JPH0820349B2 - Torsion tester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a torsion tester for a test piece having a linear shape with a small diameter such as a piano wire.

[Prior Art] As a conventional torsion tester, one shown in FIGS. 11 and 12 is known.

In the figure, 1 is a motor, 2 is a pulley fixed to a motor shaft 1a of the motor 1, and 3 is a rotating shaft supported in parallel with the motor shaft 1a by a bearing 5 provided on a support base 4a. The rotational force of the motor shaft 1a is transmitted to the rotary shaft 3 by a belt 7 connecting a pulley 6 provided on the rotary shaft 3 and a pulley 2 provided on the motor shaft 1a.

Further, the rotational force of the rotating shaft 3 is converted into swinging rotation of the swinging shaft 8 by a cam, a crank, a group of gears and the like (not shown). A long groove 8a for inserting one end B1 of a rod-shaped test piece B is linearly formed at the tip of the swing shaft 8 (see FIGS. 12 (a) and 12 (b)). The one end B1 of the test piece B fitted in the 8a is firmly fixed by a bolt or the like.

On the other hand, a fixed shaft 9 is supported by a fixed base 10 mounted on the support base 4b at a position facing the swing shaft 8 and is always fixed by a support mechanism (not shown) built in the fixed base 10. Of the rocking shaft 8 is held at one end thereof, and a long groove 9a into which the other end B2 of the test piece B can be fitted.
Is formed to face the long groove 8a formed in
The other end B2 of the test piece B fitted into the inside 8a can be firmly fixed with bolts, nuts and the like.

The test piece B is held by the long grooves 8a and 9a so that the central axis of the test piece B coincides with the central axis L of the swing shaft 8 and the fixed shaft 9.

In addition, the fixed body 10 can adjust the attachment position on the support base 4b along the central axis L so as to correspond to the length of the test piece B. The fixed shaft 9 is
Although it is always held at a constant rotation position, it can be rotated by a predetermined angle manually by way of a support mechanism in the fixed base 10 if necessary.

As described above, in the conventional torsion tester, the swing shaft 8 and the fixed shaft 9 hold both end portions B1 and B2 of the test piece B,
The dynamic torsional fatigue strength of the test piece B is measured by repeatedly swinging the swing shaft 8 by driving the motor 1 and counting the number of swings until the test piece B is broken by the swing rotation. can do.

The initial stress setting of the torsional load is performed by previously rotating the fixed shaft 9 by manual operation.

The rotation angle of the fixed shaft 9 at this time is calculated by using the required stress setting value.

[Problems to be Solved by the Invention] As described above, in the conventional torsion tester, the applicable test piece is a relatively large diameter of about 10 mm, and a small diameter such as a piano wire. The test piece could not be applied.

In other words, in the conventional testing machine, since the linear long grooves 8a and 9a formed on the swing shaft 8 and the fixed shaft 9 respectively hold the both ends B1 and B2 of the test piece B, the long groove 8a, 9a
Even if the groove width of is narrow enough to accommodate a small diameter, sufficient gripping force cannot be obtained, and even if the piano wire spins in the long grooves 8a and 9a or is chucked, each chuck There is a possibility that stress concentration may occur at the part and data may not be obtained.

Further, when the initial stress is set for the test piece B, in the conventional tester, the fixed shaft 9 to be rotated is used.
Since the angle was calculated and the stress was set according to the calculated value, it is impossible to know whether or not the stress actually required is applied to the test piece B, and the test must be performed in an uncertain state. I didn't get it.

Further, with the above-mentioned conventional testing machine, it is only possible to check the number of times of rocking until the test piece is broken, and it is not possible to know the progress state of fatigue fracture. That is, a crack is generated in the test piece in the process until the test piece is completely broken, but it is not possible to confirm the occurrence and progress of the crack G, and it is not possible to obtain sufficient data. It was

The present invention has been made in view of the above problems, and an object thereof is to provide a torsion tester capable of obtaining accurate and sufficient test data for a test piece having a small diameter.

[Means for Solving the Problems] The present invention includes a swing shaft that swings and rotates by a predetermined driving unit, and a chuck portion that swings integrally with the swing shaft and fixes a test piece at one end. A swing side chuck body, a fixed shaft provided to face the swing shaft, a rotating body rotatably supported at one end of the fixed shaft, and one end held by the rotating body, A chuck body for holding the test piece is provided on the fixed side chuck body provided at the other end, and a strain gauge attached to a portion from the chuck portion of the fixed side chuck body to the one end is provided. Curves for arranging the chuck parts such that the longitudinal direction of the test piece held by the chuck parts coincides with the swing axis and to fit and lock both end parts of the test piece in the chuck body. The long groove is formed.

