiece. The advantage here is that can be pressed by the plant cuff of the entire working head with a predetermined force to the workpiece to be machined, whereby the articulated robot can be brought under bias. Upon subsequent pressing of the machining tool to the workpiece, the reduction in the contact force measured at the further sensor can be determined, thereby directly deducing the pressing force applied by the machining tool. This can serve, for example, for matching with the forces measured in the sensors.

In addition, it can be provided that a vibration sensor is formed on the working head, which serves to detect vibrations on the workpiece. The advantage here is that by means of the vibration sensor, the vibrations transmitted from the machining tool to the workpiece can be detected and subsequently evaluated in the arithmetic unit.

Furthermore, it can be provided that the vibration sensor is received in the plant sleeve. The advantage here is that a recorded in the plant cuff vibration sensor can be brought directly into contact with the workpiece.

According to a particular embodiment, it is possible that the vibration sensor is freely swinging on the working head, in particular in the plant cuff, added and coupled to the workpiece. The advantage here is that by this measure, the vibrations of the working head can be coupled and thus the vibrations occurring on the workpiece can be detected.

Furthermore, it is also conceivable that the vibration sensor is recorded at a different location on the articulated robot.

According to an advantageous development can be provided that the vibration sensor is in the form of an acceleration sensor, in particular in the form of a piezoelectric sensor, by means of which its own orientation and also an amplitude and direction of the vibration of the workpiece can be determined when the vibration sensor is applied to the workpiece. The advantage here is that by means of such a trained acceleration sensor, the vibrations of the workpiece can be detected and evaluated not only quantitatively but also qualitatively. In addition, the spatial orientation of the vibration sensor can be detected by means of the vibration sensor in the form of an acceleration sensor.

In an alternative variant, it can be provided that the vibration sensor is designed in the form of a laser Doppler vibrometer. The advantage here is that a non-contact detection of the surface vibration of the workpiece is made possible by means of a laser Doppler vibrometer.

According to the invention, a method for machining a workpiece by means of an articulated-arm robot described above is provided, wherein a machining tool for machining the workpiece is received or clamped in the work spindle. When pressing the machining tool to the workpiece, the radial force and the axial force is detected in the bearings by means of the sensors. In the arithmetic unit can be calculated by the pressing force of the machining tool to the workpiece. By detecting the vibration in combination with the detected pressing force of the machining tool on the workpiece can be concluded, for example, to wear on the cutting edge or on the workpiece nature.

• - einer Basis;
• - einer Arbeitskopfaufnahme;
• - mehreren Hebelarmen, welche zwischen der Basis und der Arbeitskopfaufnahme angeordnet sind, wobei die Hebelarme mittels Drehgelenken miteinander gekoppelt sind und wobei pro Drehgelenk zumindest ein Stellmotor ausgebildet ist, welcher zur Verstellung des Winkels zwischen den beiden mittels dem betreffenden Drehgelenk gekoppelten Hebelarmen dient;
• - einem Arbeitskopf, welcher an der Arbeitskopfaufnahme angeordnet ist, wobei der Arbeitskopf eine in einem Spindelgehäuse angeordnete Arbeitsspindel umfasst, welche zumindest an einer ersten Lagerstelle und einer zweiten Lagerstelle im Spindelgehäuse gelagert ist, wobei am Arbeitskopf ein Vibrationserfassungsmittel, insbesondere ein Vibrationssensor ausgebildet ist, welcher zur Erfassung von Schwingungen am Werkstück dient; und
• - einer Recheneinheit, welche zur Steuerung der Stellmotoren dient.

Also provided is a method for machining a workpiece by means of a articulated robot with

• - a base;
• - a working head receptacle;
• - A plurality of lever arms, which are arranged between the base and the working head receptacle, wherein the lever arms are coupled to each other by means of pivot joints and wherein at least one servomotor is formed per hinge, which for adjusting the angle between the two lever arms coupled by means of the respective pivot joint is used;
• - A working head, which is arranged on the working head receiving, wherein the working head comprises a spindle housing arranged in a work spindle which is mounted at least at a first bearing point and a second bearing in the spindle housing, wherein on the working head, a vibration detection means, in particular a vibration sensor is formed serves to detect vibrations on the workpiece; and
• - A computing unit, which serves to control the servomotors.

