DE102015206613A1 - Optical deformation measurement of bearings - Google Patents

Abstract

Method for the optical determination of a deformation state of a bearing element (2), the method comprising at least the following steps: a) applying (I) at least one optically detectable marking (4) on a surface of the bearing element (2); b) optical detection (II) of the applied marking (4) before a load of the bearing element (2); c) loading (III) of the bearing element (2); d) second optical detection (IV) of the applied marking (4) after the load of the bearing element (2); and e) evaluating (V) a change in the optical marking (4) due to the load in order to determine the state of deformation of the bearing element (2).

Description

The present invention relates to a method for determining a deformation state of a bearing element according to the preamble of claim 1 and to a measuring device for carrying out the method and a bearing element.

To determine local deformation states of bearing elements, strain gauges (DMS) are known in the prior art, which are applied to a location at which a deformation is to be measured. With the help of a DMS uniaxial deformations can be measured. By combining several strain gages, two-axis deformation states can also be measured.

A disadvantage of the use of the DMS, however, is that the point at which a DMS is to be applied, must be pretreated in order not to interfere with the functioning of the DMS. For example, this site must be degreased, roughened and sanded, marked, conditioned and neutralized with a solvent. The pretreatment, however, already alters the system to be measured so that deformations on untreated bearing elements can not necessarily be concluded from the measured deformations. Furthermore, it is disadvantageous that a DMS is usually glued to the point to be measured, so that the measurement of the deformation takes place via an intermediate material, which also deviations in the measurement results can occur. Alternatively, a DMS can also be applied to the site to be measured via a frictional connection. However, this can lead to slippage of the DMS and thus to a falsification of the measurement results.

From the prior art, for example from the DE 10 2008 061 553 A1 , Furthermore, the use of glass fiber sections for measuring the deformation of a bearing ring is known.

A disadvantage of this method, however, is that this method requires a high expenditure on equipment and thus high costs. In addition, the bearing ring is structurally changed by the insertion of the glass fiber, which has a great influence on the deformation.

Object of the present invention is therefore to provide a method for determining the real stress of bearing elements, with the reliable statements regarding life and / or performance of the bearing element are possible, the method is simultaneously inexpensive and easy to handle.

This object is achieved by a method for the optical determination of a deformation state of a bearing element according to claim 1 and by a measuring device according to claim 7 and by a bearing element according to claim 10. Further advantages and advantageous embodiments are specified in the subclaims.

According to the invention, a method for the optical determination of a deformation state of a bearing element is presented, the method having at least the following steps: a) applying at least one optically detectable marking on a surface of the bearing element; b) optically detecting the applied mark before a load of the bearing element; c) loading the bearing element; d) second optical detection of the optical marking after the load of the bearing element; and e) assessing a change in the optical marking due to the load in order to determine the deformation state of the bearing element. The assessment can be done, for example, by merely looking at the loaded bearing element. Preferably, however, a result is generated before and after the loading of the bearing element, which can be compared with each other.

Using the presented method, it is possible to determine the deformation state of a bearing element exactly. Since the presented method is a non-contact measurement, measurement errors due to intermediate elements, as they occur, for example, when using stretch marks, can be avoided.

At the same time, the method enables the immediate visualization of the deformation measurement and the evaluation, so that reliable statements with regard to the use behavior and / or the service life of the bearing elements are possible. A long pretreatment of the point to be measured can be dispensed with by the method presented, so that the method is simultaneously inexpensive and easy to apply.

Before the start of the process, a position for the deformation measurement on the surface of the bearing element can be selected, which is predefined either during manufacture of the bearing element or defined by the application of the optical marking. Alternatively, the position can also be chosen freely, as long as it is optically measurable.

According to a further advantageous embodiment, the optically detectable marking comprises a measurement pattern. In this case, the measurement pattern may have a random structure, the for example, consists of any geometric elements. Advantageously, the random structure can be applied at any time to the point to be measured, so that it is possible to measure the deformation state of any bearing element, that is, for example, also of bearing elements already in operation. Alternatively or additionally, the measurement pattern has a predefined shape, which, for example, is applied to the position to be measured with the aid of a laser. By using a predefined measuring pattern, preferably a uniform measuring quality and a calibration of a measuring device can be achieved, whereby the quality of the measurement can be increased. Furthermore, a predefined measurement pattern allows, for example, a structure and implementation of a uniform "deformation database", so that statements about the degree and the cause of the deformation of the bearing element are possible.

Another advantage of using a measurement pattern is, for example, that the measurement is on a surface rather than just at one point. As a result, 2- or 3-dimensional deformation states of a bearing element can be determined.

