JP3852424B2 - Displacement measuring device for material testing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a displacement measuring apparatus for measuring displacement due to a load of a test piece.
[0002]
[Prior art]
Conventionally, a pair of upper and lower levers (arms) of a lever-type elongation measuring device can be moved in the direction of specimen load, and a gauge jig is sandwiched between the upper and lower arms so that the distance between the upper and lower arms is the gauge length. Thus, it is known that the upper arm is moved by an actuator until the lower arm comes into contact with the stopper. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-281349 (2nd page, FIG. 1 and FIG. 4)
[0004]
[Problems to be solved by the invention]
The upper and lower arms are preferably attached to the center part of the test piece held by the upper and lower grippers with a predetermined gauge length. However, in conventional stretch measurement devices, the arm attachment position is determined by a gauge jig and stopper. It was. For this reason, the work of accurately attaching the arm to the center portion of the test piece with a predetermined gauge length is complicated, and if the attachment position of the arm differs depending on the test piece, a problem also arises in the reliability of the collected test data.
[0005]
The present invention provides a displacement measuring apparatus capable of attaching an arm accurately and simply to a predetermined position of a test piece.
[0006]
[Means for Solving the Problems]
(1) A displacement measuring apparatus for a material testing machine according to a first aspect includes a guide rail, an upper arm and a lower arm held so as to be reciprocally movable on the guide rail, a driving means for moving the upper arm and the lower arm, First detection means for detecting the positions of the arm and lower arm, second detection means for detecting the positions of the upper gripping part and the lower gripping part for gripping the test piece, and the detection result of the second detection means Calculating a central position between the gripping part and the lower gripping part, calculating an origin position which is equidistant from the central position and takes a predetermined gauge length, and based on the detection result of the first detection means, And a control means for controlling the drive means so as to move the lower arm to the origin position.
[0007]
(2) The first detection means when the second detection means of the displacement measuring apparatus of claim 1 is also used as the first detection means, and the upper arm and the lower arm are brought into contact with the upper grip portion and the lower grip portion, respectively. It is preferable to detect the positions of the upper grip portion and the lower grip portion based on the detection result of the detection means.
Furthermore, the second detection means of the displacement measuring device may be configured to detect the positions of the upper grip portion and the lower grip portion based on signals from non-contact displacement sensors provided on the upper arm and the lower arm, respectively. it can.
[0008]
(3) A displacement measuring method using the above displacement measuring device includes a step of calculating the center positions of the upper grip portion and the lower grip portion, and the upper arm and the lower arm are equidistant from the center position and have a predetermined gauge length. And a step of determining the end of the load test on the test piece, and a step of removing the upper arm and the lower arm from the test piece and returning to the original position by the end determination. To do.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a displacement measuring apparatus for a material testing machine according to the present invention will be described with reference to the drawings.
FIG. 1 is a front view schematically showing a configuration of a material testing machine main body to which a displacement measuring apparatus according to an embodiment of the present invention is attached. FIG. 2 is a side view (a) and a front view (b) schematically showing the configuration of the displacement measuring apparatus according to the present embodiment. The displacement measuring apparatus 10 is installed on the front surface or the back surface of the test piece 100 shown in FIG.
[0010]
The test machine main body 1 includes a motor M, a speed reducer 2, a screw rod 3, a cross head 4, a yoke 5, an upper grip portion 6, a lower grip portion 7, and a load cell 8.
[0011]
The displacement measuring apparatus 10 includes a pair of support columns 11, a guide rail 12, a pair of pulleys 13, a pair of pulse motors 14 with a clutch, a linear scale 15, an upper arm 16, a lower arm 17, a pair of wires 18, and a pair of balance weights 19. It has. Hereinafter, the components constituting a pair are represented by adding “a” or “b” as necessary.
A control panel 20 for inputting various operations to the displacement measuring device 10 is connected to the displacement measuring device 10. The control panel 20 is provided with a reset button 21 and a start button 22.
[0012]
The column 11 is erected on the base 9 of the tester main body 1 in the load direction of the test piece 100. The guide rail 12 and the linear scale 15 are provided between the pair of support columns 11a and 11b. The linear scale 15 is attached to the guide rail 12. The pulley 13 and the pulse motor 14 are installed at the upper end of the column 11, and the rotating shaft of the pulley 13 and the rotating shaft of the pulse motor 14 are connected.
[0013]
A lower arm 17 and an upper arm 16 are held on the guide rail 12 so as to be movable up and down. Wires 18a and 18b are wound around the pair of pulleys 13a and 13b, respectively, a lower arm 17 is connected to one end of the wire 18b, and a balance weight 19 is suspended from the other end. Similarly, the upper arm 16 is connected to one end of the wire 18a, and the balance weight 19 is suspended from the other end.
