JP2837939B2 - Auxiliary device for torsional fatigue test - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an auxiliary device for a torsional fatigue test, particularly for performing a torsional fatigue test using a tensile or compression fatigue test device. It relates to an auxiliary device.

(Conventional technology) The torsional fatigue test among the material tests is less frequent than the fatigue tests such as tension, compression, and rotation bending, and therefore, the JIS does not have a general rule of definition.

This is because the frequency of use is low and the maximum value of torsional stress exists on the material surface, but the fatigue strength varies depending on the surface condition (surface roughness, streak direction, hardness, etc.) and the size of the material There are many unstable factors such as the influence of heat treatment (mass effect, etc.) due to heat treatment or the modification by oxidation of the surface. Therefore, it seems difficult to expand and interpret the results of a small specimen as in a normal fatigue test. is there.

However, the need is of course high, so
Many tests based on actual machines have been conducted.

The torsion testers are roughly classified into a constant torsion angle tester and a constant torque tester. The constant torsion angle tester is shown in FIG. 7A and the constant torque tester is shown in FIG.

FIG. 7A shows a Schenk type bending (torsional) fatigue tester, and FIG. 7A itself is a bending tester, but the test piece 2 of the test piece mounting portion 1 is pivoted as shown in FIG. 7B. When it is tilted by θ with respect to the axis 3 ′ of 3, bending and torsion become possible, bending at θ = 90 ° and twisting at θ = 0 °.

That is, the test piece 2 in FIG.
If it is matched, it becomes a torsion tester.

Incidentally, the torsional load method shown in FIG. 7A is based on a method in which an arm 6 having an eccentric (eccentric amount e) from a rotary shaft and one end rotatably attached to a disk 5 rotated by a drive source (eg, a motor) 4 3 is rotatably connected to the other end of an arm 7 fixed in the radial direction, so that the rotation of the disk 5 due to the eccentricity e causes the arm 7 to swing through the arm 6 to twist. A torque is applied to the shaft 3.

Therefore, since the torsion angle of the shaft 3 is determined by the eccentricity e of the arm 6 on the disk 5, the method of FIG. 7A is a constant torsion angle fatigue tester.

Reference numeral 8 denotes a fixed portion for supporting a torsional reaction force, and a pre-torque load device and a torsional torque measuring device are also provided here.

FIG. 8 shows a MAN test machine, 10 is a fixed table, and a test piece 11 is fixed to a fixed table 10 and a disk (or arm) 12.
The disc (or arm) 12 is directly connected to a DC motor 13 (however, it does not rotate once since it is a test machine, so there is no brush). Then, a torsion test is performed by rotating the disk (or arm) 12. Therefore, this testing machine
Since the torque can be set by the electric current, constant torque torsion is possible.

Note that, similarly to the fixing base 10 shown in FIG. 7A, a pre-torque load device, a torsional torque measuring device, and the like are provided here. The disk (or arm) 12 is provided with various switches. For example, if the switch is switched after a certain angle of twist and the current of the electric motor 13 is switched, self-vibration can be generated. Therefore, by fixing the position of the switch, as shown in FIG. A constant torsion angle load becomes possible.

That is, the method of FIG. 8 can apply both a constant torsion angle and a constant torque.

The above is a typical example of a fatigue tester having a constant torsion angle and a constant torque load. In addition, there is a flywheel type repetitive load method improved based on the above two examples.

 By the way, the functions required for the torsional fatigue tester are as follows: a- (1). Able to set torsion angle (at constant torsion angle), a- (2). B. Torque can be set (at constant torque). C. Load repetition (pulsation) is possible. D) Torque measurement is possible. E. The load can be counted repeatedly. It is possible to stop instantaneously at the time of rupture.

Furthermore, as a fatigue testing machine, for repeated small displacement,
Special local wear and fatigue of the tester itself are liable to occur, and the number of repetitions of one test is as large as 10 ⁵ to 10 ⁸ . Measures to prevent fatigue of the test machine itself and wear of the moving parts; g. The fast repetition rate is essential.

