Testing method and testing equipment for the non-destructive determination of strength- and / or forming-related material properties of a sheet metal component to be tested, based on the plane torsion test.

Abstract

Test method for determining strength and / or forming-related material properties of a sheet metal to be tested (1) on the basis of the planar torsion test, in which at least a section of the sheet metal (1) forming a test area (12) is subjected to a torsional load by means of a clamping tool (2, 3) and at least the torque and angle of rotation of the clamping tool (2, 3) are recorded, characterized by the fact that the clamping tool (2, 3) consists of clamping pins (2, 3), a sheet metal component (1) which is preferably fixed in place and formed from sheet metal is clamped between the clamping pins (2, 3) arranged on the upper and lower sides of the respective test area (12) of the sheet metal component (1), The clamping pins (2, 3) are then rotated perpendicular to the sheet metal plane in the test area (12) in the same direction relative to the preferably stationary sheet metal component (1), and The torque required to rotate the tension pins (2, 3) and thus to locally shear the sheet metal component (1) in the test area (12) and the relative angle of rotation of the tension pins (2, 3) are measured and recorded.

Description

[0001] The invention relates to a testing method for the non-destructive determination of strength and / or forming-related material properties of a sheet metal component to be tested based on the plane torsion test according to the preamble of claim 1 and to a testing device suitable for carrying out the testing method according to the preamble of claim 11.

[0002] In order to assess the properties of a finished component for operational use or of a material for the production process, tests are required, including those relating to strength. For the mechanical testing of sheet metal semi-finished products and sheet metal products, this usually requires cutting a sample from the manufactured workpiece, which is then examined on a special testing system. However, destructive sampling is not always desirable, as this could impair the functionality or integrity of finished components. Furthermore, sampling is not always possible with curved components, as testing curved samples is more complex than testing flat samples.

[0003] For testing the strength and / or formability of sheet metal or sheet materials, it is important to determine the flow properties of the sheet materials, from which conclusions for forming can then be derived. For this purpose, the so-called plane torsion test was developed under laboratory conditions. In this test, a sheet material in the form of a larger section of a flat sheet is subjected to torsion, and the torsional moment and angle of twist under torsion are measured. For this test, the sheet is clamped between two clamping rings arranged on the top and bottom of the sheet. The clamping rings are pressed together, holding the sheet to be tested between them. The clamping rings thus fix the sheet and hold it non-rotatably at the edges.In the middle area of ​​the clamping rings, inner clamping jaws are then pressed onto the top and bottom of the sheet and against each other on both sides of the sheet. These jaws can be rotated axially relative to the stationary and non-rotating clamping rings. If the clamping jaws are now pressed onto the sheet held between the clamping rings and thus against each other and then rotated relative to the clamping rings, a shear load is created in the sheet section between the clamping rings and the clamping jaws due to torsion. This shear load can be recorded with regard to the angle of rotation, for example, visually, and with regard to the torsional load, for example, via a torque measurement. With continuous measurement, a flow curve of the sheet material can be recorded, from which further material parameters relevant for forming can be determined based on plastomechanical relationships.Of particular interest here is the determination of the yield strength of the sheet material, since this value can be used to determine the beginning of the plastic flow of the sheet material, which is important for the forming process.

[0004] In the classic planar torsion test, a round and flat section of sheet metal is examined. Only specially manufactured round sheet metal blanks can be used for this purpose, which must then be disposed of as waste. Furthermore, the material behavior can only be determined under laboratory conditions; the forming behavior of fully or partially formed sheet metal components cannot be captured this way. Furthermore, non-destructive testing of the material behavior of fully or partially formed sheet metal components is not possible with this classic planar torsion test.

[0005] The disadvantages of the currently available procedures are obvious. Although the destructive taking of samples followed by complex testing does provide the desired material properties, it is only possible on special sample blanks and, in particular, cannot be carried out on finished components without causing the impairment of the finished components caused by the sampling. Furthermore, it is not possible to carry out 100% testing of finished components, for example in series production, which can then be used immediately after a positive test, for example in assembly, further processing or in some other way. Furthermore, the conventional methods do not allow for a quasi-destructive determination of the local strength of components or for testing in hard-to-reach areas of such components.