• - Anregen und dadurch in Schwingung versetzen des Werkstückes mittels dem Knickarmroboter oder einem im Knickarmroboter gespannten Bearbeitungswerkzeug;
• - Erfassen der Bauteilschwingungen mittels dem Vibrationserfassungsmittel, insbesondere dem Vibrationssensor;
• - Berechnen zumindest einer Eigenfrequenz und/oder der zugehörigen Eigenform des Werkstückes;
• - Bearbeiten des Werkstückes unter Berücksichtigung der ermittelten Eigenfrequenz und/oder der zugehörigen Eigenform des Werkstückes.

The method comprises the following method steps:

• - Excite and thereby vibrate the workpiece by means of the articulated robot or a tensioned in the articulated robot robot machining tool;
• - Detecting the component vibrations by means of the vibration detection means, in particular the vibration sensor;
• - calculating at least one natural frequency and / or the associated eigenform of the workpiece;
• - Processing of the workpiece taking into account the determined natural frequency and / or the associated eigenform of the workpiece.

An advantage of this method is that by determining the natural frequency of the workpiece, the further processing of the workpiece taking into account this natural frequency can be done. In particular, care can be taken here that the machining tool is operated at a frequency that is different from the natural frequency or the integer multiple of the natural frequency so as not to cause the workpiece to vibrate excessively during the machining process.

In particular, it is also conceivable that a plurality of natural frequencies are determined and taken into account.

• - Anregen und dadurch in Schwingung versetzen des Werkstückes mittels dem Knickarmroboter oder einem im Knickarmroboter gespannten Bearbeitungswerkzeug;
• - Erfassen der Bauteilschwingungen mittels dem Vibrationssensor;
• - Berechnen zumindest einer Eigenfrequenz und/oder der zugehörigen Eigenform des Werkstückes;
• - Bearbeiten des Werkstückes unter Berücksichtigung der ermittelten Eigenfrequenz und/oder der zugehörigen Eigenform des Werkstückes.

According to the invention may also be a method for machining a workpiece by means of a Knickarmroboter described above, wherein in the work spindle, a machining tool for machining the workpiece is received or clamped. When pressing the machining tool to the workpiece, the radial force and the axial force is detected in the bearings by means of the sensors. In the arithmetic unit can be calculated by the pressing force of the machining tool to the workpiece. In addition, the following method steps can also be provided in connection with these method steps:

• - Excite and thereby vibrate the workpiece by means of the articulated robot or a tensioned in the articulated robot robot machining tool;
• - Detecting the component vibrations by means of the vibration sensor;
• - calculating at least one natural frequency and / or the associated eigenform of the workpiece;
• - Processing of the workpiece taking into account the determined natural frequency and / or the associated eigenform of the workpiece.

Furthermore, it can be provided that a machining tool for machining the workpiece is received in the work spindle.

In addition, it is conceivable that at least one sensor for detecting a radial force is formed at the first bearing point and at the second bearing point and that at least one sensor for detecting an axial force is formed on at least one of the two bearing points, wherein upon pressing the machining tool to the Workpiece by means of the sensors, the radial force and the axial force is detected in the bearings and in the arithmetic unit thereby the pressing force of the machining tool is calculated.

Furthermore, it can be provided that the sensors simultaneously serve as vibration detection means. By this measure, the vibration on the workpiece can be tapped directly by means of the work spindle.

Furthermore, it is conceivable that the excitation and thereby vibrate the workpiece by applying a blow to the workpiece.

Alternatively, it can be provided that the excitation and thereby vibrate the workpiece is realized by means of the work spindle, wherein the work spindle is actively set in the bearings active relative to the spindle housing in vibration. The advantage here is that the workpiece can be gently vibrated. The workpiece can be excited and then the natural frequency can be tapped directly by means of the work spindle.

Especially when using a Magentlagerung for the work spindle, the Work spindle are simply vibrated to stimulate the workpiece. Subsequently, by determining the field strength, the vibration can be detected by means of the work spindle.

In addition, it can be provided that the machining tool is designed in the form of a drill and this is set during machining of the workpiece in the axial direction in oscillation, wherein the frequency of the vibration of the machining tool is selected differently to the natural frequency of the workpiece.

