DE102014007337A1 - Method for the X-ray intrinsic voltage measurement on a component and apparatus for carrying out the method - Google Patents

Abstract

The invention relates to a method for radiographic measurement of residual stresses on a component, a component section or a test body (B), with material of the component, the component section or the test body (B) being removed up to the given measurement depth in order to determine the internal stress in at least one predetermined measurement depth, and then the radiographic residual stress measurement is carried out at this specified measurement depth. According to the invention, the material removal is carried out at least in regions by means of laser radiation. The invention also relates to a device (5) for performing the method.

Description

The invention relates to a method for X-ray internal stress measurement on a component according to the features of the preamble of claim 1 and an apparatus for carrying out the method.

From the prior art, it is generally known to carry out a roentgenographic intrinsic voltage measurement on components. In this case, the strain of the metal grid is determined as a result of the prevailing voltage. Initially, this method is limited only to very shallow areas. By deformation-free removal of thin layers, in particular by electrochemical removal, but also residual stress depth profiles can be determined. The electrochemical removal is very expensive.

The invention is based on the object to provide a comparison with the prior art improved method for X-ray internal stress measurement on a component and an apparatus for performing the method.

The object is achieved by a method for X-ray diffraction measurement on a component with the features of claim 1 and an apparatus for performing the method with the features of claim. 9

Advantageous embodiments of the invention are the subject of the dependent claims.

In a method for X-ray internal stress measurement on a component, material of the component is removed up to the predetermined measurement depth to determine the residual stress in at least one predetermined measurement depth and then the X-ray internal stress measurement is performed at this predetermined measurement depth.

According to the invention, the removal of material is carried out at least in regions by means of laser radiation.

The inventive method allows in a simple way X-ray residual stress depth measurements, d. H. not only X-ray residual stress measurements on a surface of the component, but also in a given measurement depth or preferably in several predetermined measurement depths in the component. As a result, it is also possible, for example, to generate X-ray residual stress gradients. The general term "component" is intended to mean, in particular, a component section or a specimen.

In the prior art, this is only possible by a very complex electrochemical removal. This electrochemical removal, for example, must be carried out in a separate workstation and requires manual disassembly, assembly, measurement and preparation steps. These manual interventions are required for radiographic residual stress measurements at various depths of the component at any depth. Furthermore, the electrochemical removal is only applicable if a respective test location on the component with the device for the electrochemical removal is sufficiently accessible and a process-safe electrochemical removal is possible. A removal depth and an exact form of the removal are also not exactly controllable.

In contrast, the method according to the invention is much simpler and more accurate and, moreover, reliable in terms of process. The entire process or individual process steps can be carried out semi-automatically or fully automatically, for example. In particular, an automated material removal by means of the laser radiation is made possible by the method, whereby the preparation technique is considerably simplified. Due to the automated removal of material by means of the laser radiation, advantageously in a measurement setup, in which the X-ray residual stress measurements are also carried out, residual stress depth profiles can be obtained with substantially shorter processing times and without manual intervention. Furthermore, however, a manual implementation of the method or individual method steps is possible. The material removal by means of the laser radiation can be carried out, for example, with a laser or with a plurality of identical or different lasers, which are used simultaneously or successively.

The automation of the removal is advantageously made possible by integrating at least one laser ablation unit and at least one X-ray internal residual stress measuring unit in a common device. This allows a fully automatic creation of a residual stress depth curve without manual intervention.

The removal of material by means of the laser radiation is also possible at such test locations, which can not be realized for reasons of preparation by means of the electrochemical removal known from the prior art. By means of the method according to the invention thus an extension of the test spectrum is made possible.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 schematically a removal of material of a component,

2 1 schematically shows a method sequence of a method for the X-ray intrinsic-voltage measurement on a surface and in several measuring depths of a component,

3 schematically a component in a measuring clamping during a material removal, and

4 schematically a device for performing a method for X-ray internal stress measurement on a component.

Corresponding parts are provided in all figures with the same reference numerals.

1 shows a removal of material of a component B up to a predetermined measurement depth in order to subsequently perform a roentgenographic intrinsic voltage measurement in this predetermined measurement depth can. This material removal is carried out at least in regions by means of laser radiation, for which purpose at least one laser ablation unit 1 . 2 is used. Such removal of material by means of laser radiation, for example, in the DE 10 2012 023 864 A1 by the assignee, the entire contents of which are hereby incorporated by reference.

