Device, method and computer program for determining the state of screw fastening

Abstract

Provided is a screw fastening state determination technique capable of determining the screw fastening state with high accuracy and with ease. A screw fastening state determination device (1) includes: an excitation mechanism (10) that applies vibration to an object (100) having a screw fixing portion (101A); and an infrared camera (20) as a temperature measurement mechanism that measures the surface temperature of the object (100). The excitation mechanism (10) applies vibration to the object (100), and the infrared camera (20) thermographs and measures the change in the surface temperature of the object (100) that is heated by the vibration applied to the object (100) by the excitation mechanism (10), thereby determining the fastening state of the screw fixing portion (101A).

Description

Technical Field

[0001] The present invention relates to an apparatus or method for determining the tightness of screws used, for example, in fixing circuit boards in electrical products, or to a computer program for automatically determining the tightness of screws by using such an apparatus or system as a hardware resource. Background Technology

[0002] Screws are now the mainstream and frequently used method for fixing circuit boards in electrical products. Generally speaking, the tightness of screws is managed by the tightening torque, but the judgment of screw looseness (poor tightening) can only rely on visual observation.

[0003] Regarding such issues, for example, Patent Document 1 discloses the following technology: In a screw fastening machine that includes a screwdriver bit for tightening screws and an adsorption tube for holding screws, the relative linear displacement of the screwdriver bit and the adsorption tube is converted into rotational displacement by a gear and rack mechanism, and the rotational displacement is detected electrically to determine the amount of screw floating.

[0004] Existing technical documents Patent documents Patent document 1: Japanese Patent Application Publication No. 8-257849. Summary of the Invention

[0005] The problem that the invention aims to solve For example, in M4 threads, a change in loosening torque from 1.5 N·m to 1.3 N·m corresponds to a float of approximately 0.1 mm. That is, to ensure a tightness of at least 0.1 mm by managing screw float relative to a specified value of less than 0.2 N·m, a high measurement accuracy of at least 0.1 mm is required. In particular, in mass production departments of electrical products with multiple screw fixing points, measuring the float of each screw individually for full product inspection is cumbersome and inefficient, necessitating a simpler and more effective judgment method.

[0006] Therefore, the object of the present invention is to provide a screw fastening state determination technology that can determine the screw fastening state with high accuracy and ease.

[0007] means for solving problems To address the aforementioned problems, the present invention provides a screw fastening state determination device for determining the fastening state of a test subject having a screw fixing part. The device comprises: a vibration unit that applies vibration to the test subject; and a temperature measuring unit that measures the surface temperature of the test subject. The screw fastening state determination device is configured such that the vibration unit applies vibration to the test subject, and the temperature measuring unit measures the change in surface temperature of the test subject as it heats up due to the vibration applied by the vibration unit, thereby determining the fastening state of the screw fixing part.

[0008] According to this screw fastening condition determination device, the excitation unit applies vibration to the test object, and based on the change in the surface temperature of the test object caused by the vibration applied by the excitation unit, the fastening condition of the screw fixing part can be determined with high accuracy and simplicity.

[0009] In addition, preferably, in the screw fastening state determination device, the temperature measuring unit includes an infrared camera, which measures the change in surface temperature of the subject based on the thermal image captured by the infrared camera.

[0010] According to the screw fastening status determination device, the surface temperature distribution of the tested object is visualized by thermal imaging captured by an infrared camera, thereby making it easy to determine the location of loose screw fixing parts and the degree of screw floating.

[0011] In addition, preferably, the screw tightness determination device further includes the following mechanism: the mechanism scans the vibration frequency applied to the test object and determines the optimal value of the vibration frequency based on the response characteristics to the obtained vibration frequency.

[0012] According to this screw fastening condition determination device, by using an optimized vibration frequency based on the vibration response characteristics, the accuracy of determining the fastening condition of the screw fixing part can be further improved.

[0013] In addition, the present invention is a method for determining the tightness of a screw, which determines the tightness of a test subject having a screw fixing part. The method for determining the tightness of a screw includes the following steps: applying vibration to the test subject; measuring the change in surface temperature of the test subject that is heated due to the applied vibration; and determining the tightness of the screw fixing part based on the change in surface temperature.

