Creep test machine and creep test method

Abstract

To provide a creep testing machine capable of increasing or decreasing a load continuously and statically and capable of simultaneously increasing or decreasing a load by the same amount in a creep test for increasing or decreasing a load.SOLUTION: A creep testing machine includes a load adjustment unit 10 that has a lever 100 erected on a mount 122, a first support shaft 108 for swingably mounting the lever 100 to the mount 122, a second support shaft 107 that is provided in the lever 100 in a position separated from the first support shaft 108 and supports a gripping part 106 for gripping a test piece T, and a third support shaft 109 that is provided in the lever 100 in a position separated from the first support shaft 108 and the second support shaft 107, and supports a connection member connected with a load part for adding a load to the test piece T, allows at least one of the first support shaft 108, the second support shaft 107, and the third support shaft 109 to be configured as a movable support shaft capable of advancing and retreating in an axial direction of the lever 100, and includes moving means P for moving the movable support shaft in the axial direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a creep testing machine that applies a load to a test piece and measures the amount of deformation of the test piece, and a creep testing method using the creep testing machine. [Background technology]

[0002] Creep tests are known as tests for verifying the life span of parts in plants such as thermal power generation facilities and nuclear power generation facilities, and in jet and rocket engines, and for measuring the strength of various new materials and composite materials, in which the amount of strain of a test piece and the time the load is applied are measured under a constant load and analyzed (see, for example, Patent Document 1). In such creep tests, the load is increased or decreased by a fixed amount for each specified strain or time, and the changes in load and strain over time are measured. For example, the time until the strain of the test piece reaches a preset first strain is collected as one piece of data, and then the load is increased or decreased by a preset amount to collect the time until the strain of the test piece reaches a second strain as the next piece of data. This process is repeated to obtain continuous data and perform analysis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-43281 [Patent Document 2] Japanese Utility Model Application Publication No. 6-80159 [Patent Document 3] Special Publication No. 2007-510151 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0004] In order to obtain highly accurate test results in creep tests in which the load is increased and decreased, the load must be increased and decreased continuously and statically so as not to apply any shock to the test specimen, and the load applied to both sides of the test specimen must be increased and decreased by the same amount and simultaneously. However, in the creep testing machine described in Patent Document 1, although it is possible to increase or decrease the load by increasing or decreasing the number of pairs of weights 40 that apply a load to the test piece by pulling the test piece from both sides, there is a problem in that it is extremely difficult to increase or decrease the load while satisfying all of the above requirements.

[0005] Furthermore, the lever type constant load testing machine described in Patent Document 2 is provided with a movable weight 3 that can move along the lever 2, and the position of the force point can be changed by moving the movable weight 3 along the lever 2 by turning the threaded rod 4 with the handle 9, and although the load can be increased or decreased statically and continuously, it is difficult to increase or decrease the load applied to both sides of the test piece by the same amount and simultaneously. Furthermore, the lever type constant load testing machine described in Patent Document 2 has the problem that the load can only be increased or decreased by an amount corresponding to the weight of the movable weight 3, and the lever type constant load testing machine becomes large when the length of the lever 2 is long.

[0006] Furthermore, in the multi-axis universal testing machine described in Patent Document 3, a load is applied to the test piece by a motor instead of a weight, and by synchronizing the drive of two paired motors, the load can be increased or decreased simultaneously on both sides of the test piece. However, there is a limit to the magnitude of the load that can be applied by the motors, and a high-output motor is required to perform creep tests on test pieces such as metals, which poses the problem of making the device larger.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a creep testing machine and creep testing method which, in a creep test in which the load is increased and decreased, can increase and decrease the load continuously and statically, and can increase and decrease the load equally and simultaneously on both sides of the test piece, and which can have a simple and compact device configuration. [Means for solving the problem]

[0008] In order to solve the above problems, the creep tester described in claim 1 is a creep tester for applying a load to a test piece and measuring the deformation of the test piece, the creep tester comprising: a lever erected on a base; a first support shaft for attaching the lever to the base so as to be able to swing; a second support shaft provided on the lever at a position spaced apart from the first support shaft and supporting a gripping portion for gripping the test piece; and a third support shaft provided on the lever at a position spaced apart from the first support shaft and the second support shaft and supporting a connecting member connected to a load portion for applying a load to the test piece, at least one of the first support shaft, the second support shaft and the third support shaft being configured as a movable support shaft that can be moved back and forth in the axial direction of the lever, and a moving means for moving the movable support shaft by a preset distance in the axial direction. Load adjustment unit and A pair of the loads adjustment Units are disposed on both ends of the test strip; The moving means includes a synchronous moving section that moves the movable support shafts of the pair of load adjustment units in synchronization with each other. It is in the composition.

