JPH1010024A - Measuring instrument of elongation between reference lines - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the mounting and precisely measure the displacement of a minute elongation area by holding a reference line setting part and a reference line fixing part by an attaching and detaching fixing means in the state where a sample piece is arranged between the reference line setting part and the reference line fixing part, and directly measuring the displacement of distance between set reference line parts by a measuring part. SOLUTION: The protruding quantity of an attractive holding rod 62 screwed to a reference line fixing member 63 according to the thickness dimension of a test piece 31 is regulated, the position of a stopper member is regulated to regulate the energizing force of a coil spring, and the pressure of the test piece 31 is set to a proper value. A reference line setting part 40 and a reference line fixing part 60 are opposed to the parallel part of the test piece 31, and the knife edge 41K of a knife edge member 41 is brought into contact with one surface 31a of the test piece 31. A pair of guide holes of an upper reference line member body 42u and a lower reference line member body 42d are opposed to a pair of attracting rods 62, the pressing surface 61 of a plunger 61 is brought into contact with the test piece 31, the rods 62 are fixed, and the elongation is measured by a differential transformer 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gauge-elongation measuring instrument intended to be attached to a material strength tester for examining mechanical properties of general industrial materials.
The present invention relates to an inter-mark line elongation measuring device that measures displacement in a micro elongation region in an initial stage of load applied to a test piece.

[0002]

2. Description of the Related Art Plates and films made of hard / semi-rigid thermoplastic resin materials, plates made of hard / semi-rigid thermosetting resin materials, fiber-reinforced thermosetting materials, thermoplastic composite materials, and the like. When performing a tensile strength test on a plate made of a metal material, etc., conditions such as the shape of the test piece and the test speed are specified by Japanese Industrial Standards so that comparisons can be made with various measurement results based on the measurement data. I have.

Examples of the shape of a test piece include a dumbbell-shaped test piece and a strip-shaped test piece. As shown in FIG. 8, a dumbbell-shaped test piece 1 prevents breakage from both ends gripped by a tester. And a pair of gripping portions 2 having a large area at both ends in order to make the cross section of a predetermined section located between the gripping portions 2 and 2 constant and having a width so as to generate high stress. And a parallel portion L formed narrow.

For example, when a tensile test is performed to determine the tensile elastic modulus, elongation at break, and breaking load of a member, the relationship between the stress that changes with an increase in the tensile load and the displacement of the distance L0 between the marked lines is measured. Is done. The distance L0 between the marked lines is the distance between the marked lines 3 indicated by two points or lines set in advance in the parallel portion L before applying stress to the test piece 1, for example, 25 mm, 50 mm, etc. Is set to

[0005] There are roughly two types of measuring methods for measuring the displacement of the distance between the marked portions of the test piece 1. A pair of contacts are directly attached to the parallel portion L of the test piece 1. Fig. 9 which directly measures the displacement of an object as elongation with a displacement sensor
(A), a contact type elongation measuring instrument such as a π gauge type strain gauge 10 as shown in (b), and a position recognition mark 21 provided on a parallel portion L of the test piece 1 as shown in FIG. Parallel part L
Instead of directly measuring the displacement, there is a non-contact type elongation measuring device such as a marking line tracking type elongation measuring device 20 that optically reads the relative displacement of the mark 21 and measures it as elongation. .

The π gauge strain gauge 10 shown in FIG.
A resistance wire strain gauge (not shown) is attached as a displacement sensor to a gauge attachment portion 11a which is a stress concentration portion of the mold spring portion 11.

The π-gauge strain gauge 10 has a hook portion 12a of a clamp member 12 on a pair of engagement edges 11b provided at both ends of a π-type spring portion 11 to which the resistance wire strain gauge is attached. By locking, π
The knife edge portion 11c, which is a contact of the shaped spring portion 11, abuts one surface side of the parallel portion L of the test piece 1, and is urged by the elastic force of a compression spring 12b provided on the clamp member 12. The plunger head portion 12c abuts on the other surface side of the parallel portion L of the test piece 1 and is held and fixed.

