Bolt axial force estimation device

Abstract

To provide a bolt axial force measurement device capable of easily and accurately estimating bolt axial force of a bolt fastening part.SOLUTION: A bolt axial force measurement device according to the present invention comprises: column parts 5, 6 facing each other in the radial direction; gripping parts 3, 4 joined to one ends of the column parts 5, 6, respectively, equipped with suction mechanism parts 3a, 4a, can grip a bolt 2; an imaging unit 7 for imaging a head top surface 2a of the bolt 2; an imaging base part 9 to which the imaging unit 7 is fixed; a slide rail 50 extending in the radial direction and fixed to the imaging base part 9; reciprocating mechanism parts 10, 11 joined to the other ends of the column parts 5, 6, movable along the slide rail 50 and moving the column parts 5, 6 in the radial direction with respect to the imaging base part 9; and a center holding mechanism 12 including a rotation operation part 13 and a link mechanism joined to the rotation operation part 13 and the other ends of the column parts 5, 6. When the rotation operation part 13 is rotated, the radial length of the link mechanism changes, the column parts 5, 6 and the reciprocating mechanism parts 10, 11 move in the radial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for measuring the axial force of a bolt, and more particularly to an apparatus for estimating the axial force of a bolt at a bolted portion of a machine structure. [Background technology]

[0002] Bolting, one of the main joining technologies for mechanical structures, is characterized by lower joining costs than other joining technologies such as welding, ease of disassembly, and excellent maintainability. In general, the axial force of a bolt changes over time after it is fastened. In recent years, there has been an increasing need to manage the axial force of each bolt at the time of manufacture and maintenance in order to improve the reliability of mechanical structures.

[0003] The most common method for managing bolt axial force is the torque management method, which manages the tightening torque according to the size and strength class of the bolt. However, in the torque management method, friction affects the relationship between the tightening torque and the axial force, so the estimation error of the axial force is relatively large at about 30%. There are several methods for quantifying the variation in the bolt axial force, such as measuring the axial force with a bolt gauge with a strain gauge embedded in the bolt, and measuring the bolt elongation with ultrasonic waves to calculate the axial force. However, there are not many cases where these methods have been applied to the management of the axial force of bolts in mass-produced products. The reason for this is that the amount of equipment required for measurement and the number of work steps are expected to increase. Therefore, technology is being developed to estimate the axial force of a bolt using the difference in the amount of deformation of the bolt head before and after tightening and the relationship between the bolt axial force and the amount of deformation of the bolt head. The relationship between the bolt axial force and the amount of deformation of the bolt head can be obtained in advance by means of finite element method (FEM) analysis or other means.

[0004] An example of a conventional bolt axial force estimation device is described in Patent Document 1. The bolt axial force estimation device described in Patent Document 1 includes a tightening machine that tightens a bolt into a fastened member, a range finder that acquires a distance image measuring the distance to the bolt head, and a control means that controls the relative attitude of the range finder's image sensor. This bolt axial force estimation device captures distance images when the bolt is provisionally tightened and when it is fully tightened, and can accurately measure the bolt axial force from the correlation between the difference in the amount of dent of the bolt head between provisionally tightened and fully tightened and the bolt axial force. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-096707 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the bolt axial force estimation device described in Patent Document 1, a distance meter acquires distance images and measures the amount of dent at a first timing when the tightening machine provisionally tightens the bolt and a second timing when the tightening machine fully tightens the bolt. At this time, a manipulator controller for driving the manipulator changes the relative attitude of an image sensor that captures an image of the bolt head in accordance with the rotation angle of the bolt from the first timing to the second timing. This cancels out the change in the orientation of the bolt head before and after the bolt is tightened, making it possible to accurately calculate the difference in the amount of displacement of the bolt head.

[0007] However, the device described in Patent Document 1 needs to be equipped with a control device including a tightening machine, a distance meter, and a manipulator controller, and a drive mechanism (manipulator) for moving the tightening machine and the distance meter. Such conventional bolt axial force estimation devices are large in size and require complicated operation, making it difficult to apply the device to measuring the bolt axial force when tightening a bolt in a narrow space in a mechanical structure or to measuring the axial force of a bolt that has already been tightened in a mechanical device. For this reason, there is a demand for a bolt axial force measurement device that is easy to carry and handle, and can measure the bolt axial force easily and with high accuracy.

[0008] An object of the present invention is to provide a bolt axial force measuring device that can estimate the bolt axial force of a bolted portion simply and with high accuracy. [Means for solving the problem]

[0009] a center holding mechanism including a link mechanism connected to the rotational operation unit and the other end of the column, the link mechanism being configured to rotate about the axial direction of the held bolt, and a link mechanism connected to the rotational operation unit and the other end of the column, the center holding mechanism being configured to rotate about the axial direction of the held bolt, and a link mechanism connected to the rotational operation unit and the other end of the column, the center holding mechanism being configured to hold the bolt in the radial direction ... When the rotary operation unit rotates, the length of the link mechanism in the radial direction changes, and the pillar portion and the reciprocating mechanism portion move in the radial direction. Effect of the Invention