[0014] According to this method for determining the tightness of screws, vibration is applied to the test subject, and the change in surface temperature of the test subject, which is heated by the vibration, is measured. This allows for a high-precision and convenient determination of the tightness of the screw fixing part.

[0015] In addition, preferably, in the screw fastening state determination method, the change in surface temperature of the subject is measured based on thermal imaging captured by an infrared camera.

[0016] According to this method for determining the tightness of screws, the surface temperature distribution of the tested object is visualized by thermal imaging captured by an infrared camera, thereby making it easy to determine the location of loose screw fixing parts and the degree of screw floating.

[0017] In addition, preferably, the screw fastening state determination method further includes the following steps: scanning the vibration frequency applied to the test object, and determining the optimal value of the vibration frequency based on the response characteristics to the obtained vibration frequency.

[0018] According to this screw fastening condition determination method, by using an optimized vibration frequency based on the vibration response characteristics, the accuracy of determining the fastening condition of the screw fixing part can be further improved.

[0019] Furthermore, the present invention is a computer program in which a system comprising an excitation unit that applies vibration to a test subject having a screw fixing part, a temperature measuring unit that measures the surface temperature of the test subject, and a measurement control device is used to cause the computer of the measurement control device to perform the following processes: controlling the excitation unit to apply vibration to the test subject; measuring the change in the surface temperature of the test subject that is heated due to the applied vibration by the temperature measuring unit; and determining the tightness of the screw fixing part based on the change in the surface temperature.

[0020] According to the computer program, the measurement and control device of the system is controlled, the excitation unit applies vibration to the test object, and based on the change in the surface temperature of the test object that is heated by the vibration applied by the excitation unit, the tightness of the screw fixing part can be determined with high accuracy and ease.

[0021] In addition, preferably, in the computer program, the temperature measurement unit includes an infrared camera, which measures the change in surface temperature of the subject based on thermal imaging captured by the infrared camera.

[0022] According to the computer program, the surface temperature distribution of the subject is visualized by thermal imaging captured by an infrared camera, thereby making it easy to determine the location of loose screw fixing parts and the degree of screw floating.

[0023] Additionally, preferably, the computer program also causes the computer of the measurement control device to perform the following processing: scanning the vibration frequency applied to the test subject, and determining the optimal value of the vibration frequency based on the response characteristics to the obtained vibration frequency.

[0024] According to the computer program, by using an optimized vibration frequency based on the vibration response characteristics, the accuracy of determining the tightness of the screw fixing part can be further improved.

[0025] In addition, the present invention is a computer-readable storage medium, characterized in that the computer-readable storage medium stores the above-described program.

[0026] Invention Effects According to the present invention, by applying vibration to the test subject, the tightness of the screw fixing part can be determined with high accuracy and ease based on the change in surface temperature of the test subject due to the heat generated by the vibration. Attached Figure Description

[0027] Figure 1 This is a diagram showing a schematic configuration of a screw fastening state determination device based on one embodiment of the present invention.

[0028] Figure 2 It is used for including Figure 1 A functional block diagram illustrating the general structure of the screw fastening status determination device and the measurement and control device system is provided.

[0029] Figure 3 This is an example of a thermal imaging result that compares the differences in exothermic responses based on the difference in tightening torque of screws when a metal plate is used as the fastener.

[0030] Figure 4 This is an example of a thermal imaging result presented by comparing the differences in exothermic responses based on the difference in the loosening angle of screws when a metal plate is used as the fastener.

[0031] Figure 5 This is an example of a thermal imaging result presented by comparing the differences in exothermic responses based on the difference in tightening torque of screws when a resin plate is used as the fastener.

[0032] Figure 6 This is an example of a thermal imaging result presented by comparing the differences in exothermic responses based on the difference in the loosening angle of the screws when a resin plate is used as the fastener.

[0033] Figure 7 This is an example of thermal imaging results measured using an actual product.

[0034] Figure 8 This is an example of thermal imaging results measured using other actual products.

[0035] Figure 9 This is a flowchart used to illustrate the optimization of excitation conditions.

[0036] Figure 10 This is an example of an infrared image taken of a target area of ​​a subject.

