JPH05332904A - Extensometer - Google Patents

Abstract

(57) [Summary] [Purpose] To enable highly accurate and automatic continuous measurement from the elastic region where the elongation is relatively small to the test sample piece to the plastic region where the elongation amount is several hundred percent. [Constitution] Each measuring element that clamps and supports two initially set reference points on the test sample piece by each tip clamping part at a predetermined reference angle, and the proximal end of each measuring element is pivotally supported on the rotating shaft. To be tilted relative to each other by the movement of each gauge point due to the load load, and at least one of the rotating shafts,
Providing each tilt angle detection means for detecting the tilt angle of each tracing stylus accompanying the movement of each gauge point as the rotation angle of each rotation axis,
By driving each following moving means by the pulse signal corresponding to the tilt angle detected by each tilt angle detecting means,
Following the movement of each gauge point, the pinching support of each tracing stylus can be moved and returned to each reference angular position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensile modulus of elasticity of a test sample piece such as plastic and the like, and an extensometer for measuring elongation at break. The present invention relates to an automatic extensometer capable of simultaneously measuring both breaking elongations.

[0002]

2. Description of the Related Art In recent years, with the rapid spread of various plastic materials, it has become necessary to improve the testing accuracy of the plastic materials. In particular, plastic materials are often used as a substitute for metallic materials in passenger cars and the like. As a result, there has been a demand for automatic and continuous measurement of tensile modulus and elongation at break with high precision to the same degree as metal materials for this plastic material.

Here, as is well known, there are various plastic materials ranging from a material having a relatively small amount of elongation to a material exhibiting an elongation of several hundred percent. Therefore, it is extremely difficult to continuously measure with high accuracy from an elastic region with a relatively small amount of elongation to a plastic region with an amount of elongation reaching several hundred percent. Conventionally, for test sample pieces such as this kind of plastic, An extensometer capable of automatically and continuously measuring this from the elastic region to the plastic region is in the present situation where no proposal has been made yet.

That is, when measuring the tensile modulus of elasticity of a plastic material using an extensometer in the related art, it is necessary to perform a highly accurate measurement operation in the elastic region, and
Since an automatic extensometer is insufficient in accuracy, a manual extensometer (for example, a strain gauge, a differential transformer, etc.) is usually used.

[0005]

However, the above-mentioned conventional manual extensometer generally has a narrow measurement range, which is disadvantageous in that it is difficult to measure the elongation at break for a test sample piece. For materials with low elongation, the break elongation of the test sample piece may be measured by this manual extensometer, but there is a problem that the measurement sensor is damaged by the impact when the test sample piece breaks. There was a point.

The present invention has been made in order to solve the above-mentioned conventional problems, and the purpose thereof is to reach several hundred percent from an elastic region having a relatively small elongation amount to a test sample piece. This kind of extensometer is capable of continuously measuring the plastic region of elongation with high accuracy and automatically, and at the same time, it is possible to measure both tensile elastic modulus and elongation at break by one measurement operation. Is to provide.

[0007]

In order to achieve the above-mentioned object, an extensometer according to the present invention has one end and the other end of a test sample piece fixed and a load in the extension direction on the other end side. An extensometer for simultaneously measuring both the tensile modulus of elasticity and the elongation at break of the test sample piece under a load, and sandwiching two gauge points initially set at intervals on the test sample piece. Parts are clamped and supported at a predetermined reference angle, and each base end part is pivotally supported on each different rotation axis, and the relative movement is caused by the movement of each gauge point due to the load applied to the test sample piece. Each set of tilting heads is connected to each measuring element of each set and at least one rotating shaft of each set, and the tilting angle of each measuring point of each set associated with the movement of each gauge point is measured. Tilt angle detection means for detecting the rotation angle of each rotation shaft Driven by a pulse signal corresponding to the tilt angle detected by each tilt angle detecting means, following the movement of each gauge point, the pinching support of each tracing stylus of each set with respect to the gauge point is performed. Each follow-up moving means that operates to move and return to each reference angular position is provided, and the number of drive pulses to each follow-up moving means is converted based on a corresponding correction value to calculate the moving distance between each reference point. It is characterized in that the tensile modulus of elasticity and the elongation at break in the test sample piece can be measured based on the difference between the respective moving distances.

