Test device for checking the tensile adhesion strength of a first element on a second element and method for checking the tensile adhesion strength

Abstract

The invention relates to a test device (1) for checking the tensile adhesion strength of a first element (3) to a second element (4), comprising a test body (6) which encloses a continuous channel (12), wherein the test body (6) is configured to be applied to the first element (3) in such a way that a first opening (15) of the channel (12) is completely covered and closed by the first element (3), a vacuum generation device (7) which is configured to establish a vacuum in the channel (12), whereby, for checking the tensile adhesion strength, the vacuum established in the channel (12) causes the first element (3) to be pulled on by the first element (3) in a test area (9) of the first element (3) until the first element (3) detaches from the second element (4) in its test area (9), and an electronic computing device (8) which is configured toto determine the tensile bond strength of the first element (3) to the second element (4).

Description

[0001] The invention relates to a testing device and a method for checking the tensile adhesion strength of a first element to a second element.

[0002] From KR 10 1680 315 B1, a fastening device for attaching a support to a coating film is known, wherein the support is used to test the adhesion of the coating film. It is provided that the support is bonded to the coating film for the test.

[0003] Furthermore, a device for determining the adhesive strength between two adhering materials is known from DE 7 313 042 U. The device comprises a testing device capable of generating and measuring a torque, and a substantially cylindrical stamp glued to the material to be tested with its contact surface. The stamp is provided with a collar having an outer polygonal circumference, through which the torque generated by the testing device can be transmitted to the stamp.

[0004] Furthermore, an adjustable automatic pull test device is known from CN 216 696 020 U. The device can be connected to a surface of an object to be tested via a suction connection or a clip connection.

[0005] Furthermore, a method for measuring the adhesion strength of a coating film is known from JP H05-142 128 A.

[0006] The object of the present invention is to provide a solution by which the tensile adhesion strength of a first element to a second element can be checked in a particularly simple and reproducible manner.

[0007] This problem is solved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description, and the figures. Features, advantages, and possible embodiments set forth in the description for one of the subject matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the dependent claims.

[0008] The invention relates to a testing device for checking the tensile adhesion strength of a first element to a second element. The first element is, for example, a component, and the second element can be, for example, a coating applied to the component. The tensile adhesion strength serves as a characteristic value for the adhesion of layers to surfaces. The tensile adhesion strength can be determined using a tensile adhesion test. Typically, in a tensile adhesion test, a stamp affixed to the first element is pulled off slowly and uniformly perpendicular to the surface of the first element, to which the stamp is attached, using a tensile testing machine until it breaks or detaches. Upon detachment, the first element, including the attached stamp, separates from the second element.Therefore, in this adhesion test, the adhesive bond of the stamp to the first element must be stronger than the bond between the first element and the second element.

[0009] In surface engineering research, methods for the quantitative evaluation of coatings, such as paints, are indispensable. A pull-off test is a common mechanical testing method for quantifying the adhesion of coatings, for example, paint systems on visible vehicle components. For the test, dollies are attached to the coating under test using an adhesive. The dolly is then subjected to a test force until the coating breaks. This test force can be generated, for example, hydraulically, pneumatically, centrifugally, or by a tensile testing machine. The tensile adhesion strength, expressed in Newtons per square millimeter, is calculated from the test force applied at the moment of breakage and the contact area.This value provides information about the bonding forces between the component and the coating and is therefore a meaningful indicator of coating quality and adhesion. Interactions between the adhesive and the coating, inaccuracies due to the adhesive's viscosity, and significant time expenditure for preparation and application are disadvantages in this regard.

[0010] Existing solutions for attaching the dolly by adhesive have several disadvantages, which are explained in more detail below. Due to the mandatory requirement for repeatability, great care must be taken when gluing the dolly, and a stable testing environment must be provided. Strictly required drying cycles of the adhesive limit the productivity of bonding the dolly to the first element. Reactive effects of the adhesive on the first element cannot be ruled out. Influences on the adhesion of the first element to the second element and a reduction in the measured tensile bond strength can occur. Depending on the material being tested, testing personnel must have access to a portfolio of suitable adhesives. Multiple uses of dollies are not possible with this type of bonding. Viscosities of the adhesive reduce the accuracy of the results.Since a homogeneous adhesive layer thickness must be maintained, bonding the dolly can only be applied to flat first elements. Fragments of the first element that detach from the second element can only be characterized and quantified with considerable effort due to contact with the adhesive. A measurement setup is often implemented on a universal testing machine, which involves increased setup and changeover effort and temporarily prevents the machine from being used for other tests.

