JP2013019754A - Acceleration sensor and vibration detecting device with the acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acceleration sensor used for a vibration measuring device, which does not inhibit vibration of a measurement object by external force and does not need attachment/detachment thereof to enable simple and reliable measurement, and a measurement method thereof.SOLUTION: An acceleration sensor is provided with vibration-proof materials on a periphery of a sensor. Also, an attachment part for attaching a jig and serving as a weight is provided on the upper portions of the vibration-proof materials.

Description

  The present invention relates to an acceleration sensor and a vibration detection apparatus using the acceleration sensor.

  In order to quantify or automate a sensory test performed as a product inspection at a manufacturing site, a vibration detection device has been proposed in which a contact-type acceleration sensor is fixed on the surface of a product and a vibration state is measured to detect an abnormality.

  In general, the frequency characteristics of a contact-type acceleration sensor vary depending on the state (roughness, material, shape) of the surface of the object to be measured. This is because a resonance phenomenon occurs in a vibration system composed of an acceleration sensor and an object to be measured.

  In order to solve the influence of the above-described contact resonance, Patent Documents 1 and 2 disclose an acceleration sensor that applies an appropriate pressure to the surface of a non-measurement object by providing a weight and an elastic body on the upper part of the pickup.

JP-A-62-259021 JP 2005-121532 A

  In any case, in order to accurately measure acceleration, the acceleration sensor must be brought into contact with the vibration detection surface perpendicularly to minimize the influence of contact resonance. However, when the vibration detection surface has an excessive inclination, the acceleration sensor must be held obliquely, and an appropriate pressure cannot be applied. Furthermore, there is a problem that the acceleration sensor easily falls off the vibration detection surface when pressed.

  As described above, the problem to be solved by the present invention is to provide an acceleration sensor and a vibration detection device that can accurately measure acceleration without falling off even if the vibration detection surface is inclined.

  In order to solve the above problems, an acceleration sensor according to the present invention is an acceleration sensor having an acceleration detection element, a case housing the acceleration detection element, and a vibration-proof material having elasticity, and the case includes the acceleration detection element. A main body portion that accommodates the element; and a flange portion that extends from the main body portion and has a bottom surface that abuts against a vibration detection surface to be measured. The vibration-proof material is located above the flange portion and around the main body portion. It is characterized by being arranged in. By pressing the buttocks through the anti-vibration material and bringing the acceleration sensor into contact with the vibration detection surface, the inclination of the vibration detection surface is absorbed by the compression of the anti-vibration material, and the acceleration sensor is always against the vibration detection surface. Pressed vertically.

  Here, the acceleration detection element is not particularly limited as long as it is a contact type, but it is preferable to use a piezoelectric acceleration detection element having a wide measurement range and capable of wide-band measurement.

  The case has a main body portion that accommodates the acceleration detection element, and a flange portion that is provided on the bottom surface that extends from the main body portion and contacts the vibration detection surface. What is necessary is just to determine the magnitude | size of a collar part suitably based on the component of an acceleration sensor.

  The anti-vibration material is arranged so as to surround the main body portion symmetrically with respect to the vertical axis passing through the center of the acceleration detecting element on the flange portion of the case. As the vibration isolator, it is preferable to use a fluororubber sponge having a hardness of 60 or less, a leaf spring, a coil spring, or the like in order to ensure sufficient anti-vibration properties. The shape of the vibration isolator can be changed as appropriate. For example, a ring-shaped anti-vibration material may be installed in the collar, and the main body may be arranged in the center of the ring-shaped anti-vibration material. A plurality of them may be arranged.

  The thickness of the anti-vibration material can be appropriately changed according to the hardness of the anti-vibration material and the allowable inclination of the vibration detection surface, but is preferably smaller than the length from the upper surface of the collar to the upper end of the acceleration sensor. If the length from the upper surface of the collar portion is longer than the length of the upper end of the acceleration sensor, a stable pressing cannot be obtained on the vibration detection surface.