[0009] The movable support shaft may be any one of the first support shaft, the second support shaft, and the third support shaft, and two or more support shafts may be movable support shafts, but it is preferable that it is the third support shaft as described in claim 2. As described in claim 3, the movable support shaft may be configured to be supported by a guide portion formed on the lever and a slider that moves along this guide hole, and the moving means may be configured to include a helical shaft that is screwed into the movable support shaft or the slider, and to move the movable support shaft by rotation of the helical shaft.

[0010] Furthermore, the moving means may be a manual one, but as described in claim 4, it may be configured to include a driving body such as a servo motor and a control means for controlling the driving of the driving body. As described in claim 5, a load support table that can be raised and lowered to support the load portion and a pair of the loads adjustmentThe unit may further include a lifting drive means for synchronously lifting and lowering the pair of load support tables.

[0011] As described in claim 6, the creep testing method of the present invention is a method of preparing a creep testing machine having a lever erected on a base, a first support shaft for attaching the lever to the base so as to be able to swing freely, a second support shaft provided on the lever at a position spaced apart from the first support shaft and supporting a gripping portion for gripping a test piece, and a third support shaft provided on the lever at a position spaced apart from the first support shaft and the second support shaft and supporting a connecting member connected to a load portion for applying a load to the test piece, wherein at least one of the first support shaft, the second support shaft and the third support shaft is a movable support shaft that can move back and forth in the axial direction of the lever, and a creep test is performed while changing the load applied to the test piece by moving the movable support shaft.

[0012] As a method of performing a creep test while changing the load, the load applied may be changed for each creep test, or the load applied may be changed stepwise or continuously during one creep test. For example, as described in claim 7, after performing a creep test while applying a first load to the test piece, the movable support shafts of the pair of load adjusting units may be moved synchronously to position the test piece at a predetermined position, and a creep test may be performed while applying a second load to the test piece. Alternatively, as described in claim 8, the movable support shafts of the pair of load adjusting units may be moved continuously synchronously to perform a creep test while changing the load applied to the test piece.

[0013] As described in claim 9, a load support table that can be raised and lowered to support the load portion and a pair of the loads adjustment A lifting and lowering drive means for synchronously lifting and lowering the paired load support tables in the unit may be provided, and the load applied to the test piece may be temporarily set to zero by synchronously lifting and lowering the load support tables during the creep test. Effect of the Invention

[0014] Since the present invention is configured as described above, the load applied to the test piece can be increased or decreased significantly by moving the movable support shaft, and the load can be increased or decreased continuously and statically. Furthermore, since the lever is erected on the base, the two paired load adjustment units can be placed close to each other, making the device configuration compact, and when the load is increased or decreased manually, it is easy to operate the movement means of the two paired load adjustment units simultaneously and by the same amount.

[0015] In particular, if a drive such as a servo motor is used as the moving means and the drive is controlled by the control means, the moving means of the pair of load adjustment units can be operated with high precision. Furthermore, by housing such a drive inside the lever, the device configuration does not become large. Furthermore, according to the present invention, it becomes easy to apply a load to the test piece T while changing the magnitude of the load stepwise during the creep test, and it also becomes possible to carry out a variety of creep tests, such as changing the magnitude of the load continuously during the creep test. It is also possible to temporarily set the load to 0 during the test.

[0016] Therefore, in the present invention, it is possible to measure the deformation characteristics and hardening characteristics of a test piece during stress fluctuation, which could not be directly measured by conventional testing machines and testing methods, and it becomes easy to determine hardening variables for mathematically expressing the deformation characteristics and creep characteristics of the test piece. By using appropriate hardening variables and hardening models obtained from creep tests, the accuracy of numerical simulations is improved, which makes it possible to highly accurately predict deformation during long-term use, thereby contributing to the design of safer equipment and facilities. BEST MODE FOR CARRYING OUT THEINVENTION