[0006] In the publication by Tekkaya, AE; Pöhlandt, K.: Determining stress-strain curves of sheet metal in the plane torsion test. In: Annals of the CIRP, Vol. 31, 1982, No. 1, pp. 171-174, - ISSN 0007-8506, a test method for determining material properties relevant to strength and / or forming properties of a sheet metal under test is proposed based on the plane torsion test. Alternative designs for the plane torsion test are also presented in DE 100 58 498 A1, DE 900 023 B, and DE 10 2005 046 313 A1.

[0007] The aim of the present invention is therefore to provide a testing method and a testing device which enables the determination of strength and / or forming properties, in particular of sheet metal components, on the basis of the plane torsion test even without taking a sample and thus in an almost non-destructive manner.

[0008] The invention with regard to the testing method is based on a testing method for determining material properties of a sheet to be tested that are relevant to strength and / or forming technology, based on the planar torsion test, in which at least one section of the sheet forming a test area is subjected to a torsional load by means of a clamping tool and at least the torque and angle of rotation of the clamping tool are recorded.Such a generic testing method is further developed in accordance with the invention in that the clamping tool is a clamping pin, wherein a sheet metal component, preferably fixed in a stationary manner and formed from the sheet metal, is clamped between clamping pins arranged on the top and bottom of the respective test area of ​​the sheet metal component, then the clamping pins are rotated perpendicular to the sheet plane in the test area in the same direction relative to the preferably stationary sheet metal component, and the torque required to rotate the clamping pins and thus to locally shear the sheet metal component in the test area and the relative angle of rotation of the clamping pins are measured and recorded.

[0009] The key advantage of the testing method according to the invention over other testing methods such as tensile testing or plane torsion testing under laboratory conditions is the ability to test finished sheet metal components in particular without taking samples. While the classic plane torsion test is limited to pre-manufactured sheet metal blanks that are representative of the strength values, the testing method according to the invention can be used to determine the respective material properties, and in particular the yield point, at selected points on the finished or forming component in any manufacturing stage in a targeted and almost non-destructive manner. This allows, on the one hand, local changes in the strength properties that result, for example, from the forming of the sheet metal component to be recorded, and, on the other hand, each individual manufactured sheet metal component can be subjected to a quality check, for example at points of particular interest orThe material properties of the sheet metal component can be tested for their specific forming requirements. This can be advantageously achieved by arranging or supporting the sheet metal component as a whole in a stationary manner, and the clamping rings around the actual test point required in the classic planar torsion test can be omitted. In particular, the relatively small local plastic twisting of the sheet metal component at the point of action of the roll pins makes separate clamping of the sheet metal component around the point of action of the roll pins unnecessary, since the sheet metal component as such can be regarded as stationary. In other words, the clamping of the sheet metal component around the point of action of the roll pins can be regarded as being any distance away from the point of action of the roll pins.This significantly reduces the space required on the sheet metal component in the test area, allowing for spot tests and tests on non-flat sections of the sheet metal component. The smaller the diameter of the dowel pins and thus the dimensions of their clamping surfaces, the lower the torque required for testing. For this reason, it is advantageous to make the dowel pins as small as possible in order to create the smallest possible imprint on the sheet metal component for non-destructive workpiece testing and to be able to measure as locally as possible. This also ensures that the torque causing the shear load in the sheet metal component is reduced to such an extent that the torque can be reliably absorbed by the sheet metal component even without the sheet metal component being clamped separately.Depending on the geometry of the dowel pins, testing on curved sections of the sheet metal component's surface is also possible, allowing for a wide range of testable component geometries. To apply the torsional load, the sheet metal component can advantageously be fixed in place and the dowel pins can be moved for this purpose. Of course, kinematic reversal is also possible with fixed dowel pins and a sheet metal component that can be rotated relative to them.