Further, the extensometer according to the present invention, in the extensometer configured as described above, when calculating the moving distance between respective reference points by the number of drive pulses to each of the following moving means, It is characterized in that conversion is performed based on a correction value changed corresponding to each measurement region.

[0009]

Therefore, in the present invention, during the measurement operation, the test sample piece is gradually loaded with the measuring load in the elongation direction, so that first the reference point position initially set corresponding to the elongation of the test sample piece, As a result, the tip holding part of each probe of each set is gradually tilted relative to the reference position, and each rotary shaft is rotated accordingly. The tilt angle corresponding to is detected by each tilt angle detecting means. Subsequently, each follow-up moving means is driven by the pulse signal corresponding to each tilt angle, and the pinching support position of each tracing stylus for each set is set so as to follow the movement of each gauge point. It is moved back to the original reference angle position,
As a result, with respect to the number of drive pulses to each tracking movement means,
By adding and converting the corresponding correction values, it is possible to calculate each moving distance between each control point, and the tensile elastic modulus of the test sample piece can be calculated by the difference of each moving distance here.
And the elongation at break can be determined.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An extensometer according to an embodiment of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a structural explanatory view schematically showing an outline of an extensometer to which an embodiment of the present invention is applied.

In the configuration of the embodiment shown in FIG. 1, a test sample piece 1 made of a plastic material is provided with upper and lower air chucks 2 and 3, respectively, and upper and lower end portions 1a and 1b.
While holding it, hold it vertically and hold it,
Initial test marks are set at different upper and lower positions on the test sample piece 1, and each of the initial test mark positions is clamped at the upper and lower ends of one pair of measuring elements 4 and 5. The parts 4a and 5a constantly hold each of them from the horizontal position, which is the reference position, with a predetermined clamping force. Regarding the measurement operation here, as shown by the white arrow in the figure, It is executed by applying a measurement load to the upper air chuck 2 side, and the elongation of the test sample piece 1 caused by the applied load is the movement of each initially set gauge point position, and by extension, each of the upper and lower gauge heads 4. The tilt angle is detected as 5.

In this case, however, in order to avoid complexity in explanation, the upper and lower measuring elements 4 and 5 are not shown in the drawing. , Only the lower stylus 5 and 5 are shown, but on the lower base 11 which is movable by the lower follower movement means, in this case, the lower vertical movement mechanism (following movement means) 21. The lower rotary shaft 12 is supported by a pair of left and right lower rotary shafts 12 pivotally supported so as to be slidably adjustable in the holding direction, and at least one of the lower rotary shafts 12 has a rotation angle. The lower tilt angle detecting means, which electrically detects, is connected to the lower encoder 13.

Further, the lower vertical moving mechanism 21 includes a pair of lower timing rolls 2 arranged at respective upper and lower positions.
2, 22 and their respective lower timing rolls 22, 2
It has a lower timing belt 23 stretched between two and a lower stepping motor 24 that drives and controls one of the lower timing rolls 22 above and below, and the lower substrate 11 is mounted on the lower timing belt 23. It is connected and supported at one point so that the control (following) movement in the vertical direction can be performed as described above.

Furthermore, the rotation angle of the lower rotary shaft 12 detected by the lower encoder 13, and thus the tilt angle of the lower rotary shafts 12 and 12 at the lower probe 5 and 5, is determined by the tensile tester controller 31. Is converted into tilt angle data by the encoder converter 32, which is input to the dedicated microcomputer 33, and the lower stepping motor 24 is controlled and driven via the stepping motor controller 34 by the pulse signal output based on the tilt angle data. And each of these configurations
The same applies to the upper side.