[0011] The test device according to the invention comprises a test body, a vacuum generation device, and an electronic computing device. The test body encloses a continuous channel and is configured to be positioned against the first element such that a first opening of the channel is completely covered and sealed by the first element. The vacuum generation device is configured to establish a vacuum in the channel via a second opening, whereby, for the purpose of checking the tensile adhesion strength, the vacuum established in the channel exerts a pull on the first element in the test area of ​​the first element covered by the first opening of the channel until the first element detaches from the second element in this test area.The test area of ​​the first element is thus the area covered by a cross-sectional area of ​​the opening, whereby the first element is subjected to a vacuum within this test area. The electronic computing unit is designed to determine the tensile adhesion strength of the first element to the second element based on the vacuum applied in the channel when the first element is detached within the test area. The test device thus enables, on the one hand, the attachment of the test specimen to the first element by means of a vacuum, and on the other hand, the execution of the tensile adhesion test using the vacuum applied in the channel. The vacuum is applied to the first element until it detaches from the second element. The use of adhesive to attach the test specimen or any other tool to the first element is therefore not required.The test specimen serves two purposes: firstly, it acts as a hold-down device for the area surrounding the test zone of the first element, thus preventing a large-scale separation of the first element from the second element; and secondly, it allows for the tight application of a vacuum to the first element within the test zone. This enables the adhesion test to be performed using the vacuum applied to the test zone of the first element. Because the adhesion test is performed solely by applying the vacuum, the influence of adhesive on the adhesion strength of the first element to the second element, which can occur in connection with existing adhesion test methods, is effectively avoided. Furthermore, testing using the vacuum applied to the test zone of the first element allows for the surface of the first element, to which the test specimen is applied, to be uneven.This allows for the testing of uneven surface areas of the first element with regard to adhesion strength. The test device thus enables a particularly simple and reproducible testing of the adhesion strength of the first element, which does not necessarily have to have a flat outer surface in the test area.

[0012] In a possible further development of the invention, the test specimen comprises a sealing element that completely encloses the first opening of the channel around its entire circumference. The sealing element is designed to come into direct contact with the first element when the test specimen is applied to it, thereby enabling the first opening of the channel to be hermetically sealed by the first element together with the sealing element. The sealing element thus ensures that the test area of ​​the first element is connected to the channel only fluidically, and that when the negative pressure is applied to the channel, the test area of ​​the first element is subjected to the negative pressure.This effectively prevents the risk of air being drawn in when adjusting the vacuum in the channel along a contact surface between the test specimen and the first element. This allows for particularly easy and precise adjustment of the vacuum in the channel and its application within the test area of ​​the first element. Specifically, the sealing element provides a contact surface for the test specimen, which, during intended use, is in contact with the first element.

[0013] In this context, it may be particularly useful for the sealing element to include a rubber seal. Due to the elastic design of the sealing element, the rubber seal ensures that the opening is reliably sealed around its entire circumference when used as intended, i.e., when the test specimen is placed against the first element. Furthermore, a rubber seal offers exceptional durability.

[0014] In a further possible embodiment of the invention, the test body comprises at least one blade, which is configured to project from the side of the test body on which the first opening is located. This allows the blade to cut into or slice the first element when the test body is applied to the element. This ensures that the test area of ​​the first element is at least partially separated from the remaining portion of the first element by means of the blade. Consequently, when performing the pull-off adhesion test using the test device, the binding forces or adhesive forces within the first element are minimally affected or distorted when the test area of ​​the first element is subjected to negative pressure.Due to the at least partial separation of the test area of ​​the first element from the rest of the first element, it can be ensured that, when a vacuum is applied to the test area of ​​the first element, the tensile bond strength of the first element can be tested particularly accurately on the second element. The blade, through its cutting action, enables a particularly simple, at least partial, separation of the test area from the rest of the first element.