[0037] Figure 11 This is an example of the response characteristics for scanning frequency.

[0038] Figure 12 This is an example of a measurement signal waveform used when optimizing excitation parameters.

[0039] Figure 13 This is a block diagram showing the structure of a computer used for measurement and control. Detailed Implementation

[0040] The following describes a device (tightness determination device) for determining the fastening state of an inspected object with screw fasteners, and its specific determination method (tightness determination method), as an example of determining the fastening state between components in an inspected object. Figure 1 This is a perspective view showing a schematic configuration of a screw tightening state determination device 1 based on one embodiment of the present invention. Furthermore, Figure 2 This is a functional block diagram used to illustrate the general configuration of a system including a screw fastening state determination device 1 and a measurement and control device 30 electrically connected to the screw fastening state determination device 1.

[0041] Figure 1 and Figure 2 The test object 100 shown in the example includes: an internal thread block 120, which is formed by cutting multiple internal threads 121, 122, 123, and 124 using a tap or milling cutter; fastened objects 111, 112, 113, and 114, for example, a plate shape assuming an electronic circuit board; and external threads 101, 102, 103, and 104, which are used to fasten the fastened objects 111, 112, 113, and 114 to the internal threads 121, 122, 123, and 124 of the internal thread block 120, respectively.

[0042] The test object 100 has screw fixing portions 101A, 102A, 103A, and 104A, which are the objects for determining the fixed state based on this embodiment. The portion of the fastened object 111 that is fixed to the internal thread block 120 by the external thread 101 corresponds to the screw fixing portion 101A. Similarly, the portion of the fastened object 112 that is fixed to the internal thread block 120 by the external thread 102 corresponds to the screw fixing portion 102A, the portion of the fastened object 113 that is fixed to the internal thread block 120 by the external thread 103 corresponds to the screw fixing portion 103A, and the portion of the fastened object 114 that is fixed to the internal thread block 120 by the external thread 104 corresponds to the screw fixing portion 104A.

[0043] also, Figure 1 and Figure 2 The specimen 100 illustrated is one of the test pieces used to verify the effectiveness of the present invention. Undoubtedly, the structure of the specimen 100 illustrated is not limited to those in the implementation of the invention. For example, the specimen can be a structure that is fixed at multiple locations by fasteners. In addition, the specimen can be a component of any shape and size other than plate-shaped and made of any material.

[0044] In addition, Figure 2 The invention describes a support platform 130 for supporting the internal thread block 120, but this support platform 130 is provided for investigating how differences in the vibration transmission structure system including the test object 100 affect the vibration response characteristics, and is not essential as an inventive element.

[0045] like Figure 1 and Figure 2 As illustrated by an example, the screw fastening state determination device 1 based on this embodiment includes an excitation unit 10 that applies vibration to the test object 100, and a temperature measuring unit 20 configured to measure the surface temperature of the test object 100. It is capable of determining the fastening state of the test object 100 having screw fixing parts 101A, 102A, 103A, and 104A. Furthermore, as... Figure 2 As shown, the screw tightness determination device 1 can also be a screw tightness determination device that is systematized by connecting the vibration unit 10 and the temperature measurement unit 20 to the measurement and control device 30.

[0046] The excitation unit 10 houses a piezoelectric element 10A within its truncated cylindrical excitation head. The vibration control unit 320 of the measurement control device 30 outputs a drive signal (also called a measurement signal) to the piezoelectric element 10A, causing the piezoelectric element 10A to expand and contract, thereby enabling the excitation unit 10 to generate vibrations based on the vibration frequency and power of the drive signal.

[0047] In the fixed state determination of this embodiment, the range of excitation frequencies used is preferably, for example, the ultrasonic frequency band of 15kHz to 25kHz. As will be described later, the location (excitation point) at which the excitation unit 10 applies vibration to the test object 100 is selected based on the actual vibration transmission system including the test object 100, which has the strongest vibration response. Such an excitation point, in addition to Figure 1 and Figure 2 Other than the end of the internal threaded block 120 shown, it may sometimes be the location of the object being fastened, or the location separated from the fixed part. In addition, depending on the situation, vibration may not be applied directly to the test object 100, but indirectly through the support table 130 or the like that supporting the test object 100.

