JP2011227007A - Material testing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material testing machine capable of easily adjusting the center of axes.SOLUTION: Four pieces of strain gauges 61 are stuck at each of an upper, a middle, and a lower position of an adjustment test specimen 10a, that is, 12 pieces of the strain gauges 61 in total are stuck on the adjustment test specimen 10a. The strain gauges 61 stuck on the adjustment test specimen 10a are connected to a data logger 62 as a measuring means, and the detected values by the strain gauges 61 are recorded and stored. The data logger 62 is connected to a personal computer 65 equipped with a display 63 and a CPU and the like in a housing 64, and in the housing 64, strains at each of the upper, middle, and lower position of the adjustment test specimen 10a are calculated based on the detected values by strain gauges 61.

Description

  The present invention relates to a material testing machine including a shaft center adjusting device for adjusting the shaft center of a gripping tool that holds a test piece.

  Such a material testing machine measures the test force and displacement at that time with a load cell and a displacement detector while applying a load to the test piece gripped at both ends by the upper gripper and the lower gripper. The test force-displacement characteristic of the test piece and the SN diagram are obtained. In such a material testing machine, an accurate material test cannot be performed unless the axes of the upper gripper and the lower gripper are aligned. For this reason, in such a material testing machine, a shaft center adjusting device for adjusting the shaft centers of the upper gripping tool and the lower gripping tool is provided.

  In addition, as a material testing machine that performs such axis adjustment, for example, by automatically adjusting the position of the XY stage provided with the lower gripper based on the detection values of a plurality of strain gauges attached to the test piece, A material testing machine capable of correcting axial misalignment has been proposed (see Patent Document 1).

JP-A 64-31033 published

By the way, when the operator performs the shaft center adjustment, it is necessary to accurately grasp the current degree of shaft center shift and to reliably perform the adjustment operation according to the situation. In particular, in a material test called a low cycle fatigue test with a number of repetitions of 10 ⁴ or less, the axial misalignment between the upper gripper and the lower gripper has a greater effect on the accuracy and reliability of the test data. High axial alignment is required. For this reason, such a highly accurate axis adjustment is a difficult task for the operator, in which a relatively long time is spent in order to achieve accuracy.

  The present invention has been made to solve the above-mentioned problems, and facilitates adjustment of the axis by enhancing the information display so that the operator can easily grasp the information required for the adjustment of the axis. An object of the present invention is to provide a material testing machine that can be used for the following.

  The invention described in claim 1 is a material testing machine including an axis adjusting device that adjusts the axis of a gripping tool that holds a test piece by operating a plurality of adjusting screws, Based on the signal from the measurement means, the load means for applying the load, the plurality of strain gauges affixed at different height positions of the test piece, the measurement means for recording signals from the plurality of strain gauges, Calculating a strain direction and a strain amount of the test piece for each of a plurality of height positions, and calculating a strain direction and a strain amount for each of the plurality of height positions calculated by the calculation means with a plurality of height positions. Display means for displaying each surface substantially orthogonal to the load axis.

  According to a second aspect of the present invention, in the first aspect of the present invention, the display unit displays an adjustment screw in the shaft center adjustment device, and an operation message of the adjustment screw is calculated by the calculation unit. Further, the display is based on the strain direction and the strain amount for each of the plurality of height positions.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the display means stereoscopically displays a strain direction and a strain amount for each of a plurality of height positions.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the plurality of strain gauges are affixed at equal intervals at the same height position of the test piece.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the adjustment screw adjusts an angle of the gripping tool and a position adjusting screw for adjusting a position of the gripping tool. It is an angle adjustment screw for

  The invention according to claim 6 is the invention according to claim 5, wherein the plurality of strain gauges are provided at the same height position of the test piece, and the position adjusting screw and the angle adjusting screw are: Adjust the position and angle of the gripper from 4 directions.

  According to the first aspect of the present invention, the display means displays the strain direction and strain amount of the test piece for each plane substantially orthogonal to the load axes at a plurality of height positions. It can be easily grasped visually, and the time spent for adjusting the axis can be shortened.

  According to the second aspect of the present invention, on the display unit, the adjustment screw of the shaft center adjustment device and the operation message of the adjustment screw are displayed on the basis of the distortion amount and the distortion direction for each of the plurality of height positions calculated by the calculation unit. Display, it is possible for the operator to easily grasp the necessary adjustment operation visually.

  According to the invention described in claim 3, since the display means displays the distortion direction and the distortion amount for each of the plurality of height positions in three dimensions, the operator can easily grasp the information visually. It becomes possible.

