JPS62170835A - Measuring instrument for elongation of material to be tested - Google Patents

Abstract

PURPOSE:To measure the rupture elongation quantity of a material to be tested automatically, by measuring the elongation quantity after a rupture by placing plural probes at a prescribed interval extending over about the overall length of the material to be tested, and calculating a uniform elongation, a local elongation, and a rupture elongation. CONSTITUTION:An extensometer 15 in which for instance, five pieces of probes 141-145 are placed is provided at an equal interval extending over the overall length of a material to be tested 11 which is held between chucking mechanisms 12, 12, an an elongation quantity signal is sent out to an elongation arithmetic part 16. By a tension tester, a tension load is applied until the material to be tested 11 is ruptured, and after it is ruptured, an elongation quantity of each section and the total elongation quantity are measured by the extensometer 15. Also, a uniform elongation is calculated from the former, a local elongation is calculated from said elongation and the latter, and also, from both the elongations, a rupture elongation against a prescribed gauge length is calculated. In such a way, even if a rupture position of the material to be tested cannot be forecast, by rupture elongation can be automatically measured from the elongation quantity after the rupture.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a test material that automatically measures the elongation at break of a test material whose cross-sectional shape is uniform over the entire length, such as a pipe or a bar. This invention relates to an elongation measuring device.

[Conventional technology]

Conventionally, in tensile testing of metals, different elongation measuring devices have been used depending on the form of the metal being tested. For example, in the case of a plate, a test material is used that has a parallel finished part, or "parallel part", which is machined so that the cross-sectional dimension of the center part is smaller and uniform than that of both ends, and the material covered by the brackets is An extensometer is provided with a pair of probes set at an initial position corresponding to a specified rating distance of the test material, and the distance between the pair of probes changes as a result of applying a tensile load to the deformation of the test material. A structure is used in which the amount of movement of the test material until breakage occurs is measured as elongation using an extensometer.

On the other hand, in the case of test materials such as pipes and wire rods, the cross-sectional dimensions are often the same as the original product, that is, test materials with a uniform cross-sectional shape that are not machined to parallel finish like plate materials are used. . In the case of such a material to be tested, it is completely impossible to predict where it will break, so stamps are placed on the material to be tested in advance at multiple specified rating distance positions, and after the material breaks, a pair of rating intervals are marked at the fracture location. is selected and the growth of the corresponding rating interval is artificially measured.

[Problem that the invention seeks to solve]

However, in measuring the elongation at break of a test material whose cross-sectional shape is uniform over the entire measurement length, the elongation measurement work is very time-consuming and is a factor that hinders the automation of the entire tensile test.

The present invention has been made in view of the above-mentioned circumstances, and is a method for measuring the elongation of a test material that enables automatic measurement of the elongation at break after the fracture of the test material, and easily realizes automation of the entire tensile test. The purpose is to provide equipment.

[Means for solving problems]

According to the elongation measuring device for a test material according to the present invention, a plurality of probes are arranged at predetermined intervals over almost the entire length of the test material, and each measuring section is measured after the test material breaks. An extensometer that obtains the amount of elongation and the total amount of elongation of all measurement sections, and the amount of elongation of each measurement section output from this extensometer and the elongation rate of each section from the initial distance force 1 of each measurement section and uniformity. Seeking growth,
It is also equipped with an elongation calculation unit that calculates the local elongation from the total elongation of all measurement sections and the initial total distance, and calculates the elongation at break of the test material for a specified rating distance from these uniform elongations and local elongations. It is.

[Effect]

Therefore, by using the above means, the present invention
Multiple measuring elements are placed over the entire length of the test material to which the tensile load is applied, and the uniform elongation and local elongation are determined using the amount of elongation in each measurement section and the total amount of elongation in all measurement sections. Since the elongation of the test material after rupture is calculated from the elongation and local elongation, the elongation after rupture can be automatically measured without using any artificial means, and the
It is possible to automate the entire test and improve the efficiency of the test work.

〔Example〕

An embodiment of the apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of the apparatus of the present invention, in which reference numeral 11 indicates the chucking mechanism 12 of the testing machine on both ends.
The test material is, for example, a tubular material to be tested, which is chucked by a tube, and a core 13 is inserted into the tube at both ends to prevent deformation due to the chucking.

An extensometer 15 is provided between the two chucking machines 112 and 12, in which, for example, five probes 141 to 145 are arranged at equal intervals over the entire length of the test material 11 to which a tensile load is applied. , a required elongation amount signal of the material under test 11 is sent to the subsequent elongation calculating section 16.

Although not shown, the extension calculation section 16 includes, for example, a microcomputer, memory, and other human output boards.
This memory stores, for example, the prescribed evaluation point path *Qa shown in FIG.
(+11111), data such as the distance between each measurement section and the distance between the two end probes 14 (+11111), that is, the entire initial measurement section distance, and other necessary coefficients are stored. The extensometer 15 uses measuring elements 141 to 145 to obtain the elongation of each measurement section after rupture in order to obtain the elongation rate ε1 of each measurement section, and also obtains the amount of elongation of the entire measurement section of the test material 11 after rupture. The total elongation amount λt (llllffl) is obtained and output.