Therefore, in the configuration of the above embodiment, the measurement load is gradually applied to the upper air chuck 2 side during the measurement operation, so that the initial reference point position corresponding to the elongation of the test sample piece 1 is set. As a result, the tip holding portions 4a, 5a of the upper and lower stylus heads 4 and 5 relatively move, and each of these stylus heads 4 and 5, that is, each lower stylus head in FIG. 5 and 5 are gradually tilted from the initially set reference position in the horizontal direction, and accordingly, the upper rotary shafts and the lower rotary shafts 12, 12 not shown are rotated. This corresponds to the rotation angle of each upper rotary shaft and each lower rotary shaft 12, 12, in other words, the elongation of the test sample piece 1 between each upper probe 4, 4 and each lower probe 5, 5. The tilt angle is
It is electrically detected by an upper encoder, a lower encoder 13, and an encoder converter 32, which are not shown.

Then, based on the tilt angle data corresponding to the elongation of the test sample piece 1 thus detected by the encoder conversion section 32, the stepping motor control section 34 is used.
The upper stepping motor (not shown) and the lower stepping motor 24 are controlled and driven by a pulse signal output from each of the upper stepping motor (not shown) and the lower board 11 to rise correspondingly, and each upper rotating shaft (not shown) Further, the upper and lower stylus heads 4 and 5 can be rotated again about the respective lower rotary shafts 12 until they reach the horizontal direction as the reference position. The number of drive pulses required for the upper stepping motor and the lower stepping motor 24 is counted by the dedicated microcomputer 33 until the tilting of each of the lower measuring elements 4 and 5 is no longer detected, and each upper rotating shaft is rotated. , And each lower rotary shaft 12
In other words, the moving distance between the reference points can be measured, and the difference between the moving distances at the measuring points can be calculated by the dedicated microcomputer 33 to obtain the target test sample. The tensile modulus of elasticity and the elongation at break of the piece 1 can be accurately and extremely easily obtained.

That is, in the structure of this embodiment, the position between the measurement points is calculated and obtained from the number of driving pulses to the upper stepping motor and the lower stepping motor 24 as described above, and the desired value is obtained. Tensile elastic modulus, and what can measure the elongation at break, as in the conventional, for example, when directly comparing the distance between the measurement points with a magnescale or the like, the response speed becomes extremely quick, In addition, the device itself can be provided at low cost because of its simple structure.

Further, in this embodiment, the number of drive pulses to the upper stepping motor and the lower stepping motor 24 and the moving distance between the respective measurement points should be held in a linear relationship. However, as a practical problem, for example, the outer diameters of the upper timing rolls and the lower timing rolls 22 and 22 are not necessarily strictly round, and the upper timing belt and the lower timing belt are not always strictly circular. Since the characteristics of No. 23 are also not uniform, there is no guarantee that the relationship between the number of drive pulses and the moving distance between each measurement point is linear. Therefore, in this embodiment means, each measurement area is It is possible to apply different correction values to.

Regarding the number of measurement areas for determining the correction value, the larger the measurement accuracy, the more preferable it is, but it is preferable, but there is a limit in terms of the memory capacity in the dedicated microcomputer 33 and the calculation speed. In particular, it is preferable to make the number of correction values dense in the region where the tensile modulus of elasticity and the elongation at break, which require high accuracy, are measured. That is, for example, the entire measurement range is 10 to 10
After dividing into 0 equal parts, the correction value at each point is obtained, and for regions where it is necessary to measure the tensile elastic modulus with high accuracy, this is again divided into 10 to 100 equal parts and correction at each point is made. A preferable means is a means for obtaining a value.

Next, an example of a method for setting each of the above measurement ranges and determining the number of correction values will be described in detail.

In this example, the total measurement range is 0-200.
mm, the tensile elastic modulus measurement range was set to 0 to 5.0 mm, and the number of correction points was set to 50 for each.
In other words, 0.1 mm in a high-precision measurement range of 0 to 5.0 mm
A correction value is calculated for each and 0 to 200 mm (0 to 5.0 m
4.0m in the normal measurement range (excluding the high-precision measurement range of m)
A correction value is obtained for each m. Therefore, the correction value is
4.0 for each of the upper and lower stylus heads 4, 5.
Since there are overlaps in mm, there will be 99 points each.

