KR102239657B1 - Method, system, and a computer program stored on a medium for gaugeless measurement of a thread - Google Patents

Abstract

The present disclosure relates to a method for gaugeless measurement of a measurement object 52, 100, in particular a thread 102 on a ball screw spindle, the method comprising repetitive or continuous probing of the threaded groove 106 Detecting a partial movement deviation in the first threaded portion (110), and partially in at least one second threaded portion (112, 114) comprising repetitive or continuous probing of the threaded groove (106). Detecting a movement deviation, and determining a total movement deviation based on the detected partial movement deviation, wherein the partial movement deviation in the threaded portions 110, 112, 114 is determined by a local coordinate reference 120 , 122, 124, respectively, and the coordinate reference 120, 122, 124 is shifted between the threaded portions 110, 112, 114. The present disclosure also relates to a corresponding measurement system, and to the use of this kind of measurement system and a corresponding computer program.

Description

Gageless measurement method of thread, computer program stored in system and media {METHOD, SYSTEM, AND A COMPUTER PROGRAM STORED ON A MEDIUM FOR GAUGELESS MEASUREMENT OF A THREAD}

The present invention relates to a method for measuring the weight of a thread on a measurement object. In particular, the invention relates to a method for measuring the weight of a ball screw spindle or, more generally, a component of a ball screw spindle provided with a corresponding thread. It is apparent that the present invention may also be applied to a roller screw, and to a spindle or drive provided with the roller screw.

Inevitable aspects and embodiments of the present invention will be described with reference to a ball screw spindle. However, this should not be understood as limiting. For example, use with a ball screw nut is also conceivable. Moreover, it is conceivable to use with any threaded component where high precision of movement/feeding and, in particular, high accuracy, or as constant as possible a ratio between the swivel and the travel associated with the swivel, is important.

DE 199 20 169 A1 discloses a method for measuring the linearity on a printing press in which a screw spindle is used, for example in the form of a recirculating ball spindle. EP 0 333 928 A2 describes the use of screw spindles for positioning in the case of robots.

The use of a recirculating ball spindle with a corresponding threaded nut in a steering system for a vehicle is described, for example, in DE 102 34 596 B3.

Measurement technology is of great importance not only in research and development, but also in individual or serial manufacturing 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 the sample part to ensure that, for example, functional dimensions and the like are within tolerances determined in the context of the design. Determining or detecting such dimensions or, where applicable, controlling such dimensions enables feedback with the product development process. Thus, changes or modifications that may be necessary to improve the degree of readiness of the product can be guided by the properties or behavior of the sample part.

In addition to the measurement tasks that entail the development process, measurement technology is also a frequently essential aid and quality control element in planning, setting up, and implementing serial manufacturing.

In order to measure the geometry of the object to be measured, as well as to detect other features such as surface properties, position tolerances, shape tolerances, and the like, the coordinate measurement technique is particularly suitable. In this case, the object to be measured is searched with a coordinate system, and the coordinate system can be determined in advance by the configuration of the measuring device to be used. Here, it is possible for spatial points, spatial curves or spatial paths, and surface elements to be detected. In this case, the detected value can be understood as an actual image of the measurement object in the coordinate space.

Coordinate measuring machines generally have a structure that allows the measuring head to be moved along a number of spatial axes within a certain coordinate space and, if appropriate, also to be axially rotated about at least one spatial axis. The drive required for this purpose can in principle be achieved manually or alternatively by means of a motor. A number of coordinate measuring machines are similar to CNC multi-axis milling machines, for example in the basic configuration of a number of coordinate measuring machines.

Screw drives, especially ball screws, are used in a variety of applications. This can, on the one hand, relate to drive elements of machine tools, measuring machines and similar equipment, in particular to slewing drives. Moreover, this type of screw drive can also be used as a standard for measuring tasks if the relationship between pitch and turn and associated feed is known.

Moreover, threaded spindles are also used in vehicle engineering technology, in particular in "recirculating ball steering systems" or screw spindle steering systems.

The ball screw drive has the advantage of obvious ease of movement. Thanks to the rolling elements (balls) used, friction losses between the spindle and the nuts arranged on the spindle can be significantly reduced.