[0017] Hereinafter, preferred embodiments of the creep testing machine of the present invention will be described with reference to the drawings. FIG. 1 is a side view illustrating the overall configuration of one embodiment of the creep testing machine of the present invention, FIG. 2 is a plan view of the creep testing machine of FIG. 1, FIG. 3 is an enlarged view illustrating details of the load adjustment unit, where (a) is the side view and (b) is a cross-sectional view along II of (a), FIG. 4 is a partial view showing a modified example of the load adjustment unit of FIG. 3, FIG. 5 is a schematic explanatory diagram of an example of a creep test using the creep testing machine of the present invention, where (a) is a graph showing the relationship between time and load and (b) is a graph showing the relationship between time and strain of the test piece, and FIG. 6 is a diagram illustrating a test piece used in the creep testing machine of this embodiment, where (a) is the plan view and (b) is a cross-sectional view along II-II of (a).

[0018] [Test piece] The test piece T on which the creep test is performed using the creep testing machine 1 of this embodiment has a cross shape as shown in Fig. 8, and its shape is well known as shown in Fig. 4 of Patent Document 1. For example, in order to determine the accurate strength of pressure vessels and pressure piping in power plants and factories, turbine blades of jet engines, etc., the stress-strain characteristics of the material under biaxial stress are required. The cross-shaped test piece T as shown in Fig. 8 is used to determine such stress-strain characteristics under biaxial stress. The test piece T can be made of steel or superalloy material, but can also be made of damaged material taken from an actual pressure vessel or pressure piping, etc. The test piece T can also be used to determine the stress-strain characteristics of non-ferrous metals, and the test piece T may be made of anisotropic materials such as engineering plastics containing reinforcing fibers.

[0019] In this embodiment, as shown in FIG. 8, the test piece T has a test piece main body Ta formed in the center, which is the subject of the creep test, and has gripped parts Tb extending in four perpendicular directions from this test piece main body Ta, with the length l of one side being approximately 50 mm and the width s of the gripped parts Tb being approximately 8.4 mm. The gripped portion Tb is intended to be gripped by the gripping portion 106 (see FIG. 3) of the load adjustment unit 10 described later, and multiple slits Tc are formed in parallel to the gripped portion Tb so that deformations in the X and Y directions do not restrict each other with respect to the load application direction.

[0020] The creep testing machine 1 of the present invention is not limited to the above-mentioned cruciform test piece T for creep testing under biaxial stress, but can also be applied to a straight-line test piece for creep testing under uniaxial stress. In addition, by increasing the number of load adjusting units 10, the creep testing machine 1 of the present invention can also perform creep testing under multiaxial stress using a test piece having, for example, eight gripped parts Tb extending in eight directions from the test piece main body Ta.

[0021] [Overall configuration of creep testing machine] As shown in Figures 1 and 2, the creep testing machine 1 of this embodiment has a stand 12 that is placed on or fixed to a horizontal floor surface, table, etc., a plurality of load adjustment units 10 (four in this embodiment) supported by a base 122 of the stand 12, a weight 128a for applying a load to a test piece T arranged in the center of the plurality of load adjustment units 10, and a wire 126 connecting the load adjustment unit 10 and the weight 128a. Further, in the center of the load adjusting unit 10, a heating furnace 13 is provided which accommodates the test piece T and heats the test piece T to a preset temperature during the creep test.

[0022] [Frame configuration] As shown in FIG. 2, in this embodiment, two pairs of paired load adjustment units 10, i.e., four load adjustment units 10, are arranged at equal intervals facing each other on the orthogonal X-axis and Y-axis on the base 122 of the stand 12. The stand 12 has a support 120 that is placed on or fixed to a horizontal floor surface, a table, or the like, and a plurality of legs 121 that stand upright on the support 120, with the base 122 being provided on the upper ends of the legs 121.

[0023] 2, the base 122 is formed in a cross shape, and four load adjustment units 10 are disposed on each of the four protrusions forming the cross. The tip of the protrusion is bent upward to form an arm 123, and a pulley 124 is rotatably supported on the upper end of the arm 123. A wire 126 connected to the load adjustment unit 10 hangs down from the pulley 124, and one or more weights 128a are suspended from the tip of the wire 126 via a rod 127. The rod 127 and the weights 128a constitute a load section 128 that applies a load to the test piece T.

[0024] Further, through holes 122a are formed in the base 122 in accordance with the arrangement positions of the four load adjustment units 10, and each of the load adjustment units 10 is supported by the base 122 in a state where it is inserted into the through hole 122a.

