Bending test device for sheet metal strips

Abstract

Bending test device (1) for sheet metal strips (38; 39; 40), comprising a first support (2) and a second support (3) for supporting a test strip (4), which is designed in the form of a sheet metal strip (38; 39; 40), and a punch (6) which is arranged between the two supports (2, 3) for applying a load in the form of a deflection of the test strip (4), wherein the punch (6) is designed to move relative to the supports (2, 3) along a vertical axis (5) of the bending test device (1), wherein the vertical axis (5) lies transversely to a bearing axis (29) formed between the two supports (2, 3), wherein the test strip (4) is arranged on and / or in the supports (2, 3) along the bearing axis (29), and wherein the supports (2, 3) each have a cylinder (13) for supporting the sheet metal strip (38; 39; 40). Stamp (6) for contacting the sheet metal strip (38; 39;40) have a punch cylinder (22), wherein, for the purpose of ensuring the positioning of the test strip (4) in the bearing axis (29), the first support (2) and / or the second support (3) and / or the punch (6) has a guide element (23) encompassing the cylinder (13; 22) over its circumference, wherein the guide element (23) is designed independently of the cylinder (13; 22).

Description

The invention relates to a bending test device for sheet metal strips according to the preamble of claim 1. Bending test devices for sheet metal strips are known in sheet metal processing. These devices can be used, for example, to characterize joining techniques that involve joining at least two sheet metal strips. For instance, a bending test device in the form of a three-point bending test machine for testing a welded joint between two components is known from publication CN 1 02 305 744 A. From the publication CN 2 10 571 778 U, a three-point bending test machine with two supports and one punch is known, wherein the supports each have a test part guide in the form of two spaced-apart radial projections, and wherein the distance between the two radial projections is adjustable. Documents CN 1 09 632 526 A and CN 2 06 906 142 U disclose a three-point bending test machine with two spaced-apart supports and a punch, wherein a distance formed between the supports is adjustable. Document CN 1 09 765 121 A describes a three-point bending tester for testing cylindrical components, featuring two spaced-apart supports and a punch. The distance between the supports is adjustable, and each support has a roller with a V-shaped groove on its circumferential surface to guide the component. The printed document CN 1 10 907 297 B describes a three-point bending test machine, wherein two spaced-apart supports and a punch are provided, and wherein the distance between the supports is adjustable and the supports each have a stop element for positioning a test piece. From publication CN 1 08 562 486 A, a three-point bending testing machine for testing rail welded joints is known, wherein two spaced-apart supports and a punch are provided. Document CN 2 07 300 728 U discloses a three-point bending test machine with two supports and a punch, wherein the supports each have a test part guide in the form of two spaced-apart projections. A three-point bending test machine is also known from publication CN 2 01 607 362 U, which has two supports and a punch. The supports are designed to hold a test strip. To ensure the test strip is positioned correctly during loading by the punch, each support has a guide element on its side. The object of the present invention is to provide an improved bending test device for sheet metal strips. The problem is solved according to the invention by a bending test device for sheet metal strips with the features of claim 1. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the respective dependent claims. A bending test device for sheet metal strips according to the invention comprises a first support and a second support for holding a test strip, which is designed in the form of a sheet metal strip. Furthermore, the bending test device for sheet metal strips comprises a punch, which is arranged between the two supports to apply a load in the form of a deflection of the test strip. The punch is designed to allow movement relative to the supports along a vertical axis of the bending test device, the vertical axis being transverse to a bearing axis formed between the two supports. The test strip is arranged on and / or in the supports along the bearing axis. To ensure the secure positioning of the test strip in the bearing axis, the first support and / or the second support and / or the punch has a guide element that encompasses the cylinder over its circumference. The guide element is designed independently of the cylinder.In other words, the test strip is secured during testing by the guide element and experiences a deflection in the direction of the