[0010] According to the present invention, it is possible to provide an axial bolt force measuring device that can estimate the axial bolt force of a bolted portion simply and with high accuracy. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a front view of the bolt axial force estimation device according to the embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of the axial force estimation device as viewed obliquely from below. [Figure 3A] 13A and 13B are diagrams illustrating the operation of the center holding mechanism when a force for rotating the center holding mechanism in a clockwise direction is applied to the rotation operation part. [Figure 3B] 13A and 13B are diagrams showing the operation of the center holding mechanism, and show the center holding mechanism when the beam portion moves in the radial direction. [Figure 4A] FIG. 2 is a diagram illustrating the installation procedures (1) and (2) of the axial force estimation device. [Figure 4B] FIG. 11 is a diagram illustrating the installation procedure (3) of the axial force estimation device. [Figure 4C] FIG. 11 is a diagram illustrating the installation procedure (4) of the axial force estimation device. [Diagram 5] 4 is a flowchart showing a procedure for installing the axial force estimation device. [Figure 6A] FIG. 4 is a schematic diagram showing wiring from an imaging unit of the axial force estimation device to an imaging control device. [Figure 6B] FIG. 6B is a cross-sectional view taken along the arrows A and A' shown in FIG. 6A. [Figure 7A] FIG. 1 is a schematic diagram showing the axial force estimation device attached to a large diameter bolt. [Figure 7B] FIG. 1 is a schematic diagram showing the axial force estimation device attached to a medium diameter bolt. [Figure 7C] FIG. 1 is a schematic diagram showing the state in which the axial force estimation device is attached to a bolt with a small diameter. [Figure 8A] FIG. 13 is a diagram showing an axial force estimation device in which the gripping portion is in contact with the head of the bolt and the positioning portion is aligned with the top surface of the bolt. [Figure 8B] 8B is a cross-sectional view taken along the arrows E and E' shown in FIG. 8A. [Figure 9]13 is a perspective view of the suction mechanism of the gripping portion as viewed from the side that contacts the bolt. FIG. [Figure 10A] 13 is a diagram showing the non-fixed magnet and the fixed magnet provided in the attraction mechanism before the attraction mechanism attracts the head of the bolt. FIG. [Figure 10B] 13 is a diagram showing the non-fixed magnet and the fixed magnet provided in the attraction mechanism when the attraction mechanism is attracting the head of a bolt. FIG. [Figure 11A] FIG. 13 is a diagram showing an axial force estimation device in which an adsorption mechanism part is adsorbed to a head part of a bolt and a grip part is fixed to the head part of the bolt. [Figure 11B] 11B is a cross-sectional view taken along the arrows F and F' shown in FIG. 11A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The bolt axial force estimation device according to the present invention has good portability and handling properties, and can estimate the bolt axial force of a bolted portion simply and with high accuracy, and can easily measure, for example, the bolt axial force when a bolt is tightened in a narrow portion of a mechanical structure, or the axial force of a bolt that has already been tightened in a mechanical device. For example, the bolt axial force estimation device according to the present invention can easily and with high accuracy estimate the bolt axial force of a bolted portion of a mechanical structure such as a wind power generation facility by using a method such as digital image correlation (DIC).

[0013] Furthermore, the bolt axial force estimation device according to the present invention can be attached to a bolt in accordance with the diameter of the bolt, and when the bolt is gripped, the shooting center of the shooting unit can be aligned with the axial center of the bolt regardless of the diameter of the bolt.

[0014] Hereinafter, a bolt axial force estimation device according to an embodiment of the present invention will be described with reference to the drawings. In the drawings referred to in this specification, the same or corresponding components are given the same reference numerals, and repeated explanations of these components may be omitted. Note that the embodiments described below are merely illustrative of the embodiments of the present invention, and do not limit the contents of the invention. EXAMPLES

[0015] 1 is a front view of a bolt axial force estimation device 1 according to an embodiment of the present invention, and shows a basic configuration of the bolt axial force estimation device 1 according to the present embodiment. Hereinafter, the bolt axial force estimation device will also be simply referred to as the "axial force estimation device."

[0016] 1 shows a state in which an axial force estimation device 1 is attached to one of a plurality of arranged fastening elements. The fastening element is a bolt 2 made of a magnetic material, and constitutes a fastening structure together with a washer and a fastened body. Note that in this embodiment, the fastening element, or bolt 2, is a hexagonal bolt as an example, but the fastening element is not limited to a hexagonal bolt and can be a bolt of any shape, such as a square bolt or a circular bolt.

[0017] In the following, the axial direction of the bolt 2 is referred to as the "axial direction", the direction in which the axial force estimation device 1 (specifically, the first gripping portion 3 and the second gripping portion 4 described later) grips the bolt 2 is referred to as the "radial direction", and the direction perpendicular to the axial and radial directions is referred to as the "depth direction". In the following description, the axial direction for the axial force estimation device 1 is the axial direction in a state in which the axial force estimation device grips the bolt 2. The radial direction is the radial direction of the bolt 2. In FIG. 1, the axial direction is the up-down direction, the radial direction is the left-right direction, and the depth direction is the direction perpendicular to the paper surface.