[Operation] In the present invention, the test piece is held in a state where both ends thereof are curved by the locking groove of the swing side chuck body and the locking groove of the fixed side chuck body. However, there is no risk that the test piece will spin in both chuck portions, and the rotational force of each chuck body is reliably transmitted to the test piece.

Further, the stress generated in the test piece also causes strain in the plate member, and an output value corresponding to the strain amount is output from the strain gauge. Therefore, by this output value, it is possible to confirm the stress that actually occurs in the test piece, and it is possible to accurately set the stress in the initial state, not only the load test of the static load and the measurement of fatigue strength, It is also possible to confirm the progress of fatigue fracture.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. The same parts as those of the above-mentioned conventional device are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is an overall plan view of the present invention, and FIG. 2 is an enlarged view of a main part in FIG.

In each drawing, 11 is a swing side chuck body whose one end is fixed in the long groove 8a of the swing shaft 8 with a bolt and a nut.
On the other end, a swing-side chuck portion 12 for holding one end of a test piece S having an extremely small diameter such as a piano wire is provided.
The chuck portion 12 is composed of two upper and lower holding plates 12A and 12B fixed to the upper surface of the other end of the chuck body 11 by screws 13, and each holding plate 12A and 12B is formed as shown in FIG. Has been done.

That is, of the two holding plates, the lower holding plate 12B has an upper surface on which an engaging groove 12B1 curved in an arc is engraved, and the engaging groove 12B1 has a small-diameter test piece S (such as a piano wire). For example, the test piece S has a sectional shape slightly larger than that of the test piece S so that a test piece having a diameter of about 1 mm can be fitted therein.

Then, by overlapping and fixing the upper pressing plate 12A having the same planar shape as the upper pressing plate 12B on the upper surface of the lower pressing plate 12B with the screw 13, one end of the test piece 12B fitted in the locking groove 12B1 is fixed. It can be locked.

The test strip outlet 12B2 in the locking groove 12B1 is formed at a position where the center of the test strip S held therein coincides with the rotation center axis L of the swing shaft 8.

On the other hand, in FIG. 2, reference numeral 14 denotes a support shaft, one end of which is fixed with a bolt, a nut or the like in a long groove 9a of a fixed shaft 9 provided so as to face the swing shaft 8, and its central axis line is oscillated. It coincides with the central axis L of rotation of the moving shaft 8 and the fixed shaft 9.

Further, 15 is a rotating body attached to the other end of the support shaft 14 via a linear ball bearing 16, which is movable in the rotating direction and the axial direction, and is erected at one end thereof. One end of the plate-shaped member 17 is fixed to the supported portion 15a.

It should be noted that one end of the plate member 17 held by the support portion 15a is located in the rotation center axis L. Reference numeral 18 is a fixed-side chuck body fixed to the other end of the plate-shaped member 17.
The chuck body 18 is composed of two holding plates 18A and 18B that hold the other end of the plate member 17 from both upper and lower sides, and an arcuate locking groove 18B1 is formed on the lower surface of the upper holding plate 18B. This locking groove 18B1 also has the same test piece S as the locking groove 12B1.
It has a slightly larger cross-sectional shape.

Then, each pressing plate 18A, 18B is fixed to the plate-like member 17 with the screw 19, so that the test piece S fitted in the locking groove 18B1.
Can be locked. Also, the locking groove 18B1
The test piece lead-out port 18B1 in the test piece S held here is
Is formed at a position coinciding with the rotation center axis L of the swing shaft 8 and the fixed shaft 9.

Therefore, when both ends of the test piece S are locked in the locking groove 18B1 of the fixed side chuck body 18 and the locking groove 12A1 of the swing side chuck portion 12, as shown in FIG. 12,18
The straight portion S3 of the test piece S in the interval is the rotation center axis L
Held on. The fixed side chuck body 20 is composed of 14 to 18 and 25 described later.

Reference numeral 22 is a strain gauge for detecting the amount of twisting strain of the plate member 17 (see FIG. 6 (a)). This strain gauge 22
Are two sets of resistors attached to the upper surface and the lower surface of the plate member 17.
R1 and R2 and R3 and R4 are connected as shown in FIG. 6 (b), and the resistance of the resistors R1 to R4 increases as the amount of twist of the plate member 17 about the central axis L increases or decreases. The value changes and a voltage output corresponding to the amount of twist is generated at the output terminal.

Further, 23 is a weight rod projectingly provided on the outer peripheral surface of the rotating body 15, and a weight 24 for setting an initial stress capable of adjusting a mounting position along the longitudinal direction thereof is attached to the weight rod 23. . Reference numeral 25 denotes a damper piece protruding downward from the rotating body 15, the lower end portion of which is immersed in high-viscosity oil stored in an oil storage portion (not shown), which causes the rotating body 15 generated during the test. It is designed to absorb the slight vibration of.