However, the use of a ball screw drive equipped with a ball screw spindle lies in and falls within the scope of the accuracy of the movement, i.e. the ratio of conversion between the rotational motion and the axial relative motion of the spindle and nut, and any deviations of movement that occur during this process .

Typical configurations of ball screw drives are standardized to enable the desired accuracy and functional reliability to be guaranteed. For the basic configuration of a ball screw drive, as an example, the international standard ISO 3408-1; 2006-Pay attention to Ballscrews: Vocabulary and Designation. It also regularly imposes corresponding specifications relating to the checking of such components to ensure the desired quality. As further information, note the international standard ISO 3408-3:2006-Ballscrews: Acceptance Conditions and Acceptance Tests, which defines the requirements and test conditions for specific classes of ball screw assemblies in this context.

Determination of the movement deviation that occurs is, in particular, associated with significant expense. A gauge in the form of a gauge nut mounted on a ball screw spindle is commonly used for this purpose. Relative rotation between the gauge nut and the spindle is then created, and the resulting travel distance is then determined.

Automating or at least partially automating this type of measurement operation, if possible, should be costly. Such measurements are, at best, suitable for random checks in the context of development or quality assurance during manufacturing.

Another disadvantage inherent in gauge-based measurements is the fact that the deformation of the spindle, in particular the sagging, is input into the measurement result, ie the travel distance or travel deviation. This is due to the accompanying principle and is inevitable from the very fact that the nut used is seated on the spindle as little or no gap as possible and, to some extent, is guided by the spindle (in the longitudinal direction of the spindles).

Moreover, gauge nuts also often exhibit deviations and other defects in construction, which in turn are reflected in the measurement results and the determined displacement deviation.

Another challenge is that ISO 3408-3:2006 stipulates that the deviation of movement in the longitudinal direction, for example parallel to the longitudinal axis of the spindle or parallel to the travel distance along the spindle, must be determined. However, since the spindle has a curvature due to, for example, sagging, this condition can actually no longer be satisfied.

Moreover, when using a gauge nut to determine the deviation of movement (error in the longitudinal direction), different measurement operations are involved in the determination of different measuring means, e.g. diameter, thread shape, and position and shape tolerance of the thread. It should be done by means of measurement.

This makes the measurement and quality assurance overall time consuming and expensive in the case of spindles and nuts of this type.

In view of this background situation, the fundamental object of the present invention is to specify a method for measuring a thread on a measurement object that can be performed in a weightless manner, that is, without the use of a gauge. The method can preferably be carried out using a measuring system for coordinate-based measurements, in particular a coordinate measuring machine.

In particular, the intent is to enable as complete measurement and check of the measurement object as possible with a single clamping (mounting) setting without the need for additional setting operations or the like. The method is preferably suitable for an automated or at least partially automated implementation.

Moreover, the method is intended to minimize or possibly avoid any errors due to the use of the gauge nut. Moreover, the method is intended to enable the displacement deviation to be determined by the thread of the measurement object, preferably irrespective of any deformation/sagging of the measurement object. In addition, the method is intended to make it possible to determine the displacement deviation as parallel to the (overall) longitudinal range of the object to be measured.

Finally, the intent is to specify a measuring system, in particular a coordinate measuring machine suitable for carrying out the method. Moreover, the intent is to embody the advantageous use of measuring systems, in particular coordinate measuring machines. Finally, the intent is to embody the computer program that performs the method.

This object of the present invention is achieved by a method for measuring the weight of a measuring object, in particular a thread on a ball screw spindle, the method comprising the following steps:

-Detecting a partial displacement deviation in the first thread section comprising repeated or continuous search of the thread groove,

-Detecting a partial displacement deviation in at least one second thread segment comprising repeated or continuous search of the thread groove, and

-Determining the total movement deviation based on the detected partial movement deviations,

The partial movement deviation in the threaded sections is detected in each case with respect to the local coordinate reference in the measurement object,

The coordinate reference is moved between the thread sections in the measurement object.

In this way, the object of the invention is fully achieved.

According to the invention, the thread on the object to be measured is divided, i.e. into several divisions or divisions, and the divisions are then measured separately to determine partial movement deviations on a division-related basis. Finally, the partial travel deviations can be combined to determine the total travel deviation for the thread. This relates, for example, to the actuating movement of the thread.

