Bending fatigue test device and bending fatigue test system

Abstract

To highly accurately evaluate bending fatigue by reproducing a repetitive load of a light load like the time of continuous processing line passage.SOLUTION: A bending fatigue test device 100 includes: a pair of rotating rolls 11, 13 in which rotational shafts 11a, 13a are arranged in parallel to each other; a strip-shaped body 15 which is wound in contact with outer peripheral surfaces 11b, 13b such that a bending direction is reversed between the outer peripheral surface 11b of the one rotating roll 11 and the outer peripheral surface 13b of the other rotating roll 13 and includes a test body SP in at least a portion thereof; a tension application unit 17 which is connected to one end side of the strip-shaped body 15, capable of extending and retracting freely in an application direction of the tension, and applies a certain level of tension; and a pulling unit 19 which is connected to the other end side of the strip-shaped body 15 and pulls the strip-shaped body 15 along the outer peripheral surfaces 11b, 13b of the rotating rolls. The pulling unit 19 presses the test body SP against the outer peripheral surfaces 11b, 13b of the rotating rolls to apply uniform bending deformation in a width direction of the strip-shaped body 15 to the test body SP.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bending fatigue test device and a bending fatigue test system. [Background technology]

[0002] In a continuous processing line for metal sheets such as aluminum sheets and steel sheets, it is necessary to join a sheet material being passed through (preceding material) to a sheet material being passed through next (following material). An evaluation method for evaluating the joining condition of the welded joint between such preceding and following materials is proposed, for example, in Patent Document 1. In the evaluation method of Patent Document 1, a sample of the welded joint is deep-drawn to a certain depth at several points in the width direction of the steel strip, and if a crack occurs in the welded joint, the joining condition of the welded joint is evaluated from the pressing depth of the punch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-287745 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the evaluation method of Patent Document 1, the bonded sample is pressed with a spherical punch, and the number of fatigue failures is predicted from the pressing depth. Therefore, this evaluation method applies a stress to the test specimen that is greater than the stress applied when the plate material passes through multiple rolls in a continuous processing line, and it is not possible to perform an evaluation that simulates fatigue under a relatively small load in an actual continuous processing line. As a result, it was not possible to accurately evaluate the fatigue state of the plate material in the continuous processing line.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a bending fatigue testing device and a bending fatigue testing system capable of evaluating bending fatigue with high accuracy by reproducing light repeated loads such as those occurring during passage through a continuous processing line. [Means for solving the problem]

[0006] The present invention comprises the following configurations. (1) A bending fatigue testing device that repeatedly generates bending stress while applying tension to a test specimen, A pair of rotating rolls whose rotation axes are arranged parallel to each other; a strip-shaped body that is wound around the outer circumferential surfaces of one of the pair of rotating rolls in such a way that the direction of curvature is reversed between the outer circumferential surface of one of the pair of rotating rolls and the outer circumferential surface of the other rotating roll, and at least a part of the strip-shaped body includes the test specimen; a tension applying part connected to one end of the band-shaped body, capable of extending and retracting in the tension applying direction, and applying a constant tension; a pulling section connected to the other end of the strip and pulling the strip along an outer circumferential surface of the rotating roll; Equipped with The pulling unit presses the test piece against the outer peripheral surface of the rotating roll to apply a uniform bending deformation to the test piece in the width direction of the strip. Fatigue testing equipment. (2) The bending fatigue test apparatus according to (1), a control device that drives the pulling unit to perform a pulling operation in which the other end of the strip is pulled by applying a tensile force greater than the tension from the tension applying unit, and a returning operation in which the tensile force is relaxed within a range in which the tension applied from the tension applying unit is not lost; A bending fatigue test system comprising: Effect of the Invention

