JP3345602B2 - Tensile test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensile tester for applying a tensile load to a test piece to test its mechanical properties and the like.

[0002]

2. Description of the Related Art A conventional general tensile test apparatus comprises a pair of upper and lower gripping tools arranged on a vertical line for gripping a test piece, and at least one of the gripping tools is not moved in a vertical direction. It comprises a means for fixing, a means for moving the other vertically upward or downward, a means for measuring displacement during movement, and a means for measuring a load applied to the test piece.

[0003] Japanese Patent Application Laid-Open No. 9-184794 discloses a technique in which one end of a test piece is fixed, and the other end is attracted and fixed by electrostatic force.

[0004]

In the tensile test apparatus having the above structure, in addition to the load applied as a tensile load to the test piece, the weight of a gripper for gripping the test piece is added, or The weight of the gripper is added to the means for measuring the load together with the load applied to the test piece. In this case, generally, the load when the test piece is gripped by the gripper and mounted on the tensile tester is set as the origin of measurement, and the gripper is moved vertically upward or downward to pull the test piece. The change from the origin of the measured load value when a load was applied was defined as the load applied to the test piece. This conventional tensile test apparatus and measuring method were effective when the weight of the gripper was sufficiently smaller than the tensile load applied to the test piece.

However, when measuring the mechanical properties of a material whose yield load is about the same as or smaller than the weight of a gripper, such as a thin film or a thin wire, a tensile force applied as a tensile load to a conventional test piece is used. In addition to the above, if the load applied to the test piece is equal to or greater than the yield load of the test piece at the time when the grip is attached to the test piece, Did not provide accurate measurements.

Further, in a tensile test apparatus in which the weight of the gripping tool is added to the load measuring means together with the load applied to the test piece, the fluctuation of the measured load value caused by the vibration of the gripping tool may not be ignored. There was no consideration for accurately measuring mechanical properties such as Young's modulus and tensile strength of a test piece. In order to avoid the influence of the weight of the gripper, an apparatus has been proposed in which the gripper is placed on a horizontal plane and the tensile direction of the test piece coincides with the horizontal direction.

[0007] However, in this case, it is difficult to obtain high reproducibility in load measurement because the deviation of the tension direction from the horizontal direction affects the frictional force between the gripper and the horizontal surface.

In the case where one end of a test piece described in Japanese Patent Application Laid-Open No. 9-184794 is fixed and the other end is attracted and fixed by electrostatic force, the effect of the load of the gripper on the test piece is not affected. Not considered.

An object of the present invention is to prevent a gravity acting on a gripper for fixing a tensile test piece from affecting a measured value of the tensile test and to accurately measure a mechanical property of the test piece. It is to provide a device.

[0010]

Means for Solving the Problems In order to achieve the above object, an invention of a tensile test apparatus according to the present invention comprises a gripper for gripping and fixing one end of a tensile test piece, and another end of the tensile test piece. And a movable-side gripper for displacing the test piece by applying a tensile load in a substantially horizontal direction, wherein the height of the movable-side gripper in the horizontal direction is fixed.
It is set lower than the fixed side gripper, and the movable side gripper is
It is floated and supported from an electromagnet provided with a magnetic force adjusting means .

[0011]

[0012]

[0013]

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a perspective view of a tensile test apparatus according to a first embodiment of the present invention, in which the longitudinal direction of a horizontally positioned surface plate is the x direction, and the direction perpendicular to the x direction is the y direction. And the vertical direction is defined as the z direction.

In FIG. 1, a test piece 1 is a thin film of metal, resin, or the like. The fixed gripping member 21 is fixed to the surface plate 10, and one end of the test piece 1 is gripped by the gripping member 2.
The test piece 1 is placed on the test piece 1, and the gripping member 22 is further placed thereon, and integrated by fastening with a bolt 23.
Is fixed to the holding tool 2 on the fixed side.

Next, the other end of the test piece 1 is placed on the movable holding member 31 placed on the electromagnet 4. Two permanent magnets (not shown) arranged in the x direction are attached to the lower surface of the gripper member 31. The electromagnet 4 is initially permanent
A DC current is supplied from the power supply device 9 through the wiring 8 so that the magnet and the electromagnet 4 attract each other, whereby the gripper member 31 is fixed to the electromagnet 4. That is, since the electromagnet 4 is mechanically fixed to the surface plate 10, the gripper member 31 is fixed to the surface plate 10. In this state, the gripper member 32 is placed on the end of the test piece 1 placed on the gripper member 31 and integrated by fastening using the bolt 33, so that the other end of the test piece 1 is gripped on the movable side. It is fixed to the tool 3.