One advantage of this configuration is that the thread is measured "in slices," so to speak, so that the sagging or some other curvature of the object to be measured has, at best, only a minor effect on the measurement result. The adaptation of the thread in each segment can then be carried out under the assumption that the curvature of the segment has been taken into account-of a sufficiently small selected size.

The term "weight measurement" should be understood to mean a coordinate based measurement in which a measurement system is used that allows spatial points to be determined by appropriate adaptations. On this basis, the extent of the thread in the longitudinal direction and thus the displacement deviation can then be determined using a plurality or a number of detected spatial points.

For example, the deviation of movement describes the deviation of the actual position of the nut on the screw spindle from the defined setpoint position. The setpoint position is typically obtained from a given pitch and (integer or non-integer) turns. That is, the setpoint position may be based on an ideal average pitch. In this context, again attention is paid to the already mentioned international standard ISO 3408-3:2006 which gives detailed information on the appropriate characteristic variables and the determination of the appropriate characteristic variables.

By means of the method according to the invention, the intent is to determine at least the thread pitch or longitudinal range of the threads in each thread section and ultimately through an appropriately large operating range of the entire thread or thread.

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

The coordinate reference may have a zero point coincident with the vertical axis of the object to be measured, for example. Starting at the zero point, it is furthermore possible to define a longitudinal direction which likewise coincides with the longitudinal axis. When the object to be measured is bent or deformed in some other way, the longitudinal direction can be at least approximated from the longitudinal axis of the object to be measured. Moreover, the coordinate reference may provide information about the current number of turns and/or the current angle of the turn, and the resulting positional deviation. At a given setpoint pitch, it will then be possible to determine the deviation between the setpoint position and the actual position along the longitudinal axis of the measurement object.

When a new thread segment is measured, it is inevitable that the coordinate reference must be re-determined. Thus, the idealized coordinate reference "travels" through the object to be measured when different segments are measured. That is, the thread is divided into a number of slices that can be slightly shifted relative to each other (laterally or angularly) to reproduce the curvatures of the object to be measured. During numerical calculation, these slices can be again coaxially aligned and combined to allow a judgment to be made on the total travel deviation. This is preferably carried out without any particularly disturbing effect from any deformation of the object to be measured.

The above-described embodiment of the method makes it possible to detect and determine the resulting total displacement deviation, taking into account the actual configuration of the measurement object in the current threaded section in each case. The alignment and combination of the coordinate criteria results in an accurate indicator of the total displacement deviation, without any sagging of the measurement object having an adverse effect.

Illustratively speaking, this approach can be compared with the determination of the total length of the chain, in which individual chain links are arranged in a configuration of curves that are considered individually using the corresponding coordinate reference. In order to be able to combine the corresponding length deviations, the chain is conceptually pulled in a straight line, and therefore the coordinate references themselves align the coordinate references themselves axially in a corresponding way.

That is, the local component axis is used to form and orient the coordinate reference for each of the threaded sections. This has the advantage that when a corresponding coaxial alignment between the various local component axes takes place, possible deviations of movement in the longitudinal direction parallel to the longitudinal axis of the measurement object can be added together as a whole.

Overall, this allows a low erroneous determination of the total travel deviation, which represents a significant parameter for the accuracy of a threaded or threaded screw drive.

In one embodiment example of the method, the total movement deviation is determined by combining the partial movement deviations. This preferably occurs independently or substantially independent of the curvature of the object to be measured. In this way, the total travel deviation can be determined independent of any sagging that may exist.

Therefore, the total movement deviation can be determined with high accuracy regardless of the actual orientation of the measurement object.

According to another embodiment example of the method, each of the local coordinate reference in the threaded sections is in such a way that the longitudinal coordinate axis is aligned with the actual longitudinal axis of the respective threaded sections and preferably coincides with the actual longitudinal axis of the respective threaded sections. Are sorted in case. It is obvious that, at least when the coordinate axis is straight in an ideal way, the alignment can include a tangent orientation or other approximation.

It is obvious that the method is not exclusively limited to external threads. The method may be used in a similar manner for internal threads, for example corresponding nuts.

