Fastener pre-tightening force detection device

Abstract

The invention provides a fastener pre-tightening force detection device. The fastener pre-tightening force detection device comprises a power switch, an optical sensor, a bolt sleeve, a stepping motor and a display assembly, the power switch is connected with the stepping motor and used for controlling starting and stopping of the stepping motor. The stepping motor drives the bolt sleeve to rotate and is used for tightening a fastener; the luminous coating of the fastener is stressed to emit light with different colors, and the luminous intensity is changed along with the stress; the light sensor receives a specific light signal, and the display assembly is connected with the light sensor and used for calculating and displaying a pre-tightening force value.

Description

Technical Field

[0001] This invention belongs to the field of fastener technology, and specifically relates to a fastener preload detection device. Background Technology

[0002] Currently, fastener preload testing methods are mainly categorized based on the measurement method: resistance strain measurement, fiber optic grating measurement, force-measuring washer measurement, ultrasonic elasticity measurement, optical elasticity measurement, and magnetic measurement. Resistance strain measurement only reflects the surface stress of the fastener, and the surface deforms during tightening, leading to discrepancies between the measurement results and the actual axial stress. Fiber optic grating measurement uses through-holes to embed the fiber optic cable, compromising the fastener's mechanical strength and making fiber fixation difficult. Force-measuring washer measurement alters the connection relationships in the fastening system, impacting anti-loosening performance and structural weight. Ultrasonic elasticity measurement requires a planar surface, placing high demands on the structural design and limiting its applicability. Optical elasticity measurement, due to its unique method, cannot be widely applied in industrial settings. Magnetic measurement requires the realization of magnetic domain processes in the fastener, is significantly affected by material structure, surface roughness, material remanence, and environmental remanence, and is currently in its immature stage. Summary of the Invention

[0003] The purpose of this invention is to provide a fastener preload detection device that uses photoresponse technology combined with sensor acquisition and calibration data conversion to achieve real-time preload detection.

[0004] This invention provides a fastener preload detection device, comprising: a power switch, a light sensor, a bolt sleeve, a stepper motor, and a display component; the power switch is connected to the stepper motor and is used to control the start and stop of the stepper motor; the stepper motor drives the bolt sleeve to rotate, for tightening the fastener; the luminescent coating of the fastener emits light of different colors under force, and the luminescence intensity changes with the magnitude of the force; the light sensor receives a specific light signal, and the display component is connected to the light sensor for calculating and displaying the preload value.

[0005] Furthermore, the display component includes: a display screen and a central processing chip; the input terminal of the central processing chip is connected to the light sensor for processing light signals and calculating the preload value; the display screen is connected to the output terminal of the central processing chip for displaying the preload value.

[0006] Furthermore, it also includes: wires; the power switch and the stepper motor are connected through the wires; the two ends of the central processing chip are respectively connected to the light sensor and the display screen through the wires.

[0007] Furthermore, it also includes: a bevel gear; the stepper motor drives the bevel gear to rotate at a constant speed, thereby causing the bolt sleeve to rotate at a constant speed.

[0008] Furthermore, it also includes: a housing; the housing is installed outside the bolt sleeve with a gap; the outer edge of the bolt sleeve is lower than the outer edge of the housing.

[0009] Furthermore, the bolt sleeve is a replaceable component.

[0010] Furthermore, the optical sensor is mounted on the inside of the housing.

[0011] Furthermore, it also includes: a handheld structure; the handheld structure includes: a housing and a handle; the power switch, the bolt sleeve, the stepper motor, and the display component are all mounted on the housing.

[0012] Furthermore, the present invention provides a detection method for a fastener preload detection device, characterized by comprising three steps:

[0013] (1) Preparation of luminescent coating for fasteners;

[0014] (2) Construction of fastener preload detection device;

[0015] (3) Fastener preload test.

[0016] Further, step (1) includes the following steps:

[0017] 1) Pre-treatment of fastener top

[0018] The stress-bearing contact surfaces of the fasteners are sandblasted with white fused alumina, and the fasteners are cleaned with petroleum ether and ethanol. They are then dried in an oven for later use.