That is, first, the π-shaped spring portion 11 is
The knife edge portion 1 is pressed against the spacer 13 having a predetermined length to set the distance L0 between the marked line portions.
1c is brought into contact with one surface side of the test piece 1. Next, while holding this state, the clamp member 12 is held with the other hand, the hook opening 12d is directed downward, the test piece 1 is straddled on the upper side of the knife edge portion 11c, and then the plunger head portion 12c Is pressed against the other surface side of the test piece 1 to compress the compression spring 12b to lower the clamp member 12, thereby locking the hook portion 12a to the engagement edge portion 11b. As a result, the π-type spring portion 11 is held and fixed to the test piece 1 and the mark line portion distance L0 is determined.

[0009] Thereafter, the distance between the marked lines changes as the stress increases. The displacement between the marked lines is indicated by the gauge
It is electrically measured as a change in the resistance value of the resistance wire strain gauge attached to “a”, and the elongation of the distance between the marked lines is directly measured.

The range of measurement by the π-gauge strain gauge 10 is limited by the elastic limit of the spring of the gauge attachment part, so that the range of measurement is set in advance by the spacer 13 and the stopper 14. Has become. Further, the π-gauge type strain gauge 10 is formed so as to be extremely light so that adverse effects such as stress concentration, moment, and inertia force do not appear in the test result due to the added weight when the π gauge type strain gauge 10 is attached to the test piece 1. Further, the code 1
Reference numeral 5 denotes an extensometer case, and reference numeral 16 denotes a V-groove bottom of the hook portion 12a, and the width of the knife edge portion 11c is set to be wider than the width W0 of the test piece.

On the other hand, a marked line portion tracking type elongation measuring device 20 shown in FIG. 10 prints or affixes, for example, a pair of position recognition marks (hereinafter abbreviated as marks) 21 on the test piece 1. At a position different from the pulling device, tracking is performed by, for example, photocells 23, which are a pair of tracking devices that move on a guide 22 arranged in parallel with the test piece pulling direction. Is measured by a displacement meter. As the displacement meter, a potentiometer 24, a differential transformer 25, or the like is appropriately selected and used depending on the material of the test piece 1 and the intended inspection accuracy.

That is, a triangle mark 21 called a benchmark printed on the parallel portion L of the test piece 1
6, the mark 21 is projected on the photocell 23 using the contrast between the mark 21 and the test piece 1. The incandescent lamp 26 is provided with a heat ray absorbing filter 27 in order to prevent the test piece 1 from being heated by the light of the incandescent lamp 26 and changing the distance L0 between the marked lines.

The photocells 23 are arranged in two upper and lower stages so as to correspond to the marks 21, respectively. The light resistance of the marks 21 projected on each photocell 23 changes, so that the electric resistance is lowered. Changes. Therefore, in order to track the respective marks 21 so that the electric resistance values of the upper and lower photocells 23, 23 are always the same, the deviation resistance from the upper and lower photocells 23, 23 is converted into a voltage and amplified by a servo amplifier. The photocell 23 is moved by rotating the drive motor 28.

The drive motor 28 is mounted on platforms 29u and 29d, and the platforms 29u and 29d are provided with a photocell 23 and an incandescent power source 26, respectively. Therefore, when the distance between the marked lines is displaced and the light amount of the mark 21 reflected on the photocells 23, 23 changes, the upper and lower photocells 23, 2
The respective platforms 29u and 29d move in the vertical direction so that 3 follows the substantially middle point of the marks 21 and 21.

The amount of displacement between the marked portions of the test piece 1 is detected by measuring the distance between the upper and lower platforms 29u and 29d. The upper and lower platforms 29u, 2
When the interval of 9d is detected by using the multi-rotation potentiometer 24, the potentiometer 24 is attached to, for example, the lower platform 29d, and the potentiometer 2
The pulley 24a is attached to the shaft 4. Then, one end of the steel wire 31 is fixed to the upper platform 29u, and the steel wire 31 is wound around the pulley 24a. Therefore, the platform 29
When u and 29d move, the potentiometer 24 rotates, and the elongation between the marked portions of the test piece is measured from the elongation output voltage that changes with the resistance value that changes with this rotation.

[0016]

However, in the contact type π-gauge type strain gauge shown in FIG. 9, the adverse effect due to the added weight when the π-gauge type strain gauge is attached to the test piece does not appear. Since each member was formed as light as possible by stealing the meat, for example, when measuring up to the breakage of the test piece, π was determined by the impact force when the test piece was broken.
While the shaped spring portion may be broken, the measurement of the high elongation member was impossible by preliminarily limiting the measurement range with the spacer and the stopper.