According to another embodiment example of the method, the longitudinal coordinate axes of the local coordinate references are oriented or aligned linearly (conceptually or computationally) to determine the total travel deviation. The partial movement deviations can then simply be added together.

According to another embodiment of the method, the threaded sections comprise at least one turn, preferably a plurality of turns, for which the partial movement deviation is determined. It is obvious that integer multiples or fractional values may be included thereby. However, the number of turns in at least one threaded segment is to be less than the total number of turns in the operating range of the thread.

Thus, the threaded section can extend over the corresponding circumferential/rotational angle along a n*2*π radian (pi radian) orbit, and n can be an integer or non-integer. Thus, n can assume values between 1 and 10 depending on the total range of the spindle, for example. You can think of higher values. For example, n may be 4.5, so in this example example, 4.5 turns (corresponding to a rotation angle of 1620° (degrees)) can be considered in the corresponding compartment.

Taking into account the perception of the setpoint pitch or setpoint travel height, the setpoint movement for a defined rotation can now be determined. By measurement, the actual movement is obtained for comparison with the setpoint movement. In terms of absolute value, the shift deviations correspond to the difference between the setpoint shift and the actual shift.

According to another embodiment of the method, the resulting partial movement deviations for the individual measurement segments are determined taking into account the rotation of the virtual gauge nut of the ideal configuration relative to the measurement object. Typically, such gauge nuts contain several turns. In the case of gauge-based measurements, the configuration of the gauge nut correspondingly also has an influence on the determination of the determined position of the gauge nut in the longitudinal direction and thus the deviation of each partial movement.

Thus, on the one hand, the gauge nut can have a flattening effect and correct the instantaneous movement deviation (eg within one turn). However, in principle, since the gauge nut itself may suffer an error, additional errors that are not directly or not due to the configuration of the thread can be input as a result.

In obtaining the numerical values of the determined spatial points describing the configuration of the thread, the corresponding measuring system then calculates the resulting travel distances, and movement variations or movement deviations based on the thread configuration and thread range. It can be based on an ideal configuration gauge nut.

According to another embodiment of the method, adjacent threaded sections at least partially overlap. In this way, a “sliding” measurement is possible, so to speak. Overall, it is thus possible to determine the total travel deviation with much greater accuracy.

According to another embodiment example of the method, at least some of the threaded sections have different lengths. Thereby, on the one hand, it is possible to take into account the fact that different sections of the thread have different curvatures. On the other hand, it is thereby possible to meet range dependent accuracy requirements. Moreover, thread sections of different lengths that at least partially overlap may be used to verify the result.

For example, a thread for a ball screw spindle can be divided into a thread inlet, a thread outlet, and a useful length between the thread inlet and the thread outlet.

According to another embodiment of the method, the object to be measured is rotated periodically or continuously during the measurement. This simplifies and accelerates the measurement, as less complex movements are required on the part of the measurement probe provided with at least one probe to search the thread contour when the measurement object itself is rotated.

Moreover, the movement of the measurement object simplifies the determination of specific positional tolerances or shape tolerances such as accuracy of operation, concentricity, roundness, cylindrical shape, and the like. This also applies to the detection of a thread groove or a specific groove shape of a thread with respect to the cross section of the thread end. Moreover, in this way, it is possible to minimize the cost involved in constructing the measuring probe itself.

According to another embodiment of the method, the object to be measured is mounted on a rotating table. The swivel table accommodates, for example, a chuck or some other mounting suitable for holding the object to be measured.

In principle, the object to be measured can be arranged to have a vertically oriented longitudinal range/long axis. Thus, the object to be measured may be erected on a rotating table or can be suspended from a rotating table mounted thereon.

However, this does not preclude arranging the measurement object with a horizontally oriented longitudinal range/longitudinal axis. However, in this case, a pronounced sagging/curvature would inevitably be expected.

According to another embodiment example of the method, the search is performed using a coordinate measuring machine. The search can be carried out by tactile or optical means. Generally speaking, contact probes and proximity probes are known. The probes are arranged on the measuring head, which is usually movable with respect to the frame of the coordinate measuring machine.