(Problems to be Solved by the Invention) The above are the components of the torsional fatigue tester.
Compared with the compression fatigue tester, the latter is better than the former, when the torque measurement of the above item c is replaced with a load measurement.
Item or A- (2) is different.

However, item (a) (1) or item (a) (2) in the mechanical element has a very large effect, and the frequency of use is influenced by the undervalue of the torsional fatigue tester. However, it is about three times as expensive.

FIG. 9 shows a Rosen type hydraulic tension / compression tester, which includes a hydraulic pump Pc, a pressurizing pump P _T , a vibrating device (balseta) V,
Compression cylinder Cc, and tensile cylinder C _T cylinder Cc of what is provided, C _T is only performed on-downward, and has a simple mechanism for no function of the rotation and the like. In addition,
W is a test piece.

The torsional fatigue tester is special among the testers, is rarely installed, and is very expensive.

On the other hand, the tensile / compression fatigue testing machine is the most permanent testing mechanism among the fatigue testing machines, is inexpensive, and has only a functional difference in twist from tension / compression.

The present invention has been made based on the above circumstances, and an object thereof is to provide a torsion fatigue test using a tension / compression fatigue test by providing an auxiliary device for converting tension / compression into torsion. An object of the present invention is to provide an auxiliary device for a torsional fatigue test.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a tensile / compression fatigue test in which an upper chuck and a lower chuck are provided and a tensile and compression fatigue test of a test piece is performed. An auxiliary device which is used by being fastened to a machine, wherein two arms each having one end slidably connected to each of an upper chuck and a lower chuck of the testing machine; and one end connected at right angles to the other ends of the arms. Two cylindrical shafts rotatably provided by bearings are provided at the other end portions of the inner diameters of the two cylindrical shafts, and the two shaft centers are made to coincide with each other and set inside the cylindrical shafts. The structure comprises two coupling means provided so as to be coupled with both ends of the test piece with rigidity against torsion.

(Operation) That is, the tensile / compression fatigue tester has not only a torsional function but also other functions in a fatigue test, such as a counting function, a machine instantaneous stop function at break, and a load load, as compared with a torsional fatigue tester. In addition to having a stabilizing function, stroke setting and load setting are possible, so that an auxiliary device of the present invention that converts an axial change due to tension / compression of a tensile / compression fatigue testing machine into rotation is added to the testing machine. Thereby, it can be used as a torsional fatigue tester.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS.

 First, a tensile / compression fatigue tester will be described in detail as a premise.

FIG. 2A shows a tensile / compression fatigue tester.
FIG. 2B is similar to FIG.
Hydraulic vibrator 20 (Hydraulic device is not shown because it is placed separately)
Is generally provided at the lower part of the apparatus.

Therefore, a load is applied by the lower chuck 21 directly connected to the vibrator 20, and the load measuring device (for example, a load cell) 22 is provided in the upper chuck 23. Further, the upper chuck 23 is attached to the reaction force support beam 24, is guided by the reaction force support rod 25, and moves up and down so that it can be set at a distance between the upper chuck 23 and the lower chuck 21.

Therefore, the tensile / compression test specimen 26 is first chucked to the lower chuck 21 and then attached (chucking) to the upper chuck 23 in accordance with the length of the test specimen. After a load of 20 is applied, an appropriate vibration (pulsation) is applied by the vibrator 20.

The tensile / compression fatigue tester configured as described above is controlled to have the following functions using a separate control device.

(1) The shaker 20 can freely apply a static load and a vibration load, and can also set the amplitude.

(2) In addition to detecting the load by the load measuring device 22, the test piece 26
The instantaneous stop of the excitation can be performed from the change in the load due to the breakage of the sample, and the number of excitation can be measured from the change in the excitation load.

Therefore, in order to make the tensile / compression fatigue tester a torsional fatigue tester, the vertical movement of the upper chuck 23 and the lower chuck 21 is performed by using an auxiliary device (hereinafter simply referred to as an auxiliary device) 30 of the torsional fatigue tester. The only thing that should be done is a rotational movement.

Note that the torsion torque may be derived by multiplying the value of the load measuring device of the upper chuck 23 by the effective radius required for torsion.

