JP4033118B2 - Test method for springy specimens - Google Patents

Description

  The present invention relates to a method for testing a springy specimen using a material testing machine.

  Using a material testing machine that measures the load-displacement characteristics of a specimen, for example, compressing a compression coil spring and performing a spring test has been conventionally performed (for example, Patent Document 1). Further, as a material testing machine capable of performing a spring test, there is one that corrects a load frame deflection and accurately measures a load-displacement characteristic of a specimen (for example, Patent Document 2).

Japanese Patent Laid-Open No. 11-2595 JP-A-3-33637

  In a spring test using a conventional material testing machine, the amount of spring deformation is measured from the amount of movement of the crosshead. That is, the crosshead movement amount at the start of the test is set and displayed as zero, and the crosshead movement amount when the spring is deformed is displayed as the spring deformation amount. For this reason, the height of the spring specimen cannot be directly displayed, and the spring test cannot be performed while displaying the spring length in the process of compressing the spring from the initial height to a predetermined amount (%).

  That is, since the conventional material testing machine cannot detect the initial spring height, the spring height (spring deformation amount) and the load are detected while detecting the spring height from the initial spring height to the maximum spring deformation height. It is not possible to perform a spring test that measures the characteristics of

  For dumbbell type specimens and round bar type specimens, a lever-type displacement meter can be attached to the specimen and the amount of deformation can be measured directly. However, a displacement gauge should be attached to the compression coil spring or tension coil spring. Therefore, the amount of deformation cannot be measured directly.

According to the first aspect of the present invention, there is provided a load frame in which a specimen having spring properties (hereinafter referred to as a spring specimen) is loaded between a pair of opposing members, an actuator for loading the spring specimen, and a specimen. Load detecting means for detecting the load of the load, distance detecting means for detecting the separation / contact distance between the pair of opposing members, and load detecting means while loading the spring specimen set between the pair of opposing members with the actuator It is applied to a test method for a spring specimen using a material testing machine equipped with a load acquiring unit detected in step 1 and a data acquiring unit that acquires a separation / contact distance detected by a distance detecting unit. Then, the test method for the spring specimen is inputted with an initial dimension of the spring specimen and a ratio to the initial dimension, and a position where the pair of opposing members are brought into contact with each other is set as a zero point position of the distance detecting means. The distance between the pair of opposing members is adjusted so that the detection value of the distance detection means becomes the initial dimension of the spring-like specimen, the spring-like specimen is set between the pair of opposing members, and the detection value of the distance detection means Between the state indicating the initial dimension and the deformed state deformed by the amount obtained by multiplying the initial dimension by the ratio, while the load is applied to the spring specimen by the actuator, the detected value of the load detecting means and the distance detecting means Is collected by a data acquisition means.

  According to a second aspect of the present invention, in the method for testing a spring specimen according to the first aspect, after detecting the deformation state, the load is applied while reducing the load on the spring specimen until the distance detecting means indicates the initial dimension. The detection values of the detection means and the distance detection means are collected.

  According to a third aspect of the present invention, in the test method for a spring specimen according to the first or second aspect, the pair of opposing members are brought into contact with each other, and the load detection means and the distance are applied while applying a load to the load frame with the actuator in that state. By collecting the detection value of the detection means, the load frame deflection characteristic is acquired and stored, and according to the stored load frame deflection characteristic, correction is performed to cancel the load frame deflection amount from the detection value of the distance detection means, and the true specimen It is characterized by detecting dimensions.

  According to the present invention, it is possible to perform a test such as compressing to what percentage of the spring height.