[0019] 2) Preparation of luminescent coating

[0020] A blue luminescent coating was prepared by dissolving polytetrafluoroethylene in xylene solution, adding blue luminescent powder, and stirring until homogeneous. Similarly, a red luminescent coating was prepared by adding red luminescent powder and stirring until homogeneous.

[0021] 3) Preparation of luminescent coating

[0022] Red luminescent coating is applied to the inner ring of the stress-bearing contact surface of the fastener. The radius of the inner ring luminescent coating is half the radius of the stress-bearing contact surface, and the thickness is less than 200μm. When the red luminescent coating is semi-dry, blue luminescent coating is applied to the outer ring. The thickness of the blue luminescent coating is lower than that of the inner ring. The fastener is then placed in an oven for curing. The luminescent coating preparation is complete.

[0023] Furthermore, step (2) includes the following steps:

[0024] 1) Fabrication of the handheld structure

[0025] The handle and shell of the handheld structure are injection molded from ABS engineering plastic. The handle is ergonomically designed and has anti-slip texture.

[0026] 2) Install the display components and stepper motors.

[0027] An LCD display is embedded in the top of the handheld structure housing, and the stepper motor and central processing chip are fixed inside the housing by a bracket;

[0028] 3) Install bolt sleeves and light sensors

[0029] The bolt sleeve is installed inside the handheld structure housing, with its outer edge 1-3mm lower than the housing. Two light sensors are installed on the inner side of the housing.

[0030] Furthermore, step (3) includes the following steps:

[0031] The light sensor detects the intensity of blue light Ia and the intensity of red light Ib. The central processing chip calculates the ratio of Ia to Ib, obtains the preload value based on the calibration relationship between the ratio of light intensity and the preload, and displays it on the screen in real time.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. The fastener preload detection device provided by the present invention is low-cost and easy to operate. It does not require strain gauges, force measuring washers or pre-embedded optical fibers. It can achieve real-time sensing simply by coating with a luminescent coating.

[0034] 2. The fastener preload detection device provided by the present invention allows the preload value to be read visually with the naked eye, providing a high degree of visualization.

[0035] 3. The fastener preload detection device provided by the present invention is not dependent on the specific structure of the fastener and does not require that the head and tail faces of the fastener be flat, thus having a wide range of applications. Attached Figure Description

[0036] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of the luminescent coating structure of a fastener predictive force detection device according to an embodiment of the present invention;

[0038] Figure 2 This is a top view of the internal structure of a fastener predictive force detection device according to an embodiment of the present invention;

[0039] Figure 3 This is a perspective view of a fastener predictive force detection device according to an embodiment of the present invention;

[0040] Figure 4 This is a simplified block diagram of a fastener predictive force detection device according to an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram illustrating the calibration relationship between the preload and luminous intensity ratio according to an embodiment of the present invention.

[0042] The components are: 1-Outer shell; 2-Bolt sleeve; 3-Stepper motor; 4-Handle; 5-Power supply; 6-Central processing chip; 7-Wire; 8-Light sensor; 9-Bevel gear; 10-Display screen. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0044] This embodiment provides a fastener preload detection device, including: a power switch 5, a light sensor 8, a bolt sleeve 2, a stepper motor 3, and a display component; wherein, the top of the preload display component includes a display screen 10, and the bottom is connected to the light sensor 8. The preload display component integrates a central processing chip 6, and the central processing chip 6 is connected to the light sensor 8 and the display screen 10 through wires 7; a gap is formed between the bolt sleeve 2 and the outer shell 1, and the light sensor 8 is embedded in the inner side of the outer shell 1.

[0045] The intelligent fastener product based on force-light response needs to be compatible with the specifications of the screw sleeve 2. During the tightening process, the luminescent coating of the intelligent fastener product emits light of different colors. The light sensor 8 receives the light signal and transmits it to the central processing chip 6. The central processing chip 6 calculates the preload value based on the change of the light signal and displays it on the display screen 10.