[0014]
In FIG. 1, the testing machine main body 1 decelerates the rotational force of the motor M by the speed reducer 2, rotates the pair of screw rods 3, and moves the crosshead 4 up and down. An upper grip 6 is connected to the fixed yoke 5 via a load cell 8, and a lower grip 7 is connected to the movable crosshead 4. When both ends of the test piece 100 are gripped by the upper gripping portion 6 and the lower gripping portion 7 and the cross head 4 is lowered, a load is gradually applied to the test piece 100 and eventually breaks. This load test starts when the operator presses a start button 22 provided on the control panel 20.
[0015]
In FIG. 2, the test piece 100 is held by the upper grip portion 6 and the lower grip portion 7. The positions of the upper arm 16 and the lower arm 17 are reset, that is, the origin position. At this origin position, the upper arm 16 and the lower arm 17 are attached so as to sandwich the test piece 100, respectively. At this time, the upper arm 16 and the lower arm 17 are located at an equal distance d up and down with respect to the center position C of the upper grip portion 6 and the lower grip portion 7. Twice the distance d is the gauge length. Although not shown, each of the upper arm 16 and the lower arm 17 has a pair of opening and closing levers and an actuator for opening and closing the opening and closing levers. The upper and lower arms 16 and 17 are opened and closed by the actuator. The test piece 100 can be attached and detached.
[0016]
When moving the arm, the upper arm 16 and the lower arm 17 are detached from the test piece 100, the clutch of the pulse motor 14 is turned on, and the pulse motor 14 is rotated. The wire 18 moves and the arm moves up and down along the guide rail 12.
[0017]
During the load test, the clutch is turned off, and the arm moves up and down along the guide rail 12 following the elongation of the test piece 100. The position of the arm is read by the linear scale 15. The rotation of the pulse motor 14, the ON / OFF of the clutch of the pulse motor 14, and the attachment of the arm to the test piece 100 are performed according to a procedure programmed in advance by pressing the reset button 21 provided on the control panel 20. It is executed immediately.
[0018]
Hereinafter, the procedure of elongation measurement using the displacement measuring apparatus of the present embodiment will be described with reference to FIG. FIG. 3 is a schematic diagram showing the operation of the displacement measuring apparatus according to the embodiment of the present invention. When the reset button 21 of the control panel 20 is pushed by the operator while the test piece 100 is gripped by the upper grip portion 6 and the lower grip portion 7, the upper arm 16 is in the order of FIGS. 3 (a) to 3 (c). And the lower arm 17 moves.
[0019]
{Circle around (1)} Before the reset button 21 is pushed, the upper arm 16 and the lower arm 17 are in arbitrary positions (see FIG. 3A).
[0020]
(2) When the reset button 21 is pushed, the clutch of the pulse motor 14 is turned on, the lower arm 17 is driven until it comes into contact with the lower grip 7, and the upper arm 16 is moved to the upper grip 6. It is driven until it comes into contact. It is detected that the output change of the linear scale 15 with respect to the pulse input to the pulse motor 14 is small, and it is detected that the upper and lower arms are in contact with the upper and lower grips. At this time, the position of the lower arm 17 and the position of the upper arm 16 are read from the output value of the linear scale 15 (see FIG. 3B).
[0021]
(3) Based on the position of the upper arm 16 and the position of the lower arm 17, the center position C of the upper and lower grips, that is, the center position C of the test piece is calculated. The gauge lengths input in advance are distributed by the distance d from the center position C, and the attachment target positions of the lower arm 17 and the upper arm 16, that is, the origin position are calculated. This origin position is stored in a memory of a control unit (not shown).
[0022]
(4) The upper arm 16 and the lower arm 17 are driven to the origin position. The pulse motor 14 is decelerated before the origin position, and the upper and lower arms are stopped at the correct position without overrunning the target position. The upper and lower arms are closed and attached to the test piece (see FIG. 3C).
[0023]
(5) When the start button 22 is pushed, the clutch of the pulse motor 14 is turned off, the crosshead 4 of the tester main body 1 is lowered, and a load is applied to the test piece 100. The upper arm 16 and the lower arm 17 descend on the guide rail 12 according to the elongation of the test piece 100. Of the upper arm 16 and the lower arm 17, the lower arm 17 has a larger descending distance. The control unit (not shown) reads the value of the linear scale 15 as the elongation of the test piece, and reads the output value of the load cell 8 as the load of the test piece.