[0007] According to the present invention, it is possible to reproduce a light repeated load such as that occurring when passing through a continuous processing line, and to evaluate bending fatigue with high accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a bending fatigue test system including a bending fatigue test device according to this embodiment. [Diagram 2] FIG. 2 is a plan view of the strip containing the test specimens. [Figure 3A] FIG. 3A is a plan view of a rotating roll portion for explaining the pulling operation in the bending fatigue testing device. [Figure 3B] FIG. 3B is a plan view of a rotating roll portion for explaining the returning operation in the bending fatigue testing device. [Figure 4] FIG. 4 is an explanatory diagram illustrating the stress generated in a plate material wound around a roll. [Diagram 5] FIG. 5 is a graph showing stresses occurring in plates having different thicknesses. [Figure 6] FIG. 6 is a flow chart illustrating the bending fatigue test performed by the bending fatigue test system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a schematic diagram of a bending fatigue test system 200 including a bending fatigue test apparatus 100 according to this embodiment. The bending fatigue test apparatus 100 includes a pair of rotating rolls 11, 13, a strip 15, a tension applying unit 17, and a traction unit 19. This bending fatigue test apparatus 100 is a test apparatus that applies tension to a test specimen SP (described later) included in the strip 15 while repeatedly generating bending stress, thereby evaluating the test specimen SP. This bending fatigue test apparatus 100 includes a control device 60, thereby constituting a bending fatigue test system 200.

[0010] The pair of rotating rolls 11 and 13 are arranged with a gap between them. The rotating roll 11 is supported rotatably around a rotating shaft 11a, and the rotating roll 13 is supported rotatably around a rotating shaft 13a. The rotating shafts 11a and 13a of the rotating rolls 11 and 13 are fixed and arranged parallel to each other. The diameters of the rotating rolls 11 and 13 are each 100 mm or more, preferably 150 mm or more, and more preferably 300 mm or more, and 1000 mm or less, preferably 900 mm or less, and more preferably 800 mm or less.

[0011] The strip 15 is formed in a long strip shape and is wound around a pair of rotating rolls 11, 13. Specifically, the strip 15 is wound in contact with the outer circumferential surfaces 11b, 13b between the outer circumferential surface 11b of one rotating roll 11 and the outer circumferential surface 13b of the other rotating roll 13 so that the direction of curvature is reversed. The strip 15 has one end connected to a driven linear member 21 and the other end connected to a driving linear member 23. As the driven linear member 21 and the driving linear member 23, for example, a cord such as a wire or a rope is used.

[0012] The tension applying unit 17 is connected to one end of the band 15 via the driven linear member 21. The tension applying unit 17 is, for example, a cable winding type leaf spring, and has a main body 25 with a winding drum (not shown) therein, and a cable 27 wound around the winding drum and pulled out from the main body 25 so as to be movable forward and backward. The winding drum is biased in one rotational direction by a biasing member (not shown) such as a power spring so as to wind up the cable 27. As a result, the tension applying unit 17 applies a constant tension to the cable 27 pulled out from the main body 25.

[0013] The tension applying part 17 has its main body 25 supported by a wall 29. A connecting member 27a such as a hook is provided at the end of the cable 27, and the driven linear member 21 connected to one end of the band-like body 15 is connected to this connecting member 27a. This allows the band-like body 15 to freely extend and retract in the tension applying direction by the tension applying part 17, and a constant tension is applied to the band-like body 15.

[0014] A wall 31 is provided at a position facing the wall 29 on which the main body 25 of the tension applying unit 17 is supported, and a pulley 35 is rotatably supported on this wall 31. The driven linear member 21 is hung on this pulley 35, and the pulling direction of the driven linear member 21 is reversed by the pulley 35 installed midway.

[0015] The traction unit 19 is connected to the other end of the band-shaped body 15 via the driving-side linear member 23. The traction unit 19 is, for example, a winch mechanism, and includes a cylindrical or columnar body 41, a motor 43 that rotates the body 41, and a traction wire (driving-side linear member) 45 wound around the body 41. The body 41 is supported by a wall 47 that is parallel to the wall 29 on which the main body 25 of the tension applying unit 17 is supported. The rotation shaft 41a of the body 41 is rotatably supported by a support member 49 fixed to the wall 47. The motor 43 rotates the rotation shaft 41a of the body 41 in the forward and reverse directions. The traction unit 19 winds up and feeds out the traction wire 45 wound around the body 41 by rotating the rotation shaft 41a of the body 41 in the forward and reverse directions by the motor 43.

