JP6676730B2 - Method and system for gaugeless measurement of thread - Google Patents

Description

  The present disclosure relates to a gaugeless measurement method for a thread on a measurement object. In particular, the present disclosure relates to a method for gaugeless measurement of a ball screw spindle, or more generally, a component of a correspondingly threaded ball screw spindle. Obviously, the present disclosure can also be applied to a roller screw and a spindle or a drive provided with the screw.

  The essential aspects and embodiments of the present disclosure will be described with reference to a ball screw spindle. However, this should not be understood as limiting. For example, it may be used together with a ball screw nut. Furthermore, use with any threaded component, where high precision and especially high accuracy of the displacement / feed-in or the possible constant between the orbit and the associated travel distance is important is conceivable. .

  Patent Document 1 discloses, for example, a method for measuring linearity in a printing press, in which a threaded spindle in the form of a circulating ball spindle is used. U.S. Pat. No. 6,086,064 discloses the use of a threaded spindle for position determination in the case of a robot.

  The use of a recirculating ball spindle with a corresponding threaded nut in a vehicle steering device is described, for example, in US Pat.

  Measurement techniques are very important not only in research and development, but also in the individual or continuous production of products, especially in terms of quality assurance. Thus, even in the early stages of product development, it may be necessary to determine the configuration of sample parts, for example, to ensure that functional dimensions, etc., are within tolerances determined in light of the design. Determining or detecting such dimensions, or controlling them where appropriate, allows for feedback in the product development process. Thus, the changes or adaptations that may be needed to improve the degree of product readiness can be governed by the properties or behavior of the sample parts.

  In addition to the measurement tasks associated with the development process, measurement techniques are often also an essential auxiliary and quality control element in planning, setting up and performing continuous manufacturing.

  Coordinate measurement techniques are particularly suitable not only for measuring the geometric shape of the measurement object, but also for detecting other features, such as surface properties, position tolerances, shape tolerances and the like. In this case, the object to be measured is probe-tested in a coordinate system that can be predetermined by the configuration of the measuring device used. Here, it is possible to detect spatial points, spatial curves or spatial paths and surface elements. In this case, the detected value can be understood as a real image of the measurement target in the coordinate space.

  Coordinate measuring machines generally allow the measuring pickup to be moved along several spatial axes in a particular coordinate space and, if appropriate, further pivoted about at least one spatial axis. It has a structure to make. The drive required for this can in principle be achieved manually or alternatively by a motor. Many coordinate measuring machines are, for example, similar in their basic configuration to CNC multi-axis milling machines.

  Screw drives, especially ball screws, are used in various applications. This can, on the one hand, relate to the drive elements of machine tools, measuring machines and similar equipment, in particular traversing drives. Furthermore, a screw drive of this kind can also be used as a reference for a measuring task, provided that the relationship between pitch, orbit and the associated infeed is known.

  Furthermore, threaded spindles are also used in vehicle engineering, especially in "recirculating ball steering devices" or screw spindle steering devices.

  The ball screw drive has the advantage of being extremely easy to move. Due to the rolling elements used (balls), the friction losses between the spindle and the nuts arranged thereon can be significantly reduced.

  However, using a ball screw drive with a ball screw spindle requires a high degree of precision in the movement, i.e., the conversion between the rotational movement of the spindle and the nut and the relative axial movement, and any occurrences during this process. Depends on the moving amount deviation.

  Conventional configurations of the ball screw drive are standardized to ensure the desired accuracy and functional reliability. Regarding the basic configuration of the ball screw drive unit, attention is paid to International Standard ISO 3408-1; 2006 Ballscrews: Vocabulary and Design as an example. This usually also entails a corresponding standard for checking such components to necessarily guarantee the desired quality. As supplementary information, attention is drawn to the international standard ISO 3408-3: 2006 Ballscrews: Acceptance Conditions and Acceptance Tests, which defines the requirements and test conditions for certain types of ball screw assemblies in the light of this.

  Determining the displacement deviation that occurs is particularly associated with significant expenditure. Gauges in the form of gauge nuts mounted on ball screw spindles are usually used for this. Thereafter, a relative rotation occurs between the gauge nut and the spindle, after which the distance traveled is determined.