  According to the invention described in claim 4, since a plurality of strain gauges are affixed at equal intervals at the same height position of the test piece, the strain direction and the strain amount for each height position can be accurately calculated. Is possible.

  According to the invention described in claim 5, since the adjustment is performed by the position adjusting screw and the angle adjusting screw, it becomes possible to perform a more precise axial center adjustment.

  According to the invention described in claim 6, four strain gauges are affixed at the same height position of the test piece, and the position adjusting screw and the angle adjusting screw adjust the position and angle of the gripper from four directions, respectively. Therefore, it is possible to associate the position of the four strain gauges with the adjustment direction of the position adjustment screw and the angle adjustment screw, calculate the distortion direction and the amount of distortion more accurately, and make the axis easy and precise. Adjustments can be made.

1 is a schematic diagram of a material testing machine according to the present invention. It is a schematic diagram of the axial center adjustment apparatus. 6 is a schematic plan view of the vicinity of an angle adjusting collar member in the shaft center adjusting device. FIG. 6 is a schematic plan view of the vicinity of a position adjusting collar member 135 in the shaft center adjusting device 13. FIG. It is a schematic diagram which shows a mode that the distortion of the test specimen 10a for a test is measured. It is explanatory drawing which shows the sticking position of the strain gauge 61 in the test piece 10a for a test. It is an example of a display which shows misalignment of an axial center, and adjustment operation of the axial center adjustment apparatus 13 corresponding to it. It is another example of a display which shows misalignment of an axial center, and adjustment operation of the axial center adjustment apparatus 13 corresponding to it. It is explanatory drawing which shows the sticking position of the strain gauge 61 in the test piece 10a for another test. It is explanatory drawing which shows the sticking position of the strain gauge 61 in the test piece 10a for another test.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a material testing machine according to the present invention.

  The material testing machine includes a base 16, a pair of left and right screw rods 17 erected on the base 16, and a nut portion screwed with the pair of left and right screw rods 17. And a cross head 23 that moves up and down. An upper grip 11 is attached to the cross head 23 via an axis adjusting device 13. In addition, the lower grip 12 is attached to the base 16 via a load cell 15. The both ends of the test piece 10 are gripped by the upper grip 11 and the lower grip 12.

  Synchronous pulleys 21 that engage with the synchronous belt 22 are disposed at the lower ends of the pair of screw rods 17, respectively. The synchronous belt 22 is also engaged with a synchronous pulley 19 that is rotated by driving of the motor 18. For this reason, the pair of screw rods 17 rotate in synchronization with the drive of the motor 18. Then, as the pair of screw rods 17 rotate in synchronization, the cross head 23 moves up and down in the axial direction of the pair of screw rods 17.

  The test force applied to the test piece 10 is detected by the load cell 15. Further, the displacement amount between the upper and lower gauge points of the test piece 10 is detected by the displacement meter 14. Signals from the load cell 15 and the displacement meter 14 are input to a control circuit (not shown). The control circuit creates a drive control signal for the motor 18 based on signals from the load cell 15 and the displacement meter 14. Thereby, the rotation of the motor 18 is controlled, and various material tests such as tension and compression are performed.

  FIG. 2 is a schematic diagram of the shaft center adjusting device 13.

  The shaft center adjusting device 13 is interposed between the cross head 23 and the upper gripper 11, and includes a connection shaft 131 that connects the crosshead 23 and the upper gripper 11, and a center of the connection shaft 131. A frame member 139 fixed to the section, an angle adjusting collar member 134 disposed on the outer periphery of the connecting shaft 131 inside the frame member 139 and fixed to the crosshead 23, and a connecting shaft inside the frame member 139. A position adjusting collar member 135 disposed on the outer periphery of 131 and fixed to the upper gripping tool 11;

  The connecting shaft 131 passes through the angle adjusting collar member 134, the frame member 139, and the position adjusting collar member 135, and the upper end portion of the connecting shaft 131 is screwed with the mounting plate 132. Is screwed to the upper grip 11. The mounting plate 132 is connected to the cross head 23 via a set of jack bolts 133. For this reason, the upper gripper 11 can be fastened to the crosshead 23 with a predetermined force by moving the mounting plate 132 upward with respect to the crosshead 23 using a set of jack bolts 133. .

  The frame member 139 includes a support portion 137 that is screwed and fixed to the connecting shaft 131, and a rectangular frame portion 136 that surrounds the connecting shaft 131. A hemispherical convex portion 138 is formed on the upper surface of the support portion 137, and a hemispherical concave portion having a shape corresponding to the convex portion 138 is formed on the lower surface of the angle adjusting collar member 134. Further, the lower surface of the support portion 137 has a planar shape, and is in contact with the upper surface of the planar position adjusting collar member 135.