[0015] In this context, it is particularly intended that the blade covers the first opening in a direction perpendicular to the opening surface, or that the blade is completely closed, with the circumferential blade defining the opening. In other words, the blade can project beyond the opening and thereby cover it in a direction perpendicular to the opening surface, ensuring that, when the test device is used as intended, the first element is cut by the blade in an area covered by the first opening, or where the vacuum is applied during the pull-off test. Specifically, the blade abuts flush against a wall of a base body of the test specimen that defines the opening, in a direction perpendicular to the opening surface.If the blade is circumferential, for example, ring-shaped, then the channel can be defined by the blade in the area of ​​the first opening. This ensures that when the test specimen is placed against the first element, the blade is the first to make contact with the surface of the first element. When the test specimen is pressed against the first element, the blade cuts a continuous, closed section of the first element, which is the test area. This allows the test area to be completely separated from the rest of the first element by the continuous blade. If a vacuum is then applied to the channel, only this test area of ​​the first element, cut off from the rest of the element by the blade, is subjected to the vacuum.In the circumferential design of the blade, the blade defines the extent of the test area of ​​the first element being inspected and ensures that this test area is completely separated from any remaining portion of the first element when the test specimen is pressed against it, particularly by adjusting the vacuum in the channel. If the blade is circumferential, the first element can be punched or pressed in by applying pressure. If the blade is not circumferential, and is specifically designed to cover the first opening in the direction perpendicular to the opening surface, the first element can be cut by rotating the blade around a central axis of the test specimen. Furthermore, the blade can be either fixed or adjustable.If the blade is adjustable, then the blade can be adjusted between a stowed position within the base body and a cutting position protruding above the base body.

[0016] In a further possible embodiment of the invention, a collection device completely covering the cross-section of the channel is arranged within the channel. This collection device can, in particular, comprise a net or a grid. Because the collection device completely covers the cross-section of the channel, material from the first element that is drawn into the channel, especially when the negative pressure is set, can be collected by means of the collection device. By collecting the material from the first element that has detached from the second element or from a remnant of the first element during the pull-off test, the quality and / or quantity of the material from the first element collected by the collection device can be examined.Furthermore, by catching the aspirated material with the collection device, it is particularly effective in preventing material from the first element, which has detached from the second element during the adhesion strength test, from being drawn into the vacuum generation device and potentially damaging it. The collection device is therefore designed to be air-permeable to ensure that the vacuum in the channel can be set and, in particular, that the vacuum can be used to pull on the first element in the test area, while simultaneously ensuring that any parts of the first element that enter the channel are reliably collected.

[0017] In a further possible embodiment of the invention, the first opening is circular. It is also possible for the channel to have a circular cross-section. The test specimen with the circular first opening can be manufactured particularly easily, for example, by drilling the channel into a base body of the test specimen. Furthermore, the circular shape of the first opening allows for a particularly simple airtight seal of the test specimen against a surface of the first element, regardless of whether this surface of the first element is flat, convex, or concave. Alternatively, the opening surface can have any geometry.

[0018] The invention further relates to a method for checking the tensile bond strength of a first element to a second element using a test device as already described in connection with the test device according to the invention. In this method, the test specimen is positioned against the first element with the side having the first opening of the channel, thereby completely covering and closing the first opening of the channel. The area of ​​the first element covered by the first opening is a test area of ​​the first element.The method further provides that a vacuum is created in the channel via the second opening of the channel using the vacuum generation device of the test apparatus. This creates a vacuum that pulls on the first element in the test area covered by the first opening of the channel until the first element detaches from the second element within this test area. The method further provides that the adhesive tensile strength of the first element to the second element is determined by the electronic computing device based on the vacuum created in the channel when the first element detaches within the test area and the opening area of ​​the first opening. This method enables a particularly simple and reproducible verification of the adhesive tensile strength of first elements attached to second elements, even in areas of the first element that are not necessarily flat.

[0019] Further features of the invention may become apparent from the following description of the figures and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0020] The drawing shows in the single figure ( Fig. 1) a schematic sectional view of a test device and of a component comprising a first element and a second element, to which the test device is attached.

[0021] In Fig. Figure 1 shows a test device 1 in a schematic sectional view, which is attached to a component 2. The component 2 comprises a first element 3 and a second element 4. The first element 3 is held against the second element 4. In this case, the first element 3 is a coating applied to the second element 4. This coating can comprise several layers and thus be designed as a composite structure. The test device 1 is configured to test the tensile adhesion strength of the first element 3 to the second element 4. For this purpose, the test device 1 is attached to the first element 3, in particular to a surface 5 of the first element 3 facing away from the second element 4. The test device 1 comprises a test specimen 6, a Fig. 1 schematically marked with a box, a vacuum generating device 7, and a [unclear] Fig. 1. Electronic computing device schematically marked with a box. 8.