[0016] The pulling wire 45 of the pulling unit 19 and the driving side linear member 23 of the band-like body 15 are connected via a load sensor 51. The load sensor 51 is, for example, a load cell, and detects the tension applied to the band-like body 15. In this configuration, the load sensor 51 is mounted on the moving body 53, but the location of the load sensor 51 is not limited thereto. The moving body 53 is, for example, a dolly, and is movable along the winding and unwinding direction of the pulling wire 45 of the pulling unit 19. As a result, the load sensor 51 detects the tension while moving along the moving direction of the band-like body 15 due to the winding and unwinding of the pulling wire 45.

[0017] Two position sensors 55, 57 are provided at lateral positions of the moving body 53 along the moving direction. These position sensors 55, 57 may be, for example, non-contact sensors such as laser sensors that detect the moving body 53, or mechanical contact sensors. One of these position sensors 55, 57, the position sensor 55, is disposed on the winding side of the pulling wire 45, and the other position sensor 57 is disposed on the feeding side of the pulling wire 45, and the position sensors are provided at an interval from each other.

[0018] 2 is a plan view of a strip 15 including a test specimen SP. The strip 15 includes the test specimen SP, and has a pair of dummy strips 71, 81 connected to both ends of the test specimen SP. The test specimen SP is configured by joining ends of two plate-like test pieces P1, P2 to each other at a joint J. The test pieces P1, P2 are, for example, plates made of aluminum or an aluminum alloy, and the ends of the test pieces P1, P2 are joined to the dummy strips 71, 81 by stitcher joining, laser welding, or the like. The test pieces P1, P2 may be plates made of other metal materials such as steel plates.

[0019] The dummy strips 71 and 81 are preferably made of the same material as the test pieces P1 and P2 constituting the specimen SP, and are preferably plate materials having the same thickness. These dummy strips 71 and 81 are joined to both ends of the specimen SP by, for example, MIG welding or the like.

[0020] The strip 15 has connecting members 75, 85 on the side opposite to the side to be joined with the test specimen SP. The connecting members 75, 85 are made of iron, for example, and are joined to the dummy strips 71, 81 by resistance spot welding or the like. Eyebolts 73, 83 are fastened and fixed to these connecting members 75, 85.

[0021] In this band-like body 15, the driven linear member 21 is connected to the eyebolt 73 fixed to one connecting member 75, and the drive linear member 23 is connected to the eyebolt 83 fixed to the other connecting member 85. In this way, the band-like body 15 is set in the bending fatigue test apparatus 100. Then, in the bending fatigue test apparatus 100, the joint J of the test specimen SP of the band-like body 15 is evaluated.

[0022] The strip 15 has a total length L1, a dimension L2 from the end where the driving-side linear member 23 is connected to the joint J of the test specimen SP, and a width W that are set to specified dimensions. The strip 15 also has a pair of dummy strips 71, 81 connected to both ends of the test specimen SP. Therefore, by adjusting the lengths of the dummy strips 71, 81 according to the size of the test specimen SP, the strip 15 can be properly set in the bending fatigue test device 100. In other words, the size restrictions on the test specimen SP are reduced, and the scope of applicable subjects for the test can be expanded.

[0023] 1, a control device 60 provided in the bending fatigue test apparatus 100 and constituting a bending fatigue test system 200 is connected to the motor 43 of the traction unit 19 and controls the driving of the motor 43. A load sensor 51 and position sensors 55, 57 are also connected to the control device 60. Detection signals are transmitted from the load sensor 51 and the position sensors 55, 57 to the control device 60.

[0024] The control device 60 drives the motor 43 of the pulling unit 19 to perform a winding operation and a letting-off operation. In the winding operation, the control device 60 rotates the body 41 of the pulling unit 19 to wind the pulling wire 45 around the body 41, and pulls the other end of the strip 15 by applying a tensile force greater than the tension from the tension applying unit 17. In the letting-off operation, the control device 60 rotates the body 41 of the pulling unit 19 in the opposite direction to that in the winding operation to let out the pulling wire 45, and loosens the tensile force within a range in which the tension applied by the tension applying unit 17 is not lost.

[0025] Fig. 3A is a plan view of the rotating rolls 11 and 13 for explaining the winding operation in the bending fatigue test apparatus 100. Fig. 3B is a plan view of the rotating rolls 11 and 13 for explaining the returning operation in the bending fatigue test apparatus 100.

