Dynamic vibration absorber with vibration frequency adjustment structure

Abstract

To enable a vibration frequency of a mass body to be adjusted even after a dynamic vibration absorber is attached to a vibration control object.SOLUTION: A dynamic vibration absorber 100 with a vibration frequency adjustment structure of the invention includes: a rod-like mass body 1; a supporting base 2 on which the mass body 1 is placed; and a vibration frequency adjustment structure 3 which adjusts a vibration frequency of the mass body 1. The vibration frequency adjustment structure 3 has: a first cushioning material 31 which contacts with a peripheral surface of the mass body 1; and pressing force variable means 33 which presses the first cushioning material 31 to the mass body 1 in a manner that enables the pressing force to be varied.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a dynamic vibration absorber that is attached to an object to be damped, such as precision manufacturing equipment, to suppress vibration of the object, and more particularly to a dynamic vibration absorber that is capable of adjusting the vibration frequency of a mass body that absorbs vibration of the object to be damped. [Background technology]

[0002] The present inventors have previously developed and disclosed dynamic vibration absorbers that are attached to an object to be vibration-damped to suppress the vibration of the object (see, for example, Patent Documents 1 and 2).

[0003] Fig. 17 shows a schematic diagram of this conventional dynamic vibration absorber 900. The conventional dynamic vibration absorber 900 is configured by accommodating a mass body 1 made of a metal rod around which a rectangular buffer material 5 made of resin rubber is wound at multiple points in the longitudinal direction (only one end point is shown in Fig. 17), in a mass body accommodating chamber 21 formed by closing a groove provided in a support base 2 with a lid 6. This conventional dynamic vibration absorber 900 attenuates the vibration of an object to be damped by tuning the width, thickness, and winding position of the buffer material 5 in advance, and by tuning the amount of compression by which the buffer material 5 is compressed by the wall and lid 6 of the mass body accommodating chamber 21 in advance, thereby harmonizing the vibration frequency of the mass body 1 with the vibration frequency of the object to be damped. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2017-187096 [Patent Document 2] Patent Publication 2019-108902 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the vibration of the object to be damped may differ between the design value (analytical value) and the actual measured value, and with the dynamic vibration absorber 900 of Patent Documents 1 and 2, even if the vibration frequency of the mass body is pre-tuned based on the design value, there was a concern that the dynamic vibration absorber would not be able to sufficiently damp the vibration of the object to be damped when actually installed. There was also a concern that aging of the cushioning material and the object to be damped itself would gradually cause the vibration frequency of the mass body and the vibration frequency of the object to be damped to gradually deviate, reducing the vibration damping effect of the object to be damped. The present invention has been made in consideration of the above-mentioned problems, and aims to provide a dynamic vibration absorber that allows the vibration frequency of the mass body of the dynamic vibration absorber to be tuned without removing the dynamic vibration absorber, even after the dynamic vibration absorber has been attached to an object to be damped. [Means for solving the problem]

[0006] The invention made to solve the above-mentioned problems is a dynamic vibration absorber with a frequency adjustment structure capable of adjusting the vibration frequency of a mass body, comprising a mass body, a support base on which the mass body is placed, and a frequency adjustment structure that adjusts the vibration frequency of the mass body, characterized in that the frequency adjustment structure has a first cushioning material abutting the mass body, and a pressing force variable means for pressing the first cushioning material against the mass body with a variable pressing force.

[0007] In the dynamic vibration absorber with frequency adjustment structure of the present invention, the first cushioning material is arranged to be pressed against the mass body with a variable pressing force by the pressing force variable means. Therefore, the amount of compression of the cushioning material can be adjusted by adjusting the pressing force applied to the cushioning material, and therefore the spring constant K and damping coefficient C of the dynamic vibration absorber can be adjusted simultaneously, making it easy to adjust the vibration frequency of the mass body of the dynamic vibration absorber.

[0008] In the dynamic vibration absorber with frequency adjustment structure of the present invention, it is preferable that the pressing force variable means is configured to be capable of changing the position at which the first buffer material is pressed against the mass body. In this way, the frequency of the dynamic vibration absorber can be adjusted by changing the position at which the first buffer material is pressed against the mass body.

[0009] In the dynamic vibration absorber with frequency adjustment structure of the present invention, it is preferable that the first cushioning material is in a sheet shape, a pressure plate made of a plate material is attached to its front surface, and the back surface is in contact with the mass body, and the pressing force varying means presses the cushioning material by pressing the front surface of the pressure plate. By forming the cushioning material in a sheet shape in this way and pressing it via the pressure plate made of a plate material, it is possible to apply a uniform pressing force to the cushioning material.