[0048] The temperature measurement unit 20 is equipped with an infrared camera. By generating a thermal imaging image based on the infrared image captured by the infrared camera, the surface temperature distribution and temperature changes of the test object 100 can be observed in real time.

[0049] For example, in a fastener using an M4 thread, the lower limit of the allowable tightening torque due to loosening is 1.3 N·m, relative to the specified tightening torque of 1.5 N·m. This difference in torque (difference in screw axial force) translates to a screw float of approximately 0.1 mm. Therefore, to reliably manage the quality of the tightening condition in M4 threads, a judgment accuracy of at least 0.2 N·m in terms of tightening torque or 0.1 mm in terms of screw float is required. The inventors of this invention, focusing on the relationship between screw loosening and heat generation during vibration, have derived a useful insight into using thermal imaging non-destructive testing as a highly accurate and convenient method for judging the screw tightening condition.

[0050] Therefore, using the screw fastening status determination device 1 described above, the following verification was performed: whether the loosening status of the screw can be determined based on the thermal imaging image obtained by measuring the surface temperature of the test object 100. The properties of the fastened object, the internal thread block, and the screw used for verification are shown in Tables 1, 2, and 3, respectively.

[0051] [Table 1]

[0052] In Table 1: Substrate No. 1 is a 0.8mm thick copper plate made from refined copper (C1100-1 / 2H). Tin plating was performed as a surface treatment.

[0053] Substrate No. 2 is a 1.0 mm thick copper plate made of refined copper (C1100-1 / 2H). Tin plating was performed as a surface treatment.

[0054] Substrate No. 3 is a 1.2mm thick copper plate made of refined copper (C1100-1 / 2H). Tin plating was performed as a surface treatment.

[0055] Substrate No. 4 is a 1.0mm thick copper plate made of refined copper (C1100-1 / 2H).

[0056] Substrate No. 5 is electro-galvanized cold-rolled steel sheet (SECC) with a thickness of 1.0 mm.

[0057] Substrate No. 6 is a glass epoxy resin substrate with a thickness of 1.6 mm. As a surface treatment, a resist coating was applied, and the through holes (TH) through which the screws pass were electroplated.

[0058] [Table 2]

[0059] In Table 2: Block No. 1 is a block made of low-carbon steel (S10C).

[0060] Block No. 2 is a block made of copper (C3406).

[0061] Block No. 3 is a block made of aluminum alloy (ADC12).

[0062] [Table 3]

[0063] In Table 3: Screw No. 1 is a 4mm (M4) washer-assembled (SEMs) screw with a trivalent chromate surface treatment. The length under the head is 10mm.

[0064] Screw No. 2 is a 4mm (M4) washer-assembled (SEMs) screw with a trivalent chromate surface treatment. The length under the head is 16mm.

[0065] exist Figure 3 An example of thermal imaging results based on this embodiment is shown. Figure 3 In the example, the metal substrate No. 1 shown in Table 1 is used as the fastener of the test object 100. In addition, the aluminum alloy block No. 3 shown in Table 2 is used as the internal thread block, and the thread No. 1 shown in Table 3 is used as the external thread.

[0066] exist Figure 3In the image, the left image shows the tightening torque at the design specification of 1.5 N·m, while the right image shows the tightening torque at 1.3 N·m. At a tightening torque of 1.5 N·m, sufficient axial force is applied, and the internal thread block integrates with the object being tightened, thus almost no vibration-based response is observed. On the other hand, if the tightening torque is changed to 1.3 N·m, loosening is not visually detectable, but an exothermic reaction is observed on the outer periphery of the washer at the screw fixing point.

[0067] Figure 4 It was used with Figure 3 This is an example of the thermal imaging results of the same subject 100. Here, in Figure 4 In the image, the left image shows the screw loosened by 45° from a state where the screw torque was increased, and the right image shows it loosened further to 90°. The screw float at 45° is equivalent to 0.08 mm, and at 90° it is equivalent to 0.18 mm, so the difference in float is 0.1 mm. An exothermic reaction was observed at the screw fixing point when loosened at 45°, and a further strong reaction was observed at the screw fixing point when loosened at 90°, with a significant reaction also observed at the end of the fastened object 111. It can be assumed that the vibration of the fastened object seen in the right image is due to the loss of the screw's fixing function.

