Jig for screw loosening test, screw loosening test device, and screw loosening test method

Abstract

To provide a jig for screw loosening test, a screw loosening test device, and a screw loosening test method capable of suppressing overall resonance of the screw loosening test device and performing the test more stably.SOLUTION: A jig 3 for screw loosening test according to the present invention includes: a base member 31; a viscoelastic member 32; a screw mounting member 33; and a screw insertion hole 331. A screw loosening test device 1 according to the present invention includes a vibration generator and the jig for screw loosening test, and has the base member, the viscoelastic member, the screw mounting member, and the screw insertion hole. A screw loosening test method according to the present invention is a method using the jig for screw loosening test including the base member, the viscoelastic member, and the screw mounting member, and includes: a step of mounting the jig on the vibration generator; a step of inserting and mounting a screw to the screw insertion hole; and a step of driving the vibration generator to generate vibration.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a screw loosening test jig, a screw loosening test device, and a screw loosening test method. [Background technology]

[0002] A bolt and nut are a type of screw that are commonly inserted into the respective holes of multiple objects to be fixed, each of which has a through hole, and by tightening the nut onto the bolt, these multiple objects to be fixed can be firmly fixed together.

[0003] On the other hand, these bolts and nuts can become loose when subjected to continuous external forces such as vibration during use, and this "loosening" is something that should be avoided as much as possible.

[0004] As a standard for objectively evaluating the "ease of loosening" of a screw, a vibration-type impact loosening test such as NAS can be given as a preferred example. NAS3350, one of the vibration-type impact loosening tests, is introduced in, for example, Non-Patent Document 1 below. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] https: / / www.jfe-tec.co.jp / download / pdf / 3E6J-010-00.pdf Summary of the Invention [Problem to be solved by the invention]

[0006] The vibration-type impact loosening test such as the NAS3350 is a method in which a screw mounting member with a screw insertion hole formed therein is fixed on a vibration generating device that generates vibrations, a screw consisting of a bolt and a nut is fixed into the screw insertion hole of this screw mounting member, the vibration generating device is driven to generate vibrations, vibration is applied to the screw under certain conditions, and the loosening of the screw is measured.

[0007] The vibration-type impact loosening test described above is capable of evaluating the performance of the "screw" with a certain degree of objectivity by standardizing the vibration conditions, but when the size of the screw becomes large enough, the resonance of the entire device becomes intense, and the impact becomes greater than expected, making accurate evaluation difficult. In addition, there is a possibility that the device will suddenly stop, making it impossible to perform the test itself.

[0008] In view of the above-mentioned problems, the present invention has an object to provide a screw loosening test fixture, a screw loosening test apparatus, and a screw loosening test method that can suppress resonance of the entire screw loosening test apparatus and perform tests more stably. [Means for solving the problem]

[0009] A screw loosening test fixture according to one aspect of the present invention which solves the above-mentioned problems comprises a base member, a viscoelastic member placed on the base member, and a screw mounting member placed on the viscoelastic member and having a screw insertion hole formed therein.

[0010] In addition, in this respect, although not limited thereto, it is preferable to have a covering member that covers the upper surface of the viscoelastic member and is disposed between the viscoelastic member and the screw attachment member.

[0011] In addition, in this respect, although not limited thereto, it is preferable that the base member has a cylindrical shape.

[0012] In addition, in this respect, although not limited thereto, it is preferable that the damping ratio in the frequency range of 3000 Hz or more is 0.1% or more.

[0013] In addition, in this respect, although not limited thereto, it is preferable that the viscoelastic member is configured to include at least one of carbon fiber reinforced plastic and monomer cast nylon.

[0014] In addition, in this aspect, although not limited thereto, it is preferable that the base member, the viscoelastic member, and the screw attachment member are fixed by a screw member.

[0015] In addition, a screw loosening test apparatus according to another aspect of the present invention comprises a vibration generating device and a screw loosening test fixture installed on the vibration generating device, and the screw loosening test fixture has a base member, a viscoelastic member installed on the base member, and a screw mounting member installed on the viscoelastic member and having a screw insertion hole formed therein.

[0016] In addition, in this respect, although not limited thereto, it is preferable that the screw loosening test fixture has a covering member that covers the upper surface of the viscoelastic member and is disposed between the viscoelastic member and the screw mounting member.