[0010] The dynamic vibration absorber with frequency adjustment structure of the present invention preferably has a second cushioning material sandwiched between the mass body and the support base on the opposite side of the first cushioning material with the mass body in between. In this way, the spring constant K and damping coefficient C of the dynamic vibration absorber can be adjusted simply by changing the compression amount of the cushioning materials (first cushioning material and second cushioning material). In other words, the vibration frequency of the mass body 1 can be easily adjusted.

[0011] It is preferable that the mass body is rod-shaped, the pressure plate is pressed against the peripheral surface of the mass body, a plurality of pressure plates are provided along the longitudinal direction of the mass body, and a first cushioning material is attached to each pressure plate. In this way, the vibration frequency of the mass body can be changed by changing the pressure plate that applies pressure among the plurality of pressure plates. Here, the term "rod-shaped" includes those that are partially or entirely hollow tubular, and is not limited to those with a circular cross section, but also includes those with a square, rectangular or other polygonal cross section.

[0012] It is preferable that the mass body is rod-shaped, with only one end in the longitudinal direction fixed to the support base and supported as a cantilever, so that the vibration frequency of the mass body can be changed by changing the compression amount of the first cushioning material or by changing the shape of the base end of the mass body (the end fixed to the support base).

[0013] It is preferable that the mass body is rod-shaped, the pressure plate and the first buffer material extend along the longitudinal direction of the mass body, and the pressure varying means is configured to be capable of pressing the surface of the pressure plate at different positions in the longitudinal direction. In this way, the natural frequency of the dynamic vibration absorber can be changed by changing the position at which the pressure plate is pressed, thereby expanding the range over which the natural frequency can be changed. Effect of the Invention

[0014] As described above, according to the dynamic vibration absorber with frequency adjustment structure of the present invention, the spring constant K and damping coefficient C of the dynamic vibration absorber can be adjusted simultaneously even after the dynamic vibration absorber has been attached to the object to be damped, so that the vibration frequency of the mass body of the dynamic vibration absorber can be tuned without removing the dynamic vibration absorber. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view showing a dynamic vibration absorber with a vibration frequency adjustment structure according to a first embodiment of the present invention. [Diagram 2] 2 is a partially transparent perspective view showing the vicinity of an end portion of a mass body around which a pressure plate and a second cushioning material are wound in the dynamic vibration absorber with frequency adjustment structure shown in FIG. 1. FIG. [Diagram 3] FIG. 2 is a front view of the dynamic vibration absorber with frequency adjustment structure shown in FIG. [Figure 4] FIG. 4 is an explanatory diagram showing a test method of Test Example 1 that was performed using the dynamic vibration absorber with frequency adjustment structure according to Example 1. [Diagram 5] 4 is a graph showing test results of Test Example 1 conducted using the dynamic vibration absorber with frequency adjustment structure according to Example 1, together with the measurement method. [Figure 6] FIG. 11 is an explanatory diagram showing a test method of a test example 2 that was performed using the dynamic vibration absorber with a frequency adjustment structure according to the first embodiment. [Figure 7] 13 is a graph showing (a) the test results of test examples 2-1 to 2-3 in which the dynamic vibration absorber with frequency adjustment structure of Example 1 was used to excite a mass body by hammering, and (b) the test results of test examples 3-1 to 3-3 in which vibration was excited by a motor. [Figure 8] FIG. 11 is a perspective view showing a dynamic vibration absorber with a vibration frequency adjustment structure according to a second embodiment of the present invention. [Figure 9] 9 is a partially see-through side view of a mass body, a pressure plate, and a support base in the dynamic vibration absorber with frequency adjustment structure shown in FIG. 8. [Figure 10] FIG. 9 is a front view of the dynamic vibration absorber with frequency adjustment structure shown in FIG. 8. [Figure 11] FIG. 11 is an explanatory diagram showing a test method of Test Example 3 that was carried out using the dynamic vibration absorber with frequency adjustment structure according to Example 2. [Figure 12] 1 is a graph showing the test results of Test Example 4-1. [Figure 13] 1 is a graph showing the test results of Test Example 4-2. [Figure 14] 1 is a graph showing the test results of Test Example 4-3. [Figure 15] FIG. 11 is an explanatory diagram showing a test method of Test Example 5, which was carried out using the dynamic vibration absorber with frequency adjustment structure according to Example 2. [Figure 16] 13 is a graph showing (a) the test results of test examples 5-1 to 5-3 in which the dynamic vibration absorber with frequency adjustment structure of Example 2 was used to excite a mass body by hammering, and (b) the test results of test examples 6-1 to 6-3 in which vibration was excited by a motor. [Figure 17] FIG. 1A is a partially transparent perspective view of a conventional dynamic vibration absorber, and FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiment. (First embodiment) 1 shows a dynamic vibration absorber with a frequency adjustment structure (hereinafter simply referred to as a "dynamic vibration absorber") 100 according to a first embodiment of the present invention. The dynamic vibration absorber 100 includes a rod-shaped mass body 1, a support base 2 on which the mass body 1 is placed, and a frequency adjustment structure 3 that adjusts the vibration frequency of the mass body 1.