[0026] 3A , in the winding operation, the pulling wire 45 is wound around the body 41, and the other end of the strip 15 is pulled in the X1 direction. As a result, the test specimen SP of the strip 15 is wound around the outer circumferential surface 13b of the rotating roll 13.

[0027] 3B, in the feeding operation, the pulling wire 45 is fed out from the body 41, and the other end of the strip 15 is pulled in the X2 direction. As a result, the test piece SP of the strip 15 is wound around the outer circumferential surface 11b of the rotating roll 11.

[0028] In this way, the specimen SP of the strip 15 is repeatedly wound around the rotating rolls 13 and 11 by repeating the winding and unwinding operations, and is curved by moving without slipping relative to the rotating rolls 11, 13. As a result, the specimen SP is repeatedly bent by the curvature of the outer circumferential surface 13b of the rotating roll 13 and by the curvature of the outer circumferential surface 11b of the rotating roll 11, which are bent in opposite directions. In addition, since no slippage occurs, scratches on the surfaces of the rotating rolls 11, 13, specimen SP, etc. can be suppressed. This makes it possible to prevent breakage from occurring at scratches, which would make it difficult to perform a proper evaluation.

[0029] The control device 60 switches between the winding operation and the letting-out operation of the traction unit 19 based on the outputs from the position sensors 55, 57. Specifically, when one position sensor 55 detects the moving body 53 and transmits a detection signal, the control device 60 switches from the winding operation of pulling the strip 15 to the letting-out operation of returning the strip 15, and when the other position sensor 57 detects the moving body 53 and transmits a detection signal, the control device 60 switches from the letting-out operation to the winding operation. The control device 60 is provided with a counter, and the counter counts the number of times the winding operation and the letting-out operation have been performed after the start of the test.

[0030] Furthermore, the control device 60 stops driving the motor 43 of the towing unit 19 when the detection value from the load sensor 51 becomes lower than a predetermined threshold value. The control device 60 is equipped with a start button (not shown) that is pressed to start a test and a stop button (not shown) that is pressed to stop a test.

[0031] In bending fatigue tests such as bending tests and bending cycle tests, a load is applied to the center of the test specimen, but the weak part of the joint of the test specimen is not necessarily located in the center. In particular, aluminum is easily thermally softened when joined, and the joint is easily weakened compared to other parts. In a continuous processing line, it is sufficient that the specimen does not break due to the low cycle stress of the tension applied in the line and the bending deformation by the rolls. However, when evaluating the presence or absence of breakage in a continuous processing line using a one-cycle tensile test or deep drawing test, a margin must be provided so that the specimen can withstand high cycles, and it is necessary to have a higher stress resistance than the actual one.

[0032] In addition, in a continuous processing line, as shown in Fig. 4, when stress is considered when tension T and bending force by roll R are applied to plate material B, the bending stress depends on the roll radius r of roll R and the thickness t of plate material B. Here, Fig. 5 shows the relationship between roll diameter 2r and stress σ when plate materials B of different thicknesses t are wound around roll R. For example, the maximum tensile stress σ when plate material B of thickness t is wound around roll R with roll radius r is max is expressed by the formula (1), where E is the Young's modulus of plate B, and A is the cross-sectional area of ​​plate B.

[0033]

number

[0034] Therefore, when evaluating the breakage of plate materials in a continuous processing line, it is necessary to take into account the actual roll diameter 2r and the thickness t of the plate material B.

[0035] Furthermore, when a load is applied to a test specimen by a roll, due to the principle of a pulley, a force twice as large as the force applied to the test specimen wrapped around the roll acts on the roll. Furthermore, when moving a roll, a force to move the roll is required in addition to the force applied to the roll. Thus, when evaluating bending fatigue by reproducing the load applied on a continuous processing line, it is necessary to take into consideration the evaluation location, the load application cycle, the diameter and plate material of the roll in the continuous processing line, and the load applied to the roll, etc.