vertical axis along the bearing axis, without leaving the bearing axis, for example, by buckling or bending. Put another way, the bending test device according to the invention ensures deflection of the test strip in a plane virtually defined by the vertical axis and the bearing axis. This enables a correct and successful test of the test strip. A further advantage of the guide element, which is independent of the cylinder, is that the guide element can be adapted to the test strip. Thus, test strips with different cross-sections can be guided securely by simply exchanging the guide element. Further secure guidance of the test strip is achieved by the comprehensive, or rather,The cylinder is fully enclosed by the guide element. A problem with bending test devices for sheet metal strips according to the prior art is that during the test, i.e., during the bending of the test strip by means of the punch, the test strip can bend or buckle laterally away from the bearing axis, causing the test to fail and consequently requiring it to be repeated. This means not only wasted working time but also the repeated production of the test strip, thus incurring costs. These costs, in particular, can be avoided with the bending test device for sheet metal strips according to the invention. Furthermore, the test using the bending test device according to the invention is repeatable and reproducible. The positioning of the test strip in the bearing axis, achieved by means of the guide element, can largely be accomplished with the guide element in only one of the supports. A preferable positioning method is to implement the guide element in both supports and in the punch. The bending test device for sheet metal strips according to the invention can cover a significantly wider range of test strips, provided that a variable distance is formed between the first support and the second support. To easily change the distance, it is proposed to mount the support on a first mounting plate, which is movable relative to a mounting plate of the bending test device. The bending test device according to the invention is further advantageously designed if the gap formed in the guide element is variable in its gap width. This means that testing of test strips of different sheet thicknesses can also be easily achieved by changing the gap width and not, for example, by replacing the supports. Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. The figures show: Fig. 1 in a perspective view of a bending test device for sheet metal strips according to the invention in a first position; Fig. 2 in a section of a support of the bending test device according to Fig. 1; Fig. 3 in a section of a punch of the bending test device according to Fig. 1; Fig. 4 in a perspective view of the bending test device for sheet metal strips according to the invention in a test position.5 in a section the bending test device according to Fig. 4, Fig. 6 in a perspective view the bending test device according to the invention for sheet metal strips in a second embodiment with angled sheet metal strips, Fig. 7 in a perspective view the bending test device according to the invention for sheet metal strips according to Fig. 6 with flat sheet metal strips, and Fig. 8 in a cross-section exemplary sheet metal shapes suitable for testing in the bending test device according to the invention. A bending test device for sheet metal strips 1 according to the invention, as shown in Fig. 1 and hereinafter referred to as bending test device 1, has a first support 2 and a second support 3, which are designed to receive at least one test strip 4, wherein the test strip 4 is made of a sheet metal part. Opposite the supports 2, 3, viewed in the direction of a vertical axis 5 of the bending test device 1, a punch 6 is arranged, which is designed to be movable along the vertical axis 5. The supports 2, 3 are spaced apart from each other, with a bearing axis 29 formed, along which the test strip 4 extends predominantly when it is arranged on the supports 2, 3. To better explain the invention, a Cartesian axis system with axes X, Y, and Z is introduced. The Z-axis corresponds to the vertical axis 5 of the bending test device 1 according to the invention. The X-axis corresponds to the bearing axis 29. In this embodiment, the supports 2 and 3 are identical in construction, except that their arrangement is mirrored with respect to the Z-axis. In other words, the second support 3 is pivoted 180° around the Z-axis relative to the first support 2. The second support 3, shown in section in Fig. 2, will be used below to explain the construction of the supports 2 and 3. The second support 3, which is also the first support 2, comprises a receiving unit 7 that has a guide element 23 for lateral guidance, or in other words, for lateral support of the test strip 4. The guide element 23 has a first element part 34 and a second element part 