[0017] Furthermore, a screw loosening testing method according to another aspect of the present invention is a screw loosening testing method that uses a screw loosening testing jig having a base member, a viscoelastic member placed on the base member, and a screw mounting member placed on the viscoelastic member and having a screw insertion hole formed therein, and includes the steps of mounting the screw loosening testing jig on a vibration generating device, inserting screws into the screw insertion holes of the screw loosening testing jig and mounting it, and driving the vibration generating device to generate vibrations.

[0018] In addition, in this respect, although not limited thereto, it is preferable to have a step of attaching a covering member, which covers the upper surface of the viscoelastic member and is positioned between the viscoelastic member and the screw attachment member, onto the viscoelastic member after the step of attaching the screw loosening test fixture onto the vibration generating device and before the step of inserting screws into the screw insertion holes of the screw loosening test fixture to attach it. Effect of the Invention

[0019] As described above, the present invention can provide a thread loosening test fixture, a thread loosening test apparatus, and a thread loosening test method that can suppress resonance of the entire thread loosening test apparatus and perform tests more stably. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram showing an outline of a thread loosening testing device according to an embodiment. [Diagram 2] FIG. 1 is a diagram showing an outline of a screw loosening test fixture according to an embodiment. [Diagram 3] FIG. 2 is an exploded view of a screw loosening test fixture according to an embodiment. [Figure 4] FIG. 4 is a diagram showing the frequency and intensity of vibration in a thread loosening test fixture according to the embodiment. [Diagram 5] FIG. 2 is a diagram showing an outline of a screw and a screw vibrator for a screw loosening test according to an embodiment. [Figure 6] FIG. 2 is a photograph of the entire thread loosening testing device according to the embodiment. [Figure 7] FIG. 2 is a photograph of the entire thread loosening testing device according to the embodiment. BEST MODE FOR CARRYING OUT THEINVENTION

[0021] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be embodied in many different forms, and the specific examples described in the following embodiments and examples can be appropriately modified and adjusted, and the present invention is not limited thereto.

[0022] FIG. 1 is a diagram showing an outline of a thread loosening testing device (hereinafter referred to as "this device") 1 according to this embodiment, and FIG. 2 is a diagram showing an outline of a thread loosening testing jig (hereinafter referred to as "this jig") 3 used in this device.

[0023] As shown in these figures, the present device 1 includes a vibration generator 2 and a present jig 3 installed on the vibration generator 2, and the present jig 3 includes a base member 31, a viscoelastic member 32 installed on the base member 31, and a screw mounting member 33 installed on the viscoelastic member 32 and having a screw insertion hole 331 formed therein. This configuration of the present device 1 enables a screw loosening test, more specifically a vibration-type impact loosening test, to be performed more stably.

[0024] The device 1 also includes a covering member 34 that covers the upper surface of the viscoelastic member 32 and is disposed between the viscoelastic member 32 and the screw mounting member 33.

[0025] In the present device 1, the vibration generator 2 is a device for generating vibrations as the name suggests, and by transmitting these vibrations to the present jig 3, it is possible to create a situation in which the screws become loose.

[0026] The structure of the vibration generator 2 is not limited as long as it can generate the vibration frequency, vibration direction, vibration width, vibration count, impact width, etc. required for performing a screw loosening test, and a commercially available vibration generator can be used, but specifically, according to standards such as NAS3350, the vibration frequency is 29.2Hz to 30Hz, the vibration direction is perpendicular to the bolt axis (vertical direction), the vibration width is 11.4mm peak-to-peak (pp), with a tolerance of plus or minus 0.4mm, the vibration count is 30,000 times, and the impact width is 19mm, so it is preferable that the vibration generator be capable of generating vibrations in this range. Note that in this device 1, since vibration is performed at approximately 30Hz as described above, in this specification, the term "approximately 30Hz" refers to a range of 28Hz to 31Hz.