  FIG. 3 is a schematic plan view of the vicinity of the angle adjusting collar member 134 in the shaft center adjusting device 13.

  The angle adjusting collar member 134 has a rectangular shape in a plan view, and an outer peripheral surface thereof is a front end portion of four screws 141, 142, 143, and 144 that are screwed with the frame portion 136 of the frame member 139. Abut. For this reason, by adjusting the four screws 141, 142, 143, and 144, the frame member 139 can be inclined together with the connecting shaft 131 to adjust the angle of the upper gripper 11. That is, of the four screws 141, 142, 143, 144, one of the two screws facing each other is loosened and the other is tightened, and the hemispherical convex portion 138 of the frame member 139 is moved to the angle adjusting collar member. The frame member 139 can be tilted together with the connecting shaft 131 by being moved along the hemispherical concave portion 134. As the connecting shaft 131 is inclined, the upper gripper 11 is inclined.

  FIG. 4 is a schematic plan view of the vicinity of the position adjusting collar member 135 in the shaft center adjusting device 13.

  The position adjusting collar member 135 has a rectangular shape in plan view, and an outer peripheral surface thereof is a tip portion of four screws 151, 152, 153, and 154 that are screwed into the frame portion 136 of the frame member 139. Abut. Therefore, by adjusting the four screws 151, 152, 153, and 154, the position of the upper gripper 11 can be adjusted by moving the frame member 139 together with the connecting shaft 131. That is, of the four screws 151, 152, 153, 154, the frame member 139 is moved along the upper surface of the position adjusting collar member 135 in a state where one of the two screws facing each other is loosened and the other screw is tightened. By doing so, the frame member 139 can be moved relative to the position adjusting collar member 135 together with the connecting shaft 131. Then, the upper gripper 11 moves with the relative movement of the connecting shaft 131.

  As described above, in the shaft center adjusting device 13, the connecting shaft 131 is adjusted by adjusting the screws corresponding to the four screws 141, 142, 143, 144 and the four screws 151, 152, 153, 154. The position and angle can be adjusted. That is, by adjusting the position and angle of the upper gripper 11, the load axes of the upper gripper 11 and the lower gripper 12, that is, the shaft center can be adjusted.

  FIG. 5 is a schematic diagram showing how the strain of the test specimen 10a is measured. FIG. 6 is an explanatory view showing a position where the strain gauge 61 is attached in the test specimen 10a.

  The strain direction and amount of axial center of the upper gripping tool 11 and the lower gripping tool 12 are as follows: the test specimen 10a on which the strain gauge 61 is attached is gripped by the upper gripping tool 11 and the lower gripping tool 12. In this state, measurement is performed with a lighter load (for example, about 20 N) applied to the test specimen 10a. As shown in FIG. 6, four strain gauges 61 are affixed at four different height positions on the upper, middle, and lower sides of the test specimen 10a.

  As shown in FIG. 5, the strain gauge 61 affixed to the test specimen 10a is connected to a data logger 62 that is a measuring means. The data logger 62 is a measuring device that records the detection value of the strain gauge 61 and stores the result, and in this embodiment, one data logger 62 is provided for each strain gauge 61 at the same height position.

  Each data logger 62 is connected to a display 63 that is a display means and a personal computer 65 that includes a ROM, a RAM, and a CPU that is a calculation means in a housing 64. In the housing 64, based on the detection value of the strain gauge 61, the strain direction and strain amount are calculated for each of the upper, middle, and lower height positions of the test specimen 10a.

  Next, an example of a method for calculating the strain direction and the strain amount will be described. First, the strain (G1 to G12) for each position of each strain gauge 61 is calculated from the detected value of each strain gauge 61 recorded by the data logger 62 and sent to the personal computer 65. As shown in FIG. 6, since four strain gauges 61 are affixed at equal intervals at the same height position, the two strain gauges 61 facing each other on a plane substantially perpendicular to the load axis at the height position. The diagonal lines connecting them are orthogonal. Each of the orthogonal diagonal lines is defined as an X-axis direction and a Y-axis direction, and an upper-position distortion in the X-axis direction = (G1-G3) / 2 and an upper-position distortion in the Y-axis direction = (G2-G4). / 2, the (X, Y) coordinates representing the strain direction and strain amount in a plane substantially orthogonal to the upper load axis are obtained. Similarly, from the distortion at the middle position in the X-axis direction = (G5-G7) / 2 and the distortion at the middle position in the Y-axis direction = (G6-G8) / 2, the surface is substantially orthogonal to the load axis at the middle position ( From the X, Y) coordinates, and the distortion in the X-axis direction at the lower position = (G9−G11) / 2 and the distortion in the Y-axis direction at the upper position = (G10−G12) / 2, The (X, Y) coordinates in the orthogonal plane are obtained. Note that the coordinate origin is the point where the load axis intersects the surface at the upper, middle and lower height positions.