 Hereinafter, the auxiliary device 30 will be described in detail.

FIG. 1 shows an auxiliary device 30 according to the present invention,
3 shows a state where the apparatus is mounted on a compression fatigue test apparatus.

That is, in FIG. 1, the upper chuck 23 and the lower chuck 21 are respectively connected to the arm 31a and the arm 31b of the auxiliary device 30.
And the arm are coupled to be able to absorb the rotational displacement.

Prior to this discussion, the rotational displacement of the arm will be described. The rotational displacement of the arm occurs when the test pieces 32, 33 (see FIG. 3) are twisted by the load applied from the chuck to the ends of the arms 31a, 31b. I do.

This is a displacement in a direction perpendicular to the axis of the chucks 23 and 21. Referring to FIG. 4, when the load of the chuck 23 or 21 changes by ΔP, the chuck 23 (or 21) and the arm 31 are moved.
The contact point with a (or 31b) (virtual contact point for the surface) Q is Q ₁
Was changed to Q ₂ from (axial displacement of the chuck 23 is [Delta] y, perpendicular displacement axis is [Delta] x) is that the [Delta] x of the time.

The angle of Q ₁ OQ ₂ is Δθ, the upper chuck 23 and the lower chuck 2
Perpendicular to the axis of the 1, and, when the angle between the surface and the Q ₁ through the axis O of the auxiliary device 30 and theta, a formula.

Δx = R ₂ cos (θ−Δθ) −R ₁ cos θ (R ₁ = ₁ , R ₂ = ₂ ) That is, when vibrated by the chuck, the auxiliary device 30
Is fixed to the tensile / compression fatigue tester, the lateral displacement Δx is constantly applied to the chuck 23 or 21. If the friction is large, a large lateral load is applied to the chuck 23 or 21. Will be. For example, in the upper chuck 23, the load measuring device 22 is liable to cause an error due to bending, and in the lower chuck 21, since a reaction force is received on the side wall of the hydraulic vibration device, oil leakage due to wear occurs. Easier to do.

Therefore, the chuck 23 (or 21) and the arm 31a
The connection with (or 31b) requires a relaxation method that absorbs the rotational displacement of the arm and reduces the lateral load.

FIG. 5 shows a method of relaxing the chuck 23 (or 21) and the arm 31a (or 31b). FIG. 5 shows a connecting rod 35 in which both ends of the chuck 21 and the arm 31a are rotatable pin joints.
With this method, both tension and compression are possible.

FIG. 6 shows a rolling flat bearing 36 on the chuck 23 side.
Further, a spherical bearing (or pin joint) 37 is provided on the arm 31a (or 31b) side, and the lateral load is a rolling flat bearing 36, and the angular change due to the rotation of the arm 31a (or 31b). Is escaped by a spherical bearing (or pin joint) 37.

Further, the rolling flat bearing 36 may be a sliding bearing depending on a load.

In addition, in order to apply a torsional force to the test piece having a short effective length in the vibration, the displacement Δy in FIG. 4 is small.
x is smaller, but Q ₁ and Q ₂ are
The closer to a plane (OX in FIG. 4) which is perpendicular to the axis of the chuck and which passes through the (torsion) axis O of the auxiliary device, the smaller the value of Δx becomes, the smaller the Δx becomes.
If it is close to Q ₁ (and Q ₂ ), the eccentric load of the chuck can be almost ignored for the vibrating cylinder.

Next, the auxiliary device 30 according to the present invention will be described with reference to FIG. 3 (a view taken along the line III-III in FIG. 1).

The excitation load applied to the arm 31b connected to the lower chuck 21 is converted into rotational torque by using a bearing 41a provided on the front housing 41 attached to the base 40 as a support point, and is converted through the cylindrical body 42. Bearing 43a provided on rear housing 43
To the end 44 supported by the

A spline is machined on the inner diameter of the end portion 44, and the spline is connected to one end of the first test piece 32.
The other end is a collar with a spline inside.
Since it is connected to one end of the second test piece 33 by 45, the torque is transmitted in this system.