[0068] Next, in Figure 5 and Figure 6 The following is an example of the thermal imaging results when the fastener of the inspected object 100 is changed to the glass epoxy resin substrate No. 6 shown in Table 1. In this embodiment, aluminum alloy block No. 3 shown in Table 2 is used as the internal thread block, and thread No. 1 shown in Table 3 is used as the external thread.

[0069] exist Figure 5 In the image, the left image shows the fastening condition with a specified value of 1.5 N·m, and the right image shows the fastening condition with a specified value of 1.3 N·m. Additionally, in... Figure 6 In the image, the left image shows the screw loosened to 45°, and the right image shows it loosened to 90°.

[0070] If based on Figure 5 and Figure 6As observed, even when the fastened material is resin, a similar reactive tendency as with metal was observed between the washer and the fastened object. It was found that a difference of 0.2 N·m in tightening torque and a difference of 0.1 mm in screw float could be identified using thermal imaging. Furthermore, significant vibration responses were observed on relatively soft resin substrates when the tightening torque was 1.3 N·m or higher. These results suggest that even considering the fastened object in this experiment as a fragile structure fixed at a single point via a through-hole, the proposed thermal imaging non-destructive inspection method is useful for identifying stress concentration points during product development.

[0071] then, Figure 7 This is an example of thermal imaging results measured using an actual product. Figure 7 The tested object is an electronic circuit unit in which the electronic circuit board is actually mounted on an aluminum die-cast housing. Additionally, Figure 8 This is an example of a thermal imaging result measured on a subject by fixing a resin housing to a metal bracket using self-tapping screws.

[0072] As described above, the structural transmission system of vibration changes depending on the size, structure, and material of the object under test; therefore, it is preferable to excite a product at multiple locations. Furthermore, it is preferable to optimize the excitation parameters at the location of each excitation point in a manner that provides optimal thermal imaging visualization.

[0073] Regarding the above-described method for identifying the tightening state using the screw tightening state determination device 1, in order to make the identification more objective and quantitative, it is preferable to automate it through the control and analysis processing of the measurement control device 30.

[0074] Specifically, it could also be, Figure 2 The vibration control unit 320 outputs a measurement signal that forms a vibration waveform to the excitation unit 10, causing the excitation unit 10 to apply vibration to the test object 100. The temperature measurement unit 20 generates a thermal imaging image based on the infrared image captured by the test object 100. The thermal imaging analysis unit 301 measures the distribution and changes of the surface temperature of the test object 100 based on the generated thermal imaging image, thereby determining the fastening status of the screw fixing parts 101A, 102A, 103A, and 104A.

[0075] Alternatively, the present invention may also be provided to the user as a program that encodes all or part of the fixed state determination process described above, so that the computer of the measurement control device 30 performs the process.

[0076] As described above, the exothermic response varies depending on the differences in the vibration transmission system of the tested object, namely, differences in the structure of the tested object (including the shape and material of components), the form of the fixing method (screw fixing or riveting, etc.), and the location of the excitation point. Therefore, the present invention preferably includes an excitation condition optimization mechanism 310, which optimizes the excitation parameters in a way that provides the best thermal imaging display for identifying the fixing state of screws, etc. More specifically, as Figure 2 As shown, the excitation condition optimization mechanism 310 includes a vibration response detection unit 311, a measurement frequency determination unit 312, an excitation power determination unit 313, a measurement period determination unit 314, and a measurement number determination unit 315. These processing units perform their respective functions by performing calculations on the computer of the measurement control device 30.

[0077] according to Figure 9 The flowchart provides a detailed explanation of the optimization process for excitation conditions.

[0078] First, the excitation condition optimization mechanism 310 sends a command to the vibration control unit 320 to keep the excitation power constant and scan the excitation frequency. The excitation unit 10 generates vibration based on the measurement signal from the vibration control unit 320, thereby applying vibration to the test object while the vibration control unit 320 scans the excitation frequency (step S11).

[0079] Next, the vibration response detection unit 311 detects the vibration response in the target area of ​​the test subject based on the image captured by the infrared camera 20 (step S12). Figure 10 An example of an infrared image taken of an object area of ​​a subject is shown.