[0027] As is clear from the above description, in the present device 1, the present jig 3 is attached onto the vibration generator 2. The specific attachment relationship of the present jig 3 to the vibration generator 2 will be described later, but as described above, the present jig 3 is attached by having a base member 31, a viscoelastic member 32 placed on the base member 31, a screw attachment member 33 placed on the viscoelastic member 32 and having a screw insertion hole 331 formed therein, and a covering member 34 that covers the upper surface of the viscoelastic member 32 and is disposed between the viscoelastic member 32 and the screw attachment member 33. An exploded view showing the attachment relationship of the present jig 3 is shown in FIG. 3.

[0028] The base member 31 in the jig 3 is a basic member that contacts the vibration generator 2 and stably transmits vibration to the screw to be tested. There are no particular limitations on the shape of the base member 31, but from the viewpoint of reliably transmitting vibration to the viscoelastic member 32 and the like provided on top of it, it is preferably made of metal, and more preferably, it is made of an aluminum alloy, magnesium alloy, titanium alloy, or the like, which can transmit vibration reliably at low frequencies but attenuates vibration significantly at high frequencies, has high dynamic rigidity, and has a low specific gravity.

[0029] The shape of the base member 31 in the jig 3 is not limited as long as it has the above-mentioned functions, but it is preferable that the shape of the base member 31 in the jig 3 can shift or suppress the resonance frequency to the high frequency side as much as possible, and more specifically, it is preferable that the bottom surface is circular, and it is preferable that the base member 31 has a cylindrical shape that has a thickness in the height direction while maintaining the bottom shape. If the bottom surface is circular, there are no corners, and it is possible to increase or suppress the resonance frequency that may occur due to the presence of corners. It is preferable that the shape of the base member 31 is circular, but even if it is polygonal, it is possible to increase the resonance frequency depending on the shape.

[0030] The size of the base member 31, more specifically, its diameter and thickness in the case of a circular shape, varies depending on the material and the magnitude of the vibration generated by the vibration generator 2, but the diameter is preferably 20 cm to 80 cm, more preferably 30 cm to 40 cm. The thickness is preferably 3 cm to 50 cm, more preferably 10 cm to 40 cm. A diameter of 20 cm or more has the advantage of being able to stably and effectively transmit the vibration of the vibration table of the vibration generator 2, and a thickness of 80 cm or less has the advantage of being able to match the size of the vibration table and suppress the occurrence of unnecessary resonance while keeping the weight low. A thickness of 3 cm or more has the advantage of being able to attenuate high-frequency vibration and suppress unnecessary resonance, and a thickness of 50 cm or less has the effect of ensuring light weight and transmitting vibration sufficiently. When the base member 31 is polygonal, it is preferably a regular square or a regular hexagon, and it is preferable that it has a thickness in the height direction. The thickness is the same as in the case of the cylindrical shape described above, and the length of one side is also the same as that of the cylinder described above, specifically, it is preferable that one side is 20 cm or more and 80 cm or less, and more preferably 30 cm or more and 40 cm or less.

[0031] Moreover, the viscoelastic member 32 in the jig 3 is a member that has both viscosity and elasticity, and specifically, it is capable of transmitting low-frequency vibrations in the vicinity of 30 Hz, which is the frequency of the vibrations applied to the screw in the screw loosening test, as is, and attenuating unnecessary high-frequency vibrations due to resonance that may occur in the base member 31 and the screw mounting member 33.

[0032] In addition, in the present jig 3, it is preferable that the damping ratio of the resonance frequency is 0.1% or more, more preferably 0.15% or more, and even more preferably 0.16% or more. The resonance frequency is preferably in the vicinity of 3000 Hz, more preferably 4000 Hz or more, 4900 Hz or more. By setting it in this range, the resonance frequency can be brought to the high frequency side and absorbed by the viscoelastic member 32, and the test can be performed more stably. The resonance frequency can be obtained by applying vibration and applying a Fourier transform to the time change in the magnitude of the vibration, and the damping ratio can be calculated by performing a Hilbert transform.

[0033] Furthermore, the shape of the viscoelastic member 32 in the jig 3 is not limited as long as it has the above-mentioned functions, but it is preferable to match the shape of the upper surface of the base member 31 or the lower surface of the screw mounting member 33. Specifically, it is preferable that the bottom surface is a polygonal shape such as a circle or a square, and more preferably a square (rectangle) that matches the bottom surface shape of the screw mounting member 33. In this way, by matching it to one of the bottom surfaces, it is possible to suppress excess protruding parts that do not overlap with the base member 31 or the screw mounting member 33, and it is possible to suppress resonance. More specifically, the shape of the viscoelastic member 32 is preferably a cylinder or a rectangular parallelepiped.