[0017] The dynamic vibration absorber 100 includes one or more (two in the illustrated example) mass bodies 1. The mass body 1 is made of a bar or tube material (bar material in the example of FIG. 1) made of metal such as iron or stainless steel.

[0018] The support base 2 is formed in the shape of a rectangular housing from a metal such as aluminum, and includes one or more (two in the illustrated example) mass body accommodating chambers 21. The mass body accommodating chamber 21 is formed in the shape of a groove that is open at the top (upper side in FIG. 1) by left and right side walls 22, 22, a middle wall 23, and a bottom wall 24. In the illustrated example, the mass body accommodating chamber 21 has a rectangular cross section, but the cross section may be polygonal or more angular, or may be arc-shaped.

[0019] The vibration frequency adjustment structure 3 mainly comprises a first cushioning material 31 that contacts the peripheral surface of the mass body 1, a second cushioning material 32 that supports the mass body 1, and an adjustment bolt (pressing force variable means) 33 that presses the first cushioning material 31 against the mass body 1 with a variable pressing force, as well as other members that cooperate with these. The vibration frequency adjustment structure 3 is provided with dynamic vibration absorbers 100 at both ends in the longitudinal direction. The adjustment bolt 33 in this embodiment is a male threaded bolt, but the pressing force variable means is not limited to this and can be any known mechanism that is capable of pressing the first cushioning material with a variable pressing force, such as a screw mechanism, a rack and pinion mechanism, hydraulic pressure, pneumatic pressure, or other mechanism.

[0020] The first buffer material 31 and the second buffer material 32 are both made of a resin such as a styrene-based thermoplastic elastomer and are provided in the form of a rectangular sheet. The first buffer material 31 is held in a flat plate shape by a rectangular pressure plate 34 made of a thin plate such as stainless steel attached to a surface 31a.

[0021] The second cushioning material 32 is wound around the peripheral surfaces of both ends of the mass body 1, covering three sides (left and right and bottom in Figure 3) excluding the top (top in Figure 3), and is sandwiched between the mass body 1 and the side surface 21a and bottom surface 21b of the mass body accommodation chamber 21.

[0022] The vibration frequency adjustment structure 3 includes, as members for adjusting the vibration frequency of the mass body 1 in cooperation with the adjustment bolt 33, a female screw hole 35a that screws into the adjustment bolt 33, a cover plate 35 through which the female screw hole 35a is inserted, and square plates 36, 36, 36 that are erected on the side walls 22, 22 and the middle wall 23 of the support base 2 to provide a space for the pressure plate 34 to move up and down and support the cover plate 35. The adjustment bolt 33 has a bolt body 33a with a male screw (not shown) engraved on its outer circumferential surface and a head 33b connected to the tip of the bolt body 33a. The head 33b is provided to the bolt body 33a so as to be rotatable around the axis of the bolt body 33a by a ball joint (not shown). The pressure plate 34 is in contact with the head 33b.

[0023] One or more pressing plates 34 can be provided along the longitudinal direction of the mass body 1. In the dynamic vibration absorber 100 according to this embodiment, four pressing plates 34 are provided in the longitudinal direction, and a first cushioning material 31 is affixed to each pressing plate 34. An adjustment bolt 33 is provided on each of the four pressing plates 34, so that the pressing force with which the mass body is pressed can be individually adjusted.