[Correction Value Setting] Here, regarding the above-mentioned correction value setting, in the state where the upper and lower stylus heads 4 and 5 are actually moved, the measured value (up to each point (actual measurement)) ( The number of pulses) may be recorded, and in this case, each point refers to a point for each 0.1 mm in the high precision measurement range of 0 to 5.0 mm for the former, and 0 for the latter. It refers to each 4.0 mm point between the normal measurement ranges of 200 mm (excluding the high-precision measurement range of 0 to 5.0 mm), and these points are, for example, a magnetic scale in advance for each point. In other cases, it may be measured and obtained. That is, in this way, for example, "the number of pulses from 0 to 1.6 mm", "the number of pulses from 0 to 8.0 mm", etc. are actually measured.

[Calculation of Correction Data] Next, the correction data for each of the points is calculated. For example, the correction data is calculated by the upper stepping motor and the lower stepping motor 2 described above.
From the rotation angle per pulse in 4 and the outer diameters of the upper timing rolls and the lower timing rolls 22 and 22, as shown in the following [Equation 1], the movement corresponding to the pulse number is performed. The distance is calculated (hereinafter referred to as a calculated value).

[0025]

[Equation 1]

[Correction Value] Further, the correction value at each point is a value obtained by dividing the actually measured distance by the calculated value as shown in the following [Equation 2].

[0027]

[Equation 2]

[Correction of Correction Value] Then, since the number of pulses is a digital value, the correction value varies, so that the moving average processing is performed here. Also,
For this moving average processing, for example, i-2, i
In this process, the arithmetic mean at the −1th, ith, i + 1th, and i + 2th five points is regarded as the ith data.

[Correction of Measured Value] Furthermore, the amount of elongation between the reference points when the tensile elastic modulus of the test sample piece 1 is measured can be easily converted by the following [Equation 3] formula to be calculated. ..

[0030]

[Equation 3]

Next, the graphs of FIGS. 2, 3 and 4 represent different examples in which the measured value by the extensometer is corrected in accordance with the above specific example. In FIG. 2, the graph is moved to the horizontal axis. When the amount mm (discontinuous) is taken on the vertical axis as the gauge accuracy,
In FIG. 3, when the horizontal axis represents the movement amount (correction value between two points) mm and the vertical axis represents the accuracy between gauge marks, in FIG. 4, the horizontal axis represents the movement amount (continuous correction value) mm and the vertical axis. The following shows the case where the gauge length accuracy is taken, and the gauge length accuracy on the vertical axis is calculated from the moving distance obtained from the pulse number and the measured moving distance as shown in the following [Equation 4]. Easy to get from the difference.

[0032]

[Equation 4]

Here, the graph shown in FIG. 2 shows the case where no correction is performed, and the graph shown in FIG. 3 shows that the correction value is obtained only at the point of 90 mm and the correction value is calculated. This is the case where it is applied to the entire measurement region (corresponding to the conventional one-point correction), and the graph shown in FIG. 4 is the case where the correction value according to this embodiment is applied. As is clear from each of these figures, the extensometer according to this example enables highly accurate measurement of the tensile elastic modulus in the entire measurement region.

In the above embodiment, the upper probe 4
In the case of moving to the position between the initial gauge marks, it may be moved in the direction opposite to the measuring direction (from the upper side to the lower side). There is a possibility that the tension will change and a measurement error will occur due to the change in tension. Therefore, in such a case, in this case, when the upper tracing stylus 4 is moved to the initial gauge point position, the initial gauge point position is once overrun downward, and then the initial mark point is again set. It is preferable to prevent the change in the tension of the timing belt at the start of the measurement from occurring by returning it to the position between the points.

