JPS6229944Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is applicable to tests for determining the circumferential strength of pipe materials at room and high temperatures, such as tensile tests, creep tests, creep rupture tests, and fatigue tests.
In particular, it relates to a jig for tensile testing of small diameter pipe materials.

The first specimen was a circumferential tensile test specimen of a conventional pipe material.
The figure and FIG. 2 will be explained.

Reference numeral 1 is a test piece in which the test tube material is cut into rounds, and the cross-sectional areas in the tube axis direction of the test parts 1a and 1b that face each other on the same circumference are the remaining untested parts 1c and 1b that face each other on the same circumference. It is processed so that the cross-sectional area in the tube axis direction is smaller than 1d. 2 and 3 are the above test pieces 1
The core is inserted so as to be almost in contact with the inner circumferential surface of the core, and is divided into two semi-cylindrical shapes on a plane including the axis, and pin holes 2a and 3a are bored in the center of each core. Pins 6 and 7 inserted into the pin holes 2a and 3a are connected to one end of tension jigs 4 and 5 that pull the cores 2 and 3 in opposite directions so that the dividing surfaces of the cores 2 and 3 are separated from each other. Further, the other ends of the tensioning jigs 4 and 5 are connected to a loading device (not shown) that applies a tensile load W to the test piece 1 via the tensioning jigs 4 and 5 and the cores 2 and 3.

Conventionally, the cores 2 and 3 are split into two parts on a plane including the axis, and inserted into the test piece 1 so that they are almost in contact with the inner circumferential surface of the test piece 1, and the split surfaces are separated from each other. When pulled in opposite directions,
The outer peripheral parts 2d and 3d of the cores 2 and 3 are in contact with almost the entire inner peripheral surface of the test piece 1, and a force in the opposite direction is applied thereto. As a result, a tensile load W is applied to the test piece 1 along the circumferential direction, and a tensile load W equally divided into two acts on the opposing test portions 1a and 1b along the circumferential direction.

Therefore, when the tensile load W is increased, test piece 1 finally
The test parts 1a and 1b are destroyed. The required tensile strength in the inner circumferential direction of the test piece 1 was determined from the load up to the time of failure.

As mentioned above, in the conventional jig, it is necessary to pass the pins 6 and 7 through the cores 2 and 3, which are divided into two parts, and the cores 2 and 3 are naturally limited in size, and the diameter of the test piece 1 It has the disadvantage that it cannot be applied when is small.

In addition, in order to eliminate such drawbacks,
There is an invention in Utility Application No. 110588/1988 (unpublished at the time of filing of this application) filed by the present inventors. By dividing the core along a plane perpendicular to the axis of the core, this design eliminates the need for bolts inside the core, which were required for attaching and removing samples.As a result, the core itself can be made smaller, making it possible to test small-diameter tube materials. That is.

An example of this is shown in FIGS. 3 and 4. In this case as well, the cores 2, 3, 4, and 5 are divided by a plane a perpendicular to the plane containing the axis, so each core 2 , 3, 4, and 5 are bent, and if the center of the test portions 1a, 1b of the test specimen 1 and the dividing center plane of the plane a are misaligned during the tensile test, the line of force of the tensile load W The center lines of the test parts 1a and 1b of the test piece 1 do not match, and a bending moment acts on the test parts 1a and 1b of the test piece 1 in addition to the tensile load W.
There is a drawback that the tensile strength test accuracy in the circumferential direction of the test piece 1 is reduced, and the test is performed between the outer periphery of the cores 2 and 3 and the untested part 1d of the test piece 1, and between the outer periphery of the cores 4 and 5. There is a problem in that a half ring (not shown) must be inserted between each untested portion 1c of the piece 1 to perform the test.

The purpose of the present invention is to provide a tensile test jig for pipe materials that eliminates these drawbacks and allows testing of small-diameter test pieces without the need for ring insertion. The tool is divided into four parts by a plane perpendicular to the axial center and a plane including the axial center, and when these parts are combined, the inner peripheral surface of the test piece is smaller in width than the non-test part. and an annular contact surface with the inner circumferential surface of the test piece having a width that can at least cover the width of the test piece sample portion, and a core having the same width, and a plane including the axis of the core. and a means for pulling the core in opposite directions so that the divided surfaces separate from each other, and the feature is that even if the tip of the core is bent, force is always applied to the center of the width of the test piece. The purpose of the present invention is to provide a jig for tensile testing of pipe materials, which allows a tensile test to be performed with high accuracy especially when the test piece is a small diameter pipe.

As mentioned above, the jig of the present invention divides a columnar core to be inserted into a tube specimen into four parts by a plane containing the axis and a plane perpendicular to the axis; The cores were then pulled in opposite directions using appropriate means.

Therefore, with the jig of the present invention, there is no need to remove the core from the jig in order to replace the test piece, and there is no need for bolts for removing the core, so the core itself can be made smaller, and it can be used for small diameter pipes. It is also possible to test

Further, in the jig of the present invention, the annular contact surface between the core and the inner circumferential surface of the test piece has a width smaller than the width of the non-test part of the test piece and larger than the width of the test part of the test piece. FIG. 5 shows an enlarged schematic cross-sectional view of a jig for tensile testing of pipe materials in the case where a discrepancy occurs in the core near the test part.
In Figure 5, the dotted line shows the case of the conventional jig, and the solid line shows how stress is applied in the case of the jig of the present invention. Since they are separated, the bending moment becomes large, but in the present invention, the distance between the supporting points to which the load is applied is short, so the bending moment becomes small. Therefore, the accuracy of the tensile test can be improved, and there is no need to insert a half ring between the outer periphery of each core and the untested part of the test piece. Tensile testing is also possible.