  Even so, it is possible to automate or at least partially automate such a measuring operation only at considerable expense. Such measurements are at best only suitable for random checks related to quality assurance during development or manufacture.

  Another disadvantage inherent in gauge-based measurement is that the deformation, in particular the deflection, of the spindle results in the measurement result, ie the travel distance or travel deviation. This is due to the principle involved and the nuts used are mounted as far as possible with little or no clearance on the spindle and are guided to a certain extent by the spindle (vertical direction of the spindle). ) Cannot be avoided.

  In addition, gage nuts also often exhibit deviations and other defects in the configuration that result in measurement results and determined travel deviations.

  As another issue, ISO 3408-3: 2006 states that, for example, a longitudinal displacement deviation parallel to the longitudinal axis of the spindle or parallel to the distance traveled along the spindle needs to be determined. Has been stipulated. However, this provision can no longer be fulfilled in practice because the spindle has a bending, for example, due to bending.

  In addition, when using gauge nuts to determine displacement deviations (longitudinal errors), other measurement tasks include, for example, determining diameter, thread shape and position, and thread shape tolerances. Need to be performed by different measuring means.

  This makes the entire measurement and quality assurance time-consuming and expensive for such spindles and nuts.

German Patent Application Publication No. 199 20 169 A1 European Patent Application Publication No. 0 333 928 A2 German Patent No. 102 34 596 B3

  Given this background situation, the underlying object of the present disclosure is to specify a method for measuring a thread on a measurement object that can be implemented in a gaugeless manner, ie without using a gauge. The method can preferably be performed using a measuring system for coordinate-based measurements, in particular a coordinate measuring machine.

  In particular, it is intended to be able to measure and check the measuring object as completely as possible in a single clamping (mounting) setup without the need for further setup work and the like. The method is preferably suitable for an automated or at least partially automated implementation.

  Furthermore, the method is intended to minimize or avoid as much as possible any errors resulting from the use of gauge nuts. In addition, the method is intended to allow the displacement deviation to be determined by the thread of the measuring object as independently as possible of any deformation / deflection of the measuring object. Furthermore, the method is intended to be able to determine the displacement deviation as parallel as possible to the (overall) longitudinal range of the measuring object.

  Finally, it is intended to identify a suitable measuring system for implementing the method, in particular a coordinate measuring machine. Furthermore, it is intended to specify an advantageous use of the measuring system, in particular a coordinate measuring machine. Finally, it is intended to specify a computer program that implements the method.

This object of the invention is a method for gaugeless measurement of a measuring object, in particular the thread of a ball screw spindle,
Detecting a partial displacement deviation in the first thread section, including a repeated or continuous probing of the thread groove;
Detecting partial displacement deviations in the at least one second thread section, including repeated or continuous probing of the thread groove;
Determining an overall displacement deviation based on the detected partial displacement deviation;
Movement deviations in these thread sections are detected in each case with respect to the local reference coordinate system,
The reference coordinate system is achieved by a method, which is offset between the thread sections.

  In this way, the objects of the invention are fully achieved.

  According to the invention, the thread to be measured is divided, i.e. into several sections or segments, which are then measured separately to determine the partial displacement deviations in relation to the sections. You. Finally, the partial travel deviations can be combined to determine an overall travel deviation for the thread. This relates, for example, to the working travel of the thread.

  One advantage of this arrangement is that, as it were, the threads are measured "in slices" so that the deflection or any other bending of the measuring object has at most a slight effect on the measurement result. As such, thread adaptation in each section may be performed assuming that section bending-of a sufficiently small and selected size-has been considered.

  The term "gaugeless measurement" is to be understood as meaning in particular a coordinate-based measurement, wherein a measurement system is used which allows the spatial point to be determined by appropriate adaptation. On this basis, the extent of the thread in the longitudinal direction and thus the displacement deviation can be determined using a plurality or a large number of detected spatial points.

  For example, the displacement deviation describes the deviation of the actual position of the nut on the screw spindle from the position of the specified set value. The location of the set point is usually obtained from a given pitch and (integer or non-integer) revolutions. In other words, the position of the set point may be based on the ideal average pitch. In this connection, the international standard ISO 3408-3: 2006, already mentioned above, is reiterated, which gives detailed information on the relevant characteristic variables and their determination.

