JP3825157B2 - Exciter for dynamic viscoelasticity measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibrator used in a dynamic viscoelasticity measuring apparatus that measures the dynamic viscoelasticity of a material .
[0002]
[Prior art]
For example, in a viscoelasticity measuring apparatus that measures the viscoelasticity of a material such as rubber or plastic by a tensile vibration method, a sinusoidal strain due to tension is applied to a test piece using a vibrator. Conventionally, for example, a vibrator as shown in FIG. 5 has been proposed. In this vibrator, a lower chuck 2 is attached to the upper end of a rod 1 extending in the vertical direction, and both ends of a test piece (not shown) are held by the lower chuck 2 and the upper chuck (not shown). Then, the rod 1 is vibrated in the vertical direction (longitudinal direction) by a so-called moving coil system so as to apply a sinusoidal strain to the test piece.
[0003]
For this reason, in the vibrator shown in FIG. 5, a bobbin 3 is attached to the rod 1, and the bobbin 3 is a cylindrical part that serves as a fixing portion via ring-shaped leaf springs 4 and 5 at a position spaced apart in the vertical direction. It attaches to the support | pillar 6, and supports the rod 1 so that a displacement in a perpendicular direction is possible. Further, a coil 8 is attached to the lower end portion of the bobbin 3 so as to wind the rod 1, and a magnetic circuit 9 is disposed on the fixed portion so that the magnetic flux crosses the coil 8. The magnetic circuit 9 includes an outer yoke 10 disposed so as to face the entire outer peripheral surface of the coil 8, and a cylindrical inner yoke 11 disposed so as to face the entire inner peripheral surface of the coil 8. And a permanent magnet 12 magnetized in the ring-shaped surface direction connecting the outer yoke 10 and the inner yoke 11, and the magnetic flux from the permanent magnet 12 crosses the coil 8 in the radial direction. .
[0004]
In this way, by passing a sinusoidal alternating current having a required frequency through the coil 8, the movable part of the coil 8, the bobbin 3 and the rod 1 is moved up and down by the electromagnetic action of the current and the magnetic flux crossing the coil 8. The test piece is subjected to sinusoidal distortion. In addition, the optical fiber 13 which comprises an optical fiber type displacement sensor is made to oppose the lower end surface of the rod 1, and the displacement amount of the rod 1 is measured.
[0005]
[Problems to be solved by the invention]
By the way, in the measurement of viscoelasticity, in addition to measuring dynamic viscoelasticity by changing temperature and displacement amplitude, the frequency dependence (frequency dispersion) of viscoelasticity is changed by continuously changing the excitation frequency over a wide range. ) Is required to be measured. However, in the above-described conventional vibrator, the rod 1 is supported by the fixed portion via the leaf springs 4 and 5 so as to be displaceable. Therefore, the frequency of the sine wave alternating current flowing through the coil 8 is changed. As a result, a resonance phenomenon occurs at a frequency corresponding to the natural frequency of the leaf springs 4 and 5, and the acceleration (G) detected based on the output of the displacement sensor and the impedance (Ω) of the drive system including the coil 8 However, as shown in FIG. 6, an extremely high resonance point appears. For this reason, at a frequency in the vicinity including the frequency corresponding to this natural frequency, there is a problem that forced vibration with a constant amplitude cannot be applied to the test piece, making it impossible to measure viscoelasticity.
[0006]
The present invention has been made paying attention to such a conventional problem, and when measuring the dynamic viscoelasticity of a material, it is possible to stabilize a specimen of a material over a wide range of frequencies without causing a resonance phenomenon. It is an object of the present invention to provide a vibrator for a dynamic viscoelasticity measuring apparatus that is appropriately configured so that it can be vibrated.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a vibrator for use in a dynamic viscoelasticity measuring device for measuring the dynamic viscoelasticity of a material ,
A rod that is slidable in the longitudinal direction in the fixed part, and a rod to which a chuck for holding the test piece of the material is attached at one end ;
A first coil and a second coil attached to the rod;
Magnetic circuit means provided in the fixed part so that the magnetic flux crosses the first coil and the second coil,
By supplying a direct current to one of the first coil and the second coil and an alternating current to the other, the rod is changed to the alternating current with reference to the electromagnetic sliding position corresponding to the direct current. Accordingly, it is configured to be capable of electromagnetically reciprocatingly sliding.