  In actual measurement, an acceleration sensor mounted on the robot arm is brought into contact with the vibration detection surface via a vibration isolator. At this time, in order to easily and reliably attach the robot arm, a jig that mediates the mechanical coupling between the vibration isolator and the robot arm may be provided. For example, a ring-shaped jig having a screw hole on the circumference can be bonded to a vibration-proof material with an epoxy adhesive, and the robot arm and the jig can be screwed together and fixed. Further, any means such as fastening, fitting, screwing, welding, adhesion, or adsorption may be used for coupling the jig and the vibration isolating material and the jig and the robot arm.

  A vibration inspection apparatus according to the present invention includes any one of the acceleration sensors described above.

  ADVANTAGE OF THE INVENTION According to this invention, the vibration of a measurement object can be reliably measured by supporting the vibration isolator with which an acceleration sensor is provided in the position different from the past. In particular, by arranging the vibration isolating material so as to be symmetric with respect to the vertical axis and supporting the sensor at a plurality of points, it is possible to reliably measure even if the vibration surface is inclined.

  Furthermore, according to the present invention, by providing the vibration-proof material with a jig, the attachment to the robot arm is easy and reliable.

  With the above configuration, even if the vibration detection surface of the measurement object is inclined, the inclination can be absorbed by the deflection of the vibration isolating material, so that the angle of the contact surface can correspond to the inclination of the vibration detection surface. . In other words, the acceleration sensor can abut on the vibration detection surface perpendicularly and can detect vibration without skidding on the measurement surface.

It is a top view which shows the acceleration sensor in the 1st form of this invention, Fig.1 (a) is a top view, FIG.1 (b) is a front view. It is a top view which shows the acceleration sensor in the 2nd form of this invention, Fig.2 (a) is a top view, FIG.2 (b) is a front view. FIG. 3A is a characteristic diagram showing a frequency-acceleration transfer coefficient in the first embodiment of the present invention, and FIG. 3A shows the acceleration transfer coefficient when the acceleration sensor is brought into contact with the vibration detection surface vertically, and FIG. ) Shows an acceleration transmission coefficient when the acceleration sensor is brought into contact with being tilted by 10 degrees from a direction perpendicular to the vibration detection surface. FIG. 4A is a characteristic diagram showing a frequency-acceleration transfer coefficient according to the second embodiment of the present invention, and FIG. 4A shows the acceleration transfer coefficient when the acceleration sensor is brought into contact with the vibration detection surface vertically, and FIG. ) Shows an acceleration transmission coefficient when the acceleration sensor is brought into contact with being tilted by 10 degrees from a direction perpendicular to the vibration detection surface. FIG. 5A is a characteristic diagram showing a frequency-acceleration transfer coefficient by a conventional acceleration sensor, FIG. 5A shows the acceleration transfer coefficient when the acceleration sensor is brought into contact with the vibration detection surface vertically, and FIG. An acceleration transmission coefficient when the sensor is brought into contact with being tilted by 10 degrees from a direction perpendicular to the vibration detection surface is shown. It is a top view which shows the concept of the vibration detection method in a production line.

(First embodiment)
Hereinafter, embodiments of an acceleration sensor according to the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view showing an acceleration sensor according to the first embodiment of the present invention, in which FIG. 1 (a) is a top view and FIG. 1 (b) is a front view. In FIG. 1A, the acceleration sensor 1 includes a case 10 provided with a vibration detection element (not shown) therein, vibration-proofing materials 11, 12, 13, 14, and an output cable 15 made of an elastic body. The

  For example, a piezoelectric element is used as the acceleration detection element. The case 10 includes a main body portion 10a that houses an acceleration detection element (not shown), and a flange portion 10b that comes into contact with the vibration detection surface. For example, an elastic body such as a fluoro rubber sponge is mechanically coupled to the flange portion 10b as the vibration isolators 11-14.

  Since the vibration isolator can be enlarged without increasing the center of gravity of the acceleration sensor by arranging the vibration isolator on the heel portion, a vibration isolating effect and a tilt absorbing effect can be obtained. That is, the acceleration sensor can be stably brought into contact with the vibration detection surface.

  In addition, about the shape of a vibration isolator, it can be changed into various shapes according to a jig | tool. In the present embodiment, four divisions are shown, but it is only necessary to arrange them symmetrically with respect to the central vertical axis, and it can be changed into two divisions, three divisions, or a ring shape.