  FIG. 1 shows a material testing machine for performing a spring test by the method for testing a spring specimen according to the present invention. A pair of left and right screw rods 12 and 13 are erected on the fixed table 11, and a yoke 14 is horizontally mounted on the upper portions of the screw rods 12 and 13. The screw rods 12 and 13 and a pair of nuts (not shown) provided on the left and right sides of the cross head 15 are screwed together, whereby the cross head 15 is supported by the screw rods 12 and 13 so as to be movable up and down. . The servo motor 16 disposed in the fixed table 11 is connected to a control device 30 that controls the operation of the material testing machine. The output shaft of the motor 16 is coupled to the screw rods 12 and 13 via the transmission device 17. A pulse encoder 18 is connected to the output shaft of the motor 16, and the pulse encoder 18 is connected to the control device 30. The control device 30 includes a microcomputer and its peripheral circuits.

  An upper holder 21 is attached to the lower surface of the crosshead 15 via a load cell 19, and a lower holder 22 is attached to the upper surface of the fixed table 11. The upper holder 21 and the lower holder 22 are opposed to each other. The spring specimen TP is held between the two. The base 11, the screw rods 12 and 13, and the crosshead 15 constitute a load frame LF.

  Then, based on the control signal from the control device 30, as the motor 16 rotates in a predetermined direction, the screw rods 12 and 13 rotate in the same direction via the transmission device 17, and the screw rods 12 and 13 are screwed. The combined cross head 15 moves up and down. As a result, a load, here a compressive load, is applied to the spring specimen TP held by the upper holder 21 and the lower holder 22. At this time, the compression load detected by the load cell 19 attached to the crosshead 15 is input to the control device 30 together with the rotation amount of the servo motor 16 detected by the pulse encoder 18, that is, the deformation amount of the spring specimen TP. The As will be described later, the spring height is calculated based on the amount of spring deformation.

  The spring specimen TP may be either a compression spring or a tension spring. In the case of the illustrated compression spring, the lower holder 22 and the upper holder 21 are like spring seat members that handle the spring winding end. Thus, in the case of a tension spring, it becomes like a stopper for locking the spring hook.

  Connected to the control device 30 are a display device 32 that displays instruction contents related to operations, load values as measurement results, various analysis contents, and the like, and an input device 31 that inputs instructions from an operator.

  The control device 30 performs overall control of inputting detection signals from the load cell 19 and the pulse encoder 18 and outputting an operation amount signal to the servo motor 16. Therefore, the control device 30 obtains the load waveform detected by the load cell 19 and the position of the crosshead 15 detected by the pulse encoder 18 by the test waveform generator 33 that generates a load pattern waveform according to the test conditions. The acquisition part 34 and the load command output part 35 which outputs the drive signal of the servomotor 16 are provided.

  The load command output unit 35 calculates the deviation between the load command value indicated by the load pattern waveform generated from the test waveform generation unit 33 and the load detection value detected by the load cell 19, or the spring height generated from the test waveform generation unit 33. The deviation between the displacement command value indicated by the displacement pattern waveform and the spring height based on the spring deformation detected by the pulse encoder 18 is calculated, and a drive signal is output to the servo motor 16.

  The control device 30 includes a spring height counter 38, an initial spring height setting unit 39, and a maximum spring deformation amount setting unit 40. The count value of the spring height counter 38 represents the spring height, and as will be described later, the position where the lower holder 22 and the upper holder 21 are in contact with each other is set to zero spring height. An initial spring height Hi corresponding to the spring test condition input from the input device 31 is set in the initial spring height setting unit 39, and a spring input from the input device 31 is set in the maximum spring deformation amount setting unit 40. A maximum spring deformation amount Hm is set according to the test conditions.

  The control device 30 further includes a deflection data storage unit 41 and a deflection correction unit 36. The deflection data storage unit 41 stores deflection characteristic data of the load frame LF stored in advance prior to the test. A method of creating the deflection characteristic data will be described later. The data deflection correction unit 36 cancels the load frame deflection amount included in the spring height detected by the pulse encoder 18 in accordance with the load frame deflection characteristic data of the load frame LF stored in the deflection data storage unit 41, and the true spring Detect height.