[0034] FIG. 4 is an image diagram for explaining the vibration and its magnitude (acceleration) in the present device 1. In this figure, (a) shows the vibration frequency and its acceleration in a screw loosening test jig without a viscoelastic member, and (b) shows the vibration frequency and its acceleration in the present jig using a viscoelastic member. In (a), not only the strong vibration used in the test near 30 Hz, but also the strong resonance vibration appears in the region near 3000 Hz. On the other hand, when the present jig 3 is used, the vibration near 30 Hz can be transmitted as it is, while the resonance frequency in this vicinity can be shifted to the higher frequency side by the base member 31, etc., and the vibration of this resonance frequency can be reduced by the absorption by the viscosity of the viscoelastic body. In other words, while the vibration level near 30 Hz is transmitted, the noise due to the resonance is absorbed, and stable vibration transmission can be performed.

[0035] The viscoelastic member 32 in the jig 3 is preferably within the above range, and specifically, the material is preferably plastic, and more specifically, the material is preferably carbon fiber reinforced plastic, monomer cast nylon, polypropylene acetal, polyethylene (preferably high molecular weight polyethylene), or a mixture of at least any of these. By selecting these materials, it is possible to ensure the properties within the above-mentioned predetermined range.

[0036] As described above, the screw mounting member 33 in the jig 3 is placed on the viscoelastic member 32 and has a screw insertion hole 331 formed therein. The screw mounting member 33 is a member for performing a screw loosening test by mounting a screw to the screw and transmitting vibrations from the vibration generator 2 to move the screw within the screw insertion hole 331 and cause the screw to collide with the screw mounting member 33 and loosen it, and measuring the degree of loosening.

[0037] As described above, the screw insertion hole 331 is formed in the screw attachment member 33 of the jig 3. The shape of the screw attachment member 33 is not limited, but it is preferable that the bottom surface is an elongated rectangular shape and that when viewed from the side, the bottom surface is a convex shape with a step portion for attaching a screw. This makes it possible to fix the screw attachment member 33 to the base member 31 with a member such as a screw.

[0038] The screw insertion hole 331 is an elongated hole, and its end is semicircular to avoid corners. The length of the screw insertion hole 331 (the length in the axial direction of the elongated hole) is not limited, but is mainly determined by the test standard and can be adjusted as appropriate. Since the device 1 is applicable to screws such as M16 and M20 in the JIS standard, it is preferable that the hole width (the length perpendicular to the long axis of the elongated hole) is 20 mm or more and 40 mm or less, and the hole length (the length of the long axis of the elongated hole) is 40 mm or more and 80 mm or less.

[0039] As is clear from the above description, the test screw inserted into the screw insertion hole 331 is a bolt, and after the bolt is inserted, it can be attached to the screw mounting member 33 by tightening a nut from the opposite direction to the bolt insertion. Although the screw may be directly inserted into the screw insertion hole 331, according to the standard, it is preferable to fix the screw to a screw vibrator and then fix the screw vibrator together in the screw insertion hole 331. An image of this case is shown in Figure 5.

[0040] Furthermore, the material of the screw mounting member 33 is not particularly limited, but it is important that it is made of a hard material in order to transmit the vibrations from the vibration generating device 2 to the screw, and it is preferable that it is made of a metal, such as stainless steel or steel.

[0041] Incidentally, the present device 1 has a covering member 34 that covers the upper surface of the viscoelastic member 32 and is disposed between the viscoelastic member 32 and the screw attachment member 33. The covering member 34 is provided on the viscoelastic member 32 and can enhance the effect of the viscoelastic member 32. More specifically, the covering member 34 sufficiently covers the upper surface of the viscoelastic member 32, thereby widening the contact area with the covering member 34 and enabling the transmission and absorption of vibration by the viscoelastic member 32 to be efficiently transmitted to the screw attachment member 33. That is, it is preferable that the area and shape of the covering member 34 are the same as those of the viscoelastic member 32. In this way, the above effect can be sufficiently achieved. However, it is possible to omit the covering member 34. In addition, the thickness of the covering member 34 can be appropriately adjusted depending on the material, but is preferably 1 cm or more, and more preferably 20 cm or less. If the covering member 34 is too thin, it is difficult to obtain sufficient contact, including its weight, and strength cannot be ensured, while if it is 20 cm or less, it is possible to prevent the covering member 34 from absorbing vibrations at frequencies that should not be absorbed.