Furthermore, it can be provided that the strength of the workpiece and / or the modulus of elasticity of the workpiece is determined by means of the determined natural frequency and / or the associated inherent shape of the workpiece, as well as knowledge of the geometric shape of the workpiece from CAD data.

In addition, the flexibility of the workpiece can be determined that a certain force is exerted on the workpiece by means of the work spindle or the tensioned in the work spindle machining tool and thereby the workpiece is deformed. The degree of deformation of the workpiece can be determined by means of the position of the individual lever arms. The amount of applied force can be determined by means of the sensors in the bearings.

Furthermore, it can be provided that a necessary position compensation is calculated on the basis of the calculated pressing force of the machining tool and on the basis of a known force-dependent component deformation of the articulated robot and the necessary position compensation is realized at least in one of the servomotors. The advantage here is that by taking into account the force-dependent component deformation of the articulated robot, the accuracy of the articulated robot can be increased.

In addition, it can be provided that on the basis of the calculated pressing force of the machining tool and based on a known force-dependent component deformation of the articulated robot a necessary position compensation is calculated and that the necessary position compensation is at least partially realized by adjusting the work spindle relative to the spindle housing. The advantage here is that by adjusting the work spindle relative to the spindle housing, the position compensation can be performed with increased accuracy. In addition, such a bearing compensation can be performed relatively quickly and with a short reaction time. The position compensation by means of the work spindle can be superimposed with the position compensation by means of the articulated robot.

Also advantageous is an expression according to which it can be provided that in a magnetic bearing the radial force and the axial force in the bearing points is detected by determining the field strength in the magnetic bearings and by detecting the deflection of the work spindle.

According to a development, it is possible that an adjustment of the work spindle is realized relative to the spindle housing, characterized in that the field strength is adapted locally in the magnetic bearings.

Furthermore, it may be useful if when using a machining tool with a symmetrical cutting structure, in particular when using a drilling tool, a contact angle between a rotation axis of the machining tool and the workpiece surface on which the machining tool is applied by means of the lever law from the detected radial forces calculated. The advantage here is that can be calculated relative to the workpiece to be machined only by determining the radial forces of the contact angle of the machining tool and if necessary, the machining tool can be nachrotreht accordingly, so that the axis of rotation of the machining tool is at right angles to the workpiece surface.

In addition, it can be provided that, in addition to the calculated pressing force of the machining tool, the contact force of the bearing sleeve on the workpiece detected by the further sensor is included in the calculation of the necessary position compensation.

Furthermore, it can be provided that the signal of the vibration sensor is evaluated in the arithmetic unit and the necessary position compensation is calculated on the basis of the signal of the vibration sensor and the measured radial force and axial force in the bearing points.

The terms radial force and axial force refer to the axis position of the work spindle.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

• 1 ein Ausführungsbeispiel eines Knickarmroboters in einer perspektivischen Ansicht;
• 2 eine Detaildarstellung eines Arbeitskopfes;
• 3 eine perspektivische Ansicht eines Spindelgehäuses;
• 4 eine schematische Schnittdarstellung eines Spindelgehäuses mit darin aufgenommener Arbeitsspindel und Darstellung der Lagersituation;
• 5 eine schematische Darstellung der Krafteinwirkung auf die Lagersituation bei einem nicht orthogonal zur Oberfläche des Werkstückes stehendem Bearbeitungswerkzeug;
• 6 ein Ausführungsbeispiel der Arbeitsspindel mit Magnetlagerung;
• 7 ein Ausführungsbeispiel der Arbeitsspindel mit hydrodynamischer Lagerung.

In each case, in a highly simplified, schematic representation:

• 1 an embodiment of a articulated robot in a perspective view;
• 2 a detailed view of a working head;
• 3 a perspective view of a spindle housing;
• 4 a schematic sectional view of a spindle housing with housed therein work spindle and showing the storage situation;
• 5 a schematic representation of the force on the storage situation in a not orthogonal to the surface of the workpiece standing machine tool;
• 6 an embodiment of the work spindle with magnetic bearing;
• 7 An embodiment of the work spindle with hydrodynamic bearing.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and these position information in a change in position mutatis mutandis to transfer to the new location.