The work of attaching the π-gauge type strain gauge to the parallel portion of the test piece is performed by locking the bottom of the V-groove of the hook portion to the tip of the engaging edge of the π-shaped spring portion, and confirming the attached state. Attachment is completed. However, it is difficult to lock the bottom of the V-groove of the hook and the tip of the engaging edge, and the measurement accuracy depends on the locking state. It was necessary to delegate the test to a worker having the above-mentioned mounting work skill.

On the other hand, in the non-contact type mark-line tracking type elongation measuring device shown in FIG. 10, the inertial force generated by the weight load when the displacement detector, which is a defect of the contact type, is attached to the test piece. In addition to eliminating the effects of moment, stress concentration, etc., it enables measurement in high-temperature atmospheres by measuring high elongation members and tracking marks on test specimens through a transparent window at room temperature. However, since this is an indirect measurement in which the contrast between the mark and the test piece is projected on a photocell and measured, the instability of the transmission element due to disturbances such as the following accuracy of the drive motor and changes in the illuminance of the illumination in the inspection room is minimal. In addition to the problem in the temperature range, there is a problem that the mark printed on the test piece becomes unclear as the test piece elongates and accurate measurement cannot be performed.

When measuring the mechanical properties of a member made of a resin material or the like, the measurement of the tensile modulus requires extremely high resolution accuracy in accordance with the following JIS rules. In such measurements, low-resolution accuracy on the order of a scale is often sufficient.

According to JIS K 7161 (ISO-577-1993), the tensile modulus is determined by measuring the stress corresponding to two defined strains, strain 0.0005 and strain 0.0025, respectively. It is defined that uniform measurement can be performed from a brittle material having a high elastic modulus to a high elongation member having a low elastic modulus. When the distance between the marked lines is set to, for example, 50 mm, the displacements at the two points of strain (0.0005 and 0.0025) are respectively
In order to determine the tensile modulus, it is required to measure an extremely small displacement in a minute elongation region.

The present invention has been made in view of the above circumstances, and is easy to attach to a test piece, and accurately measures the displacement of the test piece in a minute elongation area in an initial stage of load. The purpose is to provide equipment.

[0022]

According to the present invention, there is provided a measuring device for elongation between benchmarks, in which two benchmarks are set in parallel with a test piece used for a material strength test, and the displacement between the benchmarks is measured. A gauge line elongation measuring device for directly measuring a pair of knife edge portions abutting on one surface side of a parallel portion of the test piece and a displacement between the gauge line portions set by the knife edge portions. A marking line setting unit provided with a measuring unit, a marking line fixing unit having a pressing unit that abuts on the other surface side of the parallel portion of the test piece, and the marking line setting unit and the marking line fixing unit are integrally formed. And detachable fixing means for fixing the fixing means.

According to this configuration, the test piece is arranged between the mark setting section and the mark fixing section, and the mark setting section and the mark fixing section are held and fixed by the attaching / detaching and fixing means. A marked part is set on the test piece. Then, the amount of displacement of the distance between the marked lines is directly measured by a measuring unit provided in the marked line setting unit.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 relate to a first embodiment of the present invention. FIG. 1 is an explanatory view showing a schematic configuration of a gauge-elongation measuring apparatus, and FIG. FIG. 3 is an explanatory view showing a configuration of a line setting unit, FIG. 3 is an explanatory view showing a configuration of a marker line fixing unit of the gauge line elongation measuring device, and FIG. FIG. In this embodiment, a rectangular test piece having a rectangular cross section is used as the test piece.

As shown in FIG. 1, an inter-mark line elongation measuring device 30 of the present embodiment includes a mark setting section 40 attached to one surface 31a side of a parallel portion of a test piece 31; And a marked line fixing portion 60 attached to the other surface 31b of the portion.