[0010] A particular advantage is that the torque is only applied until the sheet metal component in the test area just begins to plastically flow. While this causes a very slight plastic deformation of the sheet metal component locally, it is very small and not significant in practice. Nevertheless, it allows the yield point of the sheet metal component in this test area to be determined without any noticeable change to the sheet metal component.

[0011] For this purpose, in a preferred embodiment, a curve of the deformation of the sheet metal component in the test area is determined based on the measurement of the torque of the torsional load as a function of the twist angle of the clamping pins or the twist time. This curve shows the transition between elastic and plastic deformation of the sheet metal component, which in turn corresponds to the local yield point of the sheet metal component in this test area. In a further embodiment, the bend in the recorded curve of the torque / twisting angle curve or the torque / twisting time curve can be used as an indicator, which indicates the transition between essentially linear elastic deformation and local plastic flow of the sheet metal component in the test area. This can be done, for example, by monitoring the change in the gradient of the determined curve.

[0012] The torque is applied only until a kink in the recorded torque / torsion angle curve becomes apparent, indicating the transition between essentially linear elastic deformation and local plastic flow of the sheet metal component in the test area. To determine the boundary between purely elastic deformation and plastic flow of a material, it is sufficient to identify the kink in the curve. This kink in the curve can be determined, for example, by changing the gradient of the measured curve.

[0013] Another advantage is that the angle of twist of the dowel pins during the test procedure corresponds to the strain in the test area of ​​the sheet metal component, assuming that the dowel pins do not slip relative to the component, and the strain can therefore be easily determined. However, if slippage of the dowel pins cannot be reliably prevented, a separate local measurement of the angle of twist should be performed. The shear stress in the test area of ​​the sheet metal component can also be calculated from the torque of the dowel pins by knowing the radius, the torque, and the sheet thickness of the sheet metal component in the test area.

[0014] In a first embodiment, the deformation of the sheet metal component in the test area can be determined tactilely, preferably by a sensor arranged on the sheet metal component. Alternatively, it is also conceivable to determine the deformation of the sheet metal component in the test area optically, preferably by optically evaluating changes in patterns or the like applied to the test area. For example, a dot pattern or a line pattern can be applied in the test area that changes due to the load. This change can then be optically evaluated, for example, using cameras, and converted into the required material properties.

[0015] The invention further comprises a testing device for the non-destructive determination of strength and / or forming-related material properties of a sheet to be tested on the basis of the plane torsion test, in which at least one section of the sheet is subjected to a torsional load by means of a clamping tool and at least the torque and angle of rotation of the clamping tool are recorded.Such a testing device is further developed in accordance with the invention in that the sheet metal component formed from the sheet metal is held or fixed in a stationary manner relative to the testing device as a whole, the testing device has two axially aligned and movable clamping pins as a clamping tool, between which the sheet metal component can be positioned in alignment with its respective testing area and the clamping pins clamp the sheet metal component between them in the axial direction, a drive device rotates the clamping pins perpendicular to the sheet metal plane in the testing area in the same direction relative to the stationary sheet metal component, and a measuring device measures and records the torque required to rotate the clamping pins and thus to locally shear the sheet metal component in the testing area and the relative angle of rotation of the clamping pins and / or the rotation time.With such a testing device, the respective material properties, and in particular the yield point, can be determined in a targeted and non-destructive manner at selected points on the finished or forming workpiece in any manufacturing stage using the testing method according to the invention, which could otherwise only be determined through complex and generally destructive tests. The advantages and properties already described above for the testing method also apply to the testing device according to the invention and are hereby expressly incorporated by reference. Of course, a kinematic reversal of the relative movement between the dowel pins and the sheet metal component is also possible and conceivable, in which the dowel pins are stationary and the sheet metal component is rotated relative to the dowel pins.

[0016] It is particularly advantageous if the clamping pins have identical, mutually facing, and preferably circular, flat clamping surfaces, between which the component to be tested is clamped. This makes the mathematical relationships for determining the material properties from the measured values ​​particularly simple.