  The method according to the present disclosure is intended to determine at least the thread pitch or the longitudinal extent of the thread over the respective thread section and ultimately the entire thread or the appropriately sized operating range of the thread. You.

  The reference coordinate system can be, for example, a coordinate system or a similar reference suitable for detecting and representing partial displacement deviations.

  The reference coordinate system may have, for example, a zero point that coincides with the vertical axis of the measurement object. Starting from the zero point, it is further possible to define a vertical direction which also coincides with the vertical axis. If the measurement object is curved or deformed in some other way, the longitudinal direction can be at least approximated on its longitudinal axis. The reference coordinate system may further provide information about the current number of revolutions and / or the current revolution angle and the resulting position shift. At a given set point pitch, it is possible to determine the deviation between the actual position along the vertical axis of the measured object and the position of the set point.

  It is imperative that when a new thread section is measured, the reference coordinate system needs to be re-determined. Thus, the idealized reference coordinate system “moves” across the measurement object when different sections are measured. In other words, the thread is split into several slices, which may be slightly offset (laterally or angularly) with respect to each other to reproduce the curvature to be measured. During evaluation, these slices are again coaxially aligned and combined to allow for an overall displacement deviation determination. This is preferably performed without any particularly disturbing effects from any deformation of the measurement object.

  The above-described embodiments of the method allow for the detection and determination of the resulting overall displacement deviation, taking into account in each case the actual configuration of the measuring object of the current thread section. The alignment and combination of the reference coordinate system precisely indicates the overall displacement deviation, while any deflection of the measurement object has no adverse effect.

  With respect to the figures, this approach can be compared to the determination of the overall length of a chain arranged in a curved configuration, wherein the individual chain links are individually considered using a corresponding reference coordinate system. In order to be able to combine the corresponding length deviations, the chains are theoretically drawn in a straight line, so that the reference coordinate systems axially align themselves in a corresponding manner.

  In other words, the local component axes are used to form and direct a reference coordinate system for each of the thread sections. This has the advantage that possible displacement deviations in the longitudinal direction parallel to the longitudinal axis of the object to be measured can be summed up as a corresponding coaxial alignment between the various local component axes takes place. Having.

  Overall, this allows the determination of a low error of the overall displacement deviation, which represents an important parameter with regard to the accuracy of the thread or of the screw drive in which it is provided.

  In an example method embodiment, the total travel deviation is determined by combining the partial travel deviations. This is preferably done independently or substantially independent of the bending of the measuring object. In this way, the overall displacement deviation can be determined independently of any possible deflections.

  Thus, the overall displacement deviation can be determined with considerable accuracy independently of the actual orientation of the measurement object.

  According to an example of another embodiment of the method, the reference coordinate system of the thread section preferably coincides, in each case, such that the longitudinal coordinate axis is aligned with the instantaneous longitudinal axis of the measured object. So that they are aligned. It is self-evident that the alignment may include a tangential orientation or other approximate orientation, at least when the coordinate axes are linear in an ideal manner.

  Obviously, the method is not exclusively restricted to external threads. The method can be used in a similar manner for internal threads, such as the corresponding nut.

  According to an example of another embodiment of the method, the longitudinal coordinate axes of the local reference coordinate system are linearly or aligned (conceptually or computerly) to determine the overall displacement deviation. Pointed. Therefore, the partial displacement deviations can simply be summed.

  According to an example of another embodiment of the method, the thread section has at least one revolution, preferably a plurality of revolutions, along which the partial displacement deviation is determined, at least once. , Preferably a plurality of turns. It is self-evident that integer multiples or fractional values can thereby be included. However, the number of turns in the at least one thread section must be less than the total number of turns in the operating range of the thread.

  Thus, the thread section may extend over n * 2 * π rad (pi rad) turns or corresponding circumferential / rotational angles along the helix, where n is an integer or non-integer. obtain. Thus, n can take on a value between 1 and 10, for example, depending on the entire range of the spindle. Larger values are possible. For example, n may be 4.5, so in this example embodiment 4.5 revolutions (corresponding to a rotation angle of 1620 ° (degrees)) may be considered in the corresponding section.

  Given the knowledge of the settling pitch or the settling thread height, the amount of movement of the defined rotation settling can now be determined. By measurement, the actual movement amount is obtained by comparison. In terms of absolute value, the movement amount deviation corresponds to the difference between the movement amount of the set value and the actual movement amount.