[0042] The material of the covering member 34 is not limited as long as it has the above-mentioned functions, but is preferably a hard substance, such as a metal. In the case of a metal, suitable examples include an aluminum alloy, a magnesium alloy, a titanium alloy, steel, and stainless steel.

[0043] In addition, in the present device 1, the base member 31, the viscoelastic member 32, the covering member 34, and the screw mounting member 33 are preferably fixed by the screw member 35. In this case, the base member 31, the viscoelastic member 32, the covering member 34, and the screw mounting member 33 are each formed with a through hole whose axis coincides when they are superimposed, and the screw member 35 can be passed through and tightened to reliably integrate them.

[0044] As is clear from the above description, a screw loosening test method can be provided by using the present device 1. The screw loosening test method according to this embodiment (hereinafter referred to as "the present method") is a screw loosening test method using a screw loosening test jig 3 having a base member 31, a viscoelastic member 32 placed on the base member 31, and a screw attachment member 33 placed on the viscoelastic member 32 and having a screw insertion hole 331 formed therein, and includes the steps of attaching the screw loosening test jig 3 on a vibration generator 2, inserting a screw into the screw insertion hole 331 of the screw loosening test jig 3 and attaching it, and driving the vibration generator to generate vibration. In this case, as described above, a covering member 34 may be provided on the viscoelastic member 32 and between the screw attachment member 33.

[0045] As described above, the present embodiment can provide a thread loosening test fixture, a thread loosening test apparatus, and a thread loosening test method that can suppress resonance of the entire thread loosening test apparatus and perform tests more stably. EXAMPLES

[0046] Here, the above-mentioned loosening test device was actually created and its effectiveness was confirmed. The details are explained below.

[0047] Example 1: Prototype jig + MC 10mm + Aluminum 3cm M20 Example 1 Based on NAS3350, a cylindrical base made of aluminum alloy with a diameter of 29 cm and a thickness of 13 cm was placed on the vibration table (circular shape with a diameter of 29 cm) of a vibration generator (IMV Corporation: J240). On top of that, a viscoelastic member made of monomer cast nylon (Mitsubishi Chemical Advanced Materials Corporation: MC nylon) with a square bottom of 5 cm x 22 cm and a thickness of 10 mm was placed. On top of that, a viscoelastic member with the same shape and area as the viscoelastic member was placed. A 3cm thick aluminum alloy covering member was installed, and a convex screw mounting member (2.54cm x 15cm square bottom, 2.54cm x 9cm top, 13cm overall height, 7.5cm step height, 5.42cm screw insertion hole length, 3.53cm width) was installed on top of it, and the base member and screw mounting member were fixed with bolts and nuts, and an M20 bolt was inserted into the screw insertion hole and fixed with a nut from the other side, completing the screw loosening test device. A photograph of the entire device in this case is shown in Figure 6.

[0048] On the other hand, a vibration sensor (piezoelectric type) was installed on the vibration table of the vibration generating device that applies vibration to the base member to detect the applied vibration (magnitude of up and down vibration), and an optical vibration sensor (laser Doppler vibrometer) was installed on the top of the screw mounting member to detect the applied vibration (magnitude of up and down vibration) and install a measuring instrument to confirm how the vibration from the vibration generating device is being transmitted to the screw mounting member.

[0049] Then, a screw loosening test was performed by applying vibration (30 Hz, amplitude 11.43 mm) to the above screw loosening test device based on NAS3350. As a result, the device continued to operate without stopping during the screw loosening test. In addition, the standard deviation of the vibration amplitude of the screw mounting member was 0.063 mm, and it was confirmed that the variation in the vibration amplitude was very small.

[0050] Example 2: Prototype jig + MC20mm + Aluminum 3cm M20 Example 2 In this example, a thread loosening test was carried out under the same conditions as in Example 1, except that the thickness of the monomer cast nylon in Example 1 was changed to 20 mm.