According to another embodiment example of the method, the measurement may also be: a diameter value, a position tolerance, a shape tolerance, a surface property and at least one additional property value selected from the group comprising groove contour shape data. Includes that.

According to another aspect, the present invention is as follows:

-A receptacle for accommodating a measurement object equipped with a thread,

-At least one measuring head accommodating a measuring probe,

-A drive unit that moves the measuring probe on at least two spatial axes, and

-Has a control device coupled to the measuring head and the drive,

The control device relates to a measuring system, in particular a coordinate measuring machine, which makes it possible for the measuring system to carry out a method according to one of the embodiments described herein.

It communicates with, for example, a drive and a measuring head or a measuring probe mounted on the measuring head to output control commands for the movement of the measuring probe and to receive signals from the measuring probe indicative of contact with the measuring object. It generally includes a control device to perform.

Moreover, the control device can be designed to process and quantify the spatial coordinates that are determined to enable the total travel deviation of the thread to be determined according to the method.

It is obvious that partial tasks or partial aspects of control/numerical finding can be performed by spatially decoupled controls, for example by separate computers that are at least temporarily coupled to the measurement system to exchange data. .

Thus, the measurement system may be equipped with an interface for exchanging data and exchanging control commands.

According to one embodiment of the measurement system, the system further has a rotating table on which a receptacle for the measurement object is mounted, and the control device is designed to generate a combined movement of the measurement head and the measurement object to measure the thread.

The combined movement may include at least temporarily time-parallel movement of the measurement head and the measurement object. However, it is also conceivable to move the measuring object and the measuring head without direct time overlap.

According to another aspect, the present invention relates to the use of a measurement system according to one of the exemplary embodiments described herein to perform a method for measuring a thread according to one of the exemplary embodiments described herein.

Finally, the invention further relates to a measuring system according to one of the exemplary embodiments described herein, in particular a coordinate measuring machine, when the computer program is executed on the control device of the measuring system, the threaded thread according to one of the exemplary embodiments described herein. It relates to a computer program having program code that makes it possible to carry out a method for measurement.

It goes without saying that the above-mentioned features of the present invention and the features to be described below can be used not only in the combinations specified in each case, but also in other combinations or as features themselves within the scope not departing from the scope of the present invention. .

Further features and advantages of the present invention will become apparent from the following description of a plurality of preferred embodiment examples with reference to the drawings. In the drawings:
1 shows a perspective view of an embodiment of a measuring system in the form of a coordinate measuring machine.
2 shows a partially cut away partial view of a perspective view of a ball screw drive with a ball screw spindle and a ball screw nut.
3 shows a perspective view of a rod equipped with ball screws for use in a vehicle steering system.
4 shows a partial view of a threaded rod.
5 shows another view of the threaded rod according to FIG. 4 in a bent state.
6 shows a simplified block diagram illustrating an embodiment of a method of measuring a thread on a measurement object, in particular determining the total travel deviation.

1 shows a measurement system comprising a measurement device 10 and a data processing device 42 that controls the measurement device 10. The measurement system is indicated by 66 overall.

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

A measurement table 12 having a receptacle 14 on which a measurement object 52 to be measured is arranged serves as a base of the measurement device 10. In the exemplary embodiment example shown in FIG. 1, a receptacle 14 is arranged on a rotating table 16. The rotating table 16 enables controlled rotation of the receptacle 14 with the measurement object 52.

The portal 18 is mounted on the measuring table 12 and can be moved in a controlled manner relative to the measuring table 12. A slide 20 is mounted on the portal 18 which can eventually be moved in a controlled manner relative to the portal. Consequently, the slide 20 serves as a mount and guide for the sleeve 22 that is mounted therein and can be moved in a controlled manner relative to the slide 20. As an example, a measuring head 24 with a probe shaft 26 and a measuring probe 28 in FIG. 1 at the end of the measuring head 24 is arranged at the measuring table end of the sleeve 22.

Thus, the three sub-assemblies movable with respect to each other and with respect to the measuring table 12, namely the portal 18, the slide 20 and the sleeve 22, have three spatial axes 30a, 30b, 30c. It enables the movement of the measuring head 24 with the measuring probe 28 accordingly. In order to determine the position of the measuring probe 28 and thus the position of the searched entities on the object 52 to be measured, the measuring device is operated with respect to each of the three spatial axes 30a, 30b, 30c. It has standards denoted as 32a, 32b, 32c from which the actual location can be determined.