  The acceleration sensor 1 having the above configuration is supported by a robot arm 16 (not shown in FIG. 1A), and is brought into contact with the vibration detection object 17 with a constant pressure to detect surface vibration.

  What is necessary is just to set suitably the press to a vibration detection surface according to the specification of an acceleration sensor. By applying an appropriate pressure to the vibration detection surface, the spring constant between the acceleration sensor surface and the vibration detection surface becomes large, and the influence of contact resonance is reduced. On the other hand, if the pressure on the vibration detection surface is excessive, the acceleration sensor is strongly pressed against the vibration detection surface and the vibration isolation material is compressed, so that sufficient vibration isolation effect and tilt absorption effect cannot be obtained. The apparent mass of the entire system increases. As a result, the contact resonance frequency is lowered and the vibration of the vibration detection object is also inhibited.

(Second embodiment)
2A and 2B are plan views showing the acceleration sensor according to the second embodiment of the present invention. FIG. 2A is a top view and FIG. 2B is a front view. As in the previous embodiment, the robot arm 26 serving as a jig is omitted in FIG. In FIG. 2A, the acceleration sensor 2 includes an attachment jig 22 on top of the vibration isolation materials 11 to 14. The attachment jig 22 is fixed to the vibration isolation materials 11 to 14 by means such as adhesion. Moreover, the screw holes 22a-22d for connecting a jig | tool and a robot arm are provided. Further, the acceleration sensor 2 is fixed to the robot arm 26 with screws.

  According to the acceleration sensor of the present invention, by providing a jig on the top of the vibration isolator, it is possible to easily and reliably connect to the jig. Furthermore, since the jig plays the role of a weight, the effect of suppressing the influence of contact resonance can be obtained. Therefore, measurement variations due to contact resonance can be suppressed.

  The shape of the jig can be changed as appropriate according to the shapes of the robot arm and the vibration isolator. Further, the joining method of the jig and the robot arm is not limited to screws, and can be changed to an appropriate method in each environment.

  In order to compare the performance of the acceleration sensor according to the present invention and the acceleration sensor according to the prior art, the output sensitivity transfer characteristic of the acceleration sensor was evaluated by the following procedure.

Example 1
The acceleration sensor according to the present invention was manufactured by housing a piezoelectric vibration detecting element in a case made of SUS304 stainless steel. The case consists of a main body part with a diameter of 14 mm and a height of 7 mm, and a flange part with a diameter of 25 mm and a height of 0.5 mm. Anti-vibration material. A vibration detection device was obtained by attaching a vibration isolator and a robot arm by suction.

(Example 2)
In the acceleration sensor of Example 2, a jig that facilitates mounting on the robot arm was added to the configuration of Example 1. The jig was a ring shape made of SUS304 stainless steel with an outer diameter of 24 mm, an inner diameter of 16 mm, and a thickness of 1 mm, and was provided with screw holes 22a, 22b, 22c, and 22d on the circumference. This jig was bonded to a vibration isolating material with an epoxy adhesive, and screwed with a robot arm and screw holes 22a, 22b, 22c, and 22d to obtain a vibration detecting device.

(Comparative example)
On the other hand, the conventional acceleration sensor includes a piezoelectric vibration detecting element housed in a case made of SUS304 stainless steel. The case does not have a heel part, and a vibration-proof material is bonded to an upper end of a main body having a diameter of 14 mm and a height of 7 mm by using an elastic adhesive having a hardness of 52 and an epoxy adhesive. Was attached by suction, and a vibration detection device was obtained.

  The vibration detection object used for the output sensitivity transmission characteristic is a 100 × 100 × 3 mm aluminum thin plate vibrated by a shaker. Each acceleration sensor supported by the robot arm was brought into contact with this thin aluminum plate at a tilt of 10 degrees from the vertical or vertical direction with a pressure of 3 N / cm, and the output sensitivity transmission characteristics were compared.