In the 1 is an articulated robot 1 shown in a perspective view. The articulated robot 1 includes a base 2 which is preferably fixed by means of fastening means on the ground of the site. For example, it is also conceivable that the base 2 is arranged on a linear guide, so that the complete articulated robot 1 is displaceable in a longitudinal direction.

With the base 2 are several lever arms 3 coupled, with the individual lever arms 3 with each other or one of the lever arms 3 with the base 2 by means of swivel joints 4 are coupled. The swivel joints 4 can be designed differently. They are preferably used to adjust an angle 5 between two mutually coupled lever arms 3 ,

In a first embodiment of swivel 4 are the two lever arms 3 with respect to their longitudinal axis arranged axially aligned with each other and by means of the rotary joint 4 can be one of the two lever arms 3 relative to the other lever arm 3 to be rotated around the central longitudinal axis.

In a second embodiment of the rotary joint 4 the two lever arms 3 are arranged side by side and the lever arms 3 can be pivoted relative to each other, so the angle 5 between the two longitudinal axes of the lever arms 3 can be varied.

Furthermore, every swivel is 4 a servomotor 6 assigned, by means of which the angle 5 between the two lever arms 3 can be adjusted. The servomotor 6 may be formed, for example in the form of a servo motor. Am from the base 2 furthest removed lever arm 3 is a working head shot 7 formed, on which a working head 8th is attached.

The working head 8th has a work spindle 9 can be added to a machining tool 10. In particular, on the work spindle 9 a tool holder for receiving a variety of editing tools 10 be formed, or can such a tool holder with the work spindle 9 be coupled. The editing tool 10 is used to edit a workpiece 11 , In particular, it can be provided that the machining tool 10 a tool for machining, such as a drill or a milling cutter.

Furthermore, it is an arithmetic unit 12 provided in which the corresponding control specifications, or corrections based on the material deformation is calculated.

In the 2 is the working head 8th shown in a detailed view, with the components of the working head 8th are shown partially cut, so that the structure of the working head 8th is apparent.

In the 3 is a spindle housing 13 for receiving the work spindle 9 shown in detail in a perspective view.

In 4 is to further illustrate the spindle housing 13 shown cut to describe the storage situation.

The exact structure of the working head 8th is based on a synopsis of 2 to 4 described. How very good 4 can be seen, is the work spindle 9 by means of a first depository 14 and a second depository 15 in the spindle housing 13 stored. The first depository 14 or the second storage location 15 are in 4 indicated schematically and can be realized by a variety of bearings. For example, it is conceivable that the bearing points 14, 15 are designed in the form of roller bearings, sliding bearings, magnetic bearings, or hydrodynamic fluid bearings. The installation situation as in 4 is shown schematically can be realized, for example, when using rolling bearings.

How out 4 it can be provided that one of the two bearing points 14 . 15 is designed in the form of a fixed bearing, which serves to absorb axial forces. In the present embodiment, the first bearing 14 is designed as a fixed bearing. In particular, it may be provided that in the first storage location 14 a sensor 16 is formed, which for detecting a radial force 17 serves. Furthermore, at the first depository 14 a sensor 18 be formed, which for detecting an axial force 19 serves. In addition, at the second depository 15 also a sensor 16 for detecting the radial force 17 is trained. Of course, also the second depository 15 or at both bearing points 14 . 15 a sensor 18 be designed to detect an axial force.

The sensors 16 for detecting the radial force 17 For example, they may be in the form of piezoelectric elements which are distributed over the circumference in the spindle housing 13 or on the work spindle 9 can be arranged. The sensors 16 can not only capture the amount of radial force 17 but also to detect the direction of the radial force 17 serve. The sensor 18 for detecting the axial force 19 may also be in the form of a piezo-element, which, for example, as an axial stop for one of the bearings 14 , 15 can serve.

Due to the well-known geometry of the bearings 14 . 15 or by a precisely measured Toolcenterpoint of the workpiece 11 can by means of the sensors 16 , 18 exactly the amount and direction of the Toolcenterpoint 20 acting force 21 be determined.

