KR20080098712A - Calibration apparatus for impact hammer using air bearing - Google Patents

Abstract

An impact hammer correction device using an air bearing fixes a test object to be hit by the impact hammer at the fixed distance from the impact hammer so that the accuracy of the impact hammer correction can be improved. An impact hammer correction device comprises an impact hammer, a fixing plate, an air bearing, a test object(10), and an analyzer. The impact hammer(11) comprises a handle(13) and a head(12) having a force transducer. On the fixing plate(14), the upper end of the handle is combined with a pin so that the head can rotate backward and forward. The air bearing(19) installed under the fixing plate at a certain distance. The test object is supported by the air bearing to move linearly, and an accelerometer(22) is adhered to one side of the air bearing. The analyzer receives signals from the force transducer and the accelerometer and calculates the impact and mobility. The head of the impact hammer falls down from a certain location so that impact is applied to the centroid of the test object.

Description

Calibration apparatus for impact hammer using air bearing}

1 is a configuration diagram showing an example of an exemplary impact excitation according to the prior art,

2 and 3 is a front view showing the configuration of the device for the impact hammer calibration according to the prior art and a side view seen from the hitting direction,

Figure 4 is a schematic diagram showing the configuration of the impact hammer calibration apparatus according to a preferred embodiment of the present invention,

FIG. 5 is an enlarged view of a portion “A” of FIG. 4 as viewed from the side.

<Description of the symbols for the main parts of the drawings>

10: test structure 11: impact hammer

12: head portion 12a: force conversion system

12b: mass rigid body 12c: replaceable mass

12d: shock tip 13: bag

14: fixing plate 15: locking part

16,20: spring 17: locking projection

18: push button 19: air bearing

21: shock absorber 22: accelerometer

23: analyzer

The present invention relates to an impact hammer calibration device using an air bearing, and more particularly, in the calibration of the impact hammer, the experimenter does not tap the impactor by hand on the test structure by using a mechanical fixing means, and the exact strength and position of the impact hammer. And it relates to an impact hammer calibration device using an air bearing capable of direction.

Impact hammers are hammers equipped to test structural behavior when used in combination with dual or multichannel spectrum analyzers.

The impact from the hammer gives the test structure a soft excitation spectrum over a wide frequency range. Force is measured by a force transducer embedded in the hammer, and the structural response is measured by means of separation, for example an accelerometer attached to the test object.

Point mobility is a method of evaluating the stiffness level or vibration sensitivity by determining the excitation node of the panel or member and analyzing the frequency response characteristics in the X, Y, and Z directions by tapping with an impulse hammer.

The apparatus required for the impact hammer calibration using the impact vibration is installed in the form of pendulums such as pendulums, such as impact hammer 110, force pendulum attached to the force transducer 12a (force transducer), as shown in Figures 1 to 3 In addition, the accelerometer 111 interlocked with the signal regulator is composed of a test structure 100 attached to one surface, and a discrete Fourier transform analyzer 23 having at least two simultaneous input channels.

The impact hammer 110 is basically a rigid mass, which is in the form of a hammer that can be held by hand for the case where the mass of the impact hammer 110 should be small, and has a force transducer 12a at one end thereof. At the other end of the force transducer 12a, an impact tip 12d is attached.

The surface area of the impact tip 12d should be large enough to withstand the maximum force without leaving permanent deformation on the tip or test structure 100. On the other hand, a small tip area may be required to achieve spatially very precise position resolution.

The velocity vector of the impact moment impact hammer 110 should coincide with the measurement axis of the force transducer 12a and should be perpendicular to the surface of the test structure 100 within a 10 degree range from the point of impact. In addition, the longer the body of the impact hammer 110 compared to the cross-sectional dimension, it is generally easier to maintain the proper direction.

In this configuration, when the experimenter applies the impact hammer 110 to the center of gravity of the test structure 100, the accelerometer 111 attached to the opposite side of the impact surface of the test structure 100 detects the momentary displacement. The signal is sent to the analyzer 23, and the impact force applied toward the center of gravity of the test structure 100 can be obtained directly from Newton's second law (F = ma).

Where m is the known mass of the mass and the accelerometer attached to the mass, and a is the acceleration of the measured mass.

On the other hand, the accuracy of mobility measured using the hand-held impact hammer 110 depends on the ability of the experimenter to maintain the correct impact position and direction, and this effect is usually accepted if the impact is carefully applied. It is within the range of possible.

However, if the test structure is small and this effect is important, very sophisticated spatial resolution techniques are required.

In addition, in the conventional impact hammer calibration using the impact hammer, the test structure is moved in the vertical, horizontal and left and right directions because of the inconsistent hitting strength and the direction of the hit. The accelerometer also moves in the vertical, horizontal and left and right directions without moving in a constant direction. This reduces the accuracy of the impact hammer calibration.