  According to an example of another embodiment of the method, the resulting partial deviation of the individual measuring sections is determined taking into account the conceptual dimensions of the ideal configuration of the gauge nut. Typically, such gauge nuts span a few turns. Thus, in the case of gauge-based measurement, the configuration of the gauge nut has an influence on the determined position of the gauge nut in the longitudinal direction and therefore also on the determination of the respective partial displacement deviation.

  Thus, on the one hand, the gauge nut can have a smoothing action and compensate for instantaneous displacement deviations (for example, within one round). However, in principle, the gauge nuts are themselves susceptible to errors, so that additional errors that do not result or are not directly attributable to the thread configuration can result.

  In the evaluation of the determined spatial point describing the configuration of the thread, the corresponding measurements are taken in order to determine the travel distance and travel variations or travel deviations that occur based on the thread configuration and the scope of the thread, in a computerized manner. The system may be based on gauge nuts in an ideal configuration.

  According to an example of another embodiment of the method, adjacent thread sections at least partially overlap. In this way, so-called "slide" measurements are possible. Overall, it is therefore possible to determine the overall displacement deviation with higher accuracy.

  According to an example of another embodiment of the method, at least some of the thread sections have different lengths. Thereby, on the one hand, it is possible to take into account that different sections of the thread have different bends. On the other hand, it is possible to respond to range-dependent accuracy requirements. In addition, thread sections of different lengths that at least partially overlap may also be used to verify the results.

  For example, the thread for a ball screw spindle may be divided into a thread entry, a thread exit, and an effective length between the thread entry and the thread exit.

  According to an example of another embodiment of the method, the measurement object is rotated periodically or continuously during the measurement. This simplifies and accelerates the measurement. This is because, when the measuring object itself is rotated, less complex movement is required for a part of the probe head that includes at least one probe for probing the thread profile.

  In addition, movement of the measurement object simplifies the determination of specific positional or shape tolerances, such as, for example, motion fidelity, concentricity, roundness, cylinder shape, and the like. This also applies to the detection of a particular groove shape of a thread, ie a cross section of a thread or flight of a thread. Furthermore, in this way it is possible to minimize the expense associated with the construction of the probe head itself.

  According to an example of another embodiment of the method, the object to be measured is mounted on a turntable. The turntable may carry, for example, a chuck or some other mount suitable for holding a measurement object.

  In principle, the measuring objects can be arranged with the vertical extent / vertical axis oriented vertically. Therefore, the object to be measured is set on the turntable or lowered from the turntable mounted on the turntable.

  However, this does not preclude placing measurement objects whose vertical range / vertical axis is oriented horizontally. In this case, however, a clear deflection / bend may necessarily be expected.

  According to an example of another embodiment of the method, the probe test is performed using a coordinate measuring machine. Probing may be performed by tactile or optical means. From a general point of view, contact probes and proximity probes are known. The probe is arranged on the measuring head, which is usually movable with respect to the frame of the coordinate measuring machine.

  According to an example of another embodiment of the method, the measuring further comprises determining at least one further property value selected from the group comprising diameter values, position tolerances, shape tolerances, surface properties and groove profile shape data. Including.

According to another aspect, the present disclosure is a measurement system, particularly a coordinate measuring machine,
A receptacle for receiving a threaded measuring object;
-At least one measuring head for receiving a measuring probe;
-A drive unit for moving the measuring probe on at least two spatial axes;
A control unit coupled to the measuring head and the drive unit;
The controller enables the measurement system to perform the method according to one of the embodiments described herein.

  This generally involves outputting a control command for movement of the measuring probe and for example receiving a signal from the measuring probe indicating contact with the object to be measured, the drive unit and the measuring unit attached thereto. And a control device in communication with the measurement head or the measurement probe.

  The controller may be further designed to process and evaluate the determined spatial coordinates and to determine the overall travel deviation of the thread according to the method.

  That the partial tasks or aspects of the control / evaluation can be performed by a spatially separated control unit at least temporarily coupled to the measurement system for exchanging data, for example by a separate computer Is self-evident.

  Thus, the measurement system may also include an interface for data exchange and control command exchange.