  That is, the control device 30 provides the monitor 32 with the load detection value obtained by the load cell 19 acquired at a predetermined sampling interval by the measurement data acquisition unit 34 and the true spring height corrected by the deflection correction unit 36 in real time. Performs output processing for numerical display and graph display. In addition, the control device 30 stores the load detection value and the true spring height corrected for deflection in the test result storage unit 37 as load-displacement characteristics.

  The deflection correction of the deflection correction unit 36 is performed as follows. As described above, the spring height detection value output from the pulse encoder 18 when the spring specimen TP is loaded, that is, the count value of the spring height counter 38 includes the deflection of the load frame LF. Therefore, the load when the spring height as the count value is acquired is obtained, and the deflection amount is calculated from the deflection data in the deflection data storage unit 41 using this load as an argument. Then, a value obtained by subtracting the deflection amount from the spring height of the spring height counter 38 is set as a true spring height.

  To create the load frame deflection characteristic prior to the spring test, the input device 31 selects the spring test mode. When the start button is operated after the deflection correction mode is selected, it is determined from the output signal of the load cell 19 that the upper holder 21 is lowered by the servo motor 16 and the upper holder 21 is in contact with the lower holder 22. For example, it is assumed that the upper and lower holders 21 and 22 are in contact with each other when the output value of the load cell 19 indicates 0.01 N. At this time, the spring height counter 38 is reset to zero so that the detection value of the pulse encoder 18 becomes zero. At this time, 0.0 mm is displayed on the height display portion 32a of the display device 32, and the deformation amount of the load frame LF is recognized as zero.

  Next, a load is applied to the load frame LF up to a predetermined load by the servo motor 16, and then the load is unloaded. For example, while visually observing the display value of the load display unit 32b of the display device 32, a load is applied to about 95% of the maximum capacity of the load cell 19, and then unloading is performed until the display value of the spring height display unit 32a indicates zero. To do. During this time, load data and deformation amount data are read at a predetermined sampling interval and stored in the deflection data storage unit 41. As a result, a deflection characteristic of the load frame LF as indicated by a symbol A in FIG. 2 is created. The horizontal axis in FIG. 2 indicates the deflection (also referred to as deformation amount) of the load frame, and the vertical axis indicates the load (also referred to as test force, load, etc.) acting on the load frame. In FIG. 2, the deflection amount of the load frame is indicated by α.

  The procedure of the spring test will be described. When the spring test mode is selected by the mode selection button of the input device 31 and the start button provided in the input device 31 is operated, the spring test is started. In the spring test, an initial spring height and a maximum spring deformation height are input in advance. Then, the upper holder 21 is raised by the servo motor 16 until the spring height of the spring height counter 38 reaches the initial spring height Hi set in the initial spring height setting unit 39. Thereby, the space | interval (separation distance) of the upper holder 21 and the lower holder 22 is set to the initial stage spring height Hi. At this time, the spring initial height Hi is displayed on the spring height display portion 32a of the display device 32.

  In this state, when the spring specimen TP is set between the upper holder 21 and the lower holder 22, and the start button is pressed again, the spring test is started. When the spring test is started, according to the spring height displacement pattern waveform, the true spring height whose deflection has been corrected matches the maximum spring deformation amount Hm predetermined in the maximum spring deformation amount setting unit 40. The spring specimen TP is compressed. During this time, the measurement data acquisition unit 34 collects detection values of the load cell 19 and the pulse encoder 18 at a predetermined sampling interval. At this time, the deflection correction unit 36 calculates the true spring height and updates the spring height counter 38.

  After the true spring height reaches the maximum spring deformation amount Hm, the upper holder 21 is moved up by the servo motor 16 until the true spring height again indicates the initial spring height Hi, and the spring specimen TP is moved. Reduce the load. That is, unloading. Also during this time, the detection values of the load cell 19 and the pulse encoder 18 are collected by the measurement data acquisition unit 34 at a predetermined sampling interval, and the spring height counter 38 is updated as described above.