The marking line setting section 40 has a knife edge 41k having a sharp tip 41k serving as a pair of contacts for abutting against one surface 31a of the parallel portion of the test piece 31 to set the marking section. The knife edge member 41 is disposed between the upper marking member main body 42u and the lower marking member main body 42d, on which the member 41 is disposed, and the lower marking member body 42d. A tubular replaceable spacer cylinder 43, which is a mark-to-mark distance setting member for setting the distance between the knife edge portions 41k to be a predetermined mark-to-mark distance, and the knife edge member 41 located on the upper side. The micro-strain 0.0 in the initial stage of the load between the marked lines set with the knife edge member 41 located on the lower side 0.0
A separation type differential transformer 50 which is a contact / separation type measurement tool which moves following the elongation of a test piece as a measurement unit for directly measuring displacement in a micro elongation region corresponding to at least 005 and 0.0025. It is mainly composed of

Referring to FIGS. 2A and 2B, the marking line setting unit will be described. The upper mark line member main body 42u
In order to maintain a parallel state between the lower mark member main body 42d and the smooth parallel movement, a guide pin 44 is disposed on the lower mark member main body 42d, while the upper mark section main body 42u is provided with a guide pin 44. A guide bush 45 into which the guide pin 44 fits is provided.

A concave portion 41a is formed on the knife edge member 41 on the side opposite to the knife edge portion 41k, and the concave portion 41a is formed on the convex portion 42a formed on the upper mark section main body 42u and the lower mark section main body 42d. The knife edge member 41 is engaged and screwed and fixed by the knife edge fixing screw 46, thereby preventing the knife edge member 41 from being displaced in a direction perpendicular to the direction in which the test piece 31 extends.

The differential transformer 50 is for directly measuring the minute displacement of the distance between the marked portions of the test piece 31. For example, the differential transformer 50 is provided on the bobbin side disposed on the upper marked portion main body 42u. The differential transformer main body 51 includes a secondary coil part 51a and a secondary coil part 51b, and a differential transformer core 52 that moves inside the differential transformer main body 51. For this reason, when the test piece 31 is pulled and extended, when the upper marking member main body 42u and the lower marking member main body 42d move while maintaining the parallel state, the differential transformer core 52 becomes the differential transformer. The elongation is measured by an output voltage that changes in accordance with a mutual inductance that changes while moving inside the main body 51.

The differential transformer core 52 is threadedly connected to a small-diameter end portion 53a of a core mounting rod 53, and a male thread portion provided at a rear end portion 53b of the core mounting rod 53 is connected to a lower mark line portion. By screwing a hexagonal nut 54 to the rear end 53b while screwing into the main body 42d, the position of the differential transformer core 52 with respect to the differential transformer main body 51 can be adjusted to be integrated with the lower marking section main body 42d. The zero point can be easily adjusted at the time of manufacturing because the fixing point is fixed.

A pair of guide holes 47 are formed in the upper mark line member main body 42u and the lower mark line member main body 42d, and a magnet member 48 constituting a detachable fixing means is disposed inside the guide hole 47. Have been.

Since the measuring range of the differential transformer 50 is very small, the differential transformer 50 is lightweight and compact, and the fitting state of the guide pin 44 is released when the guide pin 44 exceeds the measuring range. The length is sufficient, and the length is set to the minimum necessary length to reduce the weight and size.

The spacer cylinder 43 is loosely fitted on a guide pin 44 provided on the lower marking member main body 42d, and the guide pin 44, the guide bush 45 and the differential transformer main body 51 are fixed with screws or the like. The fixing device is disposed on the upper mark section main body 42u and the lower mark section main body 42d, respectively. Further, the magnet member 4
8 is fixed in the guide hole 47 with an adhesive or the like.

On the other hand, the marking line fixing member 60 shown in FIG.
Is a plunger 61 having a pressing surface 61a serving as a pressing portion that contacts the other surface 31b side of the parallel portion of the test piece 31,
A pair of suction / holding rods 62, 62, which constitute a detachable fixing means engaged with the pair of guide holes 47 and sucked by the magnet member 48, and the plunger 61 and the suction / holding rods 62, 62 are arranged. Marking line fixing part body 6 to be installed
3 mainly.

As shown in FIG. 3, the plunger 61 is a spring-type plunger having a coil spring, and is arranged on the marking line fixing portion main body 63 via a plunger arrangement member 64. . This plunger arrangement member 6
4 is provided with a through hole 64a through which the small diameter portion 61b of the plunger 61 is inserted, and a plunger arrangement in which the large diameter portion 61c of the plunger 61 and the coil spring 65 for urging the plunger 61 are disposed. An installation hole 64b is provided.