[0018] 1 shows, as an example, a diagram in which the axial direction is the top-bottom direction (up-down direction) and the bolt 2 is located above the axial direction of the axial force estimation device 1. The axial force estimation device 1 can also be used when the axial direction is in a direction other than the top-bottom direction, for example, in the horizontal direction.

[0019] The axial force estimation device 1 includes a first gripping portion 3, a second gripping portion 4, a first pillar portion 5, a second pillar portion 6, a slide rail 50, an imaging portion 7, and an imaging base portion 9.

[0020] The first gripping portion 3 and the second gripping portion 4 are a pair of gripping portions that face each other and can hold the head of the bolt 2 by pinching it in the radial direction. The first gripping portion 3 and the second gripping portion 4 are joined to one end portion in the axial direction of the first column portion 5 and the second column portion 6, respectively. The axial force estimation device 1 is fixed to the bolt 2 by the gripping portions 3 and 4 pinching and holding the head of the bolt 2. The gripping portions 3 and 4 are each equipped with an adsorption mechanism portion 3a and 4a, and are fixed to the bolt 2 by adsorbing the bolt 2 through the action of the adsorption mechanism portion 3a and 4a. The bolt 2 has a bolt head surface 2a.

[0021] The suction mechanism parts 3a, 4a generate an attraction force to attract the bolt 2. The suction mechanism parts 3a, 4a are provided with positioning parts 3b, 4b, respectively, and are connected to the column parts 5, 6 so as not to rotate. The positioning parts 3b, 4b are flat parts protruding in the radial direction, and come into contact with the bolt head surface 2a.

[0022] The first pillar portion 5 and the second pillar portion 6 are a pair of members extending in the axial direction and facing each other. Reciprocating mechanisms 10 and 11 are joined to the other axial ends of the pillar portions 5 and 6, respectively.

[0023] The reciprocating mechanisms 10 and 11 are members that are installed on a slide rail 50 and are movable in the radial direction along the slide rail 50. The reciprocating mechanisms 10 and 11 connect the pillars 5 and 6 to the imaging base 9 via the slide rail 50, and move the pillars 5 and 6 relative to the imaging base 9 in the radial direction.

[0024] The slide rail 50 extends in the radial direction and is fixed to the imaging pedestal unit 9. The imaging unit 7 is fixed to the imaging pedestal unit 9 via a connection unit 8. The slide rail 50 is movable in the radial direction relative to the reciprocating mechanism units 10 and 11. The imaging unit 7 moves as the slide rail 50 moves.

[0025] The slide rail 50 and the reciprocating mechanisms 10, 11 are installed so as to be parallel in the radial direction when the gripping parts 3, 4 grip the head of the bolt 2. Therefore, even if the slide rail 50 and the reciprocating mechanisms 10, 11 move relatively in the radial direction, the distance from the photographing part 7 to the bolt top surface 2a can be kept constant.

[0026] The photographing unit 7 is a device for photographing the bolt head surface 2a, and can be composed of, for example, a camera. The photographing unit 7 is fixed to the photographing base 9 so that the photographing center (for example, the center of the lens) coincides with the axis of the bolt 2 in the radial and depth directions when the gripping units 3, 4 grip the head of the bolt 2.

[0027] The imaging base part 9 can be formed of a plate-like member, and the imaging part 7 is fixed to it via a connection part 8 .

[0028] The axial positions of the columns 5 and 6 of the slide rail 50 are fixed at predetermined positions. With this configuration, the distance between the photographing part 7 and the bolt top surface 2a is uniquely determined. Therefore, in this embodiment, the distance (photographing distance) from the photographing part 7 to the bolt top surface 2a can be kept constant.

[0029] In addition, the distance from the photographing part 7 to the bolt top surface 2a can be changed by changing the axial length of the connection part 8. For example, even if the size of the photographing part 7 changes, the distance between the photographing part 7 and the bolt top surface 2a can be set to an appropriate value by changing the axial length of the connection part 8.

[0030] The axial force estimation device 1 further includes a center holding mechanism 12, a rotation operation unit 13, and a handle 13a.

[0031] FIG. 2 is a perspective view of the axial force estimation device 1 as viewed obliquely from below.

[0032] 2, the axial force estimation device 1 includes two beam portions 14. The two beam portions 14 are members extending in the depth direction and face each other in the radial direction.

[0033] The pillar portion 5 has a pair of pillar portions 5a (the pillar portion 5a on the front side and the pillar portion 5a on the back side) that face each other in the depth direction. The pillar portion 6 has a pair of pillar portions 6a (the pillar portion 6a on the front side and the pillar portion 6a on the back side) that face each other in the depth direction. The pillar portions 5a and 6a are members that extend in the axial direction.

[0034] The pillars 5 and 6 have one axial end joined to the gripping portions 3 and 4, and the other axial end joined to the beam portion 14. That is, one end of a pair of pillars 5a (the front pillar 5a and the back pillar 5a) is joined to the gripping portion 3, and the other end joined to one beam portion 14. One end of a pair of pillars 6a (the front pillar 6a and the back pillar 6a) is joined to the gripping portion 4, and the other end joined to the other beam portion 14.