[0017] In another embodiment, however, it is also conceivable for the clamping surfaces to be profiled, preferably domed, to ensure a particularly small contact area for the clamping pins with the sheet metal component. This allows the torque to be introduced into the sheet metal component via a very small contact area, which also reduces the overall torque acting on the sheet metal component and improves the non-destructive nature of the testing procedure.

[0018] It is also conceivable for the clamping surfaces to have point-like profiles, allowing the sheet metal component to be clamped between the clamping pins in a form-fitting and friction-locking manner. For example, pyramid-shaped projections can be provided in the clamping surfaces, which slightly imprint themselves on the sheet metal component and improve torque transmission.

[0019] Especially for spot tests, including on curved areas of the sheet metal component, it is advantageous if the radial dimensions of the dowel pins are kept as small as possible. This allows tests to be performed even on sections of the sheet metal component with tight radii or corners.

[0020] It is particularly advantageous if the clamping pins are held on a tong-like holder that can also be positioned on tightly curved test areas of the sheet metal component. This tong-like holder can then be easily positioned and adjusted to suit the respective test areas of the sheet metal component in order to carry out the test. In a further embodiment, such a tong-like testing device can be automatically positioned relative to the sheet metal component by positioning devices, preferably by industrial robots, or conversely, the sheet metal component can be positioned relative to the tong-like testing device. Alternatively, it is also conceivable to integrate the testing device as a stationary testing device into a process chain for manufacturing the sheet metal component. As a further alternative, it is conceivable for the testing device to be mobile and arranged on a movable base unit and to be positioned and aligned relative to the sheet metal component.

[0021] A particularly preferred embodiment of the testing method and testing device according to the invention is shown in the drawing.

[0022] They show: Fig. 1 - a very basic representation of the basic function of the testing device with open clamping pins for testing a flat section of the sheet metal component, Fig. 2 - the test facility according to Fig. 1 with the clamping pins closed and the torsional torque applied to the sheet metal component, Fig. 3 - Schematic representation of the tong-like structure of the testing device with the measuring device for the torque and optical detection of the angle of rotation in the test area of ​​the sheet metal component Fig. 4 - Illustration of the arrangement of the clamping pins of the testing device according to the invention along the contour of a curved sheet metal component, Fig. 5 - Representation of the load curve of the test area of ​​the sheet metal component with recognizable transition from elastic to plastic deformation for different sheet metal materials.

[0023] In the Fig. 1 shows, in a very schematic representation, the basic function of the testing device according to the invention with open clamping pins 2, 3 for testing a flat test section 12 of the sheet metal component 1 arranged between the clamping pins 2, 3. The clamping pins 2, 3 have a clamping surface 7 arranged on the end face and facing the other clamping pin 3, 2, which has a flat design here, but in another embodiment can also be curved or designed in another way to suit the test. The two clamping pins 2, 3 can be subjected to clamping forces 4 directed towards one another by a clamping drive (not shown in detail) in such a way that they move towards the sheet metal component 1 and, as in Fig. 2, clamped between themselves. The sheet metal component itself, as shown in the Fig. 1 and Fig. 2 only indicated by the part number 5, be fixed in a fixed position, for example held as a whole in a holding device, so that the sheet metal component cannot move or deform unduly under the load applied during the test.

[0024] To carry out the test procedure, after moving the clamping pins 2, 3 together as shown in Fig. 2, the clamping pins 2, 3 are rotated in the same direction relative to the stationary sheet metal component 1 by a drive device (not shown in detail), thereby applying a torsional load to the sheet metal component 1. This torsional load leads to a shear load in the sheet metal plane of the sheet metal component 1. The evaluation of this load can be used to provide information about the strength behavior and, in particular, the yield strength of the sheet metal component in this test area. This material behavior is fundamentally known from classic planar torsion tests under laboratory conditions and will only be described in more detail here to the extent that it is relevant for understanding the present invention.

[0025] Now, as in the Fig. 3 can be seen in principle, the torque during the rotation of the clamping pins 2, 3 is recorded by means of a measuring device 9 which is only indicated and at the same time the rotation of the sheet metal component in the test area is recorded, curves can be obtained according to Fig. 5, from which the locally prevailing yield strength of the material of the sheet metal component can be determined.