[0025] Reference numeral 125 denotes a weight support base serving as a load support base for supporting a weight 128a, and includes a lifting table 125a that can be raised and lowered with the weight 128a placed thereon. In the weight support bases 125 of a pair of opposing load adjustment units 10, for example, as shown in FIG. 1, the two lifting tables 125a may be connected by a connecting bar 125b, and the two lifting tables 125a may be raised and lowered synchronously by one hydraulic jack. In the initial state before the creep test, the two lifting tables 125a of the pair of load adjustment units 10 are raised and the weight 128a is placed thereon so that no load is applied to the two paired load adjustment units 10. When the creep test is started by attaching a test piece T to the two load adjustment units 10, the hydraulic jack is driven to slowly lower the two lifting tables 125a at the same time, so that the same amount of load can be statically applied to both sides of the test piece T at the same time. In addition, by simultaneously raising the two lift tables 125a and placing weights 128a on each of the two lift tables 125a at the same time, the load acting on the test piece T can be set to zero not only at the end of the creep test but also during the creep test.

[0026] [Load adjustment unit configuration] The load adjustment unit 10 has a lever 100 that is erected on a base 110 fixed to a base 122 by a bolt or the like and is swingable by a first support shaft 108. The lower end side of the lever 100 passes through a through hole 122a of the base 122 and extends below the base 122, and a balancer 112 is attached to one end of the lever 100 for maintaining the lever 100 in a vertical position with the support shaft 108 as a fulcrum in an unloaded state. A second support shaft 107 is provided above and spaced a distance L2 from the first support shaft 108, parallel to and in the same direction as the first support shaft 108, and an attachment arm 105 extending from the second support shaft 107 toward the other load adjustment unit 10 facing in the horizontal direction is attached to the lever 100 so as to be able to swing freely via the second support shaft 107. A gripping portion 106 is attached to the very tip of the tip of the attachment arm 105 via a connecting pin 106a, and the gripped portion Tb of the test piece T is gripped by the tip of the gripping portion 106.

[0027] The mounting arm 105 can be moved back and forth in the axial direction using the handle 105a, and the distance between the gripping portions 106, 106 of the two opposing load adjustment units 10 can be adjusted, making it easier to attach the test piece T and allowing the distance to be adjusted to an appropriate value according to its length.

[0028] A third support shaft 109 is provided above and spaced a distance L1 from the second support shaft 107, parallel to and in the same direction as the first support shaft 108 and the second support shaft 107. A connecting member 102 extends horizontally from this third support shaft 109 in the opposite direction to the mounting arm 105, and is attached to the lever 100 via the third support shaft 109 so as to be able to swing freely. A wire connecting hole 102a is formed at the tip of the connecting member 102, and one end of a wire 126 is connected to this wire connecting hole 102a.

[0029] An elongated guide hole 103 having a long axis in the up-down direction is formed through the upper part of the lever 100, and a slider 115 that moves up and down along this guide hole 103 is inserted into the guide hole 103. The third support shaft 109 is supported by this slider 115, and can move up and down along the guide hole 103 together with the slider 115 between an upper limit position (i) and a lower limit position (ii) shown in Fig. 3. In this embodiment, the third support shaft 109 is a movable support shaft. An upper end member 104 is attached to the upper end of lever 100 so as to close the upper open portion of guide hole 103. A through hole 104a is formed in this upper end member 104, which penetrates to guide hole 103, and helical shaft 101 extends into guide hole 103 by inserting through this through hole 104a.

[0030] A shaft head 101a is formed at the upper end of the helical shaft 101, and is located above an upper end member 104. A bearing 101b is provided between the shaft head 101a and the upper end member 104 to rotatably support the shaft head 101a while preventing the helical shaft 101 from dropping from the through hole 104a into the guide hole 103. The helical shaft 101 is screwed into a helical hole 109a formed through the center of a third support shaft 109, and the third support shaft 109 is raised and lowered along the guide hole 103 by rotating the helical shaft 101 via the shaft head 101a.

[0031] With the above configuration, when a tool such as a wrench or a handle is engaged with the shaft head 101a and the shaft head 101a is rotated in the direction C in the figure, the helical shaft 101 rotates and the third support shaft 109 screwed into the helical shaft 101 moves up and down along the guide hole 103. This allows the distance L1 between the second support shaft 107 and the third support shaft 109 to be changed between long and short. In addition, it is preferable to provide a scale along the guide hole 103 so that the magnitude of the distance L1 that is changed from long to short can be visually confirmed.