[0024] (How to adjust the vibration frequency) When adjusting the vibration frequency of the mass body 1, the natural frequency of the precision equipment or the like to be damped is measured or analyzed in advance, and the vibration frequency of the mass body 1 is adjusted to match this natural frequency. The vibration frequency of the mass body 1 is adjusted by rotating the adjustment bolts 33 to bring the pressure plate 34 into contact with the mass body 1 and varying the amount of compression of the first buffer material 31 and the second buffer material 32. The vibration frequency of the mass body 1 may be adjusted using some of the adjustment bolts 33, or may be adjusted using all of the adjustment bolts. The vibration frequency of the mass body 1 may be adjusted while measuring the vibration frequency of the mass body 1 with an acceleration sensor or the like, or may be adjusted using a scale or the like provided on the adjustment bolts.

[0025] (Test Example 1 using Example 1) Next, a test example 1 in which the vibration frequency of the mass body 1 was measured will be described using Example 1 according to the first embodiment. However, the present invention is not limited to this example and this test example.

[0026] Example 1 The dynamic vibration absorber 100 shown in Fig. 1 was used as the dynamic vibration absorber according to Example 1. The materials and dimensions of each member are as follows. Mass: Stainless steel (SUS304) round bar, φ25mm x 400mm, 2 pieces Support: Aluminum (A5052) Width 100mm x Length 400mm x Thickness 40mm Mass containment chambers: 2 -First cushioning material: styrene-based thermoplastic elastomer, thickness 3mm Second cushioning material: Same as the first cushioning material, attached to both ends of mass body 1, length in the longitudinal direction of mass body 1: 60 mm Adjustment bolt: SUS304 equivalent, M6 x length 50mm (high lock screw, made by Misumi Corporation) Pressing plate: SUS304 thin plate, width 25mm x length 75mm x thickness 0.1mm ·Lid plate: A5052 plate width 100mm x 150mm x thickness 6mm Square plate: A5052 plate, width 10mm x length 150mm x thickness 15mm

[0027] (Test Example 1) Next, a first test example performed using the dynamic vibration absorber according to the first embodiment will be described. As shown in FIG. 4, the dynamic vibration absorber of Example 1 was placed on an iron surface plate (not shown) via three rectangular aluminum stands 4, and an accelerometer (PCB 356A17) was installed at the positions Q1 in the center of the mass and Q2 on the end face. As shown in the measurement method of FIG. 5, the mass was vibrated by hitting it with an impact hammer (PCB: 086C03, white tip) at the position P1 adjacent to Q1 while changing the pressing plate that applies pressure (push) and the magnitude of pressure, and the acceleration of the mass was measured by the accelerometer. From the data thus obtained by the accelerometer, the relationship between the vibration frequency (Hz) of the mass and the transfer function (g / N) by the impact hammer was obtained using an FFT analyzer (model OR35-4) manufactured by OROS and software for data analysis (NVGate Mescope VES). Here, the transfer function (g / N) refers to the accelerance consisting of the ratio of the acceleration measured by the accelerometer to the force input by the impact hammer, and "g" is the gravitational acceleration of 9.8 m / s 2 and "N" stands for Newton.

[0028] (Results of Test Example 1) The results of Test Example 1 are shown in Figure 5. It was found that the wider the area of ​​the first cushioning material to which pressure is applied, and the greater the magnitude of pressure applied to the first cushioning material, the higher the vibration frequency of the mass body. It was found that by adjusting the area over which the first cushioning material is pressed against the mass body and the magnitude of the applied pressure, the vibration frequency of the mass body can be matched to the vibration frequency of the object to be damped.

[0029] (Test Examples 2 and 3 using Example 1) In order to investigate the vibration damping effect of the dynamic vibration absorber of Example 1 on a vibration damping target, a steel gantry-type test specimen A shown in Fig. 6 was used as the vibration damping target, and two vibration methods for the test specimen A were used, namely hammer vibration (Test Example 2) and motor vibration (Test Example 3). Vibration tests were performed on the test specimen A to compare the following cases: when the dynamic vibration absorber of Example 1 was not placed on the test specimen A (Test Examples 2-1 and 3-1), when the dynamic vibration absorber of Example 1 that was not tuned was placed on the test specimen A (Test Examples 2-2 and 3-2), and when the dynamic vibration absorber of Example 1 that was tuned was placed on the test specimen A (Test Examples 2-3 and 3-3). The test specimen A has a long plate A2 fixed by welding along one long side A3 on the top surface A1, and has a natural frequency of 90 Hz.