The power 21 is caused by the fact that the editing work 10 for machining the workpiece 11 , especially at its Toolcenterpoint 20 on the workpiece 11 is applied or pressed. Neglecting the friction between the workpiece 11 and the editing tool 10 so can the power 21 always at a right angle to the surface of the workpiece 11 stand. Due to the friction between the machining tool 10 and the workpiece 11 may be the angle of attack of the force 21 from the right angle to the surface of the workpiece 11 differ.

The fact that by means of the sensors 16 . 18 the amount and the angle of the force 21 to the Toolcenterpoint 20 can also be determined on the overall system articulated robot 1 acting force can be calculated.

By means of finite element calculations or empirical investigations, a force-dependent deformation of the articulated robot can be achieved 1 , in particular the lever arms 3 or the swivel joints 4 for each position of the articulated robot 1 and also be determined for each force effect. This can be done with knowledge of the deformation of the articulated robot 1 , his current position and the current power 21 to the Toolcenterpoint 20 the deformation-related deviation of the Toolcenterpoint 20 from its target position to its actual actual position. This deviation can be compensated in a position compensation, as already described.

Furthermore, it is also conceivable that by determining the angle of the force 21 to the Toolcenterpoint 20 determines whether the editing tool 10 actually at right angles to the surface of the workpiece 11 is applied. Optionally, this can also be done in the arithmetic unit 12 a necessary compensation is calculated and carried out.

How out 4 Furthermore, it can be provided that at the working head 8th a plant cuff 22 is formed, which for abutment on the workpiece 11 serves. With the plant cuff 22 can be a suction housing 23 coupled to which a suction hose 24 connected. The suction housing 23 can be fixed at the working head 8th be attached.

Furthermore, it is also conceivable that the spindle housing 13 together with the work spindle 9 by means of a linear guide 25 relative to a base 26 of the working head 8th slidably disposed on this. In other words, it can be achieved that the spindle housing 13 together with the work spindle 9 linear relative to the base 26 of the working head 8th is displaceable.

This can be a delivery of the editing tool 10 purely by the linear adjustment of the spindle housing 13 be achieved. Of course, the actual machining process or drilling process by exclusive displacement of the spindle housing 13 be achieved. Because the plant cuff 22 with the base 26 of the working head 8th is coupled, in such a shift operation, the work spindle 9 and thus also the machining tool 10 to the plant cuff 22 postponed.

Furthermore, it can also be provided that the base 26 of the working head 8th together with the plant cuff 22 relative to the working head shot 7 is displaceable. For example, it is conceivable that the base 26 of the working head 8th together with the plant cuff 22 by means of a Pneumatic cylinder is displaceable, wherein the pneumatic cylinder, the plant cuff 22 can press against the workpiece with a predefined force. The spindle housing 13 can by means of an electric drive relative to the plant cuff 22 be displaceable. This allows the spindle housing 13 exactly advanced or delivered.

Furthermore, it can be provided that in the plant cuff 22 another sensor 27 is formed, which for detecting the pressing force of the plant cuff 22 to the workpiece 11 serves. In the arithmetic unit 12 can be a resultant force from the radial force 17 which the sensors 16 is measured and from the axial force 19 which in the sensors 18 is measured, and from that force, which in the other sensor 27 is measured.

Furthermore, it is also conceivable that in the plant cuff 22 a vibration sensor 28 is arranged, which for detecting vibrations in the workpiece 11 is trained. The vibration sensor 28 For example, by a magnetic force on the workpiece 11 be held and freely swingable in the plant cuff 22 be included. This can be achieved by the vibration sensor 28 only the vibrations of the workpiece 11 be recorded.

A free-swinging suspension of the vibration sensor 28 in the plant cuff 22 can be achieved, for example, that the vibration sensor 28 embedded in a gel pad and thereby relative to the plant cuff 22 is displaceable. Furthermore, it is also conceivable that the vibration sensor 28 by means of an elastic membrane or other elastic element with the plant cuff 22 is coupled. For example, it is also conceivable that the vibration sensor 28 by means of a spring-based suspension free-swinging with the plant cuff 22 is coupled.

As in 2 Obviously, it is also conceivable that in the area of the plant cuff 22 around the work spindle 9 or the editing tool 10 at least three measuring elements 29 are arranged, by means of which in each case the distance to the surface of the workpiece 11 can be determined. By knowing the surface condition or the surface geometry of the workpiece 11, for example from a CAD model, and measuring the actual distance of the surface to the respective measuring element 29 can be calculated, whether the editing tool 10 orthogonal to the surface of the workpiece 11 is aligned.