[0036] According to the bending fatigue test apparatus 100 having the above-described configuration, the test object is bent by a rotating roll simulating the roll of an actual continuous processing line, so that the test load can be applied evenly to the entire joint J. This makes it possible to perform a bending fatigue test under conditions similar to the load in a continuous processing line. In particular, the joint J of this test specimen appears as a line when viewed macroscopically, but is actually a band of a certain width (for example, about 30 mm), and it is difficult to predict which position within this band width will become the weakest part and break. Therefore, in order to obtain high measurement accuracy, it is important to apply the test load evenly to the entire band-shaped joint J. On the other hand, when fatigue testing is performed by deep drawing, a load is actively applied to the center of drawing. Therefore, if there is variation in the strength distribution, for example, the material strength of the test piece is high in the center and weak on the sides of the center, a proper evaluation cannot be performed. In this regard, the bending fatigue testing device 100 of this configuration can apply a test load that is uniform along the width direction to all of the band-shaped joints J, making it possible to perform high-precision fatigue testing.

[0037] Next, an evaluation test performed by the bending fatigue test system 200 including the bending fatigue test apparatus 100 according to this embodiment will be described with reference to the flow chart shown in FIG.

[0038] First, when the start button is pressed to start the test, the control device 60 operates the traction unit 19, and the traction unit 19 performs a winding operation (S1). Then, the traction wire 45 is wound around the body 41, and the other end of the strip 15 is pulled in the X1 direction (see FIG. 3A). As a result, the test specimen SP of the strip 15 is wound around the outer circumferential surface 13b of the rotating roll 13.

[0039] When the position sensor 55 on the winding side detects the moving body 53 by towing (S2), the detection signal is sent to the control device 60. When the detection signal is input, the control device 60 counts the number of operations using a counter included in the control device 60 (S3). Then, the operation of the towing unit 19 is switched from the winding operation to the sending operation (S4). Then, the towing wire 45 is sent out from the body 41, and the other end of the strip 15 is pulled in the X2 direction (see FIG. 3B). As a result, the test specimen SP of the strip 15 is wound around the outer circumferential surface 11b of the rotating roll 11.

[0040] When the position sensor 57 on the sending side detects the moving body 53 by towing (S5), the detection signal is transmitted to the control device 60. When the detection signal is input, the control device 60 counts the number of operations using a counter included in the control device 60 (S6). Next, if the number of operations counted by the counter is equal to or less than a predetermined number of operations set in advance (S7), the operation of the towing unit 19 is switched from the sending operation to the winding operation (S1).

[0041] When the number of operations counted by the counter reaches a preset number of operations (S7), the test is terminated. Alternatively, the test may be terminated manually by pressing a stop button. When the above operations are performed in automatic operation, it is preferable to turn on the automatic operation lamp during the test and turn off the automatic operation lamp when the test is completed, so that the status of the bending fatigue test apparatus 100 can be notified to those around.

[0042] During the bending fatigue test, if the joint J of the test piece SP breaks before a preset number of operations, the load detection value of the load sensor 51 drops. Therefore, the control device 60 continues to detect whether the detection value from the load sensor 51 has become lower than a predetermined threshold during the test, and if so, determines that the joint J of the test piece SP has broken, and stops driving the motor 43 of the traction unit 19.

[0043] According to the bending fatigue test apparatus 100 and bending fatigue test system 200 of this configuration, the band 15 including the test specimen SP is brought into contact with the outer circumferential surfaces 11b, 13b of the pair of rotating rolls 11, 13, whereby the band 15 is repeatedly curved in different directions to perform a bending fatigue test. This allows the bending fatigue test to be performed on the test specimen SP under conditions similar to those of an actual continuous processing line in which plate materials are passed between multiple rolls. Therefore, compared to a test that continues until the test specimen SP is broken, a test under light load conditions allows a judgment as to whether or not the plate materials to be products will be damaged in an actual continuous processing line.

[0044] In particular, by contacting and curving the strip 15 including the test specimen SP with the outer peripheral surfaces 11b, 13b of rotating rolls 11, 13 having a diameter similar to that of the rolls installed in an actual continuous processing line (e.g., diameter 100 mm to 1000 mm), a bending fatigue test can be performed under conditions that more closely resemble those of an actual continuous processing line.

[0045] Moreover, by curving the strip 15 with the outer circumferential surfaces 11b, 13b of the rotating rolls 11, 13 to which the rotating shafts 11a, 13a are fixed, bending stress can be smoothly applied to the strip 15 including the test specimen SP.