[0035]

As described above in detail with reference to the embodiments,
According to this invention, with one end of the test sample piece and the other end fixed, a load in the extension direction is applied to the other end side, the tensile elastic modulus of the test sample piece, and the elongation at break. In an extensometer that simultaneously measures both of the above, each set of measuring elements of each set that clamps and supports two initially set gauge points on a test sample piece by each tip clamping part at a predetermined reference angle is provided. The base end part of is pivotally supported on the rotary shaft so that it is relatively tilted by the movement of each gauge point due to the load load, and at least one rotary shaft,
Each tilt angle detection means for detecting the tilt angle of each tracing stylus of each set accompanying the movement of each gauge point as the rotation angle of the corresponding rotary shaft is provided, and corresponds to the tilt angle detected by each tilt angle detection means. By driving each follow-up moving means by a pulse signal, the pinching support of each contact point of each set can be moved back to the reference angular position by following the movement of each gauge point. By converting the number of drive pulses to the moving means based on the corresponding correction value, the moving distance between each gauge point can be calculated over the entire measurement range, and as a result, the difference between these moving distances can be calculated. Therefore, both the tensile modulus of elasticity and the elongation at break in the test sample piece can be measured with high accuracy in a single operation. In addition, when the correction value changed corresponding to the measurement region is used, More
Effective measurement becomes possible.

[Brief description of drawings]

FIG. 1 is a structural explanatory view schematically showing a part of an extensometer to which an embodiment of the present invention is applied with an outline omitted.

FIG. 2 is a graph showing the measurement accuracy between gauge marks when no correction is made to the measurement value obtained by the extensometer.

FIG. 3 is a graph showing the measurement accuracy between gauge marks when a general one-point correction is performed on the measurement value obtained by the extensometer.

FIG. 4 is a graph showing the measurement accuracy between gauge marks when the correction value of the example is applied to the measurement value of the extensometer.

[Explanation of symbols]

 1 test sample piece 1a upper end portion of test sample piece 1b lower end portion of test sample piece 2 upper air chuck 3 lower air chuck 4 upper stylus 4a upper tip of the stylus 5 lower stylus 5a lower tip of the lower stylus 11 Lower Base 12 Lower Rotating Shaft 13 Encoder (Tilt Angle Detection Means) 21 Lower Vertical Moving Mechanism (Following Moving Means) 22 Lower Timing Roll 23 Lower Timing Belt 24 Lower Stepping Motor 31 Tensile Tester Controller 32 Encoder Converter 33 Dedicated Micro Computer 34 Stepping motor controller

Claims (2)

[Claims] 1. A test sample piece is fixed at one end and the other end, and a load is applied in the elongation direction to the other end to measure both the tensile modulus and the elongation at break of the test sample piece. An extensometer for simultaneous measurement, which is initially set at a distance of 2 on the test sample piece.
Each gauge point is clamped and supported by each tip clamping part at a predetermined reference angle, and each base end is pivotally supported on each different rotation axis, and each reference point is accompanied by a load applied to the test sample piece. One set each being relatively tilted by the movement of the gauge, and each measuring element of each set, and being connected to at least one rotating shaft of each set,
Corresponding to the tilt angle detection means for detecting the tilt angle of each tracing stylus of each set accompanying the movement of each gauge point as the rotation angle of each rotation axis, and the tilt angle detected by each tilt angle detection means. Driven by a pulse signal, following the movement of each gauge point, each follow-up moving means that operates so as to move and return the pinching support of each tracing stylus of each set to the reference point to the reference angular position. The number of driving pulses to each of the following moving means is converted under a corresponding correction value to calculate the moving distance between each gauge point, and the test sample piece is calculated by the difference between the moving distances. An extensometer, which is configured so that the tensile modulus of elasticity and the elongation at break can be measured. 2. When calculating the moving distance between the respective control points by the number of drive pulses to each of the following moving means,
The extensometer according to claim 1, wherein the extensometer is converted based on a correction value changed corresponding to each measurement region.