The present invention has been made in view of the above, the upper end of the impact hammer is fixed so that the impact head is rotatable in the front and rear direction, the test structure is supported by the air bearing so as to move linearly under the impact from the impact hammer, Provides impact hammer calibration device using air bearing that the impact hammer transmits impact force to the test structure at the exact position and same intensity, and the accelerometer performs linear motion instead of circular motion to accurately measure impact hammer calibration using impact vibration. Its purpose is to.

The present invention for achieving the above object in the impact hammer calibration apparatus,

An impact hammer composed of a head portion having a bag portion and a force conversion system; A fixing plate to which the upper end of the bag is coupled by a pin such that the head is rotatable in the front-rear direction; An air bearing installed at a position spaced apart from the fixed plate by a predetermined distance; A test structure hit by the head part, supported by the air bearing, installed to be linearly movable, and having an accelerometer attached to one side thereof; And an analyzer for receiving a signal from the force transducer and the accelerometer and calculating impact force and mobility, wherein the head of the impact hammer falls at a predetermined position to apply an impact to the center of gravity of the test structure at a constant intensity. It features.

As a preferred embodiment, the edge of the fixing plate is characterized in that the engaging portion formed in the sawtooth in the circumferential direction.

In a more preferred embodiment, the inside of the bag portion is supported by a spring and is provided in the form corresponding to the locking portion, and the outer side of the bag includes a push button installed to press the locking projections, the operation of the push button According to the characterized in that the locking projection is locked and released to the locking portion.

In particular, a scale is formed on the edge of the fixing plate, it is characterized in that holding the impact hammer through the operation of the push button to fix the desired position while watching the scale.

In addition, the air bearing is characterized in that it is installed in a structure that is supported while maintaining a constant interval in contact with the inner wall surface of the cylinder by the air pressure after supplying a constant pressure of air to the inside of the open cylinder.

In addition, the air bearing is characterized in that it is installed on the top of the shock absorber elastically supported by a spring to block the transmission of vibration from the bottom.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a schematic view showing the configuration of the impact hammer calibration apparatus according to the preferred embodiment of the present invention, and FIG. 5 is an enlarged view of the "A" part of FIG.

The present invention relates to an impact hammer calibration apparatus capable of accurately measuring impact hammer calibration using an air bearing (19).

The impact hammer 11 is composed of a head portion 12 having a known mass and a bag portion 13 integrally formed in the vertical direction of the head portion 12, wherein the head portion 12 has a cross-sectional diameter. It is relatively longer in length.

The head portion 12 is basically one mass rigid body 12b, and a replaceable mass body 12c is detachably installed at a rear end portion of the head portion 12, and a force transducer is installed at the front end portion thereof. 12a) is detachably attached and the impact tip 12d is attached in front of the force transducer 12a, generating a force pulse only for a desired time.

In addition, in order to prevent the impact hammer 11 from being bounced back, it is necessary to reduce the mass of the impact hammer 11 and adjust the rigidity of the impact tip 12d.

In order to reduce the mass of the impact hammer 11, the conventional impact hammer 110 is to replace the tip and mass while taking the form of a hand-held hammer.

However, the accuracy achievable using the hand-held impact hammer 110 depends on the proficiency of the experimenter impacting the correct position and direction. In the case of the small test structure 10, it is necessary to consider a suitable mechanical device capable of inducing the impact hammer 11 to realize reproducibility of the excitation position and direction.

Accordingly, the present invention provides an impact hammer 11 having an upper end of a bag 13 fixed thereto and having a structure in which the head 12 is rotatable in the front-rear direction.

Here, the head part 12 is rotated in the front-rear direction while the upper end of the bag 13 is fixed to the circular fixing plate 14 by a pin. In addition, a sawtooth engaging portion 15 is formed in the circumferential direction at the edge of the fixing plate 14. At this time, the scale of the fixed plate 14 is formed with a sawtooth visible from the front.

The bag 13 is disposed to correspond to the catching part 15, and a locking protrusion 17 is installed in a structure supported by a spring 16, and an experiment is performed on the bag 13 opposite to the locking protrusion 17. When the user presses the locking protrusion 17 at the desired position to fix the bag 13 and presses it again, the push button 18 has a structure in which the head 12 is rotated by gravity by releasing the locking protrusion 17. It is installed.

In addition, the present invention is installed in the lower portion of the fixed plate 14 so that the impact tip (12d) of the head portion 12 in the center of gravity of the test structure 10 and the non-contact type of the test structure 10 without friction resistance It provides an air bearing 19 to support.

 The air bearing 19 injects air into a cylinder having both ends opened, and the test structure 10 is spaced apart at regular intervals by the air pressure, so that the head portion 12 of the impact hammer 11 is provided. When the shock is applied to the test structure 10, the test structure 10 moves in a straight line without frictional resistance.