In a further advantageous embodiment, the application of the at least one optically detectable marking on the surface of the bearing element during manufacture of the bearing element takes place. By integrating the marking into the manufacturing process, working hours and costs can be reduced. Alternatively or additionally, the at least one optically detectable marking can also be applied to the surface of the bearing element after production of the bearing element. This can be done for example by a Lackierverfahren or the like. Thus, a deformation of any bearing element can be determined at any time.

According to a further advantageous embodiment, the application of the at least one optically detectable marking on the surface of the bearing element by means of color coding, in particular by painting and / or gluing and / or stamping takes place. Alternatively or additionally, the application of the optically detectable marking takes place by forming a depression, in particular by scoring. Furthermore, it is alternatively or additionally possible to apply the optical marking to the point to be measured by forming an increase, in particular by welding on material. Of course, other methods known from the prior art for applying a marking to a surface are possible.

According to an advantageous embodiment, the optical detection of the applied mark is carried out continuously. As a result, preferably the deformation of the bearing element can be continuously documented over time, so that the deformation can be determined in real time and statements about the behavior of the bearing element during operation are possible. Alternatively, the optical detection of the applied marking takes place discontinuously. Thus, for example, the initial state before the loading and the final state after the loading of the bearing element can be detected optically, wherein a first and a second result is generated. The two states or the two results can then be compared with one another, the results preferably being quantified. Thus, knowledge about the degree of deformation can be gained. Of course, further measurements during the loading can be carried out, which provide further discontinuous measurement results.

The loading of the bearing element may, for example, be the radial and / or tangential expansions of the bearing elements that arise on a shaft during assembly of the bearing element. Also, the bearing element can be charged during operation of the bearing, while inter alia, also act on the bearing loads that are not known exactly in advance. Only by knowing these stresses of the bearing elements statements can be made regarding the life and / or the operational behavior of the bearing.

According to a further advantageous embodiment, the optical detection of the applied mark is carried out with a camera. As a result, for example, a 2-dimensional deformation measurement can be performed. Advantageously, the measurement and evaluation can be done in real time. Alternatively, the optical detection of the applied mark can be done with two cameras, whereby a deformation measurement in the three spatial directions can be performed. For a 3-dimensional measurement, the two cameras can preferably be arranged next to each other, with their lenses being aligned with the position to be measured, so that stereoscopic images are possible.

The at least one camera is advantageously connected to a computer-aided evaluation unit, which at least stores and evaluates the images of the camera. Possibilities of computer-aided evaluation of images are known from the prior art. Advantageously, the evaluation unit determines from the differences of the individual images the position and shape change of the measuring pattern at the measuring point and the deformation state over time. For predefined measurement patterns, for example, the effect of Interference of overlapping line patterns are used (moiré pattern). In addition, the evaluation unit can be designed such that it automatically compares the measured deformation state with, for example, a deformation state calculated using the finite element method (FEM) and indicates deviations.

Preferably, the at least one camera is connected to the evaluation unit via radio or a similar wireless connection. However, it is also possible to connect the camera via a line, for example via a cable to the evaluation unit.

Another aspect of the invention relates to a measuring device which is applicable for the optical determination of a deformation state of a bearing element with a method described above. In this case, the measuring device on a support which is rotatably on the bearing element can be arranged. This makes it possible to measure the deformation state of the bearing element directly on site in real time and also during operation of the bearing. Thus, statements about the operational behavior of the bearing element and its life are possible. The non-rotatable embodiment of the carrier can be generated for example by a screw or magnetically. In general, however, a temporary gluing or the like is conceivable. Furthermore, the carrier allows a non-contact measurement, so that act on the point to be measured no other influences that could falsify the measurement results.

According to a further advantageous embodiment, the carrier is designed adjustable in size. For this purpose, positioning aids and / or suction buttons and / or magnets and / or screw connections are preferably arranged on the carrier and / or on the bearing element, which enable a universal use of the carrier on bearing elements of different sizes. Advantageously, the carrier is formed telescopically and so adjustable in its axial length and / or in its radial width to the respective size of the bearing element to be measured. As a result, advantageously, the deformation measurement of different bearing elements can be performed with the same measuring device, which in turn can save costs.

In a further advantageous embodiment, the measuring device has a camera holder for at least one camera at a fixed position. Thus, the camera already described above can be fixedly connected to the measuring device.