[0026] To measure the twist of sheet metal component 1 in test area 12, in the simplest case of a constant twisting speed of the dowel pins 2, 3, the time of the twist can be used, which is proportional to the twist of the dowel pins 2, 3 and thus to the twist of the material of sheet metal component 1 in test area 12, as long as the dowel pins 2, 3 do not slip on the sheet metal component. Of course, it is also conceivable to measure the twist of the dowel pins 2, 3 via an angle measurement on the dowel pins 2, 3 themselves.

[0027] In the Fig. 3 shows another method of detecting the rotation, which uses an optical sensor 8, such as a camera, to detect, for example, point- or line-shaped markings 11 applied to the surface of the sheet metal component 1 and their relative positional changes with increasing rotation of the clamping pins 2, 3. From this, the displacement of the material of the sheet metal component 1 in the test area 12 can then also be calculated.

[0028] Further on, the Fig. 3 shows that the clamping pins 2, 3, as well as the drives for clamping and rotating the clamping pins 2, 3, and the necessary measuring devices 8, 9, can be attached to a tong-like base body 10, into which the sheet metal component 1 can be inserted for testing, or instead, the tong-like base body 10 can be pushed over the respective test area 12, and the test can then be performed. Such a tong-like testing device can also be handled automatically, for example, using an industrial robot.

[0029] In the Fig. Figure 4 shows a schematic diagram of the arrangement of the clamping pins of the testing device according to the invention along the contour of a curved sheet metal component 1. The clamping pins 2, 3, thanks to the pincer-like base body 10 and the small spatial configuration of the clamping pins 2, 3, enable easy pivoting and thus adaptation of the position of the clamping pins 2, 3 to the locally present curvature structure of the sheet metal component 1. This allows for spot tests of the material properties of the sheet metal component 1 to be carried out even on such curved sheet metal components 1.

[0030] In the Fig.Figure 5 shows typical load curves for the test area of ​​flat sheet metal components with a recognizable transition from elastic deformation 13 to plastic deformation 14 for various sheet metal materials. From these curves, the respective yield strength 15 of the sheet metal component in the test area can be determined based on the change in the gradient of the measured values. The torques are plotted against the angle of rotation in each case. Two tests were conducted for each material, and reproducible curves were determined. An additional horizontal line represents the yield strength 15 determined from a previously conducted tensile test, which corresponds well with the change in the curve of the measured values ​​of the test sequence performed here.

[0031] To represent this value, the expected torque was calculated from the value for R po,2The measured torque / angle curves show a division between an initially elastic straight line 13 and a flatter curve 14, which is typical of plastic strain hardening. The boundary 15 between these two regions can be found in good agreement with the values ​​from the tensile test, even though the transition is not abrupt.

[0032] The following relationships apply to the calculation of the yield stress from the torque in the test method according to the invention:

[0033] The shear stress τ is calculated from the torque M. The shear strain as a function of the radius r is: τ=M2⋅π⋅s⋅r2 with the sheet thickness s. This corresponds to the force / circumferential area at the radius r.

[0034] Applying a yield condition, the yield stress k f The yield stress k is determined by the yield condition according to von Mises. fthrough kƒ=12[(σx−σy)2+(σx−σy)2+(σx−σy)2+6(τxy2+τxy2+τxy2)] calculated and for τ= τ xy as the only voltage component follows kƒ=3⋅τ

[0035] The influence of the sheet's anisotropy can also be taken into account when calculating the stresses. The dependence of the flow stress on the plane anisotropy of rolled sheets is averaged by the plane torsion test, since direction-dependent properties are not captured. The consideration of the vertical anisotropy r n can be done using the Hill yield criterion, where k f and the degree of deformation φ from kƒ=3⋅τ2(2rn+1)3(rn+1);φ=γ3⋅3(rn+1)2(2rn+1) so that for r n = 1 the isotropic flow condition applies.