In addition, the measuring device allows the measuring head 24 or at least the probe shaft 26 with the measuring probe 28 to be rotated or axially rotated about at least one of the spatial axes 30a, 30b, 30c. It can also have "rotation-axis rotation functionality". The obtained degrees of freedom of rotation are shown in Fig. 1 as 34a, 34b, and 34c. The rotating table 16 also enables rotation about the spatial axis 30c and thus provides a degree of rotational freedom similar to 34b.

For simplicity, the measuring device 10 can be compared to a CNC machining center, which may have, for example, "3-axis functionality" or, alternatively, 5-axis functionality.

In principle, the control of the measuring device 10 can be carried out in a simple way in this case by means of a direction controller 38 and a control element 36 with a switch element 40. In this case, the direction controller 38 can be designed as a control lever or a joystick, for example. It is also possible for a plurality of direction controllers 38 to be provided for control in several spatial directions and, optionally, to axially or rotate the measuring head 24 about various spatial axes. Furthermore, a switch element 40 is provided on the control element 36 from which a signal can be generated which enables the measurement of the explored geometric element.

Except for manual or partially automated control via the control element 36, the measuring device 10 is also designed to be controlled by the data processing device 42, the data processing device 42 being the measuring device 10. It forms part of the (all) control device 60. 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 combined data processing device 42, the control device 60 may further have assemblies and components incorporated into the measurement device 10.

The data processing device 42 has input elements 46a, 46b, for example a display 44 for outputting information such as a keyboard, keypad, mouse, touch screen, trackball, 3-D input element, and the like. In principle, therefore, the operator can receive output information and write inputs and commands.

In addition, 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 be implemented as a processor unit, for example, and may be designed to perform program commands. The storage module 50 may serve as a database or, alternatively, may be connectable to a central database, for example a central product data management system.

Furthermore, the data processing device 42 can cause the measurement device 10 to control, i.e., cause the rotation of the rotating table 16 and movement of the portal 18, the slide 20 and the sleeve 22. Is designed to be. Conversely, the data processing device 42 can receive and process the position values detected by the measurement device 10. If present, elements 16, 18, 20, 22 are coupled to the drive.

The measurement object 52 has threads in at least some sections or sections. In particular, the thread is a “ball screw”.

2 uses a partially cut-away illustration of a perspective view to show an exemplary embodiment of a ball screw drive 70 comprising a screw spindle 72 and a nut 74. Rolling elements in the form of balls 76 are arranged between the screw spindle 72 and the nut 74. Rolling elements 76 ensure friction-optimized relative movement between nut 74 and screw spindle 72. The relative movement includes a relative rotation about the longitudinal axis of the ball screw drive 70 and a relative translational movement along the longitudinal axis of the ball screw drive 70.

3 uses an example of a perspective view to show a shaft component 80 that can be used, for example, in a steering system for a vehicle. The shaft component 80 may also be referred to as a steering rod. The shaft component 80 includes a ball screw section 82 and a rack section 84. For example, the steering column can be actuated by teeth on the shaft component 80 through the rack section 84. Through the ball screw section 82, a servo steering system can be operated, for example on a shaft component, to facilitate steering commands.

The embodiments illustrated by way of example with reference to FIGS. 2 and 3 represent a number of further conceivable embodiments of spindles or shaft components provided with threaded sections, in particular ball screw sections.

4 and 5 show a measurement object 100 configured as a screw spindle. 4 shows an ideal state of the measurement object 100. 5 shows a partially deformed (bent) state of the measurement object 100. It is obvious that the example of the transformation in FIG. 5 is exaggerated for clarity.

The measurement object 100 has a thread 102 configured as a ball screw. The vertical axis of the measurement object 100 is denoted by 104. In the example according to FIG. 5, the measurement object 100 is deformed in at least some compartments or compartments, in particular due to sagging. Thus, the longitudinal axis 104 is bent in the area of the thread 102.

As already mentioned above, it is advantageous to divide the thread 102 into segments 110, 112, 114 to determine the total displacement deviation, preferably regardless of a given strain/curvature.