[0051] As a result, the equipment continued to operate without stopping during the screw loosening test. In addition, it was confirmed that the standard deviation of the vibration amplitude of the screw mounting component was 0.022 mm, and the variation in the vibration amplitude was very small.

[0052] Example 3: Prototype jig + MC 40mm + Aluminum 3cm M20 Example 3 In this example, a thread loosening test was carried out under the same conditions as in Example 1, except that the thickness of the monomer cast nylon in Example 1 was changed to 40 mm.

[0053] As a result, the equipment continued to operate without stopping during the screw loosening test. In addition, the standard deviation of the vibration amplitude of the screw mounting component was 0.023 mm, confirming that the variation in the vibration amplitude was very small.

[0054] Example 4: Prototype jig + tie bar 20mm + aluminum 3cm M20 Example 4 In this example, a screw loosening test was carried out under the same conditions as in Example 2, except that the material of the monomer cast nylon in Example 2 was changed to ultra-high molecular weight polyethylene (Tiber (registered trademark), manufactured by Mitsubishi Chemical Advanced Materials Corporation).

[0055] As a result, the equipment continued to operate without stopping during the screw loosening test. In addition, it was confirmed that the standard deviation of the vibration amplitude of the screw mounting component was 0.022 mm, and the variation in the vibration amplitude was very small.

[0056] Example 5: Prototype jig + polypropylene acetal 20mm + aluminum 3cm M20 Example 5 In this example, a thread loosening test was carried out under the same conditions as in Example 2, except that the material of the monomer cast nylon in Example 2 was changed to polypentane acetal.

[0057] As a result, the equipment continued to operate without stopping during the screw loosening test. In addition, it was confirmed that the standard deviation of the vibration amplitude of the screw mounting component was 0.025 mm, and that the variation in the vibration amplitude was very small.

[0058] Example 6: Prototype jig + MC 10mm + Aluminum 3cm M16 Example 6 In this example, the bolt M20 tested in Example 1 was changed to M16, and the dimensions of the convex screw mounting component were adjusted to match this (square bottom shape 2.54 cm x 15 cm, top surface 2.54 cm x 9 cm, overall height 13 cm, stepped portion height 7.5 cm, screw insertion hole length 5.12 cm, width 3.23 cm), and other than this, a screw loosening test was performed under almost the same conditions as in Example 1 above (but using NAS3354).

[0059] As a result, the equipment continued to operate without stopping during the screw loosening test. In addition, the standard deviation of the vibration amplitude of the screw mounting component was 0.042 mm, confirming that the variation in the vibration amplitude was very small.

[0060] Example 7: IMV jig + MC 20mm + aluminum 3cm M20 Example 7 In this example, a screw loosening test was carried out under the same conditions as in Example 2, except that the base member in Example 2 was a square (5 cm thick) aluminum alloy base member with a side length of 40 cm and notches at the corners (hereinafter referred to as the "IMV base member"). Photographs of this test are shown in Figure 7.

[0061] As a result, the equipment continued to operate without stopping during the screw loosening test. In addition, it was confirmed that the standard deviation of the vibration amplitude of the screw mounting component was 0.032 mm, and the variation in the vibration amplitude was very small.

[0062] Comparative Example 1 In this comparative example, the viscoelastic member and the covering member made of aluminum alloy used in the above-mentioned Example 1 were not provided, and the base member and the screw mounting member were directly connected to each other, and a screw loosening test similar to that in Example 1 was performed.

[0063] However, in this comparative example, the vibration tester experienced severe resonance and stopped midway, making it impossible to carry out the test.

[0064] Comparative Example 2 In this comparative example, a screw loosening test was performed under the same conditions as in Comparative Example 1 above, except that the bolts used in Comparative Example 1 above were changed from M20 to M16 (the dimensions of the screw mounting member were the same as in Example 6 above).