35, and further has a slot 10 for securely receiving the test strip 4. In the present embodiment, the slot 10 is realized by means of the two spaced-apart element parts 34, 35. It could also simply be designed as a groove, provided that the two element parts 34, 35 were manufactured in one piece. The guide element 23 encompasses the cylinder 13 over its circumference, being independent of the cylinder 13. For testing, the test strip 4 can be inserted into the slot 10, or in other words, placed into it. In the present embodiment, the cylinder 13 is held on a first mounting plate 11 of the bending test device 1 by means of a first support arm 8 and a second support arm 9, wherein the guide element 23 is also arranged between the support arms 8, 9, bearing support on the first mounting plate 11. At an end 19 of the guide element 23 facing the punch 6, thus at an end 19 of the element parts 34, 35 facing the punch 6, the guide element 23 has a locking element 20 which is arranged facing the gap 10, wherein the locking element 20, which is formed in the form of a chamfer, serves to simplify the reception of the test strip 4 and / or to improve the positioning of an angled test strip 4. To change the gap width SB of the gap 10, the second support 3 has an adjustment unit 12, which is movably mounted between the two support arms 8, 9. In the present embodiment, the adjustment unit 12 has a spacer element 21, which is arranged on both sides of the guide element 23 between the guide element 23 and a first bearing support 16 and a second bearing support 17 of the mounting unit 7. In the illustrated embodiment, each element part 34, 35 of each support 2, 3 has the spacer element 21. Alternatively, one of the element parts 34, 35 could be configured without a spacer element 21 or with a spacer element 21 having a thickness D different from the other spacer elements 21, resulting in an asymmetrical arrangement of the test strip 4. Furthermore, the adjustment unit 12 includes an adjustment element 18, which is arranged interchangeably to further secure the gap width SB. In another embodiment, not shown in detail, the adjusting element 18 is preferably designed as a rotatable knurled nut on both sides of the cylinder 13 to change the gap width SB, so that an axial movement of the guide element 23, or of the two element parts 34, 35, can be effected by means of a rotational movement of the adjusting element 18. In other words, the gap 10 can be adjusted in its gap width SB by means of a rotational movement. It should be mentioned here that the bending test device 1 advantageously has a mounting plate 30, usually in the form of a table top of a so-called machine table, which is designed to extend horizontally, particularly in the direction of the X-axis and the Y-axis, and which supports the two supports 2, 3, each of which is fixedly arranged on a first mounting plate 11. In other words, a first mounting plate 11 is assigned to the first support 2 and a first mounting plate 11 is assigned to the second support 3. The first mounting plates 11 are also fixedly, preferably screwed, to the mounting plate 30. The two first mounting plates 11 are axially movable on the mounting plate 30 in the direction of the X-axis by means of a locking unit 31. This means that the supports 2, 3 are each attached to the first mounting plate 11, which is movable relative to the mounting plate 30.Furthermore, a distance 27 is formed between the first support 2 and the second support 3, which is variable. The locking unit 31 is exemplified by a first locking element 32, which is designed as a hole completely penetrating the first mounting plate 11 in the direction of the Z-axis, for example in the form of an elongated hole, and a second locking element (not shown) designed for position securing, which can, for example, be designed as a screw-nut pair extending through the elongated hole in the direction of the Z-axis. However, the locking unit 31 could also be designed in a different form to secure the position of the support 2; 3. Fig. 3 shows a detailed cross-sectional illustration of the punch 6. The punch 6 is shown, by way of example, attached to a second mounting plate 28 of the bending test device 1, which is axially movable relative to the mounting plate 30 along the Z-axis, in the direction of the arrow, see Fig. 1. The punch 6, like the supports 2 and 3, has the guide element 23 in the form of the first element part 34 and the second element part 35. It further comprises a punch cylinder 22, which is attached to the second mounting plate 28 by means of two punch arms of the punch 6, a first punch arm 24 and a second punch arm 25. The guide element 23 is designed to bear against the second mounting plate 28. In its axial extension direction along the Y-axis, the punch cylinder 22 completely penetrates the guide element 23. Thus, the guide element 23 encompasses the entire