Next, the DC current supplied from the power supply device 9 to the electromagnet 4 is temporarily interrupted, and a current of the opposite polarity is caused to flow while gradually increasing. When the intensity of the current reaches a predetermined value, the repulsive force acting between the permanent magnet attached to the gripper member 32 and the electromagnet 4 becomes greater than the gravity acting on the gripper 3, and the gripper 3 It moves in the z direction, that is, floats. Since the repulsive force acting between the permanent magnet attached to the gripper 32 and the electromagnet 4 is inversely proportional to the square of the distance between the two magnets, the repulsive force balances with gravity when the flying height reaches a predetermined value, and z Movement in the direction stops.

On the other hand, before the grasping tool 3 floats, a predetermined current that is independently controlled is applied to the electromagnet 5. Permanent magnets (not shown) are also attached to the side of the grip 3 that faces the electromagnet 5, and the grips 3 are stabilized in the y direction by applying repulsive forces to each other. In this state, ideally, the gripper 3 is stationary. However, it is difficult to realize that the magnetic field generated by the electromagnet 4 is completely uniform and the lines of magnetic force are completely vertical. It is also difficult to make the surface plate 10 completely horizontal in the x-axis direction. Therefore, the gripper 3 moves in either the positive or negative x direction.

At this time, since the test piece 1 has a predetermined strength in the tensile direction, the test piece 1 is not deformed by the tensile load even if the movable gripper 3 moves in the positive x direction. Stay as long as possible. However, since the test piece 1 has almost no strength in the compression direction, the test piece 1 is easily deformed when the gripper 3 moves in the negative x direction. In the present embodiment, the test piece 1 is prevented from being deformed by avoiding the movement of the movable gripper 3 in the negative direction.

FIG. 2 is an explanatory view of the reason why this deformation can be prevented. In the figure, the surface plate 10 is inclined by a small angle θ with respect to the horizontal (in the figure, the small angle θ is exaggerated). Due to this inclination, the movable gripper 3 is at a lower position than the fixed gripper 2. In this case, the gripper 3
Assuming that the mass of the gripper 3 is M and the gravitational acceleration is g, and that the mass of the test piece 1 can be ignored, the gravity F acting on the test piece 1 can be expressed as follows.

F = Mg (Equation 1) Next, a component parallel to the surface plate 10 of gravity, that is, the test piece 1
Can be expressed as: Fx = Fsin θ (Equation 2) Here, since θ is a small angle, the following approximate expression holds.

Sin θ = θ (Equation 3) From Equations 1 to 3, the tensile force Fx acting on the test piece 1 is expressed as Fx = Mg θ (Equation 4). If θ is adjusted to 0.01 rad by using an angle adjusting means (not shown), Fx becomes 1/100 of Mg.

In this embodiment, aluminum is used as the material of the grippers 31 and 32 and the screw 33. The dimensions after combining these, a is 10mm respectively, 12 mm and 6 mm, length of x, y and z directions Figure 1, the density of aluminum is 2700 kg / m ^3, combined grippers 3 The mass is about 1.9 g. This one
Four permanent magnets each having a mass of 0.5 g were attached for the experiment. Finally, the combined mass of the grippers 3 is 3.9 g.

As the material of the thin film test piece 1 for measuring mechanical properties and the like in the tensile test apparatus as in the present embodiment, for example, copper or aluminum is used. These yield stresses are 59 MPa and 29 MPa, respectively. In this example, an experiment was performed using an aluminum thin film of which yield stress was small and whose mechanical properties were difficult to measure.