The output side of the strain gauge 22 is electrically connected to the one shown in FIG. Ie strain gauge
An oscilloscope 27 and a breakage detection sensor 28 are connected to the subsequent stage of the amplifier 22 via an amplifier 26.
A drive control circuit 29 of the motor 1 which is a drive means of the swing shaft 8 is connected to the output side of the.

Here, the breakage detection sensor 28 is for outputting a stop signal to the motor drive control circuit 29 when the output value of the strain gauge 22 amplified by the amplifier 26 becomes equal to or lower than a predetermined set level, Upon receiving this stop signal, the motor drive control circuit 29 acts to stop the drive of the motor 1.

It should be noted that, in FIG. 1, other configurations are the same as those shown in the above-mentioned prior art.

 Next, the operation will be described based on the above configuration.

When the test piece S is a spring material that constitutes a coil spring and the torsional fatigue due to the expansion and contraction of the coil spring is tested, first, both ends of the test piece S are moved to the swing side chuck portion 12 and the fixed side chuck as described above. The weight is locked in the respective locking grooves 12B1 and 18B1 of the portion 18, and then the position of the weight 24 provided on the weight rod 23 is adjusted to set the stress in the initial state. The moment rotates about the support shaft 14 to generate a torsional stress in the test piece S via the plate-like member 17 and the chuck portion 20. At this time, the plate-like member 17 is also twisted as the test piece S is twisted. Torsional strain is generated, and an output corresponding to the strain amount is output from the strain gauge 22, so that the inspector can accurately set the stress while checking the output value with the oscilloscope 27.

When the oscillating rotation of the oscillating shaft 8 is started by the driving of the motor 1 after the initial stress setting, the counter (not shown) is operated at the same time and the counting of the oscillating rotational speed is started.
Further, the one end portion S1 of the test piece S also swings and rotates together with the swing side chuck body 11 due to the swing rotation of the swing shaft 8.
Is twisted, and the stress generated at that time also causes torsion in the plate member 17. Therefore, the strain gauge 22 outputs an output according to the strain amount of the plate member 17, and the output value is displayed on the oscilloscope 27.

FIG. 8 shows the output waveform of the strain gauge 22 during the test.

In the figure, when no fatigue failure has occurred in the test piece S, the output waveform of the strain gauge 22 has a constant amplitude value H1 based on the initial stress setting value H0 as shown by W1.

On the other hand, as shown in FIG. 9, when a crack G is slightly generated in the test piece S, the torsional stress generated in the test piece S is reduced and the amount of torsional strain of the plate member 17 is reduced. The output value from the strain gauge 22 decreases, and the output waveform displayed on the oscilloscope 27 is as shown by W2 in FIG.

That is, the amplitude value H2 of the output waveform W2 is smaller than the amplitude value H1 in the state where no fatigue fracture has occurred. The amplitude value H2 of this output waveform W2 decreases as the crack G of the test piece W expands, and when the test piece W is completely broken, the amplitude value H2 decreases.
H2 becomes 0.

Thus, in this embodiment, the oscilloscope 22
By observing the output waveform of the strain gauge 22 displayed on the screen, not only whether or not the test piece S is broken, but also the progress of fatigue failure can be confirmed.

Then, when the test piece S is completely broken and the output value of the strain gauge 22 output via the amplifier 26 becomes equal to or lower than a preset level, the break detection sensor 28 outputs a stop signal to the motor drive control circuit 29. Then, the driving of the motor 1 is stopped. Therefore, the counting operation of the counter is stopped, and the count value until the test piece S is broken is displayed. The fatigue strength of the test piece can be confirmed from this count value.

In addition, in the above-described embodiment, since both end portions S1 and s2 of the test piece S are curved according to the locking grooves 12B1 and 18B1 and are two-dimensionally held, so to speak, no matter how small the diameter of the test piece S is, The parts S1 and S2 do not idle in the chuck parts 12B and 18B, and the rotational force of the swing shaft 8 and the rotating body 15 is reliably transmitted to the test piece S.

In addition, since the locking grooves 12B1 and 18B1 are formed in an arc shape, it is possible to prevent stress concentration from occurring at both ends S1 and S2 of the test piece S locked here, so that a good locking state can be obtained. Can be obtained. That is, for example, when the test piece is held by the locking groove bent in an L shape, stress concentrates on a corner portion of the test piece, and this portion is broken in an extremely short time. I cannot get the test results.

By the way, as the torsion test, there is a so-called dynamic torsion load test in which the test piece S is repeatedly loaded and unloaded in both forward and reverse directions as described above, and a static torsion test in which the test piece is twisted in one direction. , When performing the latter test, the rotating body
It can be easily carried out by rotating 15 by a manual operation or the like.