circumference of the punch cylinder 22, being independent of the cylinder 22. Between the two element parts 34, 35, a further gap 26 is formed, which serves to receive the test strip 4. In an embodiment not shown in detail, the further gap 26 is designed to be adjustable for further secure receipt of the test strip 4 in the punch 6, whereby the element parts 34, 35 can be moved axially along the Y-axis. The punch cylinder 22 has a groove 33 formed around its circumference, by means of which the test strip 4 is additionally guided. The two element parts 34, 35 are demountable, so that test strips 4 in different shapes can be tested in the bending test device 1. Figures 4 and 5 show the bending test device 1 according to the invention, which is designed as a three-point bending test device, in a test position. Figure 5 illustrates a section along the Y-axis for a better understanding of a realized three-point system. To achieve the test position, the punch 6 is moved axially along the Z-axis, or along the vertical axis 5 of the bending test device 1, to deflect the test strip 4. As can be seen particularly in Figure 5, the test strip 4 rests against the cylinders 13 of the supports 2, 3 and against the punch cylinder 22. To prevent lateral bending or buckling of the test strip 4, the guide elements 23 are arranged laterally to receive the test strip 4.In other words, to ensure that the test strip 4 does not bend transversely to a longitudinal extension of the test strip 4, which runs along the X-axis using the introduced Cartesian axis system, the first support 2, the second support 3 and the punch 6 each have the guide element 23. Figure 6 shows a second embodiment of the bending test device 1 according to the invention, in which the guide element 23 of the punch 6 is removed. This has the advantage that the test strip 4 can be angled. A first strip section 36 of the test strip 4, extending along the Z-axis, is placed in the guide elements 23 of the supports 2, 3, with a second strip section 37 extending along the Y-axis over the guide elements 23. Naturally, the test strip 4 extends along the X-axis. The bending test device 1 designed according to the second embodiment is also suitable for testing completely flat test strips 4, as shown by way of example in Fig. 7. The test strip 4 is supported and secured against the guide element 23. Two flat test strips 4 are illustrated by way of example, wherein the test strip 4 shown above is formed from a first sheet metal strip 38 and a second sheet metal strip 39 by means of spot welding, whereas the test strip 4 shown below is joined from the first sheet metal strip 38 and the second sheet metal strip 39 by means of laser welding. During the testing process, the punch 6 moves vertically along the Z-axis onto the test strip 4, which rests on the two supports 2 and 3. The test strip 4 is prevented from bending laterally, particularly in the direction of the Y-axis, by the guide elements 23 of the supports 2 and 3 and the punch 6, which laterally define the test strip 4. The test strip 4 can be loaded by the punch 6 on both sides, on one side only, or centrally in the case of a three-sheet connection. Figure 8 shows exemplary cross-sectional shapes of joined test strips 4, which are preferably suitable for testing in the bending test device 1 according to the invention. From left to right, these are: two angled sheet metal strips 38, 39; an angled first sheet metal strip 38 joined with a flat second sheet metal strip 39; two flat sheet metal strips 8, 39; two flat sheet metal strips 38, 39 joined offset from each other; or two flat sheet metal strips 38, 39 joined with a third sheet metal strip 40 arranged offset from each other. The bending test device 1 according to the invention is designed for testing a joint between joined test strips 4, which consist of at least two sheet metal strips 38, 39. Point-like joints, in which, for example, the test strip 4 projects beyond the guide element 23 on one or both sides, can be tested by modifying the punch 22 and / or omitting the element parts 34, 35. It can also be used to test individual sheet metal strips 38, 39, 40, for example, to investigate a notch effect caused by notches in the sheet metal – geometrically or metallurgically – during a manufacturing step. In this case, the individual sheet metal strip 38, 39, 40 forms the test strip 4. Spot welds, such as those produced by resistance welding, friction welding, riveting, or similar processes, can be tested. Linear welds, such as those produced by laser welding, MIG welding, MAG welding, TIG welding, or similar processes, can also be tested, as can planar welds. In another embodiment of the bending test device 1 according to the invention, not shown in detail, the bending test device 1 is designed as a four-point bending test device. This device has an additional punch cylinder which, viewed in the direction