In order to prevent the plunger 61 and the coil spring 65 disposed in the plunger mounting hole 64b from falling off and to adjust the urging force of the coil spring 65, a female screw is provided in the plunger mounting hole 64b. Part is provided,
A stopper member 66 is screwed into the female screw portion.
Further, a male screw portion is formed on the outer peripheral surface of the plunger arrangement member 64, and this male screw portion can be screwed into a female screw portion formed in a through hole of the reference line fixing member 63 to adjust the amount of protrusion. I can do it. Further, the suction holding rod 62 is screwed and fixed to the marking line fixing member 63 so that the amount of protrusion of the tip end surface 62a of the suction holding rod 62 can be adjusted according to the thickness of the test piece 31. ing.

A method for attaching the gauge-to-mark line elongation measuring device to the test piece will be described. First, the protrusion amount of the suction holding rod 62 screwed and fixed to the marked line fixing member 63 is adjusted according to the thickness dimension of the test piece 31, and the stopper member screwed to the plunger arrangement member 64. The urging force of the coil spring 65 is adjusted by adjusting the position of 66, and the pressing force of the plunger 61 on the test piece 31 is set to an appropriate value.

Next, as shown in FIG. 1, the mark setting section 40 and the mark fixing section 60 face each other with respect to the parallel portion of the test piece 31, and the mark setting section 40 is gripped with one hand. Then, the knife of the knife edge member 41 is set by pressing the upper mark line member main body 42u and the lower mark line member main body 42d against both end surfaces of the spacer cylinder 43 whose distance between mark lines is set to, for example, 50 mm. The edge portion 41k is brought into contact with one surface 31a of the test piece 31.

Next, the pair of guide holes 47 of the upper marking line member main body 42u and the pair of suction rods 62 arranged in the marking line fixing portion main body 63 are opposed to each other, and the marking line fixing portion main body 63 is moved to the upper marking line member. The suction rod 62 is inserted into the guide hole 47 by approaching the main body 42u. Then, the suction rod 62
Moves linearly in the guide hole 47, and the pressing surface 61 a of the plunger 61 urged by the compression spring 65
1 while being in contact with the other surface side 31b.
2 is attracted and fixed by the attraction force of the magnet member 48.

Subsequently, a pair of guide holes 47 of the lower marking line member main body 42d and a pair of suction rods 62 arranged in the marking line fixing portion main body 63 are opposed to each other, and the marking line fixing portion main body 63 is moved to the lower marking line. The suction rod 6 is linearly approached to the member body 42u.
2 is fixed by suction by the suction force of the magnet member 48. As a result, as shown in FIG. 4, the marked line setting unit 40 and the marked line fixing unit 60 are integrally fixed and held to the parallel portion of the test piece 31, and the mounting of the interline mark elongation measuring device is completed.

Here, the test is started. When the test is started, a load is applied to the test piece 31 so that the test piece 3
A slight elongation occurs in the parallel portion of No. 1. Then, the knife edge member 4 which abuts on the test piece 31 and sets the mark line
1 and the lower marking member main body 42d are slightly moved in response to the minute elongation, and the difference between the differential transformer 50 provided in the marking line setting section 40 is different. The dynamic transformer core 52 is the differential transformer body 5
1 and the elongation is measured by an output voltage that changes with the changing mutual inductance at this time.

When further extension occurs in the parallel portion of the test piece 31, minute displacements of the test piece 31, such as a displacement of 0.025 mm corresponding to a strain of 0.0005 and a displacement of 0.125 mm corresponding to a strain of 0.0025, are sequentially measured. Is done.

Further, when a load is applied to the parallel portion of the test piece 31 and elongation occurs, the differential transformer core 52 comes out of the inside of the differential transformer main body 51, and the upper mark line member main body 42u of the mark setting section 40 and the upper part. The lower mark line member main body 42d is separated from and held by the test piece.

As described above, by linearly moving the marked line fixing portion constituting the marked line elongation measuring device toward the marked line setting portion, the attractive force of the magnet member provided in the marked line setting portion can be used. The mark fixing part and the mark setting part are integrally fixed, and the test piece is pressed against the knife edge member by the pressing force of the plunger pressed by the urging force of the compression spring, and the interline mark elongation measuring instrument is pressed. In addition to being easily held and fixed to the test piece, it is possible to accurately measure the minute measurement area by the differential transformer provided in the marking line setting section. This allows
Anyone can easily attach the elongation measuring device to the test piece without skill, so that inspection accuracy and inspection workability are greatly improved, and an inspection work environment by automation can be constructed. Will be possible.