In addition, the air bearing 19 is installed on the shock absorber 21 using the spring 20, and can absorb the vibration from the bottom surface, the accelerometer 22 on the opposite side of the impact surface of the test structure 10 ) Is installed, and the accelerometer 22 measures the response signal of the test measurement object 10.

In this case, a stopper may be installed in the air bearing 19 so that the test structure 10 does not completely escape to the outside by the impact.

The force transducer 12a and the accelerometer 22 of the impact hammer 11 are electrically connected to the analyzer 23, the force transducer 12a detects the shock pulse and sends a signal to the analyzer 23, The accelerometer 22 detects the acceleration of the test structure 10 due to the impact and sends the signal to the analyzer 23.

The analyzer 23 receives signals from the force transducer 12a and the accelerometer 22, calculates impact force, and measures mobility.

Referring to the operation of the impact hammer calibration apparatus according to the present invention by such a configuration as follows.

The experimenter determines the position of the impact hammer 11 through the scale of the fixed plate 14 and fixes it to the fixed plate 14. That is, when the head portion 12 of the impact hammer 11 is lifted up and then the button 18 is pressed when the bag portion 13 matches the scale of the desired position while looking at the scale, the locking protrusion ( As the 17 is locked to the locking portion 15 of the fixing plate 14, the head 12 is fixed.

The head portion 12 having a constant position energy in the fixed position releases the locking projection 17 which is locked to the locking portion 15 by using the push button 18 so that the head portion 12 is free of the test structure ( Free fall toward the center of gravity of 10).

Then, when the impact tip 12d of the head portion 12 impacts the center of gravity of the test structure 10, the test structure 10 supported by the air bearing 19 moves inside the cylinder without frictional resistance. Will move.

Accordingly, when the impact hammer 11 impacts the test structure 10, the detection signal is input from the force transducer 12a and the accelerometer 22, and the analyzer 23 accurately measures the impact force and the mobility of the test structure. can do.

Particularly, the upper end of the bag 13 of the impact hammer 11 is hinged to the fixing plate 14 with a pin, and according to the operation of the push button 18, the engaging protrusion 17 and the locking part 15 of the sawtooth type are operated. Locking and unlocking, the impact hammer 11 is rotated at a certain position, the test structure 10 by using the cylinder-shaped air bearing 19 and the shock absorber 21 from the impact hammer 11 By fixing to strike at a certain distance, the impact of a certain intensity can be reproduced at a certain position of the test structure 10 to improve the impact force and the accuracy of the impact hammer calibration.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be carried out without departing from the spirit.

As seen above, according to the impact hammer calibration device using the impact vibration according to the present invention, the upper end of the hammer portion of the impact hammer is coupled to the fixed plate by a pin, the saw-like locking projection and the locking according to the operation of the push button By locking and releasing the part, the impact hammer rotates at a certain position, and by using a cylinder-type air bearing and a shock absorber, the test structure is fixed to be hit at a certain distance from the impact hammer, thereby ensuring a constant strength of the test structure. It can be reproduced at a certain position of the to improve the impact force and the accuracy of the impact hammer calibration.

Claims (6)

In the impact hammer correction device using the impact vibration, An impact hammer composed of a head portion having a bag portion and a force conversion system; A fixing plate to which the upper end of the bag is coupled by a pin such that the head is rotatable in the front-rear direction; An air bearing installed at a position spaced apart from the fixed plate by a predetermined distance; A test structure which is supported by the air bearing and is installed to be linearly movable and has an accelerometer attached to one side thereof; And An analyzer for receiving a signal from the force transducer and the accelerometer to calculate impact force and mobility; The shock hammer calibration apparatus using a shock vibration comprising a, wherein the impact of the head of the impact hammer falls at a certain position to apply a shock at a constant strength to the center of gravity of the test structure. The method according to claim 1, Impact hammer correction device using a shock vibration, characterized in that the engaging portion of the sawtooth-shaped in the circumferential direction formed on the edge of the fixing plate. The method according to claim 2, The inside of the bag portion is supported by a spring and installed in a form corresponding to the locking portion, and the outer side of the bag portion includes a push button installed to press the locking projections, the locking projection according to the operation of the push button Impact hammer calibration device using a shock vibration, characterized in that the locking and unlocking. The method according to claim 3, A scale is formed on the edge of the fixing plate, holding the impact hammer through the operation of the push button, the impact hammer calibration device using the impact vibration, characterized in that fixed to the desired position while watching the scale. The method according to claim 3, The air bearing is provided with a structure having a structure that is supported at a constant interval non-contact with the inner wall of the cylinder by the air pressure after supplying air of a constant pressure to the inside of the open cylinder cylinder Impact hammer correction device. The method according to any one of claims 1 to 5, The air bearing is a shock hammer calibration device using an impact vibration, characterized in that installed on top of the shock absorber elastically supported by a spring to block the transmission of vibration from the floor.

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