  Thus, during the spring test data collection, the true spring height calculated by the deflection correction unit 36 is corrected in real time according to the load frame deflection characteristics, and the actual spring height and test load after deflection correction are calculated. Are displayed numerically and graphically on the monitor 32 in real time.

  In FIG. 2, symbol B indicates a load-spring deformation amount characteristic based on a detected value before deflection correction, and symbol C indicates a load-spring deformation amount characteristic after deflection correction.

  As described above, the spring test method according to this embodiment can provide the following operational effects.

(1) The spring initial height and the maximum spring deformation height can be specified as the spring test conditions.
(2) It is possible to perform a test such as compressing to what percentage of the spring height.
(3) The spring height can be displayed on the display device 32 during the test.
(4) The deflection data of the load frame LF is measured in advance, and the true spring height obtained by correcting the deflection of the load frame in real time can be obtained from the detected spring height data, and an accurate spring test is performed. Can do. In particular, the switching point for unloading from spring compression is more accurate due to the true spring height.

  The above description is merely an example, and various modifications can be made without impairing the characteristics of the present invention. For example, a testing machine that applies a load by driving a pair of screw rods with a servo motor has been described, but the present invention can also be applied to a testing machine that applies a load with a hydraulic cylinder, a hydraulic ram, or an electromagnetic actuator. Furthermore, the present invention can be applied not only to the spring test but also to an evaluation test of an elastic mat or the like.

It is a figure which shows an example of the material testing machine which tests with the testing method of the spring test piece by this invention. It is a graph which shows the load-spring deformation amount characteristic in a spring test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 15 Crosshead 16 Servo motor 18 Pulse encoder 19 Load cell 21 Upper holder 22 Lower holder 30 Control apparatus 31 Input apparatus 32 Display apparatus 33 Test waveform generation part 34 Measurement data acquisition part 35 Load command output part 36 Deflection correction part 37 Test result Storage unit 38 Spring height counter 39 Initial spring height setting unit 40 Maximum spring deformation setting unit 41 Deflection data storage unit

Claims (3)

A load frame in which a specimen having spring properties (hereinafter referred to as a spring specimen) is installed and loaded between a pair of opposing members;
An actuator for loading the spring specimen;
Load detecting means for detecting a load load of the spring specimen;
Distance detecting means for detecting a separation distance between the pair of opposing members;
A data acquisition means for acquiring a load load detected by the load detection means and a separation / contact distance detected by the distance detection means while loading the spring specimen set between the pair of opposing members with the actuator. In the test method of the spring specimen using the equipped material testing machine,
Enter the initial dimension of the spring specimen and the ratio to the initial dimension,
The position where the pair of opposing members are brought into contact with each other is set as the zero point position of the distance detecting means,
Adjusting the distance between the pair of opposing members so that the detection value of the distance detection means is the initial size of the spring specimen;
Set the spring specimen between the pair of opposing members,
A load is applied to the spring specimen by the actuator between a state where the detection value of the distance detecting means indicates the initial dimension and a deformed state in which the initial dimension is deformed by an amount obtained by multiplying the ratio. On the other hand, the spring test specimen testing method is characterized in that detection values of the load detection means and the distance detection means are collected by the data acquisition means. In the test method of the spring test piece according to claim 1,
After detecting the deformation state , the detection values of the load detection means and the distance detection means are collected while reducing the load on the spring test specimen until the distance detection means indicates the initial dimension. Test method for springy specimens. In the test method of the springy specimen according to claim 1 or 2,
Is brought into contact with each other the pair of opposed members, to obtain the load frame deflection characteristics by taking the detection value of said distance detecting means and said load detecting means while applying a load to the load frame by the actuator in the state Remember,
A test method for a springy specimen, wherein a true specimen size is detected by performing correction for canceling the amount of deflection of the load frame from a detection value of the distance detecting means according to the stored load frame deflection characteristics.

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