  In this embodiment, the X axis is substantially the same as the line connecting the screw 141 and the screw 142 and the line connecting the screw 151 and the screw 152 in the axis adjusting device 13 described above, and the Y axis is This is substantially the same as the line connecting the screw 143 and the screw 144 and the line connecting the screw 153 and the screw 154 in the axis adjusting device 13 described above. Note that the unit of numerical values for the X-axis and the Y-axis is microstrain (με). Strain is a dimensionless amount because it is represented by the amount of deformation per unit length, but in the technical field related to strain measurement, strain (ε: strain) is conventionally used as a unit representing strain. For this reason, in this embodiment as well, a strain is used as a numerical unit.

  Each (X, Y) coordinate obtained by the above-described calculation method is plotted on a coordinate map 71 described later for each of the upper, middle, and lower height positions and displayed on the display 63. FIG. 7 is a display example showing the misalignment of the shaft center and the adjustment operation of the shaft center adjusting device 13 corresponding thereto.

  In this display example, the coordinate diagram 71 for each of the upper, middle, and lower height positions is displayed three-dimensionally based on the central axis that is the load axis. The operator can visually grasp the deviation of the (X, Y) coordinates plotted in the coordinate map 71 from the central axis, that is, the deviation of the axial center, as an image by such a stereoscopic display.

  Further, in this display example, an adjustment operation corresponding to the degree of misalignment (distortion direction and distortion amount) of the axis displayed on the coordinate diagram 71 and the arrangement diagram 72 of the adjustment screw simulating the axis adjustment device 13 is performed. A necessary adjustment screw is indicated by an arrow, and a specific operation of the adjustment screw is displayed on the operation message display unit 73. 72. A00, A90, A180, and A270 in FIG. 72 correspond to the screws 144, 141, 143, and 142 that are angle adjustment screws shown in FIG. In addition, C00, C90, C180, and C270 in FIG. 72 correspond to the screws 154, 151, 153, and 152 that are position adjustment screws shown in FIG.

  The contents of the operation message displayed on the operation message display unit 73 are stored in a storage unit (ROM or the like) in the housing 64 of the personal computer 65 for each of the position adjustment and the angle adjustment in accordance with the degree of axial misalignment. Stored.

  Next, axial center adjustment will be described. The axial center adjustment is performed in the order of position adjustment and then angle adjustment. For example, in the coordinate diagram 71 for each of the upper, middle and lower height positions, as shown in FIG. 7, when the respective (X, Y) coordinates are not on the same axis parallel to the central axis, An operation is performed to bring the upper and lower coordinates closer to the middle coordinate so that the middle and lower coordinates are on the same axis. This operation is position adjustment for operating the screws 151, 152, 153, and 154. At that time, an operation message such as “Loose C90 and tighten C270” read from the storage unit is displayed on the operation message display unit 73. Then, the operator operates the adjustment screw according to the operation message to adjust the position. Thereafter, an operation of bringing the inside coordinates closer to the coordinate center is performed. This operation is an angle adjustment for operating the screws 141, 142, 143, and 145. At this time, an operation message such as “Loose A270 and tighten A90” read from the storage unit as shown in FIG. 7 is displayed on the operation message display unit 73. Then, the operator operates the adjustment screw according to the operation message to adjust the angle.

  The data from the strain gauge 61 is measured and recorded by the data logger 62 while the operator operates the adjusting screw for adjusting the axis, and real-time coordinates are displayed in the coordinate diagram 71. The operator adjusts the axis while viewing the display on the display 63, and determines that the axis has been substantially adjusted if the deviation of the axis at each of the upper, middle, and lower height positions is within the threshold value. To finish the operation. Note that the threshold here is assumed to be a deviation of about 50 microstrain in the X-axis and Y-axis, for example.

  FIG. 8 is another display example showing the misalignment of the shaft center and the adjustment operation of the shaft center adjusting device 13 corresponding thereto. In this display example, in place of the coordinate diagram 71 shown in FIG. 7, the shift of the axial center for each of the upper, middle and lower height positions is shown in a coordinate diagram 74 which is a two-dimensional view of each height position.