[0030] (Test example 2: Hammer vibration test) (Test Example 2-1) The test specimen A shown in Figure 6 was vibrated in the vertical direction by hitting the corner P2 on one long side A3 of the top surface A1 with an impact hammer without placing a dynamic vibration absorber. Acceleration data of the test specimen A was obtained using accelerometers installed at the corner Q3 on the other long side A4 of the top surface A1 of the test specimen A and at the center Q4 of the other long side A4. The time (s) from the start of vibration and the acceleration (m / s) of the test specimen A were then calculated using an OROS FFT analyzer (model OR35-4) and data analysis software (NVGate Me'scope VES). 2 ) relationship was sought.

[0031] (Test Example 2-2) As shown in FIG. 6, the dynamic vibration absorber according to Example 1 was placed in the center of the upper surface A1 of the test body A without adjusting the vibration frequency of the mass body to 90 Hz. Except for this, excitation and measurement were performed in the same manner as in Test Example 2-1. The time (s) from the start of excitation and the acceleration (m / s) of the test body A were measured. 2 ) relationship was sought.

[0032] (Test Example 2-3) Except for adjusting the vibration frequency of the mass body in the dynamic vibration absorber according to Example 1 to 90 Hz in advance, the dynamic vibration absorber was placed on the test body A in the same manner as in Test Example 2-2, and vibration and measurement were performed to measure the time (s) from the start of vibration in the test body A and the acceleration (m / s 2) relationship was sought.

[0033] (Results of Test Example 2) The results of Test Example 2 are shown in Figure 7(a). The results in Figure 7(a) show that when instantaneous vibration is applied to test body A (object to be vibration-damped), by installing a dynamic vibration absorber, the vibration is damped faster than when test body A is used alone, and a vibration damping effect is obtained, and that when a dynamic vibration absorber is installed, adjusting the vibration frequency of the mass body to match the natural frequency of test body A results in faster vibration damping and a higher vibration damping effect than when adjustments to match the natural frequency of test body A are not made.

[0034] (Test example 3: Motor vibration test) (Test Example 3-1) Instead of vibrating the test specimen A with an impact hammer, a vibration motor (12V) was placed at the center P3 of the long plate A2 of the test specimen A in the longitudinal direction to vibrate it. Except for this, the time (s) from the start of vibration and the acceleration (m / s) of the test specimen A were measured in the same manner as in Test Example 2-1. 2 The vibration was applied by driving the vibration motor and adjusting it so that the vibration motor resonated with the test piece A, which has a natural frequency of 90 Hz.

[0035] (Test Example 3-2) The dynamic vibration absorber according to Example 1 was placed on the test specimen A as shown in FIG. 6 without tuning the vibration frequency of the mass body. In the same manner as in Test Example 3-1, the time (s) from the start of vibration and the acceleration (m / s 2 ) relationship was sought.

[0036] (Test Example 3-3) Except for adjusting the vibration frequency of the mass body in the dynamic vibration absorber according to Example 1 to 90 Hz in advance, the dynamic vibration absorber was placed on the test body A in the same manner as in 3-2, and vibration was applied by a vibration motor. The time (s) from the start of vibration in the test body A and the acceleration (m / s 2 ) relationship was sought.

[0037] (Results of Test Example 3) The results of Test Example 3 are shown in Figure 7(b). The results in Figure 7(b) show that when continuous vibrations are applied to test body A (the object to be vibration-damped), placing a dynamic vibration absorber on it provides a higher vibration-damping effect than test body A alone, and that when a dynamic vibration absorber is placed on it, adjusting the vibration frequency of the mass body to match the natural frequency of test body A provides a higher vibration-damping effect than when it is not adjusted to match the natural frequency of test body A.

[0038] Second embodiment 8 and 9 show a dynamic vibration absorber with a frequency adjustment structure 200 according to a second embodiment of the present invention. The dynamic vibration absorber 200 includes a square rod-shaped mass body 201, a support base 202 on which the mass body 201 is placed, and a frequency adjustment structure 203 that adjusts the frequency of the mass body 201.

[0039] Mass body 201 is formed by cutting and machining a metal material such as SUS304 stainless steel, and includes a rectangular mass body main body 211 and a base 212 extending like a brim from the lower end of a base end surface 211a of mass body main body 211. Base 212 is a thin plate that is thinner in the top and bottom than mass body main body 211, and its bottom surface is flush with the bottom surface of mass body main body 211, as shown in FIG.