For this purpose, it is proposed to define a coordinate reference or coordinate system for each of the partitions 110, 112, 114. In this case, the vertical axes 130, 132, 134 of each coordinate reference (120, 122, 124) or each coordinate reference (120, 122, 124) are the vertical axes in each division (110, 112, 114) (104) will be aligned with the actual course in each case. The thread 102 can now be searched in sections to determine the partial movement deviation, and a given curvature of the axis 104 is taken into account at least in part in each section 110, 112, 114. This has the advantage that the curvature of the axis 104 does not cause a random change in each movement along the thread 102.

To detect the total travel deviation, the partial movement deviations for the segments 110, 112, 114 are added together, resulting in an overall more accurate measurement that better corresponds to the actual conditions.

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

Moreover, it is conceivable to vary the lengths of the sections 110, 112, 114 to account for the various sections of the thread 102 in an appropriate manner. Each of the sections 110, 112, 114 preferably comprises two or more turns of the thread 102. Based on the pitch given in this way, the resulting movement can be determined according to the current angle of rotation. The comparison between the actual values and the setpoint values then gives the respective movement deviation.

In Fig. 5, the "virtual" nut is denoted as 140. This is an aid for calculating the numerical value of the data obtained during the measurement of the sections 110, 112, 114. The basis for this approach is that “gauge nuts” are commonly used to determine displacement deviations, particularly resulting from threads 102. These gauge nuts often span several turns, and therefore the resulting movement deviation is "averaged" over, say, several turns.

It is now proposed to simulate the use of gauge nuts of this type, which is advantageous in that gauge nuts of an ideal configuration can be taken as a basis for quantifying the measurement results. So, for the sake of numerical purposes, the block represented by 140 is associated with the thread groove present there and, if present, the ideal dimensions for any rolling element, resulting in any errors that may be associated with the actual gauge nuts. Nor can it have an effect on the determined movement deviations.

Another advantage of dividing the thread 102 into segments 110, 112, 114 is that the “simulated” gauge nut 140, so to speak, reduces the curvature of the longitudinal axis 104 in each segment 110, 112, 114. Is to follow. This further increases the accuracy of detection of movement deviation.

The path of the thread 102 or the thread groove 106 forming the thread 102 is searched continuously or intermittently to determine the actual movement obtained along the thread 102 during rotation of the spindle type measurement object 100 . This allows the use of a measuring system configured as a coordinate measuring machine or using a coordinate measuring machine. Depending on the configuration of the coordinate measuring machine, additional dimensions, parameters, shape deviations, configuration deviations, and the like may be determined.

Overall, it is therefore possible to avoid a separate measurement operation for the resulting movement deviation, which is difficult due to the use of gauge nuts.

Dividing the thread 102 into two or more segments 110, 112, 114 following the actual curvature of the measurement object 100 increases the accuracy of the measurement.

Referring to Fig. 6, an exemplary embodiment of a method of measuring a thread of a measurement object is illustrated by a block diagram.

The method includes a step S10 comprising providing a measurement system using a coordinate measuring machine. It is thus possible to search the measurement object to detect corresponding spatial coordinates that reflect the contour of the measurement object.

This is followed by a step (S12) comprising mounting the measurement object on a rotating table in the coordinate measuring machine. The object of measurement is in particular a shaft component or spindle provided with a threaded section. The measurement object is mounted or clamped in such a way that the rotating table rotates the measurement object in a limited manner around the longitudinal axis of the measurement object.

In a subsequent step S14, a multiple or continuous search of the thread path of the first thread section is performed to determine the moving characteristic of the thread (equivalent to pitch times turning). Moreover, this involves determining the shift deviation from the setpoint shift. Step S16 involves a similar or the same type of measuring operation in the further threaded section. The measurements for each division in steps S14 and S16 are based on a coordinate reference (coordinate system) that follows the actual curvature of the measurement object, respectively. This increases the accuracy of the measurement, especially in the case of sagging of the measurement object.

The measurement in steps S14 and S16 preferably takes place in such a way that a plurality of turns of the thread are detected in each case. Steps S14 and S16 are typical examples in which two or more divisions are measured in succession.