[0032] In this embodiment, the helical hole 109a formed in the third support shaft 109 and the helical shaft 101 constitute a moving means P for moving the movable support shaft. Also, in this embodiment, the lever 100, which has the first support shaft 108 as a fulcrum, the second support shaft 107 as a point of application, and the third support shaft 109 as a point of force, amplifies the load of the load section 128 at a ratio according to the distances L1 and L2 by the leverage, and transmits the amplified load to the test piece T. The load adjustment units 10 having the above configuration are arranged on the base 122 in pairs, one on each end of the test piece T. In this embodiment, two pairs (four) of load adjustment units 10 are arranged on the base 122 so that a creep test can be performed on the cross-shaped test piece T.

[0033] [Another embodiment of the load adjustment unit] FIG. 4 shows another embodiment of the load adjusting unit. The load adjustment unit 10 in FIG. 3 rotates the helical shaft 101 manually using a tool such as a wrench or a handle. The creep tester 1 of the present invention has a configuration in which the lever 100 is erected, so that two paired load adjustment units 10 can be arranged close to each other. In this embodiment, by using a small test piece T with a side length l of about 50 mm, the interval between the paired load adjustment units 10 can be about 40 cm, and the size of the device and the side length H (see FIG. 2) can be within a range of about 60 cm. Therefore, it becomes easy for one operator to simultaneously operate the helical shafts 101 of the two load adjustment units 10 with both hands, and it is also easy to make the rotation angles of the helical shafts 101 of the two load adjustment units 10 the same. However, in order to raise and lower the third support shaft 109 of the two load adjustment units 10 more precisely, it is preferable to rotate the helical shaft 101 using a driving body such as a servo motor.

[0034] In the load adjustment unit 10' of the embodiment shown in Fig. 4, the helical shaft 101' is connected to a rotating shaft of a driver M such as a servo motor, and the helical shaft 101' is rotated by driving the driver M. The driving of the driver M can be controlled by a control unit (not shown) provided outside the load adjustment unit 10', and for example, by outputting a command to the driver M to rotate the helical shaft 101' by a preset rotation angle after a preset time has elapsed or after a preset strain amount has been reached, the third support shaft 109 can be raised and lowered by the same amount in synchronization between the two paired load adjustment units 10'.

[0035] In this manner, by raising and lowering the third support shaft 109 using a driving body M such as a servo motor, it is possible to synchronize the raising and lowering of the two third support shafts 109 in the paired load adjustment unit 10' with high precision and to precisely match the amount of raising and lowering. As in the example of Figure 4, by forming a hollow portion inside the lever 100 and accommodating the driver M within the lever 100, the driver M and the helical shaft 101' do not protrude outside the load adjustment unit 10', and the load adjustment unit 10' can be accommodated within the same size (height) as the load adjustment unit 10 of the previous embodiment.

[0036] [Explanation of creep test method] Next, a creep testing method of the present invention using the creep testing machine 1 having the above configuration will be described together with the operation of the creep testing machine 1 having the above configuration. First, in the initial state before the start of the creep test, the lift table 125a of the weight support stand 125 is raised to place the weight 128a thereon so that no load is applied to the paired load adjustment unit 10 (10'). Also, in this initial state, the positions of the third support shafts 109 are aligned by the support shaft moving means P (P') so that the distance L1 between the second support shaft 107 and the third support shaft 109 in the two load adjustment units 10 (10') is the same. Next, a test piece T shown in FIG. 8 is prepared, and each of the four gripped portions Tb is gripped by the gripping portions 106 of two pairs of four load adjustment units 10 (10'). After the gripping is completed, when the creep test is started, the lifting tables 125a of the weight supports 125 of the load adjustment units 10 (10') are lowered in synchronization, and loads are applied to the test piece T from four directions simultaneously.

[0037] The magnitude of the load F applied to the test piece T is determined by the weight (W) of one or more weights 128a, the distance L2 from the first support shaft 108, which is the fulcrum, to the second support shaft 107, which is the point of application, and the distance L1+L2 from the first support shaft 108 to the third support shaft 109, which is the point of force, and the relationship L2×F=(L1+L2)×W is established. If the ratio of the distances L1 and L2 is 9:1 (L1:L2=9:1), then a load ten times the weight (W) of the one or more weights 128a will be applied to the test piece T.