[0036] The shear stress in the sheet metal is greatest at the very edge of the clamping. This can be calculated from the torque, the sheet thickness, and the radius of the clamping. Identifying the yield point as the transition between purely elastic and elastic-plastic deformation requires a change in the material behavior, which can be reflected in the measurement curves. This can generally be perceived by a change in the gradient of the torque-angle curve. Therefore, measuring the torque during loading is essential. In principle, the torque-time curve can be used to identify the yield point in addition to the torque-angle curve, provided the loading progresses at a constant rate.

[0037] The test method according to the invention enables the local measurement of the strength of sheet metal components without taking samples. The possible applications are diverse and can include, among others, the following: Semi-finished product production: Testing of sheet quality in the production of steel or aluminum strip, Sheet metal forming: Testing of local strength resulting from cold forming of sheet metal, also possible for validating FEM simulations. Can also be used as part of a process chain for 100% testing. Large-area components: Testing the required strength of large-area (sheet metal) parts, including central regions, Repair and maintenance: Determination of the current maximum stress limits for components in operation, Recycling: Identification of materials for recycling purposes.

[0038] The implementation of the test device according to the invention can be realized in different ways depending on the field of application: Stationary testing device integrated into process chains, which can test different positions on both sides of components, Positioning of the test device by robot arms, Compact testing device for integration into gauges of sheet metal forming parts to simultaneously check geometry and strength at selected positions, Mobile test units on rolling carts for flexible use at different locations, Handheld device for manual measurements.

[0039] The following principles are conceivable as measurement methods for determining the deformation of the sheet metal component in the test area: indirectly by measuring the angle of rotation of the punch Simple implementation, but problematic is that deviations can occur due to slippage between the clamping pin 2, 3 and the sheet metal component 1 and due to setting processes tactile measurement by a sensor that measures the angle of rotation independently of the punch High accuracy and defined radial distance Non-tactile measurement using optical methods such as digital image correlation using a camera-based method by comparing images of the surface of the sheet metal component and determining pattern differences. For this purpose, the surface is provided with a stochastic dot pattern, for example, whose displacement is measured. Part number list 1 sheet metal component 2 roll pins 3 dowel pin 4 Tension 5 Bracket sheet metal component 6 Torque 7 clamping surface 8 optical measuring system 9 Torque measurement 10 pincer-like body 11 markings 12 Test area 13 elastic deformation 14 plastic deformation 15 Yield strength