[0080] exist Figure 11 An example is shown where the power response characteristics are represented by a curve for the scanned excitation frequency. Based on such response characteristics obtained by scanning the excitation frequency, the measurement frequency determination unit 312 determines the frequency with the maximum response as the optimal frequency for measurement (step S13).

[0081] Next, the excitation condition optimization mechanism 310 generates a measurement waveform with the determined optimal frequency and issues commands to the vibration control unit 320. Figure 12 An example of the measurement signal waveform used for excitation is shown. For example... Figure 12 As shown, in the measurement of this embodiment, the excitation step of the power changing in a sinusoidal, step-like manner is repeated multiple times.

[0082] The excitation power determination unit 313 adjusts the power (amplitude) of the measurement signal in a manner most efficient for thermal imaging (step S14). The optimized power is, for example,... Figure 12The amplitude of the low-frequency components, which are sinusoidal and vary in a stepwise manner, is shown. Figure 12 The amplitude of any one or both of the high-frequency (ultrasound) components shown within the circle.

[0083] The measurement period determination unit 314 uses a measurement signal having the optimal frequency and vibration power set in steps S13 and S14 to determine a measurement period suitable for obtaining a recognizable thermal imaging display (step S15). Furthermore, the measurement period mentioned here is, for example, equivalent to... Figure 12 The time required for one excitation step is shown. Furthermore, the measurement count determination unit 315 repeats the excitation step multiple times to determine the optimal number of measurements (number of excitation steps) that can most effectively obtain response information (step S16).

[0084] It can also be provided to the user in the following form: a program 400 encoded so that the computer of the measurement control device 30 executes the processing based on the excitation condition optimization mechanism 310 described above.

[0085] That is, such as Figure 13 As shown, the measurement and control device 30 includes a central processing unit (CPU, GPU, DSP) 30B, a storage device (ROM, RAM, hard disk, cache memory) 30C, an input device (keyboard, touch screen, mouse) 30D, and a display device (LCD) 30E, all interconnected via a bus 30A. The storage device 30C functions as a computer-readable storage medium. Furthermore, the storage device 30 stores a program 400 for enabling the aforementioned functional units to function.

[0086] In other words, the program 400 stored in storage devices 3C, 5C, and 8C is a program 400 that causes the computer of the measurement control device 30 to execute predetermined processing. The computer program 400 is as follows: using a system that includes an excitation unit 10 that applies vibration to a test subject 100 having screw fixing parts 101A, 102A, 103A, and 104A, a temperature measuring unit 20 that measures the surface temperature of the test subject 100, and a measurement control device 30, the computer of the measurement control device 30 executes the following processing: controlling the excitation unit 10 to apply vibration to the test subject 100; measuring the change in surface temperature of the test subject 100 that is heated by the applied vibration using the temperature measuring unit 20; and determining the tightening state of the screw fixing parts 101A, 102A, 103A, and 104A based on the change in surface temperature.

[0087] Furthermore, the program 400 is a computer program 400 as follows: the temperature measurement unit 20 includes an infrared camera, which measures the change in surface temperature of the subject 100 based on the thermal image captured by the infrared camera.

[0088] Furthermore, program 400 is a computer program 400 that also causes the computer of the measurement control device 30 to perform a process of scanning the vibration frequency applied to the test object 100 and determining the optimal value of the vibration frequency based on the response characteristics to the vibration frequency obtained therefrom.

[0089] According to the above-described embodiment, a screw fastening state determination device and a screw fastening state determination method can be provided. The device applies vibration to the test object, and the temperature measuring unit measures the change in surface temperature of the test object that is heated due to the vibration applied to the test object. This allows for high-precision and convenient determination of the fastening state of the screw fixing part.

[0090] In addition, the temperature measurement unit includes an infrared camera, which measures the change in surface temperature of the subject based on the thermal image captured by the infrared camera. That is, the surface temperature distribution of the subject is visualized by the thermal image captured by the infrared camera, thereby making it easy to determine the location of loose screw fixing parts and the degree of screw floating.

