JPH06147967A - Mechanical impedance measuring instrument - Google Patents

Abstract

PURPOSE:To provide a mechanical impedance measuring instrument which can make highly reliably mechanical impedance measurement by suppressing the occurrence of vibrations in the other direction than the direction in which the vibrations become a kind of noise. CONSTITUTION:In the title measuring instrument which finds the mechanical impedance of an object to be measured by pressing its front-end tip 1 against the object with a prescribed static load and measuring the dynamic load and acceleration when the tip 1 is vibrated in a prescribed direction, a means which applies a static load to plate springs 6 and 6' which are the constituents of the instrument in the direction opposite to the static load applied to the object to be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the mechanical impedance of an object such as a mechanical structure or a living body.

[0002]

2. Description of the Related Art A mechanical impedance measuring device measures a dynamic load and an acceleration when a tip tip is pressed against an object to be measured with a predetermined static load and vibration is applied in a predetermined direction (axial direction described later). Then, the mechanical impedance of the object to be measured is obtained. Conventionally, this device has an impedance head in which a load meter and an accelerometer are integrated, a piezoelectric element for vibrating the impedance head, a drive unit composed of a giant magnetostrictive alloy, an electromagnetic coil, etc., and a tip tip for contacting an object to be measured. , A leaf spring that holds the load cell that senses that the tip is in contact with the object to be measured with a predetermined static load and all of them (vibration system) that are integrated, and that further isolates the vibration from the outer cylinder. Was configured.

[0003]

However, when the mechanical impedance is measured, if vibration occurs in a direction other than the predetermined direction, it becomes a kind of noise, which causes a problem that the reliability of the measurement result deteriorates. Originally, the mechanical impedance measuring device should be made to vibrate only in a predetermined direction, but since it is actually supported by a leaf spring, it is not possible to increase the rigidity in other directions too much due to its structure. , Vibration in the other direction is also occurring.

An object of the present invention is to solve this problem.

[0005]

Therefore, the first aspect of the present invention is to provide a dynamic load and an acceleration when a tip tip is pressed against an object to be measured with a predetermined static load and further vibration is applied in a predetermined direction. A mechanical impedance measuring device for measuring a mechanical impedance by providing a means for applying a static load in a direction opposite to the static load to a leaf spring which is a constituent member of the mechanical impedance measuring device. 1) ”is provided.

Further, the present invention secondly provides a "mechanical impedance measuring device (claim 2)" according to claim 1, wherein the means for applying the static load in the opposite direction is a coil spring. Further, the present invention is thirdly "the mechanical impedance measuring device according to claim 1 (claim 3), wherein the means for applying the static load in the opposite direction is an electromagnetic coil in which a bias current is passed. I will provide a.

[0007]

In the measurement by the mechanical impedance measuring device of the present invention, the static contact load applied to the tip 1 and the static load in the reverse direction applied by means such as the coil spring 14 and the electromagnetic coil which applies a bias current (hereinafter, (Reverse load)
Are balanced, and the deformation of the leaf spring 6 supporting the vibration system becomes zero or almost zero.

In this state, vibration in directions other than the predetermined direction is suppressed because the plate spring 6 has a high rigidity, and the vibration is vibration in only the predetermined direction. This is because the rigidity of the leaf spring 6 in directions other than the predetermined direction becomes maximum when the deformation of the leaf spring 6 is zero. That is, the mechanical impedance measuring device of the present invention,
Since a means for applying a reverse load that balances the contact load applied to the tip 1 is provided, the rigidity of the leaf spring 6 in a direction other than the predetermined direction is increased, and the occurrence of vibration in a direction other than the predetermined direction, which is a kind of noise, is suppressed. Therefore, it is possible to perform reliable mechanical impedance measurement.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0010]

FIG. 1 shows an embodiment of the present invention. Tip 1
Is an impedance head 2 with a built-in load cell and accelerometer
Is screwed into. A load cell 4 for measuring a static load in the direction of the shaft 12 is connected to the impedance head 2 by a shaft 3. Further, the shaft 12 is attached to the load cell 4.
All of the above members have a cylindrical shape and are arranged coaxially with the shaft 12.