  As shown in the coordinate diagram 74 of this display example, even when a two-dimensional diagram for each of the upper, middle, and lower height positions is arranged so that the scales of the X and Y axes are aligned in the vertical direction, the axis You can visually grasp the whole image of the misalignment of the mind.

  In this way, in the two display examples described above, by displaying the misalignment of the axial center for each of the upper, middle and lower height positions, the operator can grasp the misalignment of the axial center as an image, so the axial center adjustment Is easy for the operator to understand. In addition, the adjustment screw layout diagram 72 and the operation message display section 73 indicate which adjustment screw should be adjusted based on the current axial misalignment. Can be easily grasped visually, and adjustment operations can be easily performed. Further, in these display examples, specific numerical values of the (X, Y) coordinates may be displayed at the same time to enhance the display of information necessary for adjusting the axis.

  In the embodiment described above, the shaft center adjusting device 13 is disposed only on the upper gripper 11 side, and the lower gripper 12 is fixed to the base 16 via the load cell. It is also possible to attach strain gauges 61 to the upper and middle positions of the test specimen 10a, which are easily affected by the position and angle change, and adjust the axial center based on the misalignment of the axial centers of those positions. is there.

  In the above-described embodiment, four strain gauges 61 are attached at the same height position of the test specimen 10a for testing. However, if the strain gauges 61 are attached at equal intervals, the number is three. May be. That is, in the specified coordinate system, it is only necessary to obtain (X, Y) coordinates representing the strain direction and strain amount in the plane at each height position, and the number of strain gauges 61 at the same height position is limited to four. It is not something.

  FIG. 9 and FIG. 10 are explanatory diagrams showing the attachment position of the strain gauge 61 in another test specimen 10a for testing. As described above, the shape of the test specimen 10a used for adjusting the shaft center is not limited to the round bar shape in the above-described embodiment, but is the thick plate shape shown in FIG. 9 or shown in FIG. Even in the case of a thin plate, by attaching four strain gauges 61 at different height positions above, inside, and below the test specimens 10a, strain at each position of each strain gauge 61 ( It is possible to adjust the axial center based on the deviation of the axial center for each different height position calculated from G1 to G12).

DESCRIPTION OF SYMBOLS 10 Test piece 10a Test piece 11 Upper grip 12 Lower grip 13 Axis center adjustment device 14 Displacement meter 15 Load cell 17 Screw rod 18 Motor 23 Crosshead 61 Strain gauge 62 Data logger 63 Display 64 Housing 65 Personal computer 71 Coordinate Fig. 72 Adjustment screw layout 73 Operation message display 131 Connection shaft 132 Mounting plate 133 Jack bolt 134 Angle adjustment collar member 135 Position adjustment collar member 136 Frame portion 137 Support portion 138 Convex portion 139 Frame member 141 Screw 142 Screw 143 Screw 144 Screw 151 Screw 152 Screw 153 Screw 154 Screw

Claims (6)

A material testing machine provided with an axis adjustment device that adjusts the axis of a gripping tool that holds a test piece by operating a plurality of adjustment screws,
A load means for applying a load to the test piece;
A plurality of strain gauges affixed at a plurality of different height positions of the test piece;
Measuring means for recording signals from the plurality of strain gauges;
Based on the signal from the measuring means, calculating means for calculating the strain direction and strain amount of the test piece for each of a plurality of height positions;
Display means for displaying the strain direction and the strain amount for each of the plurality of height positions calculated by the computing means for each plane substantially orthogonal to the load axis at the plurality of height positions;
A material testing machine characterized by comprising: The material testing machine according to claim 1,
The display means displays an adjustment screw in the shaft center adjustment device, and displays an operation message of the adjustment screw based on a distortion direction and a distortion amount for each of a plurality of height positions calculated by the calculation means. Material testing machine. In the material testing machine according to claim 1 or 2,
The display means is a material testing machine that three-dimensionally displays strain directions and strain amounts at a plurality of height positions. In the material testing machine according to any one of claims 1 to 3,
The plurality of strain gauges are material testing machines that are affixed at equal intervals at the same height position of the test piece. The material testing machine according to any one of claims 1 to 4,
The material testing machine, wherein the adjusting screw is a position adjusting screw for adjusting the position of the gripping tool and an angle adjusting screw for adjusting the angle of the gripping tool. The material testing machine according to claim 5,
The plurality of strain gauges are provided with four pieces at the same height position of the test piece, and the position adjusting screw and the angle adjusting screw adjust the position and angle of the gripper from four directions, respectively.