[0035] One beam portion 14 connects a pair of pillar portions 5a (the pillar portion 5a on the front side and the pillar portion 5a on the rear side) to each other. The other beam portion 14 connects a pair of pillar portions 6a (the pillar portion 6a on the front side and the pillar portion 6a on the rear side) to each other.

[0036] These parts are preferably joined by mechanical fastening, such as with bolts, but may be joined by other methods, such as welding or adhesives.

[0037] The center holding mechanism 12 includes a link mechanism and a rotation operation unit 13. The link mechanism includes two beams 14, a rotating plate 12a, a first link 12b, and a second link 12c. The rotation operation unit 13 and the rotating plate 12a are rotatable around the axial direction as the rotation axis. The link mechanism is joined to the rotation operation unit 13 and the other end of the pillars 5 and 6, and moves the pillars 5 and 6 in the radial direction when the rotation operation unit 13 rotates. As described later, the link mechanism is a mechanism that aligns the shooting center of the shooting unit 7 (e.g., the center of the lens) with the axis of the bolt 2.

[0038] The rotation operation unit 13 is a cylindrical member and includes a handle 13a. The rotation operation unit 13 can be rotated around the axial direction by the handle 13a. The rotation operation unit 13 is connected to the rotating plate 12a via a key groove 12d so as to transmit a rotational force applied by the handle 13a to the rotating plate 12a.

[0039] 4A to 4C , so that the rotation force applied by the handle 13a is not transmitted to the photographing base 9 to rotate the photographing unit 7. The rotation operation unit 13 is connected to the photographing base 9 so that the central axis of the rotation operation unit 13 coincides with the photographing center of the photographing unit 7 (for example, the center of the lens).

[0040] The rotary plate 12a rotates due to the rotational force of the rotary operation unit 13. A first link 12b and a second link 12c are connected to the rotary plate 12a.

[0041] The first link 12b and the second link 12c are rod-shaped members. The first link 12b is connected to one end of the rotating plate 12a and one of the beams 14. The second link 12c is connected to the other end of the rotating plate 12a and the other beam 14. When the rotating plate 12a rotates, the first link 12b and the second link 12c move in the rotation direction of the rotating plate 12a, causing the two beams 14 to move in the radial direction.

[0042] When the rotation operating unit 13 is rotated by the handle 13a, the link mechanism (rotating plate 12a, first link 12b, second link 12c, and two beam portions 14) provided in the center holding mechanism 12 changes its radial length as the two beam portions 14 move radially, and the pillar portions 5, 6 and the reciprocating mechanism portions 10, 11 move radially.

[0043] The rotating plate 12a and the two beam portions 14 are connected to the first link 12b and the second link 12c in such a manner that the degree of freedom of the rotation operation portion 13 in the rotational direction is not impaired.

[0044] The reciprocating mechanism unit 10 includes a pair of reciprocating mechanism units 10 (the reciprocating mechanism unit 10 on the front side and the reciprocating mechanism unit 10 on the rear side) facing each other in the depth direction. The reciprocating mechanism unit 11 includes a pair of reciprocating mechanism units 11 (the reciprocating mechanism unit 11 on the front side and the reciprocating mechanism unit 11 on the rear side) facing each other in the depth direction.

[0045] The slide rails 50 include a pair of slide rails 50 (a front slide rail 50 and a rear slide rail 50) facing each other in the depth direction.

[0046] The bolt axial force estimation device 1 according to this embodiment has the above-mentioned configuration, and when a rotational force is applied to the rotation operation unit 13, the rotating plate 12a rotates, causing the beam portion 14 and the column portions 5, 6 to move radially, and the gripping portions 3, 4 joined to the column portions 5, 6 move radially to change the facing distance. The gripping portions 3, 4 can change the facing distance between each other depending on the rotation direction of the rotation operation unit 13 while maintaining the horizontal angle by the reciprocating mechanism portions 10, 11 and the slide rail 50.

[0047] 3A and 3B are diagrams showing the operation of the center holding mechanism 12. In this embodiment, when the handle 13a is rotated clockwise as viewed from below (the side where the handle 13a is located), the gripping parts 3 and 4 approach each other, and when the handle 13a is rotated counterclockwise as viewed from below, the gripping parts 3 and 4 move away from each other.

[0048] 3A shows, as an example, the center holding mechanism 12 when a force to rotate clockwise as viewed from below (the side where the handle 13a is located) is applied by the handle 13a to the rotation operation unit 13. When the rotation plate 12a rotates due to the rotation force of the rotation operation unit 13, the first link 12b and the second link 12c move in the rotation direction of the rotation plate 12a, causing the two beam portions 14 to move in the radial direction.

[0049] 3B shows the center holding mechanism 12 when the two beams 14 move radially. When the two beams 14 move radially and approach each other, the pillars 5, 6 (FIGS. 1 and 2) also move radially and approach each other. Then, the gripping parts 3, 4 (FIGS. 1 and 2) joined to the pillars 5, 6 also move radially to change the opposing distance between them, and they move closer to each other and clamp the bolt 2. The pillars 5, 6 and the gripping parts 3, 4 move radially as the reciprocating mechanisms 10, 11 move radially along the slide rail 50.