The shaft 12 is held at two places by leaf springs 6 and 6 '. The electromagnetic coil 7 is adhered to the coil holder 8, and the coil holder 8 is fixed to the shaft 12. The yoke 9 is press-fitted into the outer cylinder 13, and the magnet 10 is further bonded. The other end of the magnet 10 is bonded to another yoke 11 so that the magnet 10
Is formed by two yokes 9 and 11. The coil spring 14 is placed between the back cover 15 and the leaf spring 6 ', and a static load of the same magnitude as the static load (upward in the axis 12 direction) when the tip 1 is pressed against the DUT is applied to the axis 12. It acts downward in the direction.

The operation of the apparatus configured as described above will be described below. First, a current having a random frequency of about 30 to 1000 Hz is passed through the electromagnetic coil 7. Since the electromagnetic coil 7 is placed in the magnetic field created by the magnet 10 and the yokes 9 and 11, when a current flows, a force for moving the electromagnetic coil 7 is generated. Due to this force, the tip 1, the impedance head 2, the shaft 3, the load cell 4, the spacer 5, the coil 7, the coil holder 8 and the shaft 12, which are directly or indirectly connected to the electromagnetic coil 7, are integrated (a vibration system). It vibrates in 12 directions.

Since the disk-shaped leaf springs 6 and 6'has a small rigidity in the axial 12 direction, they do not show a large resistance to the movement in the axial 12 direction, but they have a relatively large rigidity in other directions, so that they vibrate. The system vibrates mainly in the direction of axis 12. Further, in this state, in the vibrating system, the coil spring 14 applies a force downward in the direction of the axis 12, so that the leaf springs 6 and 6 ′ are deformed and the reference position of vibration (position of zero amplitude) moves downward. is doing. At this time, the rigidity of the leaf springs 6 and 6'in the radial direction becomes small, and the radial vibration easily occurs.

To perform the measurement, the outer cylinder 13 is manually (not shown).
And hold the whole device against the object to be measured so that the tip 1 is perpendicular to the surface of the object to be measured (not shown). At that time, care must be taken so that the pressing load reaches a specified value, but it is difficult to actually apply the pressing load by hand, so the pressing load is measured by the load cell 4 and automatically when the load falls within the specified range. The acceleration and dynamic load at that time are measured.

At this time, the static load (reverse load) generated in the coil spring 14 has the same magnitude as the pressing load but in the opposite direction, and the reverse load and the pressing load by the coil spring 14 are balanced and the leaf springs 6, 6 ' It will not be deformed. In this state, the radial stiffness of the leaf springs 6 and 6 is maximized, and radial vibration is suppressed. Although the reverse load is applied by the coil spring 14 in the embodiment, the same effect can be obtained by applying a reverse load by applying a bias current to the electromagnetic coil 7 in an apparatus having no coil spring 14.

[0016]

As described above, the mechanical impedance measuring apparatus of the present invention is provided with a means for applying a static reverse load that balances the static contact load applied to the tip 1, so that it can be used in a direction other than the predetermined direction. The rigidity of the leaf springs 6 and 6'in the direction is increased, vibrations in a direction other than the predetermined direction, which is a kind of noise, are suppressed, and highly reliable mechanical impedance measurement can be performed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 1 ... Tip 2 ... Impedance head 3 ... Shaft 4 ... Load cell 5 ... Spacer 6 ... Leaf spring 6 '... Leaf spring 7 ... Electromagnetic coil 8 ... Coil Holder 9 ・ ・ ・ Yoke 10 ・ ・ ・ Magnet 11 ・ ・ ・ Yoke 12 ・ ・ ・ Shaft 13 ・ ・ ・ Outer cylinder 14 ・ ・ ・ Coil spring (an example of means for applying reverse load) 15 ・ ・ ・ Back cover

Claims (3)

[Claims] 1. A mechanical impedance measuring device for measuring a mechanical impedance by measuring a dynamic load and acceleration when a tip tip is pressed against an object to be measured with a predetermined static load and further vibration is applied in a predetermined direction, A mechanical impedance measuring device, characterized in that a means for applying a static load in a direction opposite to the static load is provided on a leaf spring which is a constituent member thereof. 2. The mechanical impedance measuring device according to claim 1, wherein the means for applying the static load in the opposite direction is a coil spring. 3. The mechanical impedance measuring device according to claim 1, wherein the means for applying the static load in the reverse direction is an electromagnetic coil in which a bias current is passed.