[0022] The test device 1 is designed to be held by means of negative pressure on the surface 5 of the first element 3 and to pull on the first element 3, in particular in a test area 9 of the first element 3, by means of negative pressure, until the first element 3 detaches from the second element 4 in the test area 9.

[0023] The test specimen 6 is designed in the form of a hollow cylinder and is rotationally symmetrical. The test specimen 6 comprises a cylindrical base body 10, which has a bore 11 in its center that at least partially delimits a channel 12 of the test specimen 6. The bore 11 runs parallel to a central axis of the cylindrical base body 10 along its longitudinal direction; in particular, a central axis of the bore 11 coincides with a central axis of the base body 10. The test specimen 6 further comprises a sealing element 13, which is arranged on the end face of the test specimen 6. This sealing element 13 is a rubber seal. The rubber seal is positioned as shown in Fig. 1 can be particularly well identified when checking the tensile adhesion strength of the first element 3 on the surface 5 of the first element 3. The sealing element 13 serves to seal the test specimen 6 against the surface 5 of the first element 3, thereby preventing ambient air from being drawn into the channel 12 along a contact surface of the test specimen 6 with the surface 5 of the first element 3.

[0024] In the present case, the test specimen 6 further comprises a blade 14, which is formed around its entire circumference. As in Fig.Since the first element 3 can be particularly well identified, the blade 14 thus encloses the test area 9 of the first element 3 around its entire circumference. In particular, the blade 14 defines the extent of the test area 9 of the first element 3 by circumferentially enclosing the channel 12 at one end and limiting a first opening 15 of the channel 12. The test specimen 6 is applied to the surface 5 of the first element 3 for checking its tensile bond strength in such a way that the first opening 15 of the channel 12 is covered and closed by the surface 5 of the first element 3. When the test specimen 6 is applied to the surface 5 of the first element 3, the blade 14 is pressed into the first element 3, thereby cutting the first element 3 with the blade 14. Thus, the blade 14 cuts out the area of ​​the first element 3 which is aligned with the first opening 15.

[0025] The vacuum generating device 7 is designed to establish a vacuum in the channel 12 via a second opening 17. When a vacuum is established in the channel 12 by means of the vacuum generating device 7, the area of ​​the first element 3, cut out by the blade 14 and representing the test area 9, is subjected to the vacuum, or rather, drawn inwards into the channel 12 by the vacuum. The sealing element 13 prevents air from being drawn into the channel 12 via the first opening 15 during normal use of the test specimen 6, thus preventing the establishment of the vacuum in the channel 12. The blade 14 is located on the side of the test specimen 6 where the first opening 15 is situated.This design enables the blade 14 to cut the first element 3 when the test specimen 6 is placed against the first element 3. In this case, the first opening 15, like the channel 12, has a circular cross-section. The blade 14 is designed to be annular in shape so that, firstly, the circular opening 15 can be defined by the blade 14, and secondly, the test area 9 of the first element 3 can be cut off from the remaining portion of the first element 3 in a circular fashion.

[0026] The vacuum generation device 7 is designed to adjust the vacuum in the channel 12, thereby holding the test specimen 6 with a holding force F. HDue to the negative pressure applied in channel 12, the surface 5 of the first element 3 is drawn towards it. Furthermore, the first element 3 is pulled through the first opening 15 in the test area 9 of the first element 3. The base body 10 of the test specimen 6 thus serves as a hold-down for the remaining portion of the first element 3 that surrounds the test area 9, while the test area 9 of the first element 3 is drawn into the channel 12 by means of the negative pressure applied in channel 12. To perform the tensile adhesion test, the negative pressure is continuously increased until the first element 3 detaches from the second element 4 in the test area 9. It is possible that at least parts of the test area of ​​the first element 3 detach from the remaining portion of the first element 3 and move in the channel 12 towards the negative pressure generating device 7.