  According to an example of an embodiment of the measuring system, the system further comprises a turntable, on which a receptacle for the measuring object is mounted, wherein the controller measures the thread. For this purpose, it is designed to produce a coupled movement of the measuring head and the measuring object.

  The coupled movement may include at least a temporal time parallel movement of the measuring head and the measuring object. However, it is also conceivable to move the measuring object and the measuring head without directly overlapping in time.

  According to another aspect, the present disclosure is directed to one of the example embodiments described herein for performing a method for thread measurement in accordance with one of the example embodiments described herein. The use of a measurement system by one.

  Finally, the present disclosure relates to a computer program, a measurement system according to one of the examples of embodiments described herein, in particular a coordinate measuring machine, when the computer program is executed on a controller of the measurement system, It further relates to a computer program having a program code enabling to implement a method for thread measurement according to one of the example embodiments described herein.

  Without departing from the scope of the present invention, the above-mentioned features of the present invention and the yet-to-be-explained features described below can be used not only in the combinations specified in each case, but also in other combinations or themselves. Needless to say.

  Further features and advantages of the present invention will become apparent from the following description of examples of preferred embodiments, with reference to the drawings.

1 shows a perspective view of an embodiment of a measuring system in the form of a coordinate measuring machine. FIG. 2 shows a perspective partial cross-sectional partial view of a ball screw drive having a ball screw spindle and a ball screw nut. 1 shows a perspective view of a rod with a ball screw for use in a vehicle steering device. Figure 3 shows a partial view of a threaded rod. FIG. 5 shows another view of the threaded rod according to FIG. 4 in a curved state. FIG. 3 shows a simplified block diagram for describing an embodiment of a method for measuring the thread on the measuring object, in particular for determining the overall displacement deviation.

  FIG. 1 shows a measuring system including a measuring device 10 and a data processing device 42 for controlling the latter. The measurement system is generally designated 66.

  In this case, the measuring device 10 is designed as a coordinate measuring machine having a portal configuration, but may have a column type configuration, a cantilever configuration, or the like in principle.

  The measuring table 12 serving as the base of the measuring device 10 has a receptacle 14 on which a measuring object 52 to be measured is arranged. In the exemplary embodiment shown in FIG. 1, the receptacle 14 is located on a turntable 16. The turntable 16 allows for controlled rotation of the receptacle 14 on which the measurement object 52 is mounted.

  The portal 18 can be attached to the measurement platform 12 and moved in a controlled manner relative to the measurement platform. Attached to the portal 18 is a slide 20, which can then be controlled and moved relative to the portal. Finally, the slide 20 performs the function of mounting and guiding a sleeve 22 attached to it and which can be controlledly moved relative to the slide 20. A measuring pick-up 24 is arranged at the measuring table end of the sleeve 22, which has, by way of example, a probe shaft 26 and a probe head 28 at its end in FIG.

  Thus, the three sub-assemblies, portal 18, slide 20 and sleeve 22, which can be moved with respect to each other and with respect to the measuring table 12, are such that the measuring pickup 24 with the probe head 28 has three spatial axes 30a, 30b, 30c. To be moved along. In order to determine the position of the probe head 28 and thus the position of the probed entity on the measurement object 52, the measuring device has a reference indicated by 32a, 32b, 32c, Can determine the actual position of the probe head 28 with respect to each of the three spatial axes 30a, 30b, 30c.

  In addition, the measuring device is provided with a "rotation-rotation-" for allowing the measurement pickup 24 or at least the probe shaft 26 with the probe head 28 to be rotated or pivoted around at least one of the spatial axes 30a, 30b, 30c. It may also have a “pivot function”. The obtained rotational degrees of freedom are indicated by 34a, 34b, 34c in FIG. The turntable 16 can also rotate about the spatial axis 30c, thus providing the same rotational freedom as 34b.

  For simplicity, the measurement device 10 may be compared to a CNC multi-task machine which may have a "3-axis function" or alternatively, for example, a 5-axis function.

  In principle, the control of the measuring device 10 can be implemented in a simple manner in this case by the control element 36 with the directional control 38 and the switching element 40. In this case, the direction control device 38 can be designed, for example, as a control lever or a joystick. For control in several spatial directions, optionally, a plurality of directional controls 38 may be provided for pivoting or rotating the measuring pickup 24 about various spatial axes. A switching element 40 is further provided in the control element 36 in which a signal enabling the measurement of the geometric element to be probed can be generated.