In the present embodiment, the magnet member is provided in the guide holes of the upper marking member main body and the lower marking member body, but the magnet member may be provided at the tip of the suction holding rod. As shown in FIG. 5, a magnet member 49 may be provided on the marking line fixing portion 60 side.

Further, the cross-sectional shape of the tip of the knife edge portion which comes into contact with the test piece is not limited to the edge shape.
An arc shape or the like may be used as long as the shape comes into line contact with the test piece.

Further, in this embodiment, the test piece is described as a rectangular test piece having a rectangular cross section. However, the test piece is not limited to a rectangular test piece, and may be a dumbbell-shaped test piece or the like. Needless to say, it's good.

Further, in the present embodiment, the contact / separation type measuring tool is a separation type differential transformer, but may be a separation type transducer or the like.

FIG. 6 is a perspective view for explaining a schematic configuration of the stable mounting maintaining means according to the second embodiment of the present invention.

As shown in the figure, in the present embodiment, the marker line fixing section main body 63 of the marker line fixing section 60 and the marker line member bodies 42u and 42d of the marker line setting section 40 are connected to the marker line fixing section 60 and the marker. Even when the line setting unit 40 is separated from the line setting unit 40, it is stably attached to the mark line fixing unit main body 63 and each of the mark line member main bodies 42u and 42d so as to maintain a stable state and be fixed to the test piece 31. A fixed guide leaf spring 71 and an engagement groove 72 which constitute the maintenance means are provided respectively.

As shown in the figure, a pair of fixed guide leaf springs 71 having engagement portions 73 opposed to the mark line fixing portion main body 63.
Are fixed to the upper guide line member main body 42u and the lower mark line member main body 42d.
Is formed with an engagement groove 72 with which an engagement portion 73 provided in the first groove is engaged.

For this reason, a pair of suction rods 62 disposed on the marking line fixing portion main body 63 are inserted through a pair of guide holes 47 of the upper marking line member main body 42u and the lower marking line member main body 42d.
The marking line fixing portion main body 63 is connected to the upper and lower marking line member main bodies 42.
u, the distal end surface of the attracting rod 62 is attracted and fixed by the magnet member, and at the same time, the engaging portion 73 of the fixed guide leaf spring 71 engages with the engaging groove 72 to make the marked line portion. The main bodies 42 u and 42 d and the marking line fixing part main body 63 are fixed and held in the parallel part of the test piece 31. Other configurations are the same as in the first embodiment.

As described above, the main body of the marked line fixing section and the main body of each marked line constituting the marked line fixing section and the marked line setting section of the interline mark elongation measuring device are attracted to the magnet member by the parallel portion of the test piece. When held by force, each mark line member body and mark line fixing portion main body are clamped by the urging force of the fixed guide leaf spring of the stable mounting and maintaining means and attached to the parallel portion of the test piece to thereby fix the mark line fixing portion. The mounting posture between the main body and the mark line member main body can be stabilized.

Thus, even when the upper marking member main body and the lower marking member main body constituting the marking line setting section are separated from each other, each marking line member body and the marking line fixing portion main body are in parallel with the test piece. In addition to being stably held and fixed, even if the impact force larger than the attractive force of the magnet member is applied to the plunger of the marking line fixing part or the knife edge member of the marking line setting part when the test piece breaks, this fixing By the guide leaf spring, the attachment state of the mark line fixing portion main body and the mark line member body to the test piece is stably maintained. Other functions and effects are the same as those of the first embodiment.

The fixed guide leaf spring is fixed to the marking line fixing portion main body by a fixing means such as an adhesive or a bolt.

In the present embodiment, the fixed guide plate spring is fixed to the marking line fixing portion main body to form the engaging groove in the marking line member main body. However, the engaging groove is provided in the marking line fixing portion main body. Alternatively, a fixed guide leaf spring may be provided on the marking line member main body.

FIG. 7 is an explanatory view showing another configuration of the marking line fixing section according to the third embodiment of the present invention.