[0038] In this state, after a preset time has elapsed or when a preset strain amount has been reached, the third support shaft 109 is moved by a preset length α. In the creep testing machine 1 of the present invention, it is easy to synchronize the helical shafts 101 of the two paired load adjustment units 10 to rotate them simultaneously by the same amount, and in the load adjustment unit 10' using a driver M such as a servo motor, the driver M can be automatically driven under preset conditions to synchronously rotate the helical shafts 101 of the two load adjustment units 10, and it is also possible to move the third support shaft 109 by the preset length α with higher accuracy.

[0039] If the connecting member 102 is raised by, for example, length α, changing the distance L1 to L1+α, the above formula becomes L2×F=((L1+α)+L2)×W. If the length α to be moved is set to just over 10% of the distance L1 and the ratio of the distance L1+α to the distance L2 is set to 10:1, the load applied to the test piece T can be increased by approximately the same amount as the weight (W) of one or more weights 128. FIG. 5 is a graph showing a schematic relationship between stress (load) and time according to the creep test method of this embodiment. As shown in this graph, by gradually changing the load as time passes from t1, t2, t3, etc. and gradually changing (increasing in this graph) the load σ acting on the test piece T, the strain (deformation) of the test piece T at each load σ1, σ2, σ3, etc. can be observed. When the load σ is changed stepwise, the load σ may be temporarily set to 0. In this case, the lifting table 125a of the paired weight support base 125 is lifted in synchronization with each other, and the weight 128a is placed on the lifting table 125a.

[0040] [Another embodiment of the creep test method] In another embodiment of the creep test method of the present invention, after the creep test is started, the third support shaft 109, which is a movable support shaft, is moved continuously at a constant speed in synchronization with the pair of load adjustment units 10, 10'. The speed may be constant from the start to the end of the creep test or may be variable during the test (including a speed of 0). FIG. 6 is a graph showing a schematic relationship between stress (load) and time according to the creep test method of this embodiment. As shown in this graph, by changing the load linearly from the start of the test to time t4 and changing the load σ acting on the test piece T from σ4 to σ5 (this graph shows the case where the load σ is increased, but it is also possible to decrease the load σ from σ4 to σ5), the strain (deformation) of the test piece T under a linear change in load can be observed.

[0041] [Yet another embodiment of the creep test method] In yet another embodiment of the creep test method of the present invention, after the creep test is started, the third support shaft 109, which is a movable support shaft, is synchronized in the paired load adjustment units 10, 10' to move the load σ so that it changes indefinitely (waveform in the example of FIG. 7) between the maximum value σ8 and the minimum value σ6 from the start of the test to time t5, as shown in the graph of FIG. 7. The minimum load σ6 may be 0, in which case the lift table 125a of the paired weight support stand 125 is lifted in synchronization, and the weight 128a is temporarily placed on the lift table 125a. The speed at which the load σ is changed may be constant from the start to the end of the creep test, or may be variable during the process (including a speed of 0).

[0042] In this way, in the present invention, at least one of the support shafts (the third support shaft 109 in the above embodiment) is made a movable support shaft, and the movable support shaft (the third support shaft 109 in the above embodiment) of the paired load adjustment units 10, 10' is synchronously moved using a driving body M such as a helical shaft or a servo motor, thereby not only making it possible to obtain a large load increasing / decreasing effect without making the device configuration complicated and large, but also making it possible to increase / decrease the load continuously and statically by the same amount synchronously on both sides of the test piece T. Furthermore, it becomes easy to apply a load of different magnitude in stages to the test piece T during the creep test, and various creep tests become possible, such as continuously changing the magnitude of the load during the creep test.

[0043] Although the preferred embodiments of the present invention have been described, the present invention is not limited to the above-mentioned embodiments. For example, in the above explanation, the movable support shaft is described as the third support shaft 109, but in the present invention, the first support shaft 108 or the second support shaft 107 can be the movable support shaft, and two or all of these three support shafts can be the movable support shafts. In addition, from the lower end side of lever 100, first support shaft 108 which is the fulcrum, second support shaft 107 which is the point of action, and third support shaft 109 which is the point of force are arranged in this order, but the arrangement of the fulcrum, point of force, and point of action is not limited to this as long as a lever action is obtained. [Brief description of the drawings]