Hereinafter, an embodiment of the jig for tensile testing of pipe materials according to the present invention will be described as shown in FIGS. 6 and 7.

10 is a test piece in which the test tube material was cut into rings;
Processed so that the cross-sectional area in the tube axis direction of the test portions 10a and 10b facing each other on the same circumference is smaller than the cross-sectional area in the tube axis direction of the remaining untested portions 10c and 10d facing each other on the same circumference. has been done.

20, 30, 40, and 50 are cores obtained by dividing the cylindrical body inserted into the test specimen 10 into four by a plane containing the axis and a plane perpendicular to the axis,
At the test piece abutting part at the tip, there are semicircular engagement parts 20b and 30, respectively, so as to be in almost contact with the test piece 10.
b, 40b, and 50b are provided in a protruding manner. The width of the engaging portion when the core is assembled on a plane perpendicular to the axis and a plane including the axis is the same as that of the sample parts 10a and 10 of the test piece.
It is larger than the width of b, and smaller than the width of the non-test parts 10c and 10d of the test piece.

Reference numerals 20a, 30a, 40a and 50a are mounting members fixed to semicircular end faces of cores 20 and the like with corresponding symbols, respectively, and the mounting members 20a and 30a are attached to the tension jig 60 and to the mounting member 40a. 50a
are connected to the tension jig 70 by bolts 80, 90 and nuts 80a, 90a, respectively.

Further, the tension jigs 60 and 70 are connected to a loading device (not shown) that applies a tensile load W to the test piece 10.

Since this embodiment is configured as described above, 4
Engagement parts 20b, 30b, 40 of the divided core
b, 50b are engaged with the inner circumferential surface of the test piece 10, and the tensile jig 6 is moved in opposite directions so that the cores 20, 30 and 40, 50 are separated from each other.
0, 70, bolts 80, 90, and a loading device (not shown), the outer circumferential portion of the core, such as the engaging portion 20b, comes into contact with almost the entire inner circumferential surface of the test piece 10, and the opposing core Forces in opposite directions act on the cores 20, 30 and the cores 40, 50.

As a result, a tensile load W is applied to the test piece 10 along the circumferential direction. In this case, a tensile load W equally divided into two is applied to the sample portions 10a and 10b facing each other on the same circumference of the test piece 10 along the circumferential direction.

Therefore, when the tensile load W is increased, the test portions 10a and 10b of the test piece 10 finally break. Therefore, the required tensile strength of the test piece 10 in the circumferential direction can be determined from the load up to the time of failure.

In addition, since the width of the engaging portion when the cores are aligned on a plane perpendicular to the axis is narrower than the untested portions 10c and 10d of the test piece, the engaging portions 20b, 30b, 40b, 5
Even if there is a slight discrepancy in 0b, the resulting bending moment is small, and accurate testing can be performed without a half ring.

As described above, according to the jig of this embodiment, even when the inner diameter of the test piece 10 is small and it is impossible to provide a pin hole inside the core, the test piece 1
It becomes possible to perform a test to determine the tensile strength in the circumferential direction of 0. In addition, since a half ring is not required, tests can be performed on small diameter pipes.

In addition, in the above examples, taking into account thermal expansion during high temperature tests such as creep tests, the test piece 10
A slight gap may be provided between the inner peripheral surface of the core 20 and the like.

Furthermore, the cores 20, 30 and 40, which were divided into four,
50 are pulled in opposite directions so as to separate from each other at the dividing surface, if there is a risk that the corners of the core 20 etc. may contact the inner peripheral surface of the test piece 10 and cause scratches, If necessary, the corners of the core 20 and the like can be rounded.

[Brief explanation of the drawing]

Figure 1 is a side view of a conventional tensile test jig, Figure 2
The figure is a cross-sectional view taken along the - line in Figure 1, Figure 3 is a side view of a tensile test jig that the present inventors had previously filed as an invention (unpublished at the time of filing of this application), and Figure 4 The figure is a cross-sectional view taken along the - line in FIG. 3, FIG. 5 is a schematic explanatory diagram of a tensile test jig, and FIG. 6 is a side view of an embodiment of the present invention.
FIG. 7 is a longitudinal sectional view taken along the - line in FIG. 3. 10... Test piece, 10a, 10b... Test part of test piece, 20, 30, 40, 50... Core, 6
0,70... tension jig, 80,90... bolt,
80a, 90a...Nut, W...Tensile load.

Claims (1)

[Scope of utility model registration request] In a test jig used for tensile strength testing in the circumferential direction of pipe materials, the test piece is divided into four parts by a plane perpendicular to the axis of the pipe material and a plane containing the axis, and the inner circumference of the test piece when these are combined. The surface contact portion has an annular contact surface with the inner circumferential surface of the test piece that has a width smaller than the width of the non-test part and has a width that can at least cover the width of the test piece part, and each has an equal width. 1. A jig for tensile testing of pipe materials, comprising: a core having a core having an axis; and means for pulling the core in opposite directions so that surfaces divided by a plane including the axis of the core are separated from each other. .