[0008]
In one embodiment of the present invention, the first coil and the second coil are arranged to be spaced apart from each other in the longitudinal direction of the rod and to wind the rod. In this way, the outer diameter of the vibrator can be reduced.
[0009]
Furthermore, in one embodiment of the present invention, as described above, when the first coil and the second coil are arranged so as to be separated from each other in the longitudinal direction of the rod and wound around the rod, The magnetic circuit means has a first permanent magnet disposed around the rod, and the magnetic flux from the first permanent magnet crosses the entire circumference of the first coil in the radial direction. A first magnetic circuit configured and a second permanent magnet disposed around the rod, and a magnetic flux from the second permanent magnet extends in the radial direction over the entire circumference of the second coil. And a second magnetic circuit configured to cross the line. In this way, since the magnetic flux can be effectively applied to each of the first coil and the second coil, the driving efficiency can be increased.
[0010]
Furthermore, in one embodiment of the present invention, as described above, when the first coil and the second coil are arranged so as to be separated from each other in the longitudinal direction of the rod and wound around the rod, The magnetic circuit means has a common permanent magnet disposed around the rod, and the magnetic flux from the permanent magnet crosses the entire circumference of the first coil and the second coil in the radial direction. Configure. In this way, since only one permanent magnet is required, the cost can be reduced.
[0011]
Furthermore, this invention is a vibrator used in a dynamic viscoelasticity measuring device for measuring the dynamic viscoelasticity of a material ,
A rod that is slidable in the longitudinal direction in the fixed part, and a rod to which a chuck for holding the test piece of the material is attached at one end ;
A coil attached to this rod;
A magnetic circuit provided in the fixed portion so that the magnetic flux crosses the coil,
By supplying an alternating current in which a direct current is superimposed on the coil, the rod can be electromagnetically reciprocated according to the alternating current on the basis of an electromagnetic sliding position corresponding to the direct current. It is characterized by that.
[0012]
In one embodiment of the present invention, the coil is arranged to wind the rod. In this way, the outer diameter of the vibrator can be reduced.
[0013]
Furthermore, in one embodiment of the present invention, as described above, when the coil is disposed so as to wind the rod, the magnetic circuit includes a permanent magnet disposed around the rod, The magnetic flux from the permanent magnet is configured to cross in the radial direction over the entire circumference of the coil. In this way, since the magnetic flux can be effectively applied to the coil, the driving efficiency can be increased.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a vibrator according to the present invention. This vibrator is used for a dynamic viscoelasticity measuring apparatus that measures the viscoelasticity of a material such as rubber or plastic by a tensile vibration method, as in the case of the vibrator shown in FIG. 5, and extends in the vertical direction. A lower chuck 22 is attached to the upper end of the rod 21, and both ends of a test piece (not shown) are held by the lower chuck 22 and the upper chuck (not shown), and the rod 21 is moved by a so-called moving coil method. The test piece is made to vibrate in the vertical direction (longitudinal direction) so as to apply a sinusoidal strain to the test piece.
[0015]
The rod 21 is slidable in the vertical direction (longitudinal direction) with respect to the outer casing 23 via support rollers 24 provided on the upper end and the lower end of a cylindrical outer casing 23 made of a magnetic material serving as a fixed portion. Provide. Bobbins 25 and 26 are attached to the rod 21 so as to be separated from each other in the longitudinal direction within the outer casing 23, the first coil 27 is wound around the bobbin 25, and the rod 21 is similarly mounted on the bobbin 26. Each of the second coils 28 is provided so as to be wound.
[0016]
Further, on the inner peripheral surface of the outer casing 23, projections 23a and 23b are formed so as to face the outer peripheral surfaces of the first coil 27 and the second coil 28, and the first coil 27 and the second coil Between the two coils 28, a small diameter portion 23c through which the rod 21 passes is formed. The small diameter portion 23c has a ring-shaped first inner yoke so as to face the inner peripheral surface of the first coil 27 via a first permanent magnet 31 magnetized in the ring-shaped surface direction on the upper surface thereof. 32 is provided, and the second inner surface of the ring shape is formed on the lower surface so as to face the inner peripheral surface of the second coil 28 through the second permanent magnet 33 similarly magnetized in the ring-shaped surface direction. A yoke 34 is provided. In this way, the magnetic flux generated by the first permanent magnet 31 constitutes the first magnetic circuit 35 traversing the first coil 27 in the radial direction over the entire circumference thereof, and the magnetic flux generated by the second permanent magnet 33 is A second magnetic circuit 36 is configured to traverse the second coil 28 in the radial direction over the entire circumference. In addition, the optical fiber 37 which comprises an optical fiber type displacement sensor is made to oppose the lower end surface of the rod 21, and the displacement amount of the rod 21 is measured.