The measuring element 29 For example, it may be in the form of a measuring pin biased by a spring against the surface of the workpiece 11 is pressed. Thus, the distance can be measured by tactile scanning. Furthermore, it is also conceivable that the measuring element 29 is formed for example in the form of an optical sensor, for example a laser sensor, which serves to detect the distance.

5 shows a schematic representation of the forces occurring 17 . 18 at the campsites 14 . 15 and the editing tool 10 if the editing tool 10 not orthogonal to the surface of the workpiece 11 is aligned and is pressed against this. Under knowledge of the geometry of the machining tool 10 and of course the geometry of the spindle housing 13 can by determining the amount and direction of the forces 17 . 18 at the campsites 14 . 15 can be the angle between the editing tool 10 and the surface of the workpiece 11 be calculated and by pivoting the machining tool 10 be balanced so that the editing tool 10 for the machining process orthogonal to the surface of the workpiece 11 stands.

6 shows in a schematic sectional view of another possible embodiment of the work spindle 9 and the spindle housing 13 with magnetic bearing 30 ,

In the embodiment according to 6 is provided that the work spindle 9 by means of a magnetic bearing 30 in the spindle housing 13 stored or optionally driven. magnetic bearing 30 can be both a radial bearing 31 as well as an axial bearing 32 exhibit. In particular, it can be provided that the magnetic bearing 30 is formed by that in the spindle housing 13 Windings 33 are formed, which with on the work spindle 9 arranged permanent magnets 34 interact.

In the windings 33 can be changed with a corresponding control, the field strength such that the work spindle 9 through the magnetic bearing 30 is held in its position. In addition, the field strength in the windings 33 the individual radial bearings 31 be changed so that the work spindle 9 is not centrally located, but is shifted to one side. As a result, a tilting or eccentricity of the work spindle 9 in the spindle housing 13 be achieved. In addition, it can be provided that the field strength in the windings 33 the axial bearings 32 adjusted so that the work spindle 9 can be moved axially. In particular, it is possible that small force-induced deformations of the articulated robot 1 by axial and / or radial displacement of the work spindle 9 be compensated. In addition, it is too conceivable that the work spindle 9 by means of the magnetic bearing 30 is added in axial and / or radial vibration, for example, to influence the chip breakage.

Furthermore, it can be provided that in the spindle housing 13 another, not shown, winding for driving the work spindle 9 is trained. Alternatively, it can be provided that the work spindle 9 is coupled with an electric motor, which for applying a torque to the work spindle 9 serves.

7 shows in a schematic sectional view of another possible embodiment of the work spindle 9 and the spindle housing 13 with a hydrodynamic plain bearing 35 ,

Similar to the formation of the magnetic bearing 30 out 6 this can be a radial bearing 31 and an axial bearing 32 be educated.

Furthermore are ever radial storage 31 and each axial bearing 32 a plurality of storage medium inflow openings 36 provided, which serve for pumping the storage medium. Especially with the radial bearings 31 can the storage medium inflow openings 36 Be arranged distributed over the circumference. By selectively pumping the storage medium, such as air or a hydraulic fluid, in certain of the circumferentially distributed Lagerermediumeinströmöffnungen 36 can the force acting on the work spindle 9 and thus also the position of the work spindle 9 to be controlled. The same applies to the axial bearings 32 ,

Of course, also storage medium outlets must 37 be provided, via which the introduced storage medium again from the interior of the spindle housing 13 can be removed. Both the storage medium inflow openings 36 and the storage medium outflow openings 37 are in 7 of course, and must of course be coupled to corresponding control valves, supply lines and a storage medium feed pump.

The embodiments show possible embodiments, it being noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments are possible with each other and this variation possibility due to the teaching of technical action by representational invention in Can the expert working in this technical field.

The scope of protection is determined by the claims. However, the description and drawings are to be considered to interpret the claims. Individual features or combinations of features from the illustrated and described different embodiments may represent for themselves inventive solutions. The task underlying the independent inventive solutions can be taken from the description.