[0065] In this test, the resonance was so severe that it stopped several times, but there were also times when the test was completed without being stopped. In this test, the equipment continued to operate during the screw loosening test without stopping, but the vibration was quite large. In addition, the standard deviation of the vibration amplitude of the screw mounting member was large at 0.12 mm, and it was confirmed that there was a large variation in the vibration amplitude. This result is thought to be due to the fact that although the base member was effective, it was difficult for the viscoelastic material, etc. to absorb the vibration. Furthermore, when the base member was an IMV material, the vibration absorption effect was small, and the test was stopped midway through each time.

[0066] (Check damping ratio) The resonant frequency and damping ratio of the fixtures used in Examples 1 to 5 were confirmed. The measurement was performed by removing the screw loosening test fixture (the component above the base member) in the examples, placing a vibration sensor (piezoelectric type) on the base member, applying vibration to the covering member with a hammer, and measuring the resonant frequency and damping ratio. The results are shown in the table below. The resonant frequency was calculated by performing a Fourier transform on the output of the vibration sensor (piezoelectric type), and the damping ratio was obtained by a Hilbert transform.

[0067] [Table 1]

[0068] As a result, it was confirmed that the fundamental frequency (resonance frequency) of all of them was around 5000Hz, and that it was possible to shift to the high frequency region of 3000Hz or more.In addition, it was found that the damping ratio of all of these was 0.1% or more, more specifically, 0.16% or more, and sufficient damping was obtained.

[0069] As described above, the effectiveness of the present device was confirmed by these Examples and Comparative Examples. More specifically, it was confirmed that the present device has the effect of sufficiently transmitting vibrations in the frequency range required for testing by providing a viscoelastic member between the screw mounting member and the base member, while sufficiently suppressing resonance with vibrations having a resonant frequency, thereby effectively suppressing unnecessary vibrations. [Industrial Applicability]

[0070] INDUSTRIAL APPLICABILITY The present invention has industrial applicability as a thread loosening test jig, a thread loosening test device, and a thread loosening test method. [Explanation of symbols]

[0071] 1. Screw loosening test equipment 2. Vibration Generator 3. Screw loosening test fixture 31 Pedestal member 32 Viscoelastic materials 33 Screw mounting material 331 Screw insertion hole 34 Covering material 35 Screw member

Claims

1. A base member; A viscoelastic member disposed on the base member; a screw attachment member that is placed on the viscoelastic member and has a screw insertion hole formed therein.

2. 2. The jig for testing a screw loosening as claimed in claim 1, further comprising a covering member which covers an upper surface of said viscoelastic member and is disposed between said viscoelastic member and said screw attachment member.

3. 2. A screw loosening test fixture according to claim 1, wherein the base member is cylindrical or polygonal.

4. 2. A screw loosening test jig according to claim 1, wherein the damping ratio in a frequency range of 3000 Hz or more is 0.1% or more.

5. 2. The jig for testing for loosening of a screw thread according to claim 1, wherein the viscoelastic member is made of at least one of carbon fiber reinforced plastic and monomer cast nylon.

6. 2. The jig for testing for loosening of threads according to claim 1, wherein the base member, the viscoelastic member and the screw mounting member are fixed by a screw member.

7. A screw loosening test apparatus comprising a vibration generator and a screw loosening test jig installed on the vibration generator, The screw loosening test fixture is a screw loosening test device having a base member, a viscoelastic member placed on the base member, and a screw mounting member placed on the viscoelastic member and having a screw insertion hole formed therein.

8. 8. A thread loosening test apparatus according to claim 7, wherein the thread loosening test fixture comprises a covering member that covers an upper surface of the viscoelastic member and is disposed between the viscoelastic member and the screw attachment member.

9. A method for testing for loosening of a screw using a screw loosening test fixture including a base member, a viscoelastic member placed on the base member, and a screw attachment member placed on the viscoelastic member and having a screw insertion hole formed therein, comprising: Attaching the screw loosening test fixture on a vibration generating device; A step of inserting a screw into the screw insertion hole of the screw loosening test jig and attaching it; and driving the vibration generating device to generate vibration.

10. After the step of mounting the screw loosening test jig on the vibration generating device and before the step of mounting the jig by inserting a screw into the screw insertion hole of the screw loosening test jig, 10. The method for testing thread loosening according to claim 9, further comprising the step of attaching a covering member onto the viscoelastic member, the covering member being disposed between the viscoelastic member and the screw attachment member and covering an upper surface of the viscoelastic member.

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