17 is a load detector, and 18 is a tensile characteristic value calculation unit that calculates the tensile characteristic value by conventionally known means.

Next, the operation of the apparatus configured as above will be explained.

The material to be tested 11 is chucked by the chucking mechanism 12.degree. 12 of the tensile testing machine, and five probes 141 to 145, for example, are set on the material to be tested 11 at equal intervals. Therefore, there are four measurement sections. When a tensile load is applied to both ends of the test material 11 using a tensile testing machine under the above conditions, and if it breaks at the position of section ■ shown in Fig. 2, the elongation distribution of each section will be as shown in Fig. 3, for example. It appears like this. The reason for this is that the elongation distribution is normally as shown in FIG. In Fig. 4, the elongation opening of the diagonally shaded area where there is a large local elongation near the break point A is "local elongation", and the elongation of the almost uniform elongation on both sides is "local elongation".
This is called "uniform elongation."

Therefore, the elongation rate of each measurement section is determined by each measurement distance after rupture with respect to the initial distance of each probe section, that is, the elongation amount, and each elongation rate when the elongation rates are arranged in order from the smallest to the largest. are respectively ε+(+-1~n), then the arithmetic mean value where n is an odd number is uniformly elongated εU (%)
For example, as shown in Figure 3, from section ■ to section ■
When the elongation rates are arranged in order from the smallest to the largest, each elongation rate is ε1. ε2. ε3. When ε4 is used, the "uniform elongation" εU (%) can be obtained from the following formula.

ε, = (ε1+ε2)/2% ・・・・・・(1
) On the other hand, the initial total measurement interval distance between the probes 141 and 145 and the total elongation after fracture are respectively ffm(til
l), λt (nv), one local elongation ``λ2(
mlll) can be determined by the following formula.

λ1-21 (ε0-4m/100)...
...(2) After that, the "elongation at break" εf from this λ1 to the specified rating distance λ0 is εf - ε.・α+(100λ1 ・β＞/(loC
%)・・・・・・(3) It can be obtained by the following. However, α and β are correction coefficients determined depending on the material. The calculations of equations (1) to (3) above are performed by the extension calculation section 16.

Furthermore, Figure 5 shows "uniform elongation" based on the actual measured values in a conventional example using measurement of the distance between scores at the fracture position at multiple scores, and the distribution of elongation between multiple scores based on experiments using this device.
This is a diagram showing the results of comparing the values obtained by separately detecting and "local elongation" and combining them as "break elongation", and it can be seen that the two match very well.

In the above embodiment, the measurement range is divided into four sections, but the number of sections is determined as appropriate depending on the total length of the test material and the degree of variation in the fracture position. In addition, although the above embodiment described a test material whose cross-sectional shape is uniform over the entire length, for example, a plate material with a parallel part due to processing, that is, a so-called proportional The same applies to molded materials. In this case, the elongation at break can be automatically measured with the same configuration even if the rating distances are different. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

〔Effect of the invention〕

As detailed above, according to the present invention, the elongation at break can be automatically measured from the amount of elongation after break even if the break position of the test material cannot be predicted, and the same configuration can be used regardless of the specified scoring distance. Elongation at break can be measured. Therefore,
There is no need to stamp a large number of score points in advance or to manually measure the distance between specified score points after breaking, and the entire test of the material under test can be automated, which can greatly contribute to streamlining the test work. We can provide an elongation measuring device for test materials.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the elongation measuring device for test materials according to the present invention, Fig. 2 is a diagram showing the relationship between the probe group and the measurement sections, and Fig. 3 is the elongation of each measurement section. Figure 4 is a diagram explaining the rate, Figure 4 is a diagram schematically representing the elongation of the test material, and Figure 5 is a diagram explaining the rate.
The figure is a characteristic diagram showing the relationship between the conventional measured elongation at break and the calculated elongation at break according to the present application. 11... Test material, 141-145... Measuring head, 1
5... Extensometer, 16... Extension calculation section. Applicant's representative Patent attorney Takehiko Suzue Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In an apparatus for measuring the elongation at break of a material to be tested by applying a tensile load to the material, a plurality of probes are arranged at predetermined intervals over almost the entire length of the material to be tested that receives the tensile load, and An extensometer that uses these probes to measure the amount of elongation in each measurement section and the total amount of elongation in all measurement sections after the test material breaks, and each measurement obtained based on the amount of elongation in each measurement section of this extensometer. The uniform elongation is determined from the elongation rate of the section, and the local elongation is determined from the initial total measured section distance and the total amount of elongation from the extensometer. 1. An elongation measuring device for a test material, comprising: an elongation calculation section that calculates elongation at break after breakage.