All information on ranges of values in objective description should be understood to include any and all sub-ranges thereof, eg the indication 1 to 10 to understand that all subsections, starting from the lower limit 1 and the upper limit 10 are included, ie all sub-areas begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, eg 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

For the sake of order, it should finally be pointed out that for a better understanding of the construction, elements have been shown partially unevenly and / or enlarged and / or reduced in size.

LIST OF REFERENCE NUMBERS

1

articulated robot

2

Base

3

lever arms

4

swivel

5

Angle between lever arms

6

servomotor

7

Working head recording

8th

working head

9

work spindle

10

processing tool

11

workpiece

12

computer unit

13

spindle housing

14

first depository

15

second depository

16

Sensor radial force

17

radial force

18

Sensor axial force

19

axial force

20

Tool Center Point

21

Force in Toolcenterpoint

22

conditioning cuff

23

extraction housing

24

suction hose

25

linear guide

26

Base working head

27

additional sensor system collar

28

vibration sensor

29

measuring element

30

magnetic bearing

31

radial bearing

32

axial bearing

33

winding

34

permanent magnet

35

bearings

36

Lagermediumeinströmöffnung

37

Lagermediumausströmöffnung

Claims (8)

Method for machining a workpiece (11) by means of an articulated-arm robot (1) having - a base (2); - A working head receptacle (7); - Several lever arms (3) which are arranged between the base (2) and the working head receptacle (7), wherein the lever arms (3) by means of swivel joints (4) are coupled together and wherein per swivel joint (4) at least one servomotor (6) is formed, which serves for adjusting the angle (5) between the two by means of the relevant rotary joint (4) coupled lever arms (3); - A working head (8) which is arranged on the working head receptacle (7), wherein the working head (8) in a spindle housing (13) arranged work spindle (9), which at least at a first bearing point (14) and a second bearing point (15) is mounted in the spindle housing (13), wherein on the working head (8) a vibration detection means, in particular a vibration sensor (28) is formed, which serves for detecting vibrations on the workpiece (11); and - a computing unit (12) which serves to control the servomotors (6), characterized in that the method comprises the following method steps: - excite and thereby vibrate the workpiece (11) by means of the articulated robot (1) or one in the articulated robot (1) tensioned machining tool (10); - Detecting the component vibrations by means of the vibration detection means, in particular the vibration sensor (28); - Calculating at least one natural frequency and / or the associated eigenform of the workpiece (11); - Machining the workpiece (11) taking into account the determined natural frequency and / or the associated eigenform of the workpiece (11). Method according to Claim 1 , characterized in that in the work spindle (9) a machining tool (10) for machining the workpiece (11) is received. Method according to Claim 1 or 2 , characterized in that at least one sensor (16) for detecting a radial force (17) is formed at the first bearing point (14) and at the second bearing point (15) and that at least one of the two bearing points (14, 15) at least a sensor (18) for detecting an axial force (19) is formed, wherein upon pressing the machining tool (10) to the workpiece (11) by means of the sensors (16, 18), the radial force (17) and the axial force (19) in the Bearing points (14, 15) is detected and in the arithmetic unit (12) characterized the pressing force of the machining tool (10) is calculated. Method according to Claim 3 , characterized in that the sensors (16, 18) serve simultaneously as a vibration detecting means. Method according to one of the preceding claims, characterized in that the excitation and thereby vibrate the workpiece (11) by applying a blow to the workpiece (11). Method according to one of Claims 1 to 4 , characterized in that the excitation and thereby vibrate the workpiece (11) by means of the work spindle (9) is realized, wherein the work spindle (9) in the bearing points (14, 15) actively relative to the spindle housing (13) vibrated becomes. Method according to one of the preceding claims, characterized in that the machining tool (10) is designed in the form of a drill and this is set during machining of the workpiece (11) in its axial direction in oscillation, wherein the frequency of the vibration of the machining tool (10) to the natural frequency of the workpiece (11) is chosen differently. Method according to one of the preceding claims, characterized in that by means of the determined natural frequency and / or the associated eigenform of the workpiece (11), and with knowledge of the geometric shape of the workpiece (11) CAD data, the strength of the workpiece (11) and / or the modulus of elasticity of the workpiece (11) is determined.

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