FIG. 3 shows the detailed dimensions of the test piece 1 in this embodiment. In the figure, since the cross-sectional dimension of the parallel portion of the test piece 1 is 2 mm in width and 1 μm in thickness, the cross-sectional area is 2 mm.
× 10 ⁻³ mm ² . The interval between the two gauge points 101 is 6 mm, and the total length is 20 mm. The combined gripping tool 3 was attached to the test piece 1 and floated by electromagnetic force, and the platen 10 was inclined to set θ = 0.01 rad. Force Fx in the x-direction of FIG. 1 at this time is added to the specimen 1, the gravitational acceleration g = 9.8m / s ^2, than the number 4, Fx = (3.9 × 10 -3) × 9.8 × 0.01 = 3.8 × 10 ⁻⁴ N (Equation 5), and the tensile stress σx applied to the parallel portion of the test piece 1
Σx = Fx / (2 × 10 ⁻³ ) = 0.19 MPa (Equation 6)

On the other hand, the yield stress of aluminum is 29 MPa as described above, and is sufficiently larger than σx, so that the test piece 1 does not yield due to the tensile stress caused by the load of the gripper 3.

As shown in FIG. 1, a sufficiently light wire 7 is attached to the grip 3 via the attachment 6 as shown in FIG. By pulling the wire 7 in the x direction in FIG. 1, the gripper 3 is displaced in the x direction, and the tensile load applied to the test piece 1 is gradually increased. This load is measured using a load sensor (not shown) attached to the wire 7 and, at that time, a reference point 101 (FIG. 3) provided in a parallel portion of the test piece 1.
) By optically measuring the displacement of the test piece 1
Can be measured. At this time, it is necessary that the longitudinal axis of the test piece 1 and the tensile direction by the wire 7 exactly match. Test piece 1 if they do not match exactly
Is subjected to a bending load and cannot be measured accurately.

In the tensile test apparatus as shown in this embodiment, since it is difficult to accurately detect the horizontal level of the earth with respect to gravity, it is not easy to accurately measure θ. However, in the present embodiment, the reference point when the gripper 3 is stationary may be used as the origin of the displacement, and even if a slight measurement error is included in θ, the measured value of the tensile load and the displacement is hardly affected.

In the present embodiment, θ = 0.01 rad. However, for example, when it is desired to measure only the Young's modulus or the like without requiring accurate values of the yield stress and the tensile strength, θ = 0.01 rad.
Even if it is about 0.1 rad, there is no problem, and the resolution of 0.1 rad is sufficient.

Embodiment 2 FIG. 4 is a perspective view of a tensile test apparatus according to a second embodiment of the present invention. Parts equivalent to parts in FIG. 1 and its description is omitted with the same reference numerals. This embodiment is different from the first embodiment in that the shape of the movable gripper 310 and the rail 40 are provided, and the cut surfaces of the gripper 310 and the rail 40 in the yz plane are concave and convex, respectively. It is in the shape of a letter.

FIG. 5 shows these details. Gripping tool 310
Is shown upside down for explanation. As shown in FIG.
And the electromagnet 12 are attached, and as shown in FIG. 4, the gripping tool 310 is levitated by the repulsive force of these magnets.

According to this embodiment, although the mass of the gripper 310 is larger than that of the first embodiment, the gripper 310 at the time of the test is used.
Is more stable, so that more reliable tensile test data can be obtained.

[0033]

According to the present invention, the tensile properties are not affected by the gravity of the gripping means for gripping the test piece, so that the mechanical properties and the like of the test piece can be accurately measured. In addition, the behavior of the gripper is stabilized, and no compressive stress is applied to the test piece before measurement.

[Brief description of the drawings]

FIG. 1 is a perspective view of a tensile test apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of the reason why deformation of a tensile test piece can be prevented.

FIG. 3 is a plan view of a tensile test piece.

FIG. 4 is a perspective view of a tensile test apparatus according to a second embodiment of the present invention.

FIG. 5 is an exploded perspective view of the holding unit of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Test piece 2 ... Fixed side gripping tool 3 ... Movable side gripping tool 4, 5 ... Electromagnet 6 ... Attachment part 7 ... Wire rod 8 ... Wiring 9 ... Power supply device 10 ... Surface plate 21, 22 ... Fixed side gripping member 23, 33 ... bolts 31, 32, 310 ... movable side gripping member 40 ... rail

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akiomi Kono 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (56) References JP-A-9-184794 (JP, A) -126062 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 3/04 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A gripper for gripping and fixing one end of a tensile test piece, and a movable gripper for gripping the other end of the tensile test piece and displacing the test piece by applying a tensile load substantially horizontally. The horizontal height of the movable-side gripper is preferably the fixed-side grip.
It is set lower than the holding tool , and the movable holding tool is an electromagnet provided with magnetic force adjusting means.
A tensile test device characterized by being supported by being lifted from the surface.