In the example shown here, the material removal is carried out completely or partially by means of laser radiation. For this purpose, in the example shown, two laser ablation units 1 . 2 used, the use of the second laser ablation unit 2 is optional. This will be in 1 as well as in the following 2 to 4 clarified by their dashed representation. This second laser ablation unit 2 is used, for example, a reworking to achieve the predetermined measurement depth with high accuracy and / or to edit a test surface such that a predetermined Prüfflächenzustand is achieved. The material removal by means of laser radiation can also be achieved by means of more than one or two lasers and / or laser ablation units 1 . 2 respectively.

Alternatively or in addition to the use of such at least a second laser ablation unit 2 This reworking can be carried out, for example, by means of a chemical and / or electrochemical fine abrasion. This will be in 1 as well as in the following 2 to 3 illustrated by the dashed representation of the unit 7 for a chemical and / or electrochemical removal. In the case of a chemical removal, for example, it is conceivable to selectively apply a substance to the surface produced with at least one laser removal step, which leads to a further fine removal and / or conditioning of the surface structure produced. If necessary, subsequent cleaning of the surface must take place in order to prevent further depths.

Im in 1 Example shown is first by means of the laser radiation of the first laser ablation unit 1 the material of the component B is removed to a laser ablation depth and then optionally removed by reworking the material of the component B to the predetermined measurement depth, said reworking in the example shown here, as already described, by means of the laser radiation of the second laser ablation unit 2 is carried out. Laser of the two laser ablation units 1 . 2 For example, each may be designed as a short-pulse laser or as an ultra-short pulse laser. In addition or as an alternative to the second laser removal step, as shown in FIG 1 illustrated, a further Feinabtrag and / or a conditioning of the surfaces produced by means of a unit 7 carried out for chemical and / or electrochemical removal.

Advantageously, the two laser ablation units 1 . 2 different lasers. In this way, for example, the material removal up to the laser ablation depth by means of a laser of the first laser ablation unit 1 take place, which allows a large material removal in a short time. Subsequently, the reworking by means of the second laser ablation unit 2 performed, the laser, for example, allows a lower, but high-precision material removal, so that the predetermined measurement depth is reached exactly.

In 2 an exemplary procedure of a method for X-ray internal stress measurement on a surface and in several measuring depths of such a component B is shown schematically. In many tasks, not only an inherent stress state directly on the surface of the component B, but a depth profile in an edge layer is of interest. This applies, for example, when it comes to a characterization of a previous shot peening treatment or a processing such as grinding. For this purpose, it is necessary that the effective residual stress in the respective measuring depth can be measured by a material removal carried out in a suitable manner.

In the prior art, an electrochemical ablation is used for this purpose, ie electrochemical polishing processes are used which allow a deformation-free material removal. Because of the necessary use of corrosive liquids under an electrical potential, this work is usually carried out away from the X-ray measuring equipment for X-ray residual stress measurement, in particular to achieve a sufficiently high removal rate in a relatively short time The component B to be examined must therefore both by means of suitable positioning devices can be positioned with sufficient accuracy in an X-ray diffractometer for X-ray internal stress measurement as well as in an electrochemical polishing device for material removal. In addition, necessary assembly and cleaning work must be carried out. Furthermore, a height of the respective material removal must also be measured for every material removal. This is relatively labor intensive and not automatable.

The method shown here and described in more detail below avoids these disadvantages completely or at least largely. It allows a considerable simplification of the preparation technique in the X-ray depth-of-field measurement by replacing the known from the prior art outside the X-ray test cell electrochemical ablation by material removal by laser radiation and optional Feinabtragung with chemical and / or electrochemical support In this method is in a first process step S1 by means of a roentgenographic residual stress measuring unit 3 a roentgenographic intrinsic voltage measurement on a surface of the component B is performed. The X-ray residual stress measuring unit 3 is in the 2 to 4 schematically shown greatly simplified as a dashed arrow.

Subsequently, in a second method step S2 in the manner described above by means of the first laser ablation unit 1 and optionally by means of the second laser ablation unit 2 and / or - additionally or alternatively to the at least second laser removal step - with the aid of the unit 7 for chemical or electrochemical material removal, remove material of component B up to the specified measuring depth.