[0050] When the axial force estimation device 1 is attached to the bolt 2 and the gripping portion 3 and the gripping portion 4 grip the bolt 2, the photographing center of the photographing portion 7 (for example, the center of the lens) coincides with the axial center of the bolt 2. When the slide rail 50 moves radially relative to the reciprocating mechanisms 10 and 11, the photographing base portion 9 moves radially and the photographing portion 7 moves. At this time, the photographing center of the photographing portion 7 coincides with the axial center of the bolt 2 due to the action of the first link 12b and the second link 12c.

[0051] The rotary operation unit 13 is connected to the photographing base 9 so that the central axis of the rotary operation unit 13 coincides with the photographing center of the photographing unit 7 (for example, the center of the lens). When the rotary operation unit 13 rotates, the first link 12b and the second link 12c move by the same angle in the rotation direction of the rotating plate 12a, and the two beams 14 move by the same distance in the radial direction. As a result, the reciprocating mechanism units 10, 11 and the columns 5, 6 move by the same distance in the radial direction relative to the slide rail 50. Therefore, the central axis of the rotary operation unit 13, the photographing center of the photographing unit 7, and the axis of the bolt 2 coincide with each other.

[0052] When estimating the bolt axial force by image analysis using digital image correlation (DIC), the displacement (e.g., displacement due to strain) occurring on the bolt head surface 2a is calculated. If the photographing center of the photographing unit 7 does not coincide with the axis of the bolt 2, this mismatch must be corrected, and it is not easy to calculate the displacement occurring on the bolt head surface 2a.

[0053] In the bolt axial force estimation device 1 according to the present embodiment, the photographing center of the photographing unit 7 coincides with the axial center of the bolt 2, so that the bolt axial force can be easily estimated.

[0054] The photographing unit 7 (FIGS. 1 and 2) fixed to the photographing base 9 does not rotate even when the rotating plate 12a rotates about the axial direction due to the rotational force of the rotation operation unit 13. As described above, the rotation operation unit 13 is connected to the photographing base 9 via the bearings 9a (FIGS. 4A to 4C) and the like, so that the rotational force of the rotation operation unit 13 is not transmitted to the photographing base 9 and the photographing unit 7 does not rotate even when the rotation operation unit 13 rotates.

[0055] When estimating the bolt axial force by image analysis using digital image correlation (DIC), a random pattern is formed on the top surface of the bolt 2, and the bolt axial force estimation device 1 estimates the bolt axial force by photographing this random pattern with the photographing unit 7. When the photographing unit 7 rotates, the orientation of the photographed random pattern changes, so when estimating the bolt axial force, it is necessary to correct the effect of the rotation of the photographing unit 7.

[0056] In the bolt axial force estimation device 1 according to the present embodiment, since the photographing unit 7 does not rotate, there is no need to correct the influence of the rotation of the photographing unit 7, and the bolt axial force can be easily estimated.

[0057] Next, a procedure for attaching the bolt axial force estimation device 1 according to this embodiment to the bolt 2 will be described with reference to FIGS. 4A to 4C and FIG.

[0058] Fig. 4A is a diagram for explaining installation procedures (1) and (2) of the bolt axial force estimation device 1 according to this embodiment. Fig. 4B is a diagram for explaining installation procedure (3) of the bolt axial force estimation device 1. Fig. 4C is a diagram for explaining installation procedure (4) of the bolt axial force estimation device 1.

[0059] 4A to 4C, the imaging base unit 9 includes a bearing 9a. The rotation operation unit 13 is connected to the imaging base unit 9 via the bearing 9a.

[0060] In this embodiment, the suction mechanism parts 3a, 4a (only the suction mechanism part 4a is shown in Figs. 4A to 4C) generate an adhesive force by rotating, and therefore are provided with a lever or a handle for rotating the suction mechanism parts 3a, 4a. That is, in this embodiment, when the suction mechanism parts 3a, 4a are rotated by the lever or the handle, they generate an adhesive force and can adsorb the bolt 2. An example of the configuration in which the suction mechanism parts 3a, 4a generate an adhesive force will be described later.

[0061] Fig. 5 is a flow chart showing the installation procedure of the bolt axial force estimation device 1 according to the present embodiment. Fig. 5 shows installation procedures (1) to (5). Installation procedures (1) to (4) shown in Fig. 5 correspond to installation procedures (1) to (4) shown in Figs. 4A to 4C.

[0062] In step (1) shown in FIG. 4A and FIG. 5, the gripping portion 3 of the axial force estimating device 1 is brought into contact with the head of the bolt 2, and the positioning portion 3b of the gripping portion 3 is aligned with the bolt head surface 2a.

[0063] In step (2) shown in FIGS. 4A and 5, the gripping portion 3 is attracted to the head of the bolt 2 by the suction mechanism 3a (not shown in FIGS. 4A to 4C), and the gripping portion 3 is fixed to the head of the bolt 2.