[0046] The outer edge of the screw sleeve 2 is 1-3mm lower than the outer edge of the outer shell 1 to facilitate the formation of a gap for optical signal transmission. The screw sleeve 2 must be a replaceable part that can be adapted to at least one of the following: double hexagonal head bolts, hexagonal head bolts, cylindrical head bolts, and pan head bolts, and the bolt size range is M3-M24. The optical sensor 8 includes at least one of the following: photosensitive element, photocell, photodiode, phototransistor, CCD, or CMOS.

[0047] The calibration relationship between preload and Ia / Ib, i.e. the correspondence between preload and the ratio of luminous intensity, was established through calibration tests.

[0048] This embodiment provides a detection method for a fastener preload detection device, mainly including the following steps:

[0049] 1. Preparation of Smart Photoresponsive Coating for Fasteners

[0050] (1) Fastener head pretreatment

[0051] The stress-bearing contact surfaces of the fasteners are sandblasted using approximately 200-mesh white fused alumina to improve coating adhesion. The fasteners are then thoroughly cleaned with petroleum ether and ethanol and dried in an oven for later use.

[0052] (2) Coating preparation

[0053] 4g of transparent adhesive polytetrafluoroethylene was dissolved in 10g of xylene solution, and 1.6g of blue luminescent material CaAl2O4:Eu was added. The mixture was stirred until homogeneous and set aside. Similarly, 1.6g of red luminescent filler (Sr,Ca)AlSiN3:Eu was added to prepare another set of coatings.

[0054] (3) Preparation of luminescent coating

[0055] Apply red luminescent paint to the inner ring of the fastener's stress-bearing contact surface, with a coating radius of half the head radius and a coating thickness controlled within 200 μm. When the coating is semi-dry, apply blue luminescent paint to the outer ring, also with a thickness controlled within 200 μm, ensuring the outer ring coating thickness is slightly lower than the inner ring. Curing this product in an 80℃ oven for 1 hour yields the intelligent photoresponsive coating. The light signal emitted by the coating will change accordingly with the application of preload.

[0056] 2. Setup of the detection device

[0057] Handle 4 and preload display component: Made of ABS engineering plastic injection molding, handle 4 is ergonomically designed with anti-slip texture on the grip area, and a 5-inch LCD display screen 10 is embedded in the top, which can display the preload value and dynamic curve in real time. The stepper motor 3 and central processing chip 6 are fixed in the internal bracket. The central processing chip 6 is mainly used for optical signal analysis and processing and real-time calculation of preload value, which is transmitted to the display screen 10 for accurate display.

[0058] The detachable screw sleeve 2 is compatible with M3-M24 bolts. The outer edge of the screw sleeve 2 is 1-3mm lower than the outer edge of the outer shell 1, forming a light signal receiving gap, and has two built-in light sensors 8.

[0059] 3. Preload test

[0060] The smart fastener based on force-light response can emit two colors of light, namely blue light and red light, during tightening and stress. The two different colors of light have different response trends to mechanical stimuli, which causes the ratio of the intensity of the two lights to change with the change of preload.

[0061] The optical sensor 8 detects the spectral information of the light signal, and the central processing chip 6 obtains the luminous intensity of blue and red light based on the spectral information, labeled Ia and Ib respectively. As the tightening process proceeds, the preload gradually increases, and Ia and Ib will show different trends. The trends of Ia and Ib are used to quantitatively calibrate the preload, establishing a calibration relationship between Ia / Ib and the preload to obtain a calibration curve. By calculating the value of Ia / Ib, the preload value can be obtained instantly, achieving high preload detection accuracy.

[0062] In practical applications, a matching bolt sleeve 2 is fitted onto the end of the intelligent luminous fastener. A stepper motor 3 tightens the fastener at a set speed. The pressure between the fastener and the connected component changes the luminous intensity of the coating. Two light sensors 8 receive their respective light signals and transmit them to the central processing chip 6. The central processing chip 6 calculates Ia / Ib based on stored calibration values ​​and converts it into a preload value in real time, which is then displayed on the display screen 10.