[0046] Furthermore, according to the bending fatigue test apparatus 100 of this embodiment, the band 15 is connected to the tension applying section 17 by the driven linear member 21, and the band 15 is connected to the traction section 19 by the driving linear member 23, so that the band 15 can be easily set in the bending fatigue test apparatus 100 and the test can be performed smoothly.

[0047] Moreover, the device can be made compact because the pulley 35 that reverses the pulling direction is interposed in the driven linear member 21 to reverse the pulling direction. This reduces the installation area of ​​the device, making it possible to install it in a space-saving manner. The pulley 35 may be interposed in the driving linear member 23, or may be interposed in both the driven linear member 21 and the driving linear member 23.

[0048] Furthermore, the band 15 can be easily moved back and forth by using a winch as the traction unit 19 to wind and let out the driven linear member. The traction unit 19 is not limited to a winch, and other well-known traction mechanisms can be adopted. For example, an actuator such as an air cylinder that moves forward and backward can be used as the traction unit. A winch is preferable because it can increase the amount of the driven linear member that can be let out compared to other cases, and the installation area of ​​the equipment can be reduced.

[0049] Furthermore, since a cable winding type leaf spring is used as tension applying portion 17, the expansion and contraction action of the biasing member inside main body portion 25 can achieve a large movement stroke and the application of a constant tension. EXAMPLES

[0050] The strip 15 was set in the bending fatigue test device 100 of the bending fatigue test system 200 configured as described above, and a bending fatigue test was performed on the test specimen SP of the strip 15 (see Figs. 1 and 2).

[0051] (Test Method) A bending fatigue test was performed on the specimen SP, in which the ends of the plate-shaped test pieces P1 and P2 were mechanically joined to each other. The number of bending times in the bending fatigue test was set to an upper limit of 700 times. In addition, dummy strips 71 and 81 were MIG-welded to the ends of the specimen SP to prepare a strip 15. Eyebolts 73 and 83 were fixed to the connecting members 75 and 85 of the dummy strips 71 and 81 of the strip 15, and the driven side linear member 21 was connected to one eyebolt 73, and the driving side linear member 23 was connected to the other eyebolt 83, and the strip was set in a bending fatigue test device 100. The diameters of the rotating rolls 11 and 13 of the bending fatigue test device 100 were selected in the range of 100 mm to 1000 mm according to the diameter of the rolls installed in the actual continuous processing line.

[0052] (Test conditions, etc.) (1) Test pieces P1 and P2 Material: Aluminum alloy plate Plate thickness: 2.5mm Width W: 100mm (2) Dummy strips 71, 81 Material: Aluminum alloy plate Plate thickness: 2.3mm Width W: 100mm (3) Belt 15 Total length L1: approx. 1950mm Dimension L2 to joint J: approx. 970 mm

[0053] (Test Results) In the test specimen SP in which the test pieces P1 and P2 were mechanically joined as described above, the joint J broke after about 250 repeated bending cycles, before the set upper limit of 700 repeated bending cycles was reached.

[0054] As described above, by performing bending fatigue testing using the bending fatigue testing system 200 equipped with the bending fatigue testing apparatus 100 of this configuration, the bending fatigue of plate material having a joint could be accurately tested under conditions approximating those of an actual continuous processing line.

[0055] The present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these are included in the scope of protection sought.

[0056] As described above, the present specification discloses the following: (1) A bending fatigue testing device that repeatedly generates bending stress while applying tension to a test specimen, A pair of rotating rolls whose rotation axes are arranged parallel to each other; a strip-shaped body that is wound around the outer circumferential surfaces of one of the pair of rotating rolls in such a way that the direction of curvature is reversed between the outer circumferential surface of one of the pair of rotating rolls and the outer circumferential surface of the other rotating roll, and at least a part of the strip-shaped body includes the test specimen; a tension applying part connected to one end of the band-shaped body, capable of extending and retracting in the tension applying direction, and applying a constant tension; a pulling section connected to the other end of the strip and pulling the strip along an outer circumferential surface of the rotating roll; Equipped with The pulling unit presses the test piece against the outer peripheral surface of the rotating roll to apply a uniform bending deformation to the test piece in the width direction of the strip. Bending fatigue test equipment. According to the bending fatigue test device of this configuration, a bending fatigue test can be performed by repeatedly bending a strip including a test specimen in different directions by contacting the outer peripheral surfaces of a pair of rotating rolls. This allows a bending fatigue test to be performed on the test specimen under conditions similar to those of an actual continuous processing line in which plate materials are passed between multiple rolls. Therefore, compared to a test in which the test specimen is continued until it breaks, a light-load test can be performed to determine whether or not the plate material to be the product will be damaged in an actual continuous processing line.