of the X-axis, is at the same height, and thus in the Z-axis direction, as the punch cylinder 22, but offset by a certain amount along the X-axis. This means that the punch 6 comprises the punch cylinder 22 and the additional punch cylinder. The additional punch cylinder could also be arranged on a further punch, which is movable independently of the punch 6, to induce a deflection. In this case, the bending test device 1 according to the invention has the punch 6 and a further punch, each of which is associated with a punch cylinder. Since twisting of the test strip 4 between the two dies of a four-point bend cannot occur, the four-point bend is particularly suitable for joining elements that protrude on one side and / or both sides of the test strip 4, such as a screw or a nail. The support arms 8, 9 and the bearing supports 16, 17 are preferably arranged on the mounting plate 11 with a force-fit connection in the form of a screw connection for secure mounting. Furthermore, this results in simplified disassembly if the guide element 23 needs to be replaced and / or the gap width SB needs to be changed. Reference symbol list 1 Bending test device for sheet metal strips 2 First support 3 Second support 4 Test strip 5 Vertical axis 6 Punch 7 Mounting unit 8 First support arm 9 Second support arm 10 Gap 11 First mounting plate 12 Adjustment unit 13 Cylinder 14 Through opening 15 Cylinder axis 16 First bearing support 17 Second bearing support 18 Adjustment element 19 End 20 Locking element 21 Spacer element 22 Punch cylinder 23 Guide element 24 First punch arm 25 Second punch arm 26 Further gap 27 Distance 28 Second mounting plate 29 Bearing axis 30 Mounting plate 31 Locking unit 32 First locking element 33 Groove 34 First element part 35 Second element part 36 First strip section 37 Second strip section 38 First sheet metal strip 39 Second sheet metal strip 40 Third sheet metal strip SB Gap width X X-axis Y Y-axis Z Z-axis

Claims

Bending test device (1) for sheet metal strips (38; 39; 40), comprising a first support (2) and a second support (3) for supporting a test strip (4), which is designed in the form of a sheet metal strip (38; 39; 40), and a punch (6) which is arranged between the two supports (2, 3) for applying a load in the form of a deflection of the test strip (4), wherein the punch (6) is designed to move relative to the supports (2, 3) along a vertical axis (5) of the bending test device (1), wherein the vertical axis (5) lies transversely to a bearing axis (29) formed between the two supports (2, 3), wherein the test strip (4) is arranged on and / or in the supports (2, 3) along the bearing axis (29), and wherein the supports (2, 3) each have a cylinder (13) for supporting the sheet metal strip (38; 39; 40). Stamp (6) for contacting the sheet metal strip (38; 39;40) have a punch cylinder (22), wherein, for the purpose of ensuring the positioning of the test strip (4) in the bearing axis (29), the first support (2) and / or the second support (3) and / or the punch (6) has a guide element (23) encompassing the cylinder (13; 22) over its circumference, wherein the guide element (23) is designed independently of the cylinder (13; 22). Bending test device (1) according to claim 1, characterized in that a distance (27) is formed between the first support (2) and the second support (3), which is variable. Bending test device (1) according to claim 1 or 2, characterized in that the support (2; 3) is attached to a first mounting plate (11) which is movable relative to a mounting plate (30) of the bending test device (1). Bending test device (1) according to one of the preceding claims, characterized in that a gap (10) formed in the guide element (23) is variable in its gap width (SB). Bending test device (1) according to claim 4, characterized in that a change in the gap width (SB) can be brought about by means of a rotary movement. Bending test device (1) according to one of the preceding claims, characterized in that the test strip (4) is formed from a first sheet metal strip (38) and a second sheet metal strip (39), wherein the two sheet metal strips (38, 39) are joined by means of a joining method. Bending test device (1) according to one of the preceding claims, characterized in that the guide element (23) has a locking element (20). Bending test device (1) according to one of the preceding claims, characterized in that a punch cylinder (22) of the punch (6), which is designed for contacting the test strip (4), has a groove (33) for at least partially receiving the test strip (4). Bending test device (1) according to one of the preceding claims, characterized in that the punch (6) has a removable guide element (23). Bending test device (1) according to one of the preceding claims, characterized in that the bending test device (1) is designed in the form of a three-point bending test device or a four-point bending test device.

Images