[0091] In addition, it also includes a mechanism and steps for scanning the vibration frequency applied to the test object and determining the optimal value of the vibration frequency based on the response characteristics to the obtained vibration frequency. That is, the excitation condition optimization mechanism uses optimized excitation parameters based on the vibration response characteristics, thereby further improving the accuracy of determining the tightness of the screw fixing part.

[0092] Furthermore, the objects for determining the fixed state based on the present invention can include not only the fixing by "screws" described herein, but also fixing by "leaf springs", fixing by "adhesives", fixing by "welding", and fixing by "riveting" such as flying riveting, press riveting, and spin riveting.

[0093] Explanation of reference numerals in the attached figures 1: Screw tightness determination device; 10: Excitation section; 20: Temperature measurement unit, infrared camera; 30: Measurement and control device; 30A: Bus; 30B: Central processing unit; 30C: Storage device; 30D: Input device; 30E: Storage device; 100: Subject; 101, 102, 103, 104: External threads; 101A, 102A, 103A, 104A: Screw fixing part; 111, 112, 113, 114: The objects being fastened; 120: Internal thread block; 121, 122, 123, 124: External threads; 130: Support platform; 301: Thermal Imaging Analysis Department; 302: Screw Float Determination Unit; 303: Tightening torque determination unit; 310: Mechanism for optimizing excitation conditions; 311: Vibration Response Detection Unit; 312: Frequency determination unit; 313: Excitation power determination unit; 314: Measurement cycle determination unit; 315: Department for determining the number of measurements; 320: Vibration Control Unit; 400: Program error.

Claims

1. A screw fastening condition determination device, which determines the fastening condition of an inspected object having a screw fixing part, wherein, The screw tightness determination device includes: The excitation unit applies vibration to the test object; and The temperature measuring unit measures the surface temperature of the object being tested. The screw fastening state determination device is configured such that the excitation unit applies vibration to the test object, and the temperature measurement unit measures the change in surface temperature of the test object that is heated due to the vibration applied to the test object by the excitation unit, thereby determining the fastening state of the screw fixing part.

2. The screw fastening state determination device according to claim 1, wherein, The temperature measurement unit includes an infrared camera, which measures the change in surface temperature of the subject based on thermal images captured by the infrared camera.

3. The screw fastening state determination device according to claim 1 or 2, wherein, The screw tightness determination device further includes the following mechanism: the mechanism scans the vibration frequency applied to the test object and determines the optimal value of the vibration frequency based on the response characteristics to the obtained vibration frequency.

4. A method for determining the tightness of screws, which determines the tightness of an inspected object having a screw fixing part, wherein... The method for determining the tightness of screws includes the following steps: Vibration is applied to the subject; The change in surface temperature of the test subject, which heats up due to the applied vibration, is measured; and The tightness of the screw fixing part is determined based on the change in surface temperature.

5. The method for determining the tightness of screws according to claim 4, wherein, The surface temperature change of the subject is measured based on thermal imaging captured by an infrared camera.

6. The method for determining the screw fastening status according to claim 4 or 5, wherein, The screw fastening status determination method further includes the following steps: scanning the vibration frequency applied to the test object, and determining the optimal value of the vibration frequency based on the response characteristics to the obtained vibration frequency.

7. A computer program, wherein, The computer program uses a system comprising an excitation unit that applies vibration to a test subject having a screw fixing part, a temperature measuring unit that measures the surface temperature of the test subject, and a measurement control device, to cause the computer of the measurement control device to perform the following processing: The excitation unit is controlled to apply vibration to the test subject; The temperature measurement unit measures the change in surface temperature of the test subject, which is heated by the applied vibration; and The tightness of the screw fixing part is determined based on the change in surface temperature.

8. The computer program according to claim 7, wherein, The temperature measurement unit includes an infrared camera, which measures the change in surface temperature of the subject based on thermal images captured by the infrared camera.

9. The computer program according to claim 7 or 8, wherein, The computer program also causes the computer of the measurement and control device to perform the following processing: scan the vibration frequency applied to the test subject, and determine the optimal value of the vibration frequency based on the response characteristics to the obtained vibration frequency.

10. A computer-readable storage medium, wherein, The computer-readable storage medium stores the program according to any one of claims 7 to 9.

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