[0057] (2) a driven linear member connecting the tension applying portion and one end of the band-shaped body; a driving side linear member connecting the pulling portion and the other end of the band-shaped body; The bending fatigue testing apparatus according to (1) is provided with: With this configuration of bending fatigue testing device, the band can be easily set into the bending fatigue testing device by connecting it to the tension applying section via the driven linear member and to the traction section via the driving linear member, allowing the testing to be performed smoothly.

[0058] (3) The bending fatigue testing device according to (2), wherein a pulley for reversing a pulling direction is interposed in at least one of the driven linear member and the driving linear member. According to the bending fatigue testing device having this configuration, the pulling direction can be reversed via the pulley, making the device more compact. This reduces the installation area of ​​the device, making it possible to install it in a small space.

[0059] (4) A bending fatigue testing apparatus as described in (2) or (3), wherein the traction unit includes a winch that winds the driving side linear member around a body by driving a motor. With this bending fatigue testing device, the winch can easily reciprocate the strip by winding in and letting out the driving linear member. For example, compared to using an actuator such as an air cylinder that moves back and forth as the pulling unit, the payout amount can be made larger and the installation area of ​​the device can be made smaller.

[0060] (5) The bending fatigue testing device according to any one of (2) to (4), wherein the tension applying portion includes a cable-wound leaf spring that applies tension to the driven linear member. According to the bending fatigue testing device having this configuration, the expansion and contraction action of the leaf spring can realize a large movement stroke and the application of a constant tension.

[0061] (6) The bending fatigue testing apparatus according to any one of (1) to (5), wherein the diameters of the rotating rolls are 100 mm or more and 1000 mm or less. With this type of bending fatigue testing device, a strip containing a test specimen is curved by contacting it with the outer peripheral surface of a rotating roll at a predetermined degree of curvature, making it possible to perform a bending fatigue test under conditions that more closely resemble those of an actual continuous processing line.

[0062] (7) A bending fatigue testing apparatus according to any one of (1) to (6), wherein the rotating shaft of the rotating roll is fixed, and the strip moves without slipping on the outer peripheral surface of the rotating roll in accordance with the rotation of the rotating roll. With a bending fatigue testing device of this configuration, the strip is curved by moving without slipping on the outer peripheral surface of the rotating roll to which the rotating shaft is fixed, so that bending stress can be smoothly applied to the strip including the test specimen.

[0063] (8) A bending fatigue testing apparatus according to any one of (1) to (7), wherein the strip has a pair of dummy strips connected to both ends of the test specimen. According to the bending fatigue test apparatus of this configuration, the length of the dummy strip can be adjusted according to the size of the test piece, so that the strip can be easily set to the desired length in the apparatus, thereby improving the degree of freedom in the test subject.

[0064] (9) A bending fatigue testing apparatus according to any one of (1) to (8), a control device that drives the pulling unit to perform a pulling operation in which the other end of the strip is pulled by applying a tensile force greater than the tension from the tension applying unit, and a returning operation in which the tensile force is relaxed within a range in which the tension applied from the tension applying unit is not lost; A bending fatigue testing system comprising: According to the bending fatigue testing system having this configuration, the control device alternates between the winding operation and the unwinding operation, so that the strip containing the test specimen is brought into contact with the outer circumferential surfaces of a pair of rotating rolls and repeatedly bent in different directions to perform the bending fatigue test. This allows the bending fatigue test to be performed on the test specimen under conditions similar to those of an actual continuous processing line in which plate materials are passed between multiple rolls. Therefore, compared to a test in which the test specimen is continued until it is destroyed, it is possible to determine whether or not the plate material to be the product will be damaged in an actual continuous processing line by a light-load test.