A test area resulting from the removal of material is just chosen so large that the X-ray internal stress measurement can be carried out expediently and at the same time the least possible interference with the residual stress state of the component B to be tested takes place. The removal of material, as described above, is particularly advantageously carried out with one or more lasers, one, several or all lasers being designed as short-pulse or ultra-short pulse lasers. The laser or lasers are advantageously chosen such that they do not produce any inadmissible surface damage with respect to material or structural changes and / or topography on the test surface to be generated. To achieve this, not only the respective laser, but also its control and / or regulation is chosen so that the material and / or microstructure state, at least in the region of the penetration depth of an X-ray beam for performing the X-ray residual stress measurement has no impermissible changes. This applies to reworking by means of laser radiation at least for those lasers that are used for reworking, in the example shown here for the laser of the second laser ablation unit 2 ,

In the case of the use of several laser ablation units shown here 1 . 2 For example, the laser of the first laser ablation unit 1 a high erosion rate, but may generate insufficient surface quality. The laser of the second laser ablation unit 2 then generates the test surface quality required for the X-ray internal stress measurement without material or structural changes and with an acceptable topography. The lasers may differ, for example, in terms of power and / or pulse rate.

To produce a flat material removal, the respective laser is usually moved by means of a scanner over the respective component surface. With a suitable optical design, it is conceivable to use a plurality of lasers, in the example shown here, the laser of the first laser ablation unit 1 and the laser of the second laser ablation unit 2 , switchable to operate with the same scanner, so that the expenditure on equipment is reduced and always the same positions are approached.

In principle, it is also conceivable that after the removal of material by the laser radiation by means of another method, the required Prüfllächengüte is set, for example by a chemical and / or electrochemical Feinabtrag, as already described above. This is done in a particularly advantageous manner, as well as the removal of material by means of the laser radiation, in the measurement setup for the X-ray residual stress measurements, so that only one Meßaufspannung is needed. For example, the surface produced with the aid of the at least one laser can be chemically and / or electrochemically conditioned by a subsequent dribbling, spraying or dabbing with a chemical substance.

After this in the second method step S2 performed in the manner described material removal to the predetermined measurement depth is then in a third method step S3 by means of the X-ray residual-stress measuring unit 3 the roentgenographic intrinsic voltage measurement is carried out at this predetermined measuring depth.

Subsequently, in a fourth method step S4, the method described above, in particular for the second method step S2, is repeated by means of the first laser ablation unit 1 and optionally by means of the second laser ablation unit 2 and additionally or alternatively to the at least second laser removal step with the aid of the unit 7 for chemical and / or electrochemical removal material of the component B removed to another predetermined measurement depth. In this case, for example, as described above, by means of the first laser ablation unit 1 Material of the component B is removed to a further Laserabtragstiefe and then optionally carried out the reworking by means of the second Laserabtragseinheit 2 or alternatively or additionally, for example, by chemical and / or electrochemical Feinabtragen, wherein material of the component B is removed to the further predetermined measurement depth.

In a fifth method step S5 is then by means of the X-ray residual stress measurement unit 3 the X-ray residual stress measurement is performed in this further predetermined measurement depth. The fourth and fifth method steps S4, S5 can be repeated several times in order to carry out the X-ray intrinsic-voltage measurement in various predefined measuring depths of the component B in this way. This is in 2 indicated schematically by the last dashed arrow. In this way, for example, an X-ray residual stress profile can be created.

As in 3 shown, the material removal and the X-ray residual stress measurement are advantageously in the same setting 4 carried out expediently in the measurement setup, in which in the method according to the prior art, only the X-ray diffraction measurement is performed. Carrying out the material removal in this measurement setup is made possible only by the use of laser radiation for material removal, because in the known from the prior art electrochemical ablation is to achieve relatively high Abtragsleistung usually worked in a manually populated, separate apparatus. The implementation of the laser-assisted removal of material and the X-ray internal stress measurement in different fixtures would alternatively be possible.

4 schematically shows a device 5 to carry out the process. The device 5 includes at least one laser ablation unit 1 . 2 and at least one X-ray residual-stress measuring unit 3 , In the example shown here, the device comprises 5 next to the first laser ablation unit 1 optionally additionally the second laser ablation unit 2 , Furthermore, a (in 4 not shown) unit for chemical and / or electrochemical Feinabtragen and / or conditioning of the surface may be provided. Furthermore, the device shown here comprises 5 the stretching 4 in which the component B is held both during the material removal and during the X-ray internal stress measurement, ie during the clamping 4 this is advantageously the measurement setup.

In addition, the device includes 5 advantageously, as in 4 exemplified, a depth gauge 6 for determining the respectively achieved depth during the respective material removal and / or after the respective material removal. This depth gauge 6 is here also shown schematically very simplistic only as a broken arrow. The depth determination by means of this depth measuring device 6 can be done for example optically and / or by a laser process.

The implementation of the material removal and the X-ray internal stress measurement and optionally also the depth determination in different devices would alternatively also be possible. The execution of the material removal and the X-ray internal stress measurement and optionally also the depth determination, although in the same device 5 but in different setups, would be possible alternatively.