If an operating transformer that outputs a displacement amount corresponding to the relative displacement between the upper arm 16 and the lower arm 17 is provided at the rear end of the arm, and the output of this operating transformer is read and used as the extension amount, the elongation can be measured more accurately. it can.
[0024]
(6) When a predetermined test end condition is satisfied, the crosshead 4 is stopped and the test is ended. The test end condition is, for example, a condition that the load cell output is zero due to the test piece breaking.
(7) When the end of the test is determined, the upper and lower arms are opened and removed from the test piece 100.
(8) Same as (2) to (7) above, when the operator presses the reset button 21 of the control panel 20 while the next test piece is gripped by the upper grip portion 6 and the lower grip portion 7. A load test is performed in the procedure.
[0025]
The above procedures (2) to (7) are automatically performed only by pressing the reset button 21 and the start button 22 on the control panel 20. The operation of attaching and removing the upper and lower arms to / from the test piece 100 may not be performed automatically, but may be performed by an operator.
[0026]
In this embodiment, the upper and lower arms are brought into contact with the upper and lower grippers to calculate the center position C of the upper and lower grippers, and the target mounting position (origin position) of the upper and lower arms is determined based on the gauge length inputted in advance. Since the upper and lower arms are calculated and moved to the origin position, the upper and lower arms can be correctly attached to the center of the test piece. As a result, when testing a plurality of test pieces under the same conditions, the upper and lower arms can be attached at the same position, and the reliability of the test data is improved.
[0027]
Hereinafter, modifications of the present embodiment will be described. In the displacement measuring apparatus of the present embodiment, when calculating the center position C between the upper and lower grips, the upper and lower arms are brought into contact with the upper and lower grips, and the positions of the upper and lower arms are detected by the output value of the linear scale. did. On the other hand, a light emitting element and a light receiving element are provided on the upper and lower arms, respectively, so that the position of the gripper is optically detected, and the center position C between the upper and lower grippers is calculated based on this output value. You can also.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a displacement measuring device capable of attaching an arm accurately and simply to a predetermined position of a test piece.
[Brief description of the drawings]
FIG. 1 is a front view schematically showing a configuration of a material testing machine main body to which a displacement measuring apparatus according to an embodiment of the present invention is attached.
FIG. 2 is a side view (a) and a front view (b) schematically showing a configuration of a displacement measuring apparatus according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing a procedure of displacement measurement using the displacement measuring apparatus according to the embodiment of the present invention.
[Explanation of symbols]
1: Test machine body 6: Upper grip part 7: Lower grip part 10: Displacement measuring device 11: Support column 12: Guide rail 13: Pulley 14: Pulse motor 15: Linear scale 16: Upper arm 17: Lower arm 20: Control panel 100: Test piece

Claims (5)

A guide rail;
An upper arm and a lower arm held so as to be reciprocally movable on the guide rail;
Driving means for moving the upper arm and the lower arm;
First detecting means for detecting positions of the upper arm and the lower arm;
A second detection means for detecting the positions of the upper grip portion and the lower grip portion for gripping the test piece;
A center position between the upper grip portion and the lower grip portion is calculated based on a detection result of the second detection means, an origin position that is equidistant from the center position and takes a predetermined gauge length is calculated, A displacement measuring apparatus for a material testing machine, comprising: a control unit that controls the driving unit to move the upper arm and the lower arm to the origin position based on a detection result of one detection unit. The displacement measuring device according to claim 1,
The second detection means is also used as the first detection means, and the detection result of the first detection means when the upper arm and the lower arm are brought into contact with the upper grip portion and the lower grip portion, respectively. A displacement measuring apparatus for a material testing machine, wherein the positions of the upper gripping portion and the lower gripping portion are detected on the basis thereof. The displacement measuring device according to claim 1,
The second detecting means detects the positions of the upper grip portion and the lower grip portion based on signals from non-contact displacement sensors provided on the upper arm and the lower arm, respectively. Displacement measuring device. The displacement measuring device according to claim 1,
The material measuring machine displacement measuring apparatus, wherein the upper arm and the lower arm are attached to and detached from the test piece by opening and closing by an actuator. In the displacement measuring method using the displacement measuring apparatus of Claims 1-4,
Calculating a center position of the upper grip portion and the lower grip portion;
Moving the upper arm and the lower arm to an origin position that is equidistant from the central position and takes a predetermined gauge length;
Determining the end of a load test on the test piece;
A displacement measuring method comprising: removing the upper arm and the lower arm from the test piece and returning to the origin position by the end determination.

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