[0040] The support base 202 has side walls 222, 222 erected on the left and right outer sides in the width direction of the mass body 201, and a mass body accommodating chamber 221 formed in a gutter shape from a bottom wall 224 and having a rectangular groove-like cross section. The side walls 222 are placed on flanges 224a formed integrally with the bottom wall 224 at both ends in the width direction of the bottom wall 224, and are connected to the bottom wall 224 by hexagon socket bolts. The bottom wall 224 is configured such that a support part 224b supporting the base part 212 of the mass body 201 is provided thick on the base end side in the longitudinal direction (right side in FIG. 9), and a part 224c on the tip side (left side in FIG. 9) of the support part 224b is formed thin and lower on the upper surface side than the support part 224b, thereby providing a gap 225 between the mass body main body 211 and the bottom wall 224 and supporting the mass body 201 in a cantilever manner.

[0041] The vibration frequency adjustment structure 203 mainly comprises a first cushioning material 231 that contacts the upper surface (circumferential surface) of the mass body 201, a pressing plate 234 affixed to the surface of the first cushioning material, and a micrometer head (pressing force variable means) 233 that presses the first cushioning material 231 against the mass body 201 with a variable pressing force via the pressing plate 234, as well as other members that cooperate with these. However, the pressing force variable means is not limited to a micrometer head, and any known mechanism can be appropriately selected as long as it is capable of pressing the first cushioning material with a variable pressing force.

[0042] The first cushioning material 231 is made of an elastic resin sheet such as a styrene-based thermoplastic elastomer, and has a rectangular plate shape. The pressing plate 234 is made of a thin metal plate, and is attached to a surface 231a of the first cushioning material 231. The first cushioning material 231 and the pressing plate 234 are placed in the center of the width direction of the mass body 201 with their longitudinal directions aligned with the longitudinal direction of the mass body 201.

[0043] The vibration frequency adjustment structure 203 is equipped with a clamping arm 235 that clamps the micrometer head 233 in a vertical position, an arm support part 236 that supports the base end side of the clamping arm 235, and a movable base 237 that supports the arm support part 236 and is bridged between the upper ends of the pair of side walls 222, 222, as members that cooperate with the first cushioning material 231, the micrometer head 233, and the pressure plate 234.

[0044] The micrometer head 233 has the spindle 233a facing downward and the stem 233b clamped by the clamping arm 235. In this state, when the constant pressure knob 233c of the micrometer head 233 is rotated, the tip of the spindle 233a moves downward and abuts against the pressing plate 234 to spin freely, and the initial state is set in which the spindle 233a abuts against the pressing plate 234 without pressing it. When the thimble 233d is rotated from this initial state, the spindle 233a extends downward from the initial state and presses the pressing plate 234 and the first cushioning material 231.

[0045] The clamping arm 235 clamps a stem 233b of the micrometer head 233 between two split tip portions 235b which are opened and closed by a hexagon socket screw 235a.

[0046] The arm support portion 236 is in the shape of a rectangular parallelepiped block, and is provided with a screw hole 236a through which a screw for fixing the base end portion of the clamping arm 235 is passed.

[0047] 8, the movable base 237 is in the form of a rectangular plate, and has screw holes at both ends in the longitudinal direction. A large number (meaning a plurality) of female screw holes 222b, 222b, ... are arranged at equal intervals in the longitudinal direction on the upper end surfaces 222a of the side walls 222, 222, and both ends of the movable base 237 are fixed to the pair of side walls 222, 222 with screws. The position of the micrometer head 233 in the longitudinal direction of the mass body 201 can be changed by changing the female screw holes 222b, 222b that connect the movable base 237.

[0048] (Test Example 4 using Example 2) Next, a vibration test (Test Example 4) conducted using the dynamic vibration absorber of Example 2 according to the second embodiment will be described.

[0049] Example 2 As the dynamic vibration absorber according to Example 2, the dynamic vibration absorber 200 shown in Fig. 8 was used. The materials and dimensions of each member are as follows. Mass: SUS304 plate, main body width 70mm x length 220mm x thickness 24mm Bottom plate: A5052 plate, width 82mm x length 265mm x thickness 20mm Side walls: A5052 board, width 47mm x length 265mm x thickness 10mm Mass Containment Chamber: 1 -First cushioning material: Styrene-based thermoplastic elastomer Width 25mm x Length 150mm x Thickness 3mm Pressure plate: A5052 plate material 25mm x length 150mm x thickness 3mm Micrometer head: Mitutoyo Corporation, MHN2-25

[0050] (Test Example 4-1) As shown in FIG. 11, the dynamic vibration absorber 200 of Example 2 is placed on an iron surface plate (not shown) via a rectangular aluminum stand 4, and an accelerometer (PCB 356A17) is installed at a corner Q5 on the tip side (right side in FIG. 11) of the mass body main body 211, and at a corner Q6 diagonally opposite to corner Q5.