As shown in the drawing, in the present embodiment, the plunger fixing nut 7 for fixing the plunger disposing member 64 disposed on the marker fixing member 63 of the marker fixing part 60.
5 is provided with a mark mark 76.

As described above, by providing the mark mark on the plunger fixing nut for fixing the plunger disposing member to the mark fixing member, the mark mark can be formed even if the interval between the mark portions of the test piece is greatly extended. Unclearness can be prevented. In this way, by combining the marked line portion tracking type elongation measuring device and the inter-marked line elongation measuring device, the displacement from the small elongation region of the test piece in the initial stage of load to the displacement in the high elongation region is reduced. It is possible to provide a measuring device capable of continuously measuring.

That is, the measuring device for continuously measuring the displacement of the test piece in the micro elongation area and the displacement in the high elongation area is composed of the inter-mark line elongation measuring device and the elongation tracking the mark mark. And an inter-mark line tracking elongation measuring device for measuring the degree of measurement.When switching from measurement by the inter-mark line elongation measuring device to measurement by the inter-mark line tracking elongation measuring device, The measurement of the displacement of the test piece is continuously performed by taking in the measurement value measured by the degree measuring device as the measurement value of the elongation measuring device between tracking lines.

Note that, instead of providing a mark on the plunger fixing nut, a mark may be provided on the mark fixing member.

The present invention is not limited to only the above-described embodiments, but can be variously modified without departing from the gist of the invention.

[0064]

As described above, according to the present invention, the elongation gauge between gauge lines which can be easily attached to the test piece and accurately measures the displacement of the test piece in the minute elongation area at the initial stage of load. Can be provided.

[Brief description of the drawings]

FIG. 1 to FIG. 4 relate to a first embodiment of the present invention, and FIG. 1 is an explanatory view showing a schematic configuration of a gauge-elongation measuring apparatus.

FIG. 2 is an explanatory diagram showing a configuration of a marking line setting unit of the interline marking elongation measuring device.

FIG. 3 is an explanatory view showing a configuration of a marking line fixing section of the interline marking elongation measuring device.

FIG. 4 is an explanatory view showing a state where the gauge between lines is attached to a test piece.

FIG. 5 is an explanatory view showing another configuration of the detachable fixing means.

FIG. 6 is a perspective view illustrating a schematic configuration of a stable attachment maintaining unit according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing another configuration of the marking line fixing unit according to the third embodiment of the present invention.

8 to 10 relate to a conventional example, and FIG. 8 is an explanatory view showing a configuration of a dumbbell-shaped test piece which is an example of a test piece.

FIG. 9 is an explanatory diagram showing a schematic configuration of a π gauge strain gauge.

FIG. 10 is an explanatory diagram showing a schematic configuration of a marking section tracking type elongation meter.

[Explanation of symbols]

 Reference numeral 40: marking line setting unit 50: differential transformer 31: test piece 60: marking line fixing unit

Claims (6)

[Claims] 1. An inter-mark line elongation measuring device for setting two mark lines in a parallel portion of a test piece used for a material strength test and measuring a displacement between the mark lines, wherein: A marking line setting unit provided with a pair of knife edges that abut on one surface side and a measuring unit that directly measures the displacement between the marking lines set with the knife edge, and a parallel portion of the test piece. A marking line fixing portion having a pressing portion abutting on the other surface side; and a detachable fixing means for integrally fixing the marking line setting portion and the marking line fixing portion. Elongation measuring instrument. 2. The measuring device according to claim 1, wherein the attaching / detaching and fixing means is a magnet member provided on at least one of the marking line setting section and the marking line fixing section. 3. A measuring section provided in the marking line setting section,
2. The measuring device according to claim 1, wherein the measuring device is a separation type measuring device. 4. The measuring device according to claim 1, wherein an inter-mark line distance setting member for setting an interval between the pair of knife edges is exchangeably provided in the mark line setting section. . 5. The marker line setting unit and the marker line fixing unit,
The mark according to claim 1 or 4, further comprising a stable attachment maintaining means for stably maintaining and fixing an attached state of the test piece to the parallel portion between the mark setting section and the mark fixing section. Wire elongation measuring device. 6. The marking line according to claim 1, wherein a marking mark serving as a score portion recognized by a marking portion tracking type elongation measuring device is provided in the marking line fixing portion. Elongation measuring device.