  Apart from manual control or partial automatic control by the control element 36, the measuring device 10 is also designed for control by a data processing device 42 which forms part of the control device 60 (whole) of the measuring device 10. You. The data processing device 42 can be designed, for example, as a measurement computer or alternatively as a client of a central main computer. In addition to the coupled data processing device 42, the controller 60 may also have assemblies and components that are incorporated into the measurement device 10.

  The data processing device 42 has a display 44 for outputting information such as input elements 46a and 46b, for example, a keyboard, a keypad, a mouse, a touch screen, a trackball, and a three-dimensional input element. Thus, in principle, an operator may receive output information and enter input information and commands.

  Furthermore, the data processing device 42 further has a processing module 48 and a storage module 50, which can be connected via at least one interface 51. The processing module 48 may, for example, serve as a processor unit and be designed to execute program commands. The storage module 50 may perform the functions of a database, or alternatively may be connectable to a central database, such as a central product data management system.

  The data processing device 42 is further designed to control the measuring device 10, ie to be able to effect, for example, rotation of the turntable 16 and movement of the slide 20, the sleeve 22 and the portal 18. Conversely, the data processing device 42 receives and processes the position values detected by the measuring device 10. If present, elements 16, 18, 20, 22 are combined in drive unit 54.

  The measurement target 52 has a thread in at least one section or a plurality of sections. In particular, the thread is a “ball screw”.

  FIG. 2 uses a perspective partial cross-sectional view to illustrate an exemplary embodiment of a ball screw drive 70 that includes a screw spindle 72 and a nut 74. A rolling element in the form of a ball 76 is arranged between the screw spindle 72 and the nut 74. The rolling elements 76 ensure that the friction in the relative movement between the nut 74 and the screw spindle 72 is optimized. The relative movement includes relative rotation about the longitudinal axis of the ball screw drive 70 and relative translation along the longitudinal axis of the ball screw drive 70.

  FIG. 3 uses a perspective view to illustrate a shaft component 80 that may be used, for example, in a vehicle steering system. Shaft component 80 may also be referred to as a steering rod. Shaft component 80 includes a ball screw section 82 and a rack section 84. For example, the steering column may act on the shaft component 80 via the rack section 84 by teeth. The servo steering device may act on the shaft components via the ball screw section 82, for example, to simplify steering commands.

  With reference to FIGS. 2 and 3, the embodiment described by way of example represents many other possible embodiments of a spindle or shaft part with a threaded section, in particular a ball screw section.

  4 and 5 show the measurement object 100 configured as a screw spindle. FIG. 4 shows an ideal state of the measurement target 100. FIG. 5 shows a state where the measurement object 100 is partially deformed (bent). Obviously, the variant of FIG. 5 has been exaggerated for clarity.

  The measurement object 100 has a thread 102 configured as a ball screw. The vertical axis of the measurement target 100 is indicated by 104. In the description according to FIG. 5, the measuring object 100 is deformed at least in one or more sections, in particular due to bending. Accordingly, the vertical axis 104 is curved in the region of the thread 102.

  As already explained above, it is advantageous to divide the thread 102 into a plurality of sections 110, 112, 114 to determine the overall displacement deviation as independently as possible of a given deformation / bend. It is.

  To this end, it is proposed to define a reference coordinate system or coordinate system for each of the sections 110, 112, 114. In this case, the respective reference coordinate system 120, 122, 124 or its longitudinal axis 130, 132, 134 is in each case aligned with the actual course of the longitudinal axis 104 in the respective section 110, 112, 114. . The thread 102 may now be probed in multiple sections to determine partial displacement deviations, where a given bend of the axis 104 is at least in each section 110, 112, 114. Partially considered. This has the advantage that the bending of the shaft 104 does not cause a random change in the respective displacement along the thread 102.

  To detect the overall displacement deviation, the partial displacement deviations of the sections 110, 112, 114 are summed, resulting in a more accurate overall measurement and better correspondence to actual conditions I do.

  In principle, it is conceivable that the sections 110, 112, 114 at least partially overlap in order to create an overlap (vertically) between the sections. However, it is also conceivable to define sections 110, 112, 114 without overlap.