[0064] In step (3) shown in FIG. 4B and FIG. 5, the rotation operation unit 13 is rotated by the handle 13a, and the grip unit 4 is moved until it comes into contact with the head of the bolt 2.

[0065] In step (4) shown in FIG. 4C and FIG. 5, the suction mechanism 4 a sucks the gripping portion 4 to the head of the bolt 2 , and the gripping portion 4 is fixed to the head of the bolt 2 .

[0066] In step (5) shown in FIG. 5, after the axial force estimation device 1 is fixed to the bolt 2, which is the object to be measured, in steps (1) to (4) above, the bolt top surface 2a is photographed by the photographing unit .

[0067] The image captured in step (5) can be subjected to image analysis using, for example, digital image correlation (DIC), and the bolt axial force of the bolt fastening portion can be estimated from the distribution of the amount of displacement, such as strain, generated on the bolt head surface 2a. Note that, in this embodiment, the image analysis is performed using the digital image correlation method as an example, but any other method can be used as the image analysis method.

[0068] As already explained, in the bolt axial force estimation device 1 according to this embodiment, the slide rail 50 and the reciprocating mechanisms 10, 11 are installed radially parallel, so that when the gripping part 4 moves radially, the distance from the photographing part 7 to the bolt top surface 2a can be kept constant.

[0069] The imaging control device analyzes the image of the bolt top surface 2a, calculates the amount of displacement caused on the bolt top surface 2a due to strain, etc., and calculates the bolt axial force. The imaging control device estimates the axial force of the bolt 2 by analyzing the image captured by the imaging unit 7 (camera) using an image analysis method such as digital image correlation (DIC). The imaging control device can be configured with a calculation device such as a computer, and may be provided in the axial force estimation device 1, or an external device not provided in the axial force estimation device 1 may be used. The imaging control device is connected to the axial force estimation device 1 by wire or wirelessly.

[0070] Fig. 6A is a schematic diagram showing wiring from the imaging unit 7 to the imaging control device 16 of the bolt axial force estimation device 1 according to this embodiment. Fig. 6B is a cross-sectional view taken along the arrows A and A' shown in Fig. 6A.

[0071] In this embodiment, the imaging unit 7 and the imaging control device 16 are connected to each other by a cable 15. The cable 15 is a wire arranged to pass through the inside of the rotary operation unit 13, which is a cylindrical member. With this configuration, the rotary operation unit 13 and the cable 15 have independent degrees of freedom in the rotational direction (direction around the axial direction) of the rotary operation unit 13, and it is possible to prevent deformation such as twisting of the cable 15 when the rotary operation unit 13 rotates.

[0072] Cable 15 is responsible for transmitting commands to capture images and information about captured images, and may also serve as a power supply function to imaging unit 7 depending on the specifications of imaging unit 7. The power supply line to imaging unit 7 may be a wiring different from cable 15.

[0073] Furthermore, the imaging unit 7 and the imaging control device 16 may be connected to each other wirelessly.

[0074] 7A to 7C, it will be described that the bolt axial force estimation device 1 according to this embodiment can be attached to the bolt 2 regardless of the diameter of the bolt 2.

[0075] Fig. 7A is a schematic diagram showing the state in which the axial force estimation device 1 is attached to a large-diameter bolt 2. The lower diagram in Fig. 7A shows the axial force estimation device 1 attached to the bolt 2. The upper diagram in Fig. 7A is a cross-sectional view taken along the arrows B and B' shown in the lower diagram.

[0076] Fig. 7B is a schematic diagram showing the axial force estimation device 1 attached to a bolt 2 having a medium diameter. The lower diagram in Fig. 7B shows the axial force estimation device 1 attached to the bolt 2. The upper diagram in Fig. 7B is a cross-sectional view taken along the arrows C and C' shown in the lower diagram.

[0077] Fig. 7C is a schematic diagram showing the state in which the axial force estimation device 1 is attached to a bolt 2 having a small diameter. The lower diagram in Fig. 7C shows the axial force estimation device 1 attached to the bolt 2. The upper diagram in Fig. 7C is a cross-sectional view taken along the arrows D and D' shown in the lower diagram.

[0078] As shown in FIGS. 7A to 7C, the axial force estimation device 1 can be attached to the bolt 2 in accordance with the diameter of the bolt 2, and when the gripping portion 3 and the gripping portion 4 grip the bolt 2, the imaging center of the imaging portion 7 (e.g., the center of the lens) can be aligned with the axial center of the bolt 2 regardless of the diameter of the bolt 2.

[0079] Fig. 8A is a diagram showing the axial force estimation device 1 in which the gripping portion 3 is in contact with the head of the bolt 2 and the positioning portion 3b of the gripping portion 3 is aligned with the bolt top surface 2a. Fig. 8B is a cross-sectional view taken along the arrows E and E' shown in Fig. 8A.