[0065] (10) A load sensor is provided to detect the tension applied to the band-shaped body, The bending fatigue testing system according to (9), wherein the control device stops the traction unit when a detection value from the load sensor becomes lower than a predetermined threshold value. According to a bending fatigue testing system of this configuration, when the detection value of the load sensor falls below a threshold value, the control device stops the traction unit, so that the device can be reliably stopped, for example, when a strip containing the test specimen breaks.

[0066] (11) A position sensor is provided to detect the movement of the band, The bending fatigue testing system according to (9) or (10), wherein the control device switches between the pulling operation and the returning operation of the towing section depending on an output from the position sensor. According to a bending fatigue testing system having this configuration, the pulling operation and the returning operation can be automatically switched based on the output from the position sensor, and the strip containing the test specimen can be smoothly moved back and forth. [Explanation of symbols]

[0067] 11,13 Rotating Roll 11a, 13a Rotation axis 11b,13b Outer surface 15 Band 17 Tensioner 19 Traction section 21 Driven side linear member 23 Driving side linear member 35 Pulley 41 Torso 43 Motor 45 Traction wire (driving side linear member) 51 Load Sensor 55,57 Position Sensor 60 Control device 71,81 Dummy strip 100 Bending fatigue test equipment 200 Bending Fatigue Test System SP test specimen

Claims

1. A bending fatigue testing apparatus that repeatedly generates bending stress while applying tension to a test specimen, A pair of rotating rolls whose rotation axes are arranged parallel to each other; a strip-shaped body that is wound around the outer circumferential surfaces of one of the pair of rotating rolls in such a way that the direction of curvature is reversed between the outer circumferential surface of one of the pair of rotating rolls and the outer circumferential surface of the other rotating roll, and at least a part of the strip-shaped body includes the test specimen; a tension applying part connected to one end of the band-shaped body, capable of extending and retracting in the tension applying direction, and applying a constant tension; a pulling section connected to the other end of the strip and pulling the strip along an outer circumferential surface of the rotating roll; Equipped with The pulling unit presses the test piece against the outer peripheral surface of the rotating roll to apply a uniform bending deformation to the test piece in the width direction of the strip. Bending fatigue test equipment.

2. a driven linear member connecting the tension applying portion and one end of the band-shaped body; a driving side linear member connecting the pulling portion and the other end of the band-shaped body; The bending fatigue testing apparatus according to claim 1 ,

3. a pulley for reversing a pulling direction is interposed between at least one of the driven linear member and the driving linear member; 3. The bending fatigue testing apparatus according to claim 2.

4. The towing unit includes a winch that winds the driving side linear member around a body by driving a motor.

3. The bending fatigue testing apparatus according to claim 2.

5. the tension applying portion includes a cable winding type leaf spring that applies tension to the driven linear member, 3. The bending fatigue testing apparatus according to claim 2.

6. The diameters of the rotating rolls are 100 mm or more and 1000 mm or less, 2. The bending fatigue testing apparatus according to claim 1.

7. The rotating roll has a fixed rotation shaft, and the strip moves on the outer circumferential surface of the rotating roll without slipping in accordance with the rotation of the rotating roll.

2. The bending fatigue testing apparatus according to claim 1.

8. The strip has a pair of dummy strips connected to both ends of the test specimen.

2. The bending fatigue testing apparatus according to claim 1.

9. A bending fatigue testing device according to any one of claims 1 to 8, a control device that drives the pulling unit to perform a pulling operation in which the other end of the strip is pulled by applying a tensile force greater than the tension from the tension applying unit, and a returning operation in which the tensile force is relaxed within a range in which the tension applied from the tension applying unit is not lost; A bending fatigue test system comprising:

10. a load sensor for detecting the tension applied to the band, The control device stops the towing unit when a detection value from the load sensor becomes lower than a predetermined threshold value.

10. The bending fatigue testing system of claim 9.

11. a position sensor for detecting the movement of the strip; The control device switches between the pulling operation and the returning operation of the towing unit in response to an output from the position sensor.

10. The bending fatigue testing system of claim 9.

Images