  Furthermore, it is conceivable to vary the length of the sections 110, 112, 114 in order to take into account the various sections of the thread 102 in a suitable way. Each of the sections 110, 112, 114 preferably includes more than one revolution of the thread 102. In this way, based on a given pitch, the resulting displacement can be determined depending on the current rotation angle. Therefore, the deviation of each movement amount is given by comparing the actual value and the set value.

  In FIG. 5, “virtual” nuts are shown at 140. This facilitates the evaluation of the data obtained during the measurement of sections 110, 112, 114. The background of this approach is that “gauge nuts” are often used, especially to determine the resulting displacement deviation of the threads 102. These gauge nuts often cover a range of several revolutions, so that the resulting displacement deviation is, as it were, "averaged" over several revolutions.

  Here, it is proposed to simulate the use of a gauge nut of this kind, the advantage of which is that an ideally configured gauge nut can be employed as a basis for evaluating the measurement results. Thus, for evaluation, the block shown at 140 is associated with the ideal dimensions for the thread present therein and, if present, for any rolling element, and thus the actual gauge nut Any errors that can be associated have no effect on the determined displacement deviation.

  Another advantage of dividing thread 102 into sections 110, 112, 114 is that the “simulated” gauge nut 140 follows a bend of longitudinal axis 104 in each section 110, 112, 114, so to speak. This further enhances the accuracy of detecting the displacement deviation.

  The course of the thread 102 or the thread groove 106 forming the thread 102 may be continuous or intermittent in order to determine the actual travel obtained along the thread 102 during rotation of the spindle type measuring object 100. The probe is inspected. This allows the use of a measurement system configured as or using a coordinate measuring machine. Depending on the configuration of the coordinate measuring machine, additional dimensions, parameters, shape errors, configuration errors, etc. may be determined.

  Overall, therefore, the use of gauge nuts makes it possible to avoid a laborious and separate measuring operation for the resulting displacement deviation.

  Dividing the thread 102 into two or more sections 110, 112, 114 that follow the actual bending of the measurement object 100 increases the accuracy of the measurement.

  Referring to FIG. 6, an exemplary embodiment of a method for measuring a thread to be measured is shown by a block diagram.

  The method includes step S10, which includes providing a measurement system using a coordinate measuring machine. Thus, it is possible to probe the measurement object to detect corresponding spatial coordinates that reflect the contour of the measurement object.

  This is followed by step S12, which involves mounting the measurement object on a turntable in the coordinate measuring machine. The measuring object is in particular a shaft part or a spindle, which comprises a threaded section. The measuring object is mounted or clamped such that the turntable can rotate the measuring object around its longitudinal axis in a defined manner.

  In a following step S14, multiple or continuous probing of the thread path of the first thread section is performed to determine the thread travel characteristic (equivalent to pitch x orbit). You. This further includes the determination of a deviation from the set value deviation. Step S16 includes a similar or the same type of measuring operation as the further thread section. The measurement for each section in steps S14 and S16 is based on a reference coordinate system (coordinate system) that follows the actual bending of the measurement target. This increases the accuracy of the measurement, especially in the case of bending of the measurement object.

  The measurements in steps S14 and S16 are preferably performed such that in each case a plurality of turns of the thread are detected. Steps S14 and S16 are representative examples of two or more sections measured consecutively.

  The measurement steps S14 and S16 are followed by an evaluation step S18. In an evaluation step S18, the coordinates determined in steps S14 and S16 are evaluated to determine an overall displacement deviation of the thread. This is done taking into account the local reference coordinate system of each section. This increases the overall accuracy of determining the overall travel deviation.

  Further, according to an exemplary embodiment, step S18 includes considering a "virtual" gauge nut configured with ideal dimensions. Such a nut may have a longitudinal extent that spans several turns of the thread. This may, for example, result in a smoothing or averaging of the deviation of the configuration detected from one round to the next. Since the evaluation in step S18 is performed mainly by computer calculations, at least the entire thread is ensured to be "virtually" traversed through the various sections by the same gauge nut of the ideal product. It is possible to

  This excludes at least the entry of any defects in the "real" gauge nut into the detected overall displacement deviation.