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fastener preload detection device, characterized in that, include: The fastener comprises a power switch (5), a light sensor (8), a bolt sleeve (2), a stepper motor (3), and a display component. The power switch (5) is connected to the stepper motor (3) and is used to control the start and stop of the stepper motor (3). The stepper motor (3) drives the bolt sleeve (2) to rotate, which is used to tighten the fastener. The luminescent coating of the fastener emits light of different colors when subjected to force, and the luminescence intensity changes with the magnitude of the force. The light sensor (8) receives a specific light signal, and the display component is connected to the light sensor (8) and is used to calculate and display the preload value.

2. The fastener preload detection device according to claim 1, characterized in that, The display component includes a display screen (10) and a central processing chip (6); the input terminal of the central processing chip (6) is connected to the light sensor (8) for processing light signals and calculating the preload value; the display screen (10) is connected to the output terminal of the central processing chip (6) for displaying the preload value.

3. The fastener preload detection device according to claim 2, characterized in that, Also includes: The power switch (5) and the stepper motor (3) are connected by the wire (7); the two ends of the central processing chip (6) are connected to the light sensor (8) and the display screen (10) respectively by the wire (7).

4. The fastener preload detection device according to claim 1 or 3, characterized in that, Also includes: The bevel gear (9) is driven by the stepper motor (3) to rotate at a constant speed, thereby causing the bolt sleeve (2) to rotate at a constant speed.

5. The fastener preload detection device according to claim 4, characterized in that, Also includes: The outer casing (1) is installed outside the bolt sleeve (2) with a gap; the outer edge of the bolt sleeve (2) is lower than the outer edge of the outer casing (1).

6. The fastener preload detection device according to claim 5, characterized in that, The bolt sleeve (2) is a replaceable part.

7. The fastener preload detection device according to claim 5, characterized in that, The optical sensor (8) is installed on the inside of the housing (1).

8. The fastener preload detection device according to claim 1, characterized in that, Also includes: Handheld structure; the handheld structure includes: a shell (1) and a handle (4); The power switch (5), the bolt sleeve (2), the stepper motor (3), and the display component are all mounted on the housing (1).

9. A detection method for the fastener preload detection device according to any one of claims 1 to 8, characterized in that, It includes three steps: (1) Preparation of luminescent coating for fasteners; (2) Construction of fastener preload detection device; (3) Fastener preload test.

10. The detection method of the fastener preload detection device according to claim 9, characterized in that, Step (1) includes the following steps: 1) Pre-treatment of fastener top The stress-bearing contact surfaces of the fasteners are sandblasted with white fused alumina, and the fasteners are cleaned with petroleum ether and ethanol. They are then dried in an oven for later use. 2) Preparation of luminescent coating A blue luminescent coating was prepared by dissolving polytetrafluoroethylene in xylene solution, adding blue luminescent powder, and stirring until homogeneous. Similarly, a red luminescent coating was prepared by adding red luminescent powder and stirring until homogeneous. 3) Preparation of luminescent coating Red luminescent coating is applied to the inner ring of the stress-bearing contact surface of the fastener. The radius of the inner ring luminescent coating is half the radius of the stress-bearing contact surface, and the thickness is less than 200μm. When the red luminescent coating is semi-dry, blue luminescent coating is applied to the outer ring. The thickness of the luminescent coating is lower than that of the inner ring. The fastener is then placed in an oven for curing. The luminescent coating preparation is complete.

11. The detection method of the fastener preload detection device according to claim 9, characterized in that, Step (2) includes the following steps: 1) Fabrication of the handheld structure The handle and shell of the handheld structure are injection molded from ABS engineering plastic. The handle is ergonomically designed and has anti-slip texture. 2) Install the display components and stepper motors. An LCD display is embedded in the top of the handheld structure housing, and the stepper motor and central processing chip are fixed inside the housing by a bracket; 3) Install bolt sleeves and light sensors The bolt sleeve is installed inside the handheld structure housing, with its outer edge 1-3mm lower than the housing. Two light sensors are installed on the inner side of the housing.

12. The detection method of the fastener preload detection device according to claim 9, characterized in that, Step (3) includes the following steps: The light sensor detects the intensity of blue light Ia and the intensity of red light Ib. The central processing chip calculates the ratio of Ia to Ib, obtains the preload value based on the calibration relationship between the ratio of light intensity and the preload, and displays it on the screen in real time.

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