Another aspect of the present invention relates to a bearing element whose deformation state can be measured by the method described above. In this case, the bearing element positioning aids for a measuring device for optically determining the deformation state of the bearing element, wherein the measuring device may preferably be formed as described above. The bearing element to be examined may be any bearing element of a rolling, sliding or linear bearing or else rotary connecting elements in general. Advantageously, the bearing element has an externally accessible point, to which the optical marking can be applied.

In the following, the invention will be described in more detail with reference to embodiments illustrated in the drawings. The drawings are purely exemplary in nature and are not intended to determine the scope of the application. This is defined solely by the appended claims.

Show it:

1 a flow chart of the steps of a preferred embodiment of the method according to the invention;

2 a schematic conceptual representation of a measuring device of a preferred embodiment;

3 a schematic conceptual representation of a measuring device of a further preferred embodiment;

4 a schematic conceptual representation of a measuring device of a further preferred embodiment;

5 : an illustration of an evaluation method of a preferred embodiment; and

6 : an illustration of a featured marker.

In the following, the same or functionally equivalent elements are identified with the same reference numerals.

1 shows a flowchart of a preferred embodiment of a method for optically determining a deformation state of a bearing element, in which in a first step I, an optically detectable mark is applied to a surface of the bearing element. The optically detectable mark may be one in the 6A and 6C act exemplified measurement pattern, which consists of any geometric elements random structure has, which is applied for example by means of a spray can on the bearing element. Alternatively or additionally, the measurement pattern, as in 6B shown, have a predefined structure, which is applied for example by means of a laser on the surface of the bearing element. In this case, the location on which the measurement pattern is arranged can additionally be marked, which is advantageous in particular for measurement patterns that are not recognizable to the naked eye ( 6A ).

In a second step II, the applied marking is optically detected before the load of the bearing element, wherein a first result is generated, which serves as an initial state or reference.

Subsequently, the bearing element is loaded in a third step III. The load may be, for example, the radial and / or tangential expansions of the bearing element that arise on a shaft during assembly of the bearing element. Of course, loads also occur during operation of the bearing element, where, for example, also loads acting on the bearing, which are not known in advance, and which can be determined with the aid of the presented method. Of course, the bearing element may also be loaded with other methods known in the art which cause deformation.

In a further step IV, as in 1 shown at least a second optical detection of the applied mark after the load of the bearing element, wherein a second result is generated.

On the basis of the optical measurement obtained, in a method step V, a change in the optical marking resulting from the load is assessed in order to determine the deformation state of the bearing element, wherein a computer-aided evaluation unit is used. For example, as in 5 represented, in each case an image of an undeformed initial state ( 5A ) and a deformed state ( 5B ) of a measurement pattern with the aid of the at least one camera. By superimposing these two states can, as in 5C shown, the deformation of the measuring pattern, in particular its translation, rotation and / or distortion, are determined so that knowledge of the deformation state during and / or after the load of the bearing element can be obtained. The evaluation unit determines from the differences of the individual images the change in position and shape of the measuring pattern at the measuring point and the deformation state over time. With predefined measurement patterns, for example, the effect of the interference of overlapping line patterns can also be used (moiré pattern). In addition, the evaluation unit can be designed such that it automatically compares the measured deformation state with, for example, a deformation state calculated using the finite element method (FEM) and indicates deviations.

The 2 to 4 show different embodiments of a measuring device 1 with which the method described above is executable. The show 2 to 4 one bearing outer ring each 2 with a measuring device arranged thereon 1 , which is designed to be one on the bearing outer ring 2 applied mark 4 to eat. For this purpose, the measuring device 1 a carrier 6 on, on which a camera 8th by means of a camera mount 10 is fastened, the carrier 6 such on the bearing outer ring 2 is positioned that the camera 8th the applied optical marking 4 can capture.

It can on the thighs 6-1 . 6-2 of the carrier 6 Positioning aids (not shown), for example be mounted in the form of feet, a fixed attachment of the carrier 6 to the bearing outer ring 2 enable. The carrier 6 can, as in the 2 and 3 , shown with its the bearing outer ring 2 touching surfaces 6a . 6b the surface contour 2a . 2 B of the bearing outer ring 2 consequences. To the carrier 6 rotatably with the bearing outer ring 2 can form, for example, a screw and / or a bond and / or magnets and / or suction cups and / or similar use can be found.

Alternatively to the carrier 6 attached positioning can also the bearing outer ring 2 , as in 4 shown positioning aids, in particular fastening means in the form of at least one recess 12 and / or at least one projection 14 have, for a fixed position of the carrier 6 at the bearing outer ring 2 to care. It is of course also possible, only recesses 12 or merely protrusions 14 for fixing the carrier 6 at the bearing outer ring 2 train.