[0017]
In this embodiment, a direct current is supplied to one of the first coil 27 and the second coil 28 and a sinusoidal alternating current is supplied to the other. Here, for example, when a direct current in the direction shown in the figure is supplied to the second coil 28, the rod 21 has a predetermined longitudinal direction due to electromagnetic action with the second magnetic circuit 36 in accordance with the supplied direct current. Ascend to the sliding position. Accordingly, when a sine wave alternating current is supplied to the first coil 27 in this state, the rod 21 is moved to the first position based on the electromagnetic sliding position corresponding to the direct current supplied to the second coil 28. In response to the sinusoidal alternating current supplied to the coil 27, the electrode 27 slides back and forth in the longitudinal direction by the electromagnetic action with the first magnetic circuit 35, thereby applying a sinusoidal strain to the test piece.
[0018]
FIG. 2 shows the frequency of the sine wave alternating current supplied to the first coil 27 when supplying the sine wave alternating current to the first coil 27 and the direct current to the second coil 28 as described above. 6 shows the acceleration (G) characteristic detected on the basis of the output of the displacement sensor and the impedance (Ω) characteristic of the drive system including the first coil 27 when changed as in FIG.
[0019]
According to this embodiment, the rod 21 is caused to have a direct current by passing a required direct current through the second coil 28 without using a mechanical component having a natural frequency such as a leaf spring. Since the rod 21 is vibrated in the longitudinal direction by the moving coil method in accordance with the sine wave alternating current that flows in the first coil 27 based on the position at the corresponding sliding position, FIG. As can be seen from the above, even if the vibration frequency is changed over a wide range, it is possible to stably vibrate without causing a resonance phenomenon as in the prior art. Therefore, the viscoelasticity of the test piece can be measured over a wide range of frequencies.
[0020]
FIG. 3 shows a second embodiment of the present invention. In this embodiment, in the first embodiment shown in FIG. 1, a ring-shaped permanent magnet magnetized in the radial direction on the inner peripheral surface of the outer casing 23 between the first coil 27 and the second coil 28. A magnet 41 is provided, and a ring-shaped inner yoke 42 is attached to the inner peripheral surface of the permanent magnet 41 so as to face the inner peripheral surfaces of the first and second coils 25 and 26, respectively. The magnetic circuit is configured so as to traverse the first and second coils 25 and 26 in the radial direction over their entire circumference. Since other configurations are the same as those in FIG. 1, the same reference numerals are given to the components having the same functions, and the description thereof is omitted.
[0021]
According to this embodiment, since the magnetic circuit for the first coil 27 and the magnetic circuit for the second coil 28 are configured using a single permanent magnet 41, the effects described in the first embodiment. In addition, there is an advantage that the whole can be made inexpensive.
[0022]
FIG. 4 shows a third embodiment of the present invention. In this embodiment, one of the first coil 27 and the first magnetic circuit 35, and the second coil 28 and the second magnetic circuit 36 are omitted from the first embodiment shown in FIG. Then, the second coil 28 and the second magnetic circuit 36) are supplied with a sine wave alternating current in which a direct current is superimposed on the coil 27, and the rod 21 is set on the basis of the electromagnetic levitation position corresponding to the direct current. The electromagnetic wave is reciprocated electromagnetically according to the sine wave alternating current, and the other configuration is the same as that of the first embodiment.
[0023]
According to this embodiment, since the rod 21 is electromagnetically reciprocated based on the desired floating position using one coil 27 and the magnetic circuit 35, the effect described in the first embodiment can be obtained. In addition, there is an advantage that the whole can be made inexpensive and thin.
[0024]
In addition, this invention is not limited only to embodiment mentioned above, Many deformation | transformation or a change is possible. For example, when using a coil for electromagnetically displacing the rod to a desired position and a coil for electromagnetically oscillating the rod based on the desired position, these coils are moved in the displacement direction of the rod. It can also be configured to be mounted and driven at a substantially symmetrical position about the rod in the substantially same plane perpendicular to the axis. If comprised in this way, the whole can be made thin like 3rd Embodiment. Moreover, the usage mode of the vibrator according to the present invention is not limited to the case where the rod is used in the vertical direction, but can be used in the horizontal direction or any other direction.