The measuring steps S14 and S16 are followed by a numerical calculation step S18. In the numerical obtaining step S18, the coordinates determined in the steps S14 and S16 are obtained in order to determine the total travel deviation for the thread. This occurs taking into account the local coordinate reference of each section. This increases the overall accuracy of the determination of the total travel deviation.

Furthermore, according to exemplary embodiments, step S18 involves considering a “virtual” gauge nut that is configured to have ideal dimensions. Such a nut may have a longitudinal range that includes several turns of the thread. This may, for example, cause leveling or averaging of configuration deviations detected from turn to turn. Since the numerical calculation in step S18 takes place mainly by calculation, it is at least possible to ensure that the entire thread is one of the ideal fabrications and is "virtually" turned through various sections by the same gauge nut.

This at least precludes the input of any defects in the “real” gauge nut into the detected total travel deviation.

In the step S20 that follows this, the measurement result is output or transmitted. On this basis, it is possible to determine the dimensional accuracy and quality of the thread. The determined data can be further processed. Based on the determined data, it is possible to determine whether the checked thread or the spindle equipped with the checked thread meets the required conditions or desired quality grading.

Claims (15)

As a method for gaugeless measurement of the thread 102 on the measurement object 52, 100:
-Detecting a partial displacement deviation in the first thread section 110 comprising repeated or continuous search of the thread groove 106;
-Detecting a partial displacement deviation in at least one second thread segment (112, 114) comprising repeated or continuous search of the thread groove (106); And
-Determining a total movement deviation based on the detected partial movement deviations,
The partial movement deviation in the threaded sections 110, 112, 114 is detected in each case with respect to the local coordinate reference 120, 122, 124 in the measurement object 52, 100,
The local coordinate reference (120, 122, 124) is moved between the threaded sections (110, 112, 114) in the measurement object (52, 100),
The total movement deviation is determined by combining the partial movement deviations irrespective of the curvature of the measurement object (52, 100),
The method, wherein the threaded sections (110, 112, 114) comprise at least one turn in which the partial movement deviation is determined. delete The method of claim 1,
Each of the local coordinates (120, 122, 124) in the threaded sections (110, 112, 114) is such that the longitudinal coordinate axis is aligned with the actual longitudinal axis of each of the threaded sections (110, 112, 114). Ordered, how. The method of claim 3,
The method, wherein the longitudinal coordinate axes (130, 132, 134) of the local coordinate references (120, 122, 124) are linearly oriented or aligned to determine the total travel deviation. delete The method of claim 1,
The method, wherein the partial movement deviations for the individual thread sections 110, 112, 114 are determined taking into account the rotation of the virtual gauge nut 140 of the ideal configuration relative to the measurement object 52, 100. The method of claim 1,
The adjacent threaded sections (110, 112, 114) at least partially overlapping. The method of claim 1,
At least some of the threaded sections (110, 112, 114) having different lengths. The method of claim 1,
The measurement object (52, 100) is rotated periodically or continuously during measurement, and the measurement object (52, 100) is mounted on a rotating table (16). The method of claim 1,
The method, wherein the search is carried out using a coordinate measuring machine (10). The method of claim 1,
The measurement also comprises determining at least one additional characteristic value selected from the group comprising the following: diameter value, position tolerance, shape tolerance, surface characteristic and groove contour shape data. As a measuring system:
-A receptacle 14 for accommodating the measurement objects 52 and 100 on which the thread 102 is provided;
-At least one measuring head 24 receiving a measuring probe 28;
-A driving unit that moves the measuring probe 28 on at least two spatial axes; And
-Having a control device 60 coupled to the measuring head 24 and the drive,
The measuring system (60) makes it possible for the measuring system to carry out the method according to claim 1. The method of claim 12,
It further has a rotating table 16 on which the receptacle 14 for the measurement object 52, 100 is mounted, and the control device 60 includes the measuring head 24 and the measuring head 24 for measuring the thread 102. A measurement system, designed to produce a combined motion of the measurement object 52, 100. A computer program stored on a medium having program code that makes it possible for the measuring system according to claim 12 to perform the method according to claim 1 when the computer program stored on the medium is executed on the control device (60) of the measuring system. delete

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