[0051] As shown in Fig. 12, the first cushioning material 231 and the pressing plate 234 were attached to the base end side of the mass body 201, and the tip of the spindle 233a of the micrometer head 233 was pressed against the position 11.5 mm from the base end of the mass body main body 211. The amount of pressing by the micrometer head 233 was changed to nine types in increments of 0.05 mm from 0.00 mm to 0.50 mm, while the mass body main body 211 was struck with an impact hammer (made of PCB: 086C03, white chip) at the position of the corner P4 adjacent to Q5 at the tip of the mass body main body 211 to vibrate it, and the acceleration of the mass body main body 211 was measured by an accelerometer. From the data thus obtained by the accelerometer, the relationship between the vibration frequency (Hz) of the mass body and the transfer function (g / N) by the impact hammer was obtained using an FFT analyzer (model OR35-4) manufactured by OROS and data analysis software (NVGate Me'scope VES).

[0052] (Test Example 4-2) As shown in Figure 13, the tip of the spindle 233a of the micrometer head 233 was pressed against a position 111.5 (11.5 + 100) mm from the base end face 211a of the mass body main body 211, and the relationship between the vibration frequency (Hz) of the mass body and the transfer function (g / N) of the impact hammer was obtained in the same manner as in test example 4-1.

[0053] (Test Example 4-3) As shown in Figure 14, except that the tip of the spindle 233a of the micrometer head 233 was pressed against a position 8.5 mm from the tip of the mass body main body 211, the relationship between the vibration frequency (Hz) of the mass body and the transfer function (g / N) of the impact hammer was obtained in the same manner as in test examples 4-1 and 4-2.

[0054] (Results of Test Example 4) 12 to 14 show the relationship between the vibration frequency (Hz) of the mass body and the transfer function (g / N) of the impact hammer obtained from the results of Test Example 4. These graphs show that, regardless of the pressing position, the greater the pressing amount of the micrometer head 233 into the first cushioning material 231, the higher the vibration frequency of the mass body 201. It was also found that the closer the position where the micrometer head 233 presses the first cushioning material 231 is to the tip side of the mass body main body 211, the higher the vibration frequency of the mass body 201.

[0055] (Test Examples 5 and 6 using Example 2) In order to investigate the vibration damping effect on a vibration damping target using the dynamic vibration absorber of Example 2, a gantry-type test specimen A was used as the vibration damping target as shown in Fig. 15, and two vibration methods for the test specimen A were used, namely hammer vibration (Test Example 5) and motor vibration (Test Example 6). Vibration tests were performed on the test specimen A to compare the cases where the dynamic vibration absorber of Example 2 was not placed on the test specimen A (Test Examples 5-1 and 6-1), where the non-tuned dynamic vibration absorber of Example 2 was placed on the test specimen A (Test Examples 5-2 and 6-2), and where the tuned dynamic vibration absorber of Example 2 was placed on the test specimen A (Test Examples 5-3 and 6-3). The natural frequency of the test specimen A was set to 90 Hz.

[0056] (Test example 5: Hammer vibration test) (Test Example 5-1) When the test specimen A shown in Figure 15 is hit with an impact hammer without a dynamic vibration absorber, the time (s) from the start of vibration and the acceleration (m / s 2 ) The results of Test Example 2-1 were used.

[0057] (Test Example 5-2) As shown in FIG. 15, the dynamic vibration absorber according to Example 2 was placed in the center of the upper surface A1 of the test body A without adjusting the vibration frequency of the mass body to 90 Hz. Except for this, excitation and measurement were performed in the same manner as in Test Example 2-2. The time (s) from the start of excitation and the acceleration (m / s 2) relationship was sought.

[0058] (Test Example 5-3) Except for adjusting the vibration frequency of the mass body to 90Hz in advance, excitation and measurement were performed in the same manner as in Test Example 5-2. The time (s) from the start of excitation and the acceleration (m / s 2 ) relationship was sought.

[0059] (Results of Test Example 5) The results of Test Example 5 are shown in Figure 16(a). In the figure, "Test 5-1" is the result of Test Example 5-1. The results in Figure 16(a) show that when instantaneous vibration is applied to test body A (object to be vibration-damped), placing a dynamic vibration absorber, even if the mass body is a cantilever-type dynamic vibration absorber, damps the vibration faster and provides a damping effect than when test body A is used alone, and that when a dynamic vibration absorber is placed, adjusting the frequency of the mass body to match the natural frequency of test body A results in faster damping of vibration and a higher damping effect than when the frequency is not adjusted to match the natural frequency of test body A.