[0080] The axial force estimation device 1 shown in Figs. 8A and 8B corresponds to the axial force estimation device 1 shown in Fig. 4A. Fig. 8B shows a dashed line 2b indicating the outline of the head of the bolt 2. In Figs. 8A and 8B, the head of the bolt 2 is in contact with the suction mechanism 3a. The head of the bolt 2 is attracted to the suction mechanism 3a and the suction mechanism 4a, and fixed to the gripping portion 3 and the gripping portion 4. The bolt 2 is thus gripped by the gripping portion 3 and the gripping portion 4.

[0081] The adsorption mechanism 3a and the adsorption mechanism 4a in this embodiment will be described with reference to Fig. 9 and Figs. 10A and 10B. In the following, the adsorption mechanism 4a provided in the second gripping unit 4 will be described as a representative of the adsorption mechanisms 3a and 4a. The adsorption mechanism 3a has the same configuration as the adsorption mechanism 4a. The adsorption mechanisms 3a and 4a and the bolt 2 are made of magnetic material.

[0082] Fig. 9 is a perspective view of the attraction mechanism 4a provided in the gripping part 4, seen from the side in contact with the bolt 2. The gripping part 4 is joined to one end of the pillar parts 6 (a pair of pillar parts 6a). As will be described with reference to Figs. 10A and 10B, the attraction mechanism 4a includes a fixed magnet 42 and a non-fixed magnet (not shown in Fig. 9), and the magnetic force of these magnets is defined as an attraction force 60. In Fig. 9, this attraction force 60 is indicated by an arrow.

[0083] 10A and 10B are diagrams showing a non-fixed magnet 41 and a fixed magnet 42 provided in the attraction mechanism 4a.

[0084] The attraction mechanism 4a includes a non-fixed magnet 41, a fixed magnet 42, and a magnet holder (not shown in FIGS. 10A and 10B) that holds the non-fixed magnet 41 and the fixed magnet 42.

[0085] The non-fixed magnet 41 has an N pole 41n and an S pole 41s, and is held by the magnet holding part so as to be rotatable around a rotation axis 70 in the radial direction (the direction in which the gripping parts 3 and 4 grip the bolt 2). The non-fixed magnet 41 rotates when a lever or handle provided on the attraction mechanism part 4a is operated. The rotation of the non-fixed magnet 41 is also referred to as the rotation of the attraction mechanism part 4a.

[0086] The fixed magnet 42 has an N pole 42n and an S pole 42s, and is fixed to a magnet holder. The fixed magnet 42 is fixed to a position where it is in contact with the non-fixed magnet 41 and faces the non-fixed magnet 41.

[0087] In this embodiment, as an example, the non-fixed magnet 41 and the fixed magnet 42 are disk-shaped. The non-fixed magnet 41 is rotatable around the central axis of the disk as a rotation axis 70.

[0088] FIG. 10A shows the non-fixed magnet 41 and the fixed magnet 42 before the attraction mechanism 4a attracts the head of the bolt 2.

[0089] Before attraction, i.e., when the attraction mechanism 4a is not attracting the head of the bolt 2, the N pole 41n of the non-fixed magnet 41 is arranged so as to contact the S pole 42s of the fixed magnet 42, and the S pole 41s of the non-fixed magnet 41 is arranged so as to contact the N pole 42n of the fixed magnet 42. For this reason, the magnetic force of the non-fixed magnet 41 and the fixed magnet 42 is generated only within these magnets and is not transmitted to the gripping portion 4.

[0090] Fig. 10B shows the non-fixed magnet 41 and the fixed magnet 42 when the attraction mechanism 4a attracts the head of the bolt 2. The non-fixed magnet 41 rotates 180 degrees from the state shown in Fig. 10A to the state shown in Fig. 10B.

[0091] When the attraction mechanism 4a attracts the head of the bolt 2, the N pole 41n of the non-fixed magnet 41 is arranged to contact the N pole 42n of the fixed magnet 42, and the S pole 41s of the non-fixed magnet 41 is arranged to contact the S pole 42s of the fixed magnet 42. In other words, the N poles and the S poles overlap between the non-fixed magnet 41 and the fixed magnet 42. Therefore, the magnetic force of the non-fixed magnet 41 and the fixed magnet 42 is transmitted to the gripping portion 4, generating an attraction force 60 shown in FIG. 9. Due to this attraction force 60, the attraction mechanism 4a provided in the gripping portion 4 attracts the head of the bolt 2, and the gripping portion 4 is fixed to the head of the bolt 2.

[0092] Fig. 11A is a diagram showing an axial force estimation device 1 in which the attraction mechanism 3a and the attraction mechanism 4a are attracted to the head of the bolt 2, and the gripping parts 3 and 4 are fixed to the head of the bolt 2. Fig. 11B is a cross-sectional view taken along the arrows F and F' shown in Fig. 11A. Fig. 11B shows the magnet of the attraction mechanism 3a provided in the gripping part 3 and the magnet of the attraction mechanism 4a provided in the gripping part 4, that is, the N pole 31n and the S pole 31s of the non-fixed magnet 31, the N pole 32n and the S pole 32s of the fixed magnet 32, the N pole 41n and the S pole 41s of the non-fixed magnet 41, and the N pole 42n and the S pole 42s of the fixed magnet 42.