Furthermore, instead of a camera 8th as in the 2 and 4 shown to be used in a stereoscopic camera arrangement, wherein, like 3 shows, two cameras 8a . 8b on the carrier 6 are attached.

The camera / s 6 itself is / are in turn with an evaluation unit 16 connected, wherein a transmission is wired by means of a cable 22 (please refer 2 ) or via radio (see 3 ) he follows. For radio transmissions, the cameras have 8a . 8b at least one transmitter 18a . 18b on, while the evaluation unit 16 a receiver 20 includes.

Instead of the bearing outer ring exemplified in the figures 2 The bearing element to be examined may be any bearing element of a rolling, sliding or linear bearing or rotary connecting elements in general. Advantageously, the bearing element has an externally accessible point, to which the optical marking can be applied.

According to the invention, a method for the optical determination of a deformation state of a bearing element is provided, which can be used to determine the real stress of the bearing element during and / or after a stress, and can be gained with the knowledge of the life and / or on the use behavior of the bearing element , This is achieved in that on a surface of the bearing element, an optically detectable mark is applied, which is optically detected before and after a load of the bearing element. Subsequently, the resulting change in the optical marking is assessed, so that conclusions about the stress of the bearing element are possible. An advantage of the presented method is, for example, that it is a non-contact measuring method for determining the deformation state of a bearing element, so that measurement errors, for example due to intermediate elements, can be avoided.

LIST OF REFERENCE NUMBERS

1

 measuring device

2

 Bearing outer ring

2a, 2b

Contact surface of the bearing outer ring

4 o

digital detectable mark

6

 carrier

6-1, 6-2

Leg of the wearer

6a, 6b

Contact surface of the carrier

8, 8a, 8b

camera

10

Retaining element for camera

12

recess

14

head Start

16

evaluation

18a, 18b

transmitter

20

receiver

22

electric wire

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008061553 A1 [0004]

Claims (10)

Optical deformation measurement of bearings Method for the optical determination of a deformation state of a bearing element ( 2 ), characterized in that the method has at least the following steps: a) applying (I) at least one optically detectable marking ( 4 ) on a surface of the bearing element ( 2 ); b) optical detection (II) of the applied marking (II) 4 ) before a load of the bearing element ( 2 ); c) loading (III) of the bearing element ( 2 ); d) second optical detection (IV) of the applied mark ( 4 ) after the load of the bearing element ( 2 ); and e) evaluating (V) a change in the optical marking due to the load ( 4 ) for determining the deformation state of the bearing element ( 2 ). Method according to claim 1, characterized in that the at least one optically detectable marking ( 4 ) comprises a measurement pattern, the measurement pattern having a random structure and / or a predefined structure. Method according to one of claims 1 or 2, characterized in that the application of (I) the at least one optically detectable marker ( 4 ) on the surface of the bearing element ( 2 ) during production and / or after production of the bearing element ( 2 ) he follows. Method according to one of the preceding claims, characterized in that the application (I) of the at least one optically detectable marking ( 4 ) on the surface of the bearing element ( 2 ) by means of color coding, in particular by painting and / or gluing and / or stamping, and / or by forming a recess, in particular notching, and / or by forming an increase, in particular welding, takes place. Method according to one of the preceding claims, characterized in that the optical detection (II, IV) of the applied marking (FIG. 4 ) takes place continuously or discontinuously. Method according to one of the preceding claims, characterized in that the optical detection (II, IV) of the applied marking (FIG. 4 ) with a camera ( 8th ) or with two cameras ( 8a ; 8b ) he follows. Measuring device ( 1 ), wherein the measuring device ( 1 ) for the optical determination of a deformation state of a bearing element ( 2 ) is applicable with a method according to one of claims 1 to 6, characterized in that the measuring device ( 1 ) a carrier ( 6 ), which non-rotatably on the bearing element ( 2 ) can be arranged. Measuring device ( 1 ) according to claim 7, characterized in that the carrier ( 6 ) is adjustable in size, preferably positioning and / or suction cups and / or magnets and / or screw connections are arranged. Measuring device ( 1 ) according to one of claims 7 or 8, characterized in that the measuring device ( 1 ) a camera mount ( 10 ) for at least one camera ( 8th ) at a fixed position. Bearing element ( 2 ) whose deformation state can be measured by means of a method according to one of claims 1 to 6, characterized in that the bearing element ( 2 ) Positioning aids ( 12 ; 14 ) for a measuring device ( 1 ) for the optical determination of a deformation state of the bearing element ( 2 ), wherein the measuring device ( 1 ) is designed according to one of claims 7 to 9.

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