Claims

[1] Test method for determining material properties relevant to strength and / or forming technology of a sheet metal (1) to be tested on the basis of the plane torsion test, in which at least one section of the sheet metal (1) forming a test area (12) is subjected to a torsional load by means of a clamping tool (2, 3) and at least the torque and angle of rotation of the clamping tool (2, 3) are recorded, characterized by , that the clamping tool (2, 3) is a clamping pin (2, 3), a sheet metal component (1), preferably fixed in a fixed position and formed from the sheet metal, is clamped between the clamping pins (2, 3) arranged on the top and bottom of the respective test area (12) of the sheet metal component (1), subsequently, the clamping pins (2, 3) are rotated perpendicular to the sheet plane in the test area (12) in the same direction relative to the preferably stationary sheet metal component (1), and the torque required to rotate the clamping pins (2, 3) and thus to locally shear the sheet metal component (1) in the test area (12) and the relative angle of rotation of the clamping pins (2, 3) are measured and recorded. [2] Test method according to claim 1, characterized by that the sheet metal component (1) or the clamping tool (2, 3) is fixed in place (5) as a whole during the test procedure. [3] Test method according to one of claims 1 or 2, characterized by that the torque of the clamping pins (2, 3) is only applied to the test area (12) of the sheet metal component (1) until the sheet metal component (1) in the test area (12) just begins to flow plastically. [4] Test method according to one of claims 1 to 3, characterized bythat, based on the measurement of the torque of the torsional load as a function of the angle of rotation of the clamping pins (2, 3), a curve of the deformation of the sheet metal component (1) in the test area (12) can be determined, from which the transition between elastic and plastic deformation of the sheet metal component (1) can be recognized. [5] Test method according to claim 4, characterized by that the torque is only applied until a bend in the recorded curve of the torque / torsion angle curve or the torque / torsion time curve becomes visible, which indicates the transition between essentially linear elastic deformation and local plastic flow of the sheet metal component (1) in the test area (12). [6] Test method according to claim 5, characterized bythat a change in the gradient of the determined curve can be taken as a criterion for the transition between elastic deformation and plastic flow of the sheet metal component (1) in the test area (12). [7] Test method according to one of the preceding claims, characterized by that the angle of rotation of the clamping pins (2, 3) during the test procedure corresponds to the elongation in the test area (12) of the sheet metal component (1). [8] Test method according to one of the preceding claims, characterized by that the shear stress in the test area (12) of the sheet metal component (1) is calculated from the torque. [9] Test method according to one of the preceding claims, characterized by that the change in shape of the sheet metal component (1) in the test area (12) is determined tactilely, preferably by a sensor arranged on the sheet metal component (1). [10] Test method according to one of the preceding claims, characterized bythat the change in shape of the sheet metal component (1) in the test area (12) is determined optically, preferably by optical evaluation (8) of changes in samples (11) applied to the test area (12). [11] Testing device for the non-destructive determination of strength and / or forming-related material properties of a sheet (1) to be tested on the basis of the plane torsion test, in which at least one section of the sheet (1) forming a test area (12) is subjected to a torsional load by means of a clamping tool (2, 3) and at least the torque and angle of rotation of the clamping tool (2, 3) are recorded, characterized by , that the sheet metal component (1) formed from the sheet metal is held or fixed in a stationary manner (5) relative to the testing device as a whole, the testing device has, as a clamping tool (2, 3), two axially aligned and movable clamping pins (2, 3), between which the sheet metal component (1) can be positioned aligned with its respective test area (12) and the clamping pins (2, 3) clamp the sheet metal component (1) between them in the axial direction (4), a drive device rotates the clamping pins (2, 3) perpendicular to the sheet plane in the test area (12) in the same direction relative to the stationary sheet metal component (1), and a measuring device (9) measures and records the torque required for twisting the clamping pins (2, 3) and thus for the local shearing of the sheet metal component (1) in the test area (12) and the relative twisting angle of the clamping pins (2, 3) and / or the twisting time. [12] Test device according to claim 11, characterized by that the clamping pins (2, 3) have identical clamping surfaces (7) facing each other, between which the sheet metal component (1) to be tested is held clamped. [13] Test device according to claim 12, characterized by that the clamping surfaces (7) are circular and flat. [14] Test device according to claim 12, characterized by that the clamping surfaces (7) are profiled, preferably dome-shaped. [15] Test device according to one of claims 12 or 13, characterized by that the clamping surfaces (7) have punctiform profiles which allow a positive and non-positive clamping of the sheet metal component (1) between the clamping pins (2, 3). [16] Test device according to one of claims 11 to 15, characterized by that the sheet metal component (1) to be tested is held or dimensioned in such a way that no twisting of the sheet metal component (1) can occur due to the torsional load during the measurement. [17] Test device according to one of claims 11 to 16, characterized bythat the radial dimensions of the clamping pins (2, 3) are designed in such a way that measurements in narrow, curved test areas of the sheet metal component (1) are also possible with the clamping pins (2, 3). [18] Test device according to one of claims 11 to 17, characterized by that the clamping pins (2, 3) are held on a pliers-like holder (10) which can also be positioned on tightly curved test areas of the sheet metal component (1). [19] Test device according to one of claims 11 to 18, characterized by that the testing device can be automatically positioned relative to the sheet metal component (1) by positioning devices, preferably by industrial robots. [20] Test device according to one of claims 11 to 18, characterized by that the testing device is integrated as a stationary testing device into a process chain for the production of the sheet metal component (1). [21] Test device according to one of claims 11 to 18, characterized bythat the testing device is arranged mobile on a movable base unit and can be positioned and aligned relative to the sheet metal component (1).

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