[0093] The axial force estimation device 1 shown in Figures 11A and 11B corresponds to the axial force estimation device 1 shown in Figure 4C. In this axial force estimation device 1, the gripping portions 3, 4 are fixed in close contact with the head of the bolt 2 by the action of an attractive force 60 (Figure 9) due to a magnetic force.

[0094] Note that the suction mechanism units 3a, 4a are not limited to a configuration in which the magnetic force of a magnet is used as an attraction force, and may have any configuration as long as the axial force estimation device 1 can be fixed to the bolt 2 for which the bolt axial force is to be measured. For example, the suction mechanism units 3a, 4a may have a configuration in which the suction surface is attached to the head of the bolt 2 by a pressure difference between both sides of the suction surface in the radial direction, which is generated by drawing a vacuum between the bolt 2 and the suction surface. The suction mechanism units 3a, 4a may also have a configuration in which the bolt 2 is mechanically clamped and fixed by a toggle mechanism or the like.

[0095] In this embodiment, the photographing unit 7 is configured with a camera, but may be configured with a device other than a camera, for example, a displacement meter or a range finder using a laser beam. For example, the photographing unit 7 can be configured with a laser displacement meter capable of measuring the deformation amount of the head of the bolt 2 in a non-contact manner. The photographing unit 7 can also be configured with a range finder that irradiates a laser beam and measures the distance to the bolt head surface 2a and the shape of the bolt head surface 2a based on the information of the reflected light, for example, a range finder that uses LiDAR (Light Detection And Ranging). Even if the photographing unit 7 is configured with these devices, the axial force estimation device 1 can estimate the bolt axial force from the information on the deformation of the bolt head surface 2a.

[0096] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to an embodiment having all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete a part of the configuration of each embodiment, or to add or replace another configuration. [Explanation of symbols]

[0097] 1...bolt axial force estimation device, 2...bolt, 2a...bolt head surface, 2b...dashed line showing the outline of the bolt head, 3...first gripping portion, 3a...suction mechanism portion, 3b...positioning portion, 4...second gripping portion, 4a...suction mechanism portion, 4b...positioning portion, 5...first column portion, 5a...column portion, 6...second column portion, 6a...column portion, 7...photographing portion, 8...connecting portion, 9...photographing base portion, 9a...bearing, 10...reciprocating mechanism portion, 11...reciprocating mechanism portion, 12...center holding mechanism, 12a...rotating plate, 1 2b...first link, 12c...second link, 12d...key groove, 13...rotation operation part, 13a...handle, 14...beam part, 15...cable, 16...imaging control device, 31...non-fixed magnet, 31n...north pole, 31s...south pole, 32...fixed magnet, 32n...north pole, 32s...south pole, 41...non-fixed magnet, 41n...north pole, 41s...south pole, 42...fixed magnet, 42n...north pole, 42s...south pole, 50...slide rail, 60...adhesive force, 70...rotation axis of non-fixed magnet.

Claims

1. A pair of pillar portions facing each other in a radial direction, which is a direction in which the bolt is gripped; a pair of gripping portions each joined to one end of the column portion and capable of gripping the head of the bolt by sandwiching it in the radial direction; a suction mechanism section provided in each of the gripping sections, the suction mechanism section having a positioning section that comes into contact with a top surface of the bolt and is capable of suctioning the bolt; An imaging unit that images the top surface of the bolt; An imaging base to which the imaging unit is fixed; A slide rail extending in the radial direction and fixed to the imaging base portion; a reciprocating mechanism that is joined to the other end of the column and is movable in the radial direction along the slide rail and that moves the column in the radial direction relative to the imaging base; a center holding mechanism including a rotation operation part that can rotate around an axial direction of the gripped bolt as a rotation axis, and a link mechanism that is joined to the rotation operation part and the other end of the column; Equipped with When the rotary operation unit rotates, the length of the link mechanism in the radial direction changes, and the pillar unit and the reciprocating mechanism unit move in the radial direction. A bolt axial force estimation device characterized by the above.

2. the photographing unit is fixed to the photographing base unit so that a photographing center coincides with an axis of the bolt when the gripping unit grips the head of the bolt, The rotation operation unit is connected to the imaging base unit so that a central axis of the rotation operation unit and an imaging center of the imaging unit coincide with each other. The bolt axial force estimation device according to claim 1.

3. The rotation operation unit is connected to the imaging base unit via a bearing so that the imaging unit does not rotate. The bolt axial force estimation device according to claim 1.

4. The photographing unit is composed of a camera, The bolt has a random pattern formed on the top surface, The bolt axial force estimation device is connected by wire or wirelessly to an imaging control device that estimates the axial force of the bolt by analyzing the image captured by the imaging unit. The bolt axial force estimation device according to claim 1.

5. The photographing unit is composed of a displacement meter or a distance meter using laser light. The bolt axial force estimation device according to claim 1.

6. The attraction mechanism attracts the bolt by magnetic force. The bolt axial force estimation device according to claim 1.

7. The suction mechanism portion suctions the bolt by an air pressure difference. The bolt axial force estimation device according to claim 1.

Images