[0025]
【The invention's effect】
As described above, according to the present invention, the rod to which the chuck for holding the test piece of material is attached at one end can be fixed to the fixed portion without using a mechanical component such as a leaf spring that inevitably has a natural frequency. Electromagnetic drive means using a coil attached to the rod and a magnetic circuit provided in the fixed part, and electromagnetically supported at the desired sliding position, and vibrated with reference to the sliding position As a result, when measuring the dynamic viscoelasticity of a material using a dynamic viscoelasticity measurement device, a material specimen is stably vibrated over a wide range of frequencies without causing an undesirable resonance phenomenon. It becomes possible to do.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram showing frequency characteristics of the vibrator shown in FIG. 1;
FIG. 3 is a diagram showing a second embodiment of the present invention.
FIG. 4 is also a diagram showing a third embodiment.
FIG. 5 is a diagram showing a conventional vibrator.
6 is a diagram showing frequency characteristics of the vibrator shown in FIG. 5. FIG.
[Explanation of symbols]
21 Rod 22 Lower chuck 23 Outer flange 23a, 23b Protruding portion 23c Small diameter portion 24 Support rollers 25, 26 Bobbin 27 First coil 28 Second coil 31 First permanent magnet 32 First inner yoke 33 Second permanent Magnet 34 Second inner yoke 35 First magnetic circuit 36 Second magnetic circuit 37 Optical fiber 41 Permanent magnet 42 Inner yoke

Claims (7)

A vibrator used in a dynamic viscoelasticity measuring device for measuring the dynamic viscoelasticity of a material,
A rod that is slidable in the longitudinal direction in the fixed part, and a rod to which a chuck for holding the test piece of the material is attached at one end ;
A first coil and a second coil attached to the rod;
Magnetic circuit means provided in the fixed part so that the magnetic flux crosses the first coil and the second coil,
By supplying a direct current to one of the first coil and the second coil and an alternating current to the other, the rod is changed to the alternating current with reference to the electromagnetic sliding position corresponding to the direct current. A vibrator for a dynamic viscoelasticity measuring apparatus , characterized in that it can reciprocate electromagnetically. The vibrator for a dynamic viscoelasticity measuring apparatus according to claim 1,
The excitation for a dynamic viscoelasticity measuring device, wherein the first coil and the second coil are arranged so as to be separated from each other in the longitudinal direction of the rod and wound around the rod. vessel. In the vibrator for a dynamic viscoelasticity measuring device according to claim 2,
The magnetic circuit means has a first permanent magnet disposed around the rod, and the magnetic flux from the first permanent magnet crosses the entire circumference of the first coil in the radial direction. A first magnetic circuit configured and a second permanent magnet disposed around the rod, and a magnetic flux from the second permanent magnet extends in the radial direction over the entire circumference of the second coil. A vibrator for a dynamic viscoelasticity measuring device , comprising: a second magnetic circuit configured to traverse the first magnetic circuit. In the vibrator for a dynamic viscoelasticity measuring device according to claim 2,
The magnetic circuit means has a common permanent magnet disposed around the rod, and the magnetic flux from the permanent magnet crosses the entire circumference of the first coil and the second coil in the radial direction. An exciter for a dynamic viscoelasticity measuring device , characterized in that it is configured as follows. A vibrator used in a dynamic viscoelasticity measuring device for measuring the dynamic viscoelasticity of a material,
A rod that is slidable in the longitudinal direction in the fixed part, and a rod to which a chuck for holding the test piece of the material is attached at one end ;
A coil attached to this rod;
A magnetic circuit provided in the fixed portion so that the magnetic flux crosses the coil,
By supplying an alternating current in which a direct current is superimposed on the coil, the rod can be electromagnetically reciprocated according to the alternating current on the basis of an electromagnetic sliding position corresponding to the direct current. A vibration exciter for a dynamic viscoelasticity measuring device . The vibrator for a dynamic viscoelasticity measuring device according to claim 5,
The exciter for a dynamic viscoelasticity measuring apparatus , wherein the coil is arranged to wind the rod. The vibrator for a dynamic viscoelasticity measuring device according to claim 6,
Moving the magnetic circuit, which has a permanent magnet disposed around the rod, characterized in that it is configured to traverse in the radial direction magnetic flux from the permanent magnet over the entire circumference of the coil Shaker for mechanical viscoelasticity measuring device .

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