[0027] To prevent damage to the vacuum generation device 7 caused by material from the first element 3 released from component 2, the test specimen 6 includes a trapping device 16. This trapping device 16 is located within the base body 10 and completely covers the cross-section of the channel 12. In particular, the trapping device 16 comprises a grid and / or a net, which allows material from the first element 3 drawn into the channel 12 to be captured by the trapping device 16 and thus prevented from reaching the vacuum generation device 7.

[0028] The test specimen 6 thus has a vacuum channel 12, which in this case is formed at least partially by a through-hole in the base body 10 of the test device 1. A vacuum -p is applied via the channel 12. Happlied to the first element 3, thereby creating an adhesive force F between the surface 5 of the first element 3 and the test specimen 6 H This creates a bond that eliminates the need to glue a dolly to the first element 3 to check the tensile adhesion strength.

[0029] To ensure a seal at the contact surface of the test specimen 6 with the surface 5 of the first element 3 despite varying components and fluctuating surface roughness or conditions, a compensating rubber seal 13 is provided on the end face of the base body 10. The blade 14, which circumferentially surrounds the channel 12, projects beyond the end face of the base body 10 and the sealing element 13, so that the blade 14 is pressed into the component 2 by means of the adhesive force, in particular at least into the first element 3. This improves the lateral circumferential sealing of the channel 12 compared to a design of the test specimen 6 without the blade 14, and the test area 9 of the first element 3 can be separated from the rest of the first element 3 surrounding the test area 9.Here, this blade 14 would be designed such that it cuts out the first element 3 with a maximum cross-sectional area equal to the size of the first opening 15. The test force F. p In the present method for checking the tensile adhesion strength of the first element 3 on the second element 4, the same applies as to the adhesion force F. HThe vacuum is generated by the negative pressure set in channel 12. The negative pressure in channel 12 is increased until the first element 3 fails, particularly in test area 9. The tensile bond strength of the first element 3 to the second element 4 is determined from the cross-sectional area of ​​the first opening 15 and the negative pressure in channel 12 at the moment of failure of the first element 3. A net or sieve in the catching device 16 prevents fragments of the first element 3 from being drawn into the vacuum generation device 7. Analysis of these fragments allows conclusions to be drawn about the extent of delamination or the amount of material detached from the first element 3.

[0030] As an alternative to the completely closed design of the blade 14, the first opening 15 of the test body 6 can be bounded by the sealing element 13 or the base body 10. In this case, a tip of the blade 14 is aligned with a wall of the test body 6 that radially outwards bounds the first opening 15 in a direction perpendicular to an opening surface of the first opening 15, or is arranged in this direction perpendicular to the opening surface of the first opening 15, overlapping the cross-sectional area of ​​the first opening 15.

[0031] In the described test device 1, it is not necessary to bond the test specimen 6 to the component 2, in particular the first element 3.

[0032] The electronic computing device 8 is configured to determine the tensile bond strength of the first element 3 to the second element 4 based on the vacuum applied in channel 12 when the first element 3 is released in test area 9. The vacuum in channel 12 thus serves, firstly, to secure the test specimen 6 to the surface 5 of the first element 3 and, secondly, to generate the test force for verifying the tensile bond strength of the first element 3. A continuous increase in the vacuum applied in channel 12 generates a continuous increase in the test force F. p This test force F p The pressure is increased until the first element 3 fails. The tensile bond strength is determined from the cross-sectional area of ​​the first opening 15 and the negative pressure in the channel 12 at the moment of failure. The test specimen 6, which is tangentially in contact with the surface 5 of the first element 3 around the test area 9, exerts an adhesive force F.H simultaneously as a hold-down device for the first element 3 outside the test area 9. This ensures that a failure of the first element 3 only occurs in the test area 9, which is subjected to negative pressure.

[0033] If the first element 3 is a particularly durable coating requiring a high test force and thus a high vacuum, the seal of the test specimen 6 can be reinforced by the blade 14, which is designed to be punch-like and is inserted in the end face of the test specimen 6. When the test specimen 6 is pressed against the surface 5 of the first element 3, the blade 14 cuts through the first element 3 into the second element 4, thus separating the test area 9 from the rest of the first element 3. In addition to the particularly good seal, the blade 14 causes a defined failure of the first element 3 in the relevant test area 9. Scoring or cutting the first element 3 can be optional for layer thicknesses of the first element 3 up to 150 µm and mandatory for layer thicknesses of the first element 3 of 150 µm and above.