Further, even in the dynamic torsion test, if the initial stress setting is not required in advance, the weight 24 of the weight rod 23 may be removed.

In the above embodiment, the holding portion of the plate member 17 in the chuck body 12 is set to be line-symmetric with respect to the rotation center axis L of the swing shaft 8 and the rotating body 15, and the test piece S is twisted. Along with this, the plate-like member 17 is also twisted, and the amount of strain is measured. However, as shown in FIG. 10, the plate-like member 17 is held at a position deviated from the rotation center axis L. However, the torsional stress of the test piece S can be measured.

That is, in this case, the plate-shaped member 17 bends in the up-down direction with the holding portion 15A as a fulcrum in accordance with the torsional stress of the test piece S, and the amount of bending at that time is detected by the strain gauge 22, whereby the test piece S The load applied to can be measured.

Further, in the above embodiment, the resistors R1 to R4 are connected to each other as shown in FIG.
Although the strain gauge 22 formed by connecting as shown in is used, as the strain gauge for detecting the strain of the plate-shaped member 17, those having other configurations are also applicable. In addition, strain gauge 22
The output of the strain gauge 22 can be recorded on a paper surface, and the output display means of the strain gauge 22 is not particularly limited to an oscilloscope.

[Effects of the Invention] As described above, according to the torsion tester of the present invention, the swing-side chuck body fixed to the swing shaft and the swing-side chuck body rotatable with respect to the fixed shaft are formed. Since both ends of the test piece are locked in the curved locking groove,
Even with a small-diameter test piece, the rotational force of both chuck bodies can be reliably transmitted to the test piece, and the stress generated at both ends of the test piece is evenly distributed according to the curved shape of the locking groove. Therefore, it is possible to obtain a good holding state without fear of breaking the both ends.

Furthermore, since the stress value generated in the test piece can be confirmed by the output of the strain gauge, the stress can be set accurately in the initial state, and in addition to the measurement of fatigue strength, the progress of fatigue fracture can be confirmed. It is also possible to obtain accurate and sufficient test data.

[Brief description of drawings]

FIG. 1 is a plan view showing the overall construction of an embodiment according to the present invention, and FIG. 2 is an enlarged view of the main parts of the embodiment, and FIG.
Shows a plan view and FIG. 2B shows a side view. Third
FIG. 4A is an exploded plan view showing the swing-side chuck portion shown in FIG. 1, FIG. 4B is a side view showing an assembled state of the one shown in FIG. 1A, and FIG. Is an exploded plan view of the fixed chuck, FIG. 6B is a side view showing the assembled state of the one shown in FIG. 6A, FIG. 5 is a plan view showing the holding state of the test piece, and FIG. 6A. Is a plan view showing the mounting state of the strain gauge,
FIG. 7B is an electrical connection diagram showing the connection state of the resistors in the strain gauge, FIG. 7 is a block diagram showing the electrical connection state in the latter stage of the strain gauge, and FIG. 8 is the strain gauge displayed on the oscilloscope. Fig. 9 is a waveform diagram showing an output waveform of Fig. 9, Fig. 9 is a side view showing a crack generation state of a test piece, Fig. 10 is an enlarged plan view of an essential part of another embodiment of the present invention, and Fig. 11 (a) is a conventional diagram. Fig. 12 (a) is a side view of Fig. 12 (a), and Fig. 12 (a) is an enlarged plan view showing the test piece mounting state of Fig. 11 (a). Figure,
FIG. 2B is a side view of what is shown in FIG. In the figure, 1 ... motor (driving means) 8 ... swinging shaft 9 ... fixed shaft 11 ... swinging side chuck body 12 ... chuck portion 12B1 ... locking groove 15 ... rotating body 17 ... plate -Shaped member 18 …… Chuck part 18B1 …… Locking groove 20 …… Fixed side chuck body 22 …… Strain gauge L …… Rotation center axis S …… Test piece

Claims (1)

[Claims] 1. A swing shaft swinging around a predetermined rotation center axis by a predetermined driving means, and one end fixed to this swing shaft and one end of a linear test piece locked. And a fixed shaft provided to face the swing shaft, and swings around one end of the fixed shaft about the same rotation center axis as the swing shaft. A rotatably supported body, a fixed-side chuck body having one end held by the rotator, and a chuck part for locking one end of the test piece provided at the other end via a plate member, A strain gauge adhered to the plate member, and a structure in which the test piece and the strain gauge are supported without a supporting member, and each chuck portion of both chuck bodies is held by the chuck member. Arranged so that the longitudinal direction of the test piece coincides with the central axis of rotation, Both ends of the test piece are fitted into the chuck bodies,
A torsion tester having a locking groove for locking.