[0060] (Test example 6: Motor vibration test) (Test Example 6-1) When the test specimen A shown in Figure 15 is vibrated by a vibration motor (12V) without a dynamic vibration absorber, the time (s) from the start of vibration and the acceleration (m / s 2 ) relationship was sought.

[0061] (Test Example 6-2) The dynamic vibration absorber according to Example 2 was placed on the test specimen A as shown in FIG. 15 without tuning the vibration frequency of the mass body. In the same manner as in Test Example 6-1, the time (s) from the start of vibration and the acceleration (m / s 2 ) relationship was sought.

[0062] (Test Example 6-3) Except for adjusting the vibration frequency of the mass body in the dynamic vibration absorber according to Example 2 to 90 Hz in advance, vibration was applied by a vibration motor in the same manner as in Test Examples 6-1 and 6-2, and the time (s) from the start of vibration in Test Body A and the acceleration (m / s 2 ) relationship was sought.

[0063] (Results of Test Example 6) The results of Test Example 6 are shown in Figure 16(b). The results in Figure 16(b) show that when continuous vibrations are applied to test specimen A (object to be vibration-controlled), even if the mass body is a cantilever dynamic vibration absorber, placing a dynamic vibration absorber on test specimen A can provide a vibration-control effect for test specimen A, and that when a dynamic vibration absorber is placed on test specimen A, adjusting the vibration frequency of the mass body to match the natural frequency of test specimen A provides a higher vibration-control effect for test specimen A than when the adjustment to match the natural frequency of test specimen A is not made.

[0064] The dynamic vibration absorber with frequency adjustment structure of the present invention is not limited to the above-mentioned embodiment. For example, the first cushioning material does not have to be sheet-shaped, and the pressing plate does not have to be provided. Three or more mass bodies may be provided. A second cushioning material may be provided in a dynamic vibration absorber with a cantilever-type mass body, and a plurality of pressing force variable means may be provided in a dynamic vibration absorber with a cantilever-type mass body. The frequency adjustment structure may be interchanged between the first and second embodiments. [Explanation of symbols]

[0065] 100,200 Dynamic vibration absorber with frequency adjustment structure 1,201 mass body 2,202 Support stand 3,203 Frequency adjustment structure 31,231 1st buffer material 32 Second buffer material 33,233 Pressure variable means 34,234 Pressing plate

Claims

1. A dynamic vibration absorber with a vibration frequency adjustment structure capable of adjusting the vibration frequency of a mass body, A mass body; A support base on which the mass body is placed; a frequency adjustment structure for adjusting the frequency of the mass body; Equipped with The vibration frequency adjustment structure includes: A first cushioning material that contacts the mass body; a pressing force variable means for variable pressing force of the first cushioning material against the mass body; A dynamic vibration absorber with a vibration frequency adjustment structure, comprising:

2. 2. The dynamic vibration absorber with frequency adjustment structure according to claim 1, wherein the pressing force varying means is configured to be capable of changing a position at which the first buffer material is pressed against the mass body.

3. The first cushioning material is in a sheet shape, has a pressing plate made of a plate material attached to a front surface thereof, and is configured so that a back surface thereof contacts the mass body, 2. The dynamic vibration absorber with frequency adjustment structure according to claim 1, wherein said pressure varying means presses said buffer material by pressing a surface of said pressure plate.

4. 2. The dynamic vibration absorber with frequency adjustment structure according to claim 1, further comprising a second cushioning material sandwiched between the mass body and the support base on the opposite side of the mass body to the first cushioning material.

5. The mass body is rod-shaped, 4. The dynamic vibration absorber with frequency adjustment structure according to claim 3, wherein the pressure plate is pressed against the peripheral surface of the mass body, and a plurality of pressure plates are provided along the longitudinal direction of the mass body, and a first cushioning material is attached to each pressure plate.

6. 2. The dynamic vibration absorber with frequency adjustment structure according to claim 1, wherein the mass body is rod-shaped, and only one end in the longitudinal direction is fixed to the support base and supported as a cantilever.

7. The mass body is rod-shaped, the pressing plate and the first buffer material extend along the longitudinal direction of the mass body, 3. The dynamic vibration absorber with frequency adjustment structure according to claim 2, wherein the pressing force varying means is configured to be able to press the surface of the pressing plate at different positions in the longitudinal direction.

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