[0034] By generating the adhesive force F HThe vacuum created between the test specimen 6 and the surface 5 of the first element 3 eliminates the need for any adhesive. This eliminates potential sources of error and productivity-reducing characteristics associated with bonding. Since no material-specific adhesive is required, the necessary measuring equipment and test setup are reduced, as is the complexity of the procedure and the need for expert knowledge. Furthermore, the test specimen 6 can be reused multiple times and does not need to be disposed of after a single use. The absence of drying cycles facilitates mobile field applications and in-line use. The end face of the test specimen 6, with its sealing element 13, also allows it to conform to non-planar surfaces of the first element 3, thus enabling the test device 1 to be used for inspecting components 2 with complex geometries, such as convex surfaces.

[0035] Overall, the invention demonstrates how a vacuum-based adhesion test can be performed. Reference symbol list 1 test device 2 components 3 first element 4 second element 5 Surface 6 test specimens 7 Vacuum generating device 8 electronic computing equipment 9 Test area 10 basic shapes 11 bore 12-channel 13 Sealing element 14 blade 15 first opening 16 Catching device 17 second opening F H Adhesive force F p Test force p H -negative pressure QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] KR 10 1680 315 B1

[0002] DE 7 313 042 U

[0003] CN 216 696 020 U

[0004] JP H05-142 128 A

[0005]

Claims

[1] Test device (1) for checking the tensile adhesion strength of a first element (3) to a second element (4), comprising - a test body (6) which encloses a continuous channel (12), wherein the test body (6) is designed to be applied to the first element (3) in such a way that a first opening (15) of the channel (12) is completely covered and closed by the first element (3), - a vacuum generation device (7) which is configured to establish a vacuum in the channel (12) via a second opening (17) of the channel (12), whereby, for checking the adhesive tensile strength, the vacuum established in the channel (12) in the test area (9) of the first element (3) covered by the first opening (15) of the channel (12) is applied to the first element (3) until the first element (3) detaches from the second element (4) in its test area (9), and - an electronic computing device (8) which is designed to determine the adhesive tensile strength of the first element (3) on the second element (4) on the basis of a negative pressure set in the channel (12) when the first element (3) is released in the test area (9). [2] Test apparatus (1) according to claim 1, wherein the test body (6) comprises a sealing element (13) which completely encloses the first opening (15) of the channel (12) around its entire circumference and is designed to bear against the first element (3) when the test body (6) is applied to the first element (3), whereby the channel (12) can be hermetically sealed by the first element (3) together with the sealing element (13) at the first opening (15). [3] Test device (1) according to claim 2, wherein the sealing element (13) comprises a rubber seal. [4] Test device (1) according to one of the preceding claims, wherein the test body (6) comprises at least one blade (14) which is configured to protrude from the side of the test body (6) on which the first opening (15) is arranged, whereby the blade (14) is configured to cut the first element (3) when the test body (6) is placed against it. [5] Test device (1) according to claim 4, wherein the blade (14) covers the first opening (15) in a direction perpendicular to the opening surface or the blade (14) is designed to be closed all around, whereby the circumferential blade (13) limits the opening (15). [6] Test device (1) according to one of the preceding claims, wherein a trapping device (16) completely covering a cross-section of the channel (12) is arranged within the channel (12), which in particular comprises a net or a grid, whereby material of the first element (3) sucked into the channel (12) can be captured by means of the trapping device (16). [7] Test device (1) according to one of the preceding claims, wherein the first opening (15) is circular. [8] Method for checking the tensile adhesion strength of a first element (3) to a second element (4) using a test device (1) according to one of the preceding claims, in which the test body (6) is applied to the first element (3) with its side having the first opening (15) of the channel (12), whereby the first opening (15) of the channel (12) is completely covered and closed by the first element (3), a vacuum is established in the channel (12) by means of the vacuum generation device (7) via the second opening (17) of the channel (12), whereby in the test area (9) of the first element (3) covered by the first opening (15) of the channel (12) a pull is exerted on the first element (3) until the first element (3) detaches from the second element (4) in its test area (9),and the adhesive tensile strength of the first element (3) on the second element (4) is determined by means of the electronic computing device (8) based on the negative pressure set in the channel (12) when the first element (3) is released in the test area (9) and the opening area of ​​the first opening (15).

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