By means of the described method and the device 5 To carry it out, the material removal is not only shortened, but it can also be automated. This is achieved by integration of the at least one laser ablation unit 1 . 2 and the optional unit 7 for chemical and / or electrochemical fine abrasion and / or surface conditioning and the at least one X-ray internal residual stress measuring unit 3 in the common device 5 to carry out the method allows. As described, for material removal the same set-up becomes particularly advantageous 4 used as for performing the X-ray residual stress measurement, as in 3 and 4 shown. In other words: In a system, laser beams are used for the removal of material for setting the respective predetermined measuring depth and also X-rays for the X-ray internal stress measurement, in steps connected in chronological succession.

By eliminating the known from the prior art manual intermediate step of disassembly of the component to be examined B, the electrochemical removal in a separate station, the measurement of Abtragtiefe and reassembly of the component to be examined B between individual X-ray measurements at different depths are not only potential Positioning error avoided, but it is also a fully automated creation of a residual stress depth curve possible, which, as described above, X-ray residual stress measurements and material removal are carried out to the next measurement depth in alternation.

Depending on the laser power, pulse rate and type of laser, removal times of, for example, a field of 5 × 5 mm and 10 μm material removal depth of less than one second to several minutes are expected, usually several seconds to minutes. However, this material removal process is considerably shorter in relation to the electrochemical removal process including the handling described for electrochemical removal.

If it is not possible or only possible with uncertainty to set the planned depth, ie the respective predetermined laser removal depth and / or measurement depth, in advance by parameter settings during material removal by means of the laser radiation, the respectively achieved depth can be determined in the course of this linked process sequence. This depth determination can be carried out optically and / or by a laser method, for example, particularly preferably in the present measuring setup, as in FIG 4 shown and already described above.

The described method and the device 5 to carry out the method mean a significant competitive advantage in the creation of residual stress depths by shortening a total trial period and in particular by a fully enabled automation. For example, an operation without personnel is possible, for example, a night operation. This will significantly increase the capacity utilization of the device 5 reached. Alternatively, however, the method can also be carried out only semi-automatically or manually, for example, preferably with the device described 5 for its implementation.

Another advantage of the described method and apparatus 5 its implementation lies in the extension of the testing options. With the method described in the prior art using the electrochemical removal, the creation of a residual stress depth curve is possible only at those test locations which are accessible both by X-ray analysis and with respect to the preparation boundary conditions during electrochemical removal. The method and apparatus described herein 5 In order to carry it out, the possible uses of the X-ray internal stress measurement expand to the extent that component zones can now also be tested which can not be achieved by the electrochemical removal known from the prior art, but only with the laser beam and thus can also be removed.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102012023864 A1 [0020]

Claims (9)

Method for the X-ray internal stress measurement on a component (B), wherein material of the component (B) is removed to the predetermined measurement depth to determine the residual stress in at least one predetermined measurement depth and then the X-ray internal stress measurement is performed in this predetermined measurement depth, characterized in that the Material removal is carried out at least partially by means of laser radiation. A method according to claim 1, characterized in that the material carried out by means of laser radiation material removal either with a laser ablation unit ( 1 ) or alternatively successively by means of at least two different laser ablation units ( 1 . 2 ) is carried out. A method according to claim 1 or 2, characterized in that by means of the laser radiation, the material of the component (B) is removed to a Laserabtragstiefe and then removed by reworking the material of the component (B) to the predetermined measurement depth. A method according to claim 3, characterized in that the reworking is carried out by means of a chemical and / or electrochemical Feinabtragens. Method according to one of the preceding claims, characterized in that the material removal is performed at least in regions by means of at least one short pulse laser or ultrashort pulse laser. Method according to one of the preceding claims, characterized in that according to the X-ray residual stress measurement in the predetermined measurement depth further material of the component (B) is removed to at least one further predetermined measurement depth and after the respective material removal in each case a further X-ray residual stress measurement in the respective further predetermined Measuring depth is performed, this further material removal is carried out at least partially by means of laser radiation. Method according to one of the preceding claims, characterized in that prior to the first material removal, a roentgenographic residual stress measurement is performed on a surface of the component (B). Method according to one of the preceding claims, characterized in that during the respective removal of material and / or after the respective removal of material a respectively reached depth is determined. Contraption ( 5 ) for carrying out a method according to one of claims 1 to 8, comprising at least one laser ablation unit ( 1 . 2 ) and at least one X-ray residual stress measuring unit ( 3 ).

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