  In step S20 following this, the measurement result is output or transmitted. Based on this, it is possible to determine the accuracy and quality of the thread dimensions. The determined data can be further processed. Based on the determined data, it is possible to determine whether the checked thread or the spindle provided with it meets the requirements or the desired quality classification.

DESCRIPTION OF SYMBOLS 10 Measuring apparatus 12 Measuring table 14 Receptacle 16 Turntable 18 Portal 20 Slide 22 Sleeve 24 Measurement pickup 26 Probe shaft 28 Probe head 30a, 30b, 30c Spatial axis 32a, 32b, 32c Reference 34a, 34b, 34c Rotational freedom 36 Control Element 38 Direction control device 40 Switching element 42 Data processing device 44 Display 46a, 46b Input element 48 Processing module 50 Storage module 51 Interface 52 Measurement target 54 Drive unit 60 Control device 66 Measurement system 70 Ball screw drive unit 72 Screw spindle 74 Nut 76 Ball 80 Shaft part 82 Ball screw section 84 Rack section 100 Measurement target 102 Thread 104 Length of measurement target 100 106 thread groove 110,112,114 thread sections 120, 122, 124 longitudinal axis 140 virtual nuts local reference coordinate system 130, 132, 134 reference coordinate system

Claims (15)

Measurement Target, in particular a method for Gejiresu measuring the threads on ball screw spindles,
- detecting a repeated or continuous including probe test, partial movement amount deviation those of the first thread section of the screw groove,
- a step of the containing repeating or continuous probing of the thread groove, to detect the partial movement amount deviation definitive at least one second thread section,
Determining a total displacement deviation based on the detected partial displacement deviation;
The partial movement amount deviation definitive in the thread section is their respective detected regarding the station office reference coordinate system,
It said local reference coordinate system is offset between the screw thread section, method. The overall movement amount deviation, the partial and the movement amount deviation curvature of the measurement Target is determined independently or by substantially independent combined method of claim 1. The thread section of the local reference coordinate system, it respectively, aligned with the actual course of the vertical axis in each of the thread sections of the longitudinal axis of the local reference coordinate system the measurement Target is preferably directed et is to coincide with that method according to claim 1 or 2. Coordinate axis of the longitudinal direction of the local reference coordinate system is directed are linearly or alignment in order to determine the overall movement amount deviation The method of claim 3. The thread section at least once in orbit, preferably a plurality of times of circulation, the partial movement amount deviation is determined along which the at least one lap, orbiting preferably a plurality of times The method according to any one of claims 1 to 4, comprising: Partial deviation arising as a result of individual thread sections is determined taking into account the dimensions of the conceptual Gejina' bets ideal configuration, according to any one of claims 1 to 5 Method. Adjacent threads section is at least partially overlap, the method according to any one of claims 1 to 6. Wherein the thread section at least some of the emissions have different lengths, the method according to any one of claims 1 to 7. The measurement Target is periodically or continuously rotated during the measurement, the measurement Target is preferably attached to the turntable, a method according to any one of claims 1-8. Preferably probe test is tactile or optical is performed using the coordinate measuring machine, the method according to any one of claims 1 to 9.   11. The method according to any of the preceding claims, wherein the measuring further comprises determining at least one further property value selected from the group comprising diameter values, position tolerances, shape tolerances, surface properties and groove profile shape data. The method described in. Measuring systems, especially coordinate measuring machines,
- a Reseputaku Le for receiving the measurement Target threaded provided,
- at least one measuring heads for receiving the measurement probe,
- a drive unit for moving the measurement probe on in at least two spatial axes,
- it has a <br/> and control equipment coupled to the drive unit and heads Contact for the measurement,
The control device is a measuring system, in particular a coordinate measuring machine, which enables the measuring system to carry out the method according to any one of claims 1 to 11. A turntable, said Reseputaku Le for the measurement Target is mounted thereon, further comprising a turntable, the control equipment, in order to measure the thread, heads for the measurement are designed to produce movement linked in our and the measurement Target measurement system of claim 12.   Use of a measurement system according to claim 12 or 13 for performing a method according to any one of claims 1 to 11. A computer program, measurement system according to claim 12 or 13, in particular a coordinate measuring machine, when the computer program is executed by the control equipment of the measurement system, any one of claims 1 to 11 A computer program having a program code enabling to carry out the method according to 1.