  FIG. 3 is a characteristic diagram showing the frequency-acceleration transfer coefficient in the first embodiment of the present invention, and FIG. 3 (a) shows the acceleration transfer coefficient when the acceleration sensor is brought into contact with the vibration detection surface vertically, FIG. 3B shows an acceleration transmission coefficient when the acceleration sensor is brought into contact with being tilted by 10 degrees from a direction perpendicular to the vibration detection surface. In FIG. 3, the transfer function was reduced by 0.1 dB by tilting the pressing angle by 10 degrees from the vertical direction.

  FIG. 4 is a characteristic diagram showing the frequency-acceleration transmission coefficient in the second embodiment of the present invention, and FIG. 4 (a) shows the acceleration transmission coefficient when the acceleration sensor is brought into contact with the vibration detection surface vertically, FIG. 4B shows an acceleration transmission coefficient when the acceleration sensor is brought into contact with being tilted by 10 degrees from a direction perpendicular to the vibration detection surface. In FIG. 4, the transfer function decreased by 0.2 dB by tilting the pressing angle by 10 degrees from the vertical direction.

  FIG. 5 is a characteristic diagram showing a frequency-acceleration transfer coefficient by a conventional acceleration sensor. FIG. 5A shows an acceleration transfer coefficient when the acceleration sensor is brought into contact with the vibration detection surface vertically. b) shows an acceleration transmission coefficient when the acceleration sensor is brought into contact with being tilted by 10 degrees from a direction perpendicular to the vibration detection surface. In FIG. 5, the transfer function was reduced by 2 dB by tilting the pressing angle by 10 degrees from the vertical direction.

  As described above, according to the acceleration sensor according to the present invention, it is understood that the decrease in the transfer function is very small even when the vibration detection surface is inclined. That is, the vibration of the vibration detection surface can be accurately measured regardless of the inclination of the vibration detection surface.

  The above acceleration sensor was applied to a production line, and the number of times the acceleration sensor failed to measure was compared. FIG. 6 is a plan view showing the concept of the vibration detection method in the production line. As shown in FIG. 6, the acceleration sensor 40 was supported by the robot arm 46, and the vibration of the vibration detection object 41 was measured. Here, the vibration detection object 41 was conveyed by the belt conveyor 42, and the measurement was continuously performed. Further, the vibration detection surface 41a was inclined by 10 degrees with respect to the vertical direction.

  Table 1 is a table comparing the number of failed measurements performed 1000 times by the above method. When the measurement was repeated 1000 times, the measurement in the configuration of Example 1 failed three times, and in the configuration of Example 2, the measurement failed once, whereas the comparative example had 22 errors.

  From the above, it can be seen that according to the acceleration sensor of the present invention, the vibration detection surface is stably brought into contact with the vibration detection object even when the vibration detection surface is inclined.

  Although the present invention has been specifically described above, the present invention is not limited to these. Even if there is a change in the member or configuration without departing from the spirit of the present invention, it is included in the present invention. That is, the present invention also includes modifications and corrections that can be made by a person concerned.

  The acceleration sensor system according to the present invention can be used as a product abnormality inspection system in a line. Moreover, it can utilize as a system which detects the abnormal vibration of the apparatus which cannot fix a vibration sensor directly.

1, 2, 40 Acceleration sensor 10 Case 10a Main body 10b Rider 11, 12, 13, 14 Vibration isolator 15 Output cable 16, 26, 46 Robot arm 17, 41 Vibration detection object 41a Vibration detection surface 22 Jig 22a, 22b, 22c, 22d Screw hole 42 Belt conveyor

Claims (4)

  An acceleration sensor, a case for accommodating the acceleration sensor, and an acceleration sensor having an elastic vibration-proof material, the case extending from the main body, the main body for housing the acceleration sensor. The vibration detecting surface of the measurement target is provided with a flange portion that abuts on the bottom surface, and the vibration isolator is disposed on the upper portion of the flange portion that faces the bottom surface and around the main body portion. Acceleration sensor.   The acceleration sensor according to claim 1, wherein the vibration isolator is disposed symmetrically with respect to a vertical axis passing through a center of the acceleration detection element.   The acceleration sensor according to claim 1, wherein a height of the vibration isolator is smaller than a height of the main body.   A vibration inspection apparatus comprising the acceleration sensor according to claim 1.

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