[0044] [Figure 1] 1 is a side view illustrating an embodiment of a creep testing machine of the present invention, showing its overall configuration. FIG. [Diagram 2] FIG. 2 is a plan view of the creep testing machine of FIG. 1. [Diagram 3] FIG. 13 is an enlarged view for explaining the details of the load adjustment unit, in which (a) is a side view and (b) is a cross-sectional view taken along line II of (a). [Figure 4] 4 is a partial view showing a modified example of the load adjusting unit of FIG. 3. FIG. [Diagram 5] 1 is a graph showing a schematic relationship between stress (load) and time according to the creep test method of this embodiment. [Figure 6] 4 is a graph showing a schematic relationship between stress (load) and time according to a creep test method of another embodiment. [Figure 7] 11 is a graph showing a schematic relationship between stress (load) and time according to a creep test method of yet another embodiment. [Figure 8] FIG. 2 is a diagram illustrating a test piece used in the creep testing machine of this embodiment, in which (a) is a plan view and (b) is a cross-sectional view taken along the line II-II in (a). [Explanation of symbols]

[0045] 1. Creep testing machine 10,10′ Load adjustment unit 100 Lever 101 Spiral axis 101a Shaft head 102 Connecting member 103 Guide hole 104 Upper end member 104a Through hole 105 Mounting arm 105a Handle 106 Gripping part 106a Connecting pin 107 Second Support Axis 108 First Support Axis 109 Third Support Axis 110 Pedestal 112 Balancer 115 Slider 12 Mounting stand 120 Support stand 121 legs 122 Foundation 122a Through hole 123 Arm 124 Pulley 125 Weight support stand (load support stand) 125a Lift table 125b connecting bar 126 Wire 127 Rod 128 Loading section 128a Weight 13 Heating furnace

Claims

1. A creep testing machine that applies a load to a test piece and measures the deformation of the test piece, A lever provided on a base; a first support shaft for attaching the lever to the base so as to be able to swing; a second support shaft provided on the lever at a position spaced apart from the first support shaft and supporting a gripping portion that grips the test piece; and a third support shaft provided on the lever at a position spaced apart from the first support shaft and the second support shaft and supporting a connecting member connected to a load portion that applies a load to the test piece, wherein at least one of the first support shaft, the second support shaft and the third support shaft is configured as a movable support shaft that can move back and forth in the axial direction of the lever, and a moving means is provided for moving the movable support shaft a preset distance in the axial direction; having A pair of the load adjustment units are disposed on both ends of the test piece, the moving means includes a synchronous moving unit that synchronously moves the movable support shafts of the pair of load adjustment units; A creep testing machine characterized by:

2. 2. The creep testing machine according to claim 1, wherein the movable support shaft is the third support shaft.

3. 3. The creep testing machine according to claim 1, wherein the movable support shaft is supported by a guide hole formed in a lever and a slider that moves along the guide hole, and the moving means includes a helical shaft that is screwed into the movable support shaft or the slider, and the movable support shaft is moved by rotation of the helical shaft.

4. 4. The creep testing machine according to claim 1, wherein the moving means comprises a driving body and a control means for controlling the driving of the driving body.

5. Further comprising a load support platform that can be raised and lowered and supports the load portion, and a lifting and lowering drive means for synchronously raising and lowering the pair of load support platforms in the pair of load adjustment units; The creep tester according to any one of claims 1 to 4,

6. a first support shaft for attaching the lever to the base in a swingable manner; a second support shaft for supporting a gripping portion for gripping a test piece, the second support shaft for supporting a connecting member connected to a load portion for applying a load to the test piece, the third ... a pair of the load adjusting units arranged on both ends of the test piece are moved in a synchronized manner to move the movable support shafts, thereby performing a creep test while changing the load applied to the test piece; A creep test method comprising:

7. 7. The creep testing method according to claim 6, further comprising the steps of: performing a creep test while applying a first load to the test piece; moving the movable support shafts of the pair of load adjustment units in synchronization to position the test piece at a predetermined position; and performing a creep test while applying a second load to the test piece.

8. 7. A creep testing method according to claim 6, characterized in that the movable support shafts of the pair of load adjustment units are continuously moved in synchronization with each other to perform a creep test while changing the load applied to the test piece.

9. a load support platform capable of being raised and lowered and supporting the load portion; and a lifting and lowering drive means for synchronously raising and lowering the pair of load support platforms in the pair of load adjustment units; synchronously raising and lowering the load support table during the creep test to temporarily reduce the load applied to the test piece to zero; The creep test method according to any one of claims 6 to 8, characterized in that

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