The other end of the second test piece 33 is connected to a slider 46 having a spline formed on the inner wall, and the slider 46 is connected to a housing 48 provided on a slide table 47 by a spline (or key) provided on the outer wall. Of the cylindrical body 49 fitted with the inner ring of the bearing 48a.

Since the cylindrical body 49 is connected to the arm 31a provided at one end thereof, the torque transmitted by this system is
The load becomes a load at the tip and is transmitted to the upper chuck 23.

Therefore, the excitation force by the chucks 23 and 21 is
The torque is converted into torque by 31a and 31b, and the test piece is twisted.

Here, since the slider 46 is slidably connected to the cylindrical body 49, two test pieces are directly connected in FIG. 3, but even if only one test piece 32 is used, the slider is moved in the test piece direction. The test can also be performed by sliding the spline on the inner wall of the slider 46 and the test piece. (The length is not limited.) The slide table 47 is a slide rail 50 provided on the base 40.
The test can be easily moved in and out because it can be moved up and down, and the inside of the tube can be easily observed because the cylindrical body is provided with a large number of holes 51.

The vibration (load) arms 31a and 31b of the auxiliary device
The reason why they are juxtaposed in the vicinity is that, as described above, it is necessary to provide them near the axes of the chucks 23 and 21 in order to reduce the unbalanced load.
Axis and two load points coincide (that is, both arms 31a and 31b)
The load points may be arranged vertically, not juxtaposed.

The tensile / compression fatigue tester can set the stroke and vibration amplitude of the vibrating cylinder. Therefore, in the torsional fatigue test, it is possible to freely set a constant torque and a constant torsion angle in addition to one-sided and two-sided vibrations.

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

[Effects of the Invention] Since the present invention is configured as described above, a simple torsional conversion into a high-frequency, low-cost tensile / compression fatigue tester is used instead of the conventional expensive and low-frequency torsional fatigue tester. Since an auxiliary device is provided so that a torsional fatigue test can be performed, there is an effect that an inexpensive and easy torsional fatigue test can be performed.

[Brief description of the drawings]

FIG. 1 is a view showing a state where an auxiliary device of the present invention is installed, FIG. 2A and FIG. 2B are views schematically showing a configuration of a main part of a tensile / compression fatigue tester, and FIG. FIG. 1 is a view taken along the line III-III of FIG. 1, FIG.
The figure shows a relaxed connection structure between the chuck and the arm, FIG. 6 shows another example of the relaxed connection structure between the chuck and the arm,
FIG. 7A is a diagram showing a configuration of a Sienk type torsional fatigue tester,
FIG. 7B is a diagram for explaining the principle of bending and torsion by a Schenk type torsional fatigue tester, FIG. 8 is a diagram showing a configuration of a MAN torsional fatigue tester, and FIG. 9 is a tensile / compression fatigue tester. FIG. 3 is a diagram schematically showing the configuration of FIG. 21,23… Chuck, 31a, 31b… Arm, 32,33 …… Test piece, 30 …… Auxiliary device, 42 …… Tube, 45 …… Collar,
46: Slider, 49: Cylindrical body.

Claims (3)

(57) [Claims] 1. An auxiliary device which has an upper chuck and a lower chuck and is used by being fastened to a tensile / compression fatigue testing machine for performing a tensile and compression fatigue test of a test piece, wherein the upper chuck and the lower chuck of the testing machine are used. Two arms each having one end slidably coupled to each of the two arms; two cylindrical members having one end coupled at right angles to the other ends of the arms and rotatably provided by bearings; At the other end of the inner diameter of the body, two axes are aligned, and both ends of the test piece set inside the cylindrical body are provided so as to be rigidly coupled to torsion. An auxiliary device for a torsional fatigue test, comprising: two connecting means. 2. The method according to claim 1, wherein at least one of the two coupling means fitted to both ends of the test piece is provided with a slider slidable in the axial direction and having rigidity against torsion. 2. The auxiliary device for torsional fatigue test according to 1. 3. The torsional fatigue test according to claim 1, wherein at least one of the two bearings rotatably supporting the two cylindrical shafts is supported so as to be movable in the axial direction. Auxiliary equipment.