Washer, fastening structure, and fastening release method

Abstract

To enable a washer to be loosened simply for maintenance or the like when it is not loosened in a fastening state.SOLUTION: A fastening structure is configured such that a nut 1 is applied to a tip portion of a screw rod 12 with a washer 2 interposed therebetween to fix an object 11 to be attached to a member 13 to be attached. The nut 1 comprises a first surface 1A having a slope part 1Aa formed along a circumferential direction so that a height gradually decreases in a tightening rotation direction. The washer 2 has a second surface 2A having a slope part 2Aa along the circumferential direction so as to correspond to the slope part 1Aa of the first surface 1A. The washer 2 and the nut 1 are superposed one on top of the other so that the slope part of the first surface 1A and the slope part of the second surface 2A are engaged. Outer shapes of the nut 1 and the washer 2 match in the circumferential direction in the state where the slope part 1Aa of the first surface 1A and the slope part 2Aa of the second surface 2A are superimposed one on top of the other so that they are engaged without any gap.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a washer, a fastening structure, and a fastening and releasing method. [Background technology]

[0002] There have long been many practical methods for preventing loosening, such as the use of spring washers, double nuts, and split pins passing through the nut and bolt. However, these methods are often ineffective and can cause loosening due to vibration, or the mechanisms and processing are complex and expensive.

[0003] In response to this, there have been proposed locking pin mechanisms in which a lock pin is inserted into a hole on the inner surface of the nut to expand the inner surface of the nut and generate anti-loosening pressure; and a locking pin mechanism in which a locking pin insertion hole is drilled diagonally through a position slightly away from the inner surface of the nut, a locking pin that is slightly longer than the length of the locking pin insertion hole and has a sharp tip is inserted, and then the nut is turned by hand to fit and tighten the male threads of the bolt until it reaches the washer, and then the nut is tightened firmly with a commercially available tool such as a wrench to fix the object to be fixed between the two washers; when the nut is tightened further, the locking pin is pressed against the washer and the tip of the lock pin comes into firm contact with the male threads, pressing the male threads and creating an anti-loosening effect; and when the locking pin is tightened even more, the tip of the lock pin bites into the male threads like a stake, further increasing the anti-loosening effect (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-293793 A [Patent Document 2] JP 2011-179679 A Summary of the Invention [Problem to be solved by the invention]

[0005] The devices described in Patent Documents 1 and 2 fix the nut by expanding the inner surface of the nut or by inserting the tip of the lock pin into the threaded rod of the bolt. Therefore, if the nut is loosened for maintenance, for example, the threaded portion of the threaded rod will be damaged, making it impossible to reuse the nut.

[0006] The present invention provides a washer, a fastening structure, and a fastening and releasing method that will not loosen when fastened and can be easily loosened for maintenance or the like, allowing the reuse of threaded rods, nuts, washers, etc. [Means for solving the problem]

[0007] The present invention relates to a fastening structure in which a threaded rod for attaching an object to be attached is passed through a mounting hole in a workpiece to protrude a tip portion of the threaded rod, a washer is sandwiched between the tip portion, and a nut is applied to fix the object to the workpiece, and the nut has a slope portion, and the slope of the slope portion is a linear, constant-angle upward plane from the lowest position to the highest position. The upward direction of the upward plane is opposite to the tightening rotation direction of the nut. The washer has a first surface, and the washer has a sloped surface formed to correspond to the sloped surface of the first surface of the nut. Tightening rotation direction of the nut and a second surface extending along the fixed angle, the washer and the nut are attached by stacking one on top of the other so that the sloping portion of the first surface and the sloping portion of the second surface mesh with each other, the outer shapes of the nut and the washer are formed to match in the circumferential direction when stacked one on top of the other so that the sloping portion of the first surface and the sloping portion of the second surface mesh with each other without any gaps, and the sloping surface of the sloping portion has a portion that exhibits an anti-loosening effect according to the fixed angle.

[0008] Here, "matching in the circumferential direction" means that the slopes of the sloped portions are in phase with each other, and when the nut and washer are placed on top of each other, the two sloped portions fit together perfectly with no gaps, making it appear as if they were a single nut. For example, in the case of a nut and washer with a hexagonal cross-section, the six corners that form the outer shape will also fit together in the same position.

[0009] In this way, the contact surface between the nut and the washer has a sloped portion where a corresponding slope of a predetermined shape is formed, so that when the nut and the washer are stacked one on top of the other, the sloped portion prevents the nut and the washer from loosening even when subjected to strong vibrations, and the fastened state is maintained. On the other hand, when it is desired to release the fastening, the fastening state can be easily released by rotating the washer and the nut together, without damaging the threaded rod, nut, washer, etc. Therefore, the components such as the threaded rod, nut, and washer can be reused.

[0010] In this case, as described in claim 2, it is preferable that the first surface and the second surface each have one, two, three, or six inclined surface portions of the same shape. In other words, it is preferable that the first surface and the second surface each have a number of inclined surface portions that is a number divisible by six.

[0011] As described in claim 3, it is desirable that the nut and the washer have a hexagonal cross section and have the same outer dimensions.

[0012] As described in claim 4, it is preferable that the surface of the washer opposite to the second surface be formed in a conical recess shape that is gradually recessed toward the center.

[0015] As described in claim 7, it is desirable that the outer peripheral surface of the inclined portion of one or both of the washer or the nut be a curved surface having a diameter the same as the parallel opposite side width of the washer or the nut, and that the curved surface rise from near the lowest position of the inclined portion.

[0016] The invention of claim 8 is a method for releasing the fastening structure of any one of claims 1 to 7, characterized in that it includes the steps of: using a tool having an engagement portion that engages with the outer periphery of a nut and a washer and a gripping portion connected to the engagement portion, engaging the engagement portion of the tool with the outer periphery of the nut and rotating the nut in a tightening rotation direction until the outer shapes of the nut and the washer are consistent in the circumferential direction; and, following the step, engaging the engagement portion of the tool with the washer in addition to the nut, and rotating the nut and the washer together in the loosening direction.

[0017] Furthermore, the invention of claim 7 provides a washer that is provided between a bolt head or a nut and an object to be attached when the object to be attached is attached to a workpiece using a bolt or a nut, the washer comprising first and second members that are used in a stacked state, the first member having a slope portion, the slope portion having a slope that is a linear, constant-angle upward plane from the lowest point to the highest point. The upward direction of the upward plane is opposite to the tightening rotation direction of the nut. The second member has a first surface, and the second member has a sloped surface formed to correspond to the sloped surface of the first surface of the first member. Tightening rotation direction of the nut and a second surface extending along the fixed angle, and when the first and second members are stacked one on the other so that the inclined surface portion of the first surface and the inclined surface portion of the second surface engage with each other without any gaps, the outer shapes of the first and second members are formed to match in the circumferential direction, and the inclined surface of the inclined surface portion has a portion that exhibits an anti-loosening effect according to the fixed angle.

[0018] The invention of claim 8 is a fastening structure in which a washer is provided between a bolt head or a nut and an object to be attached when the object to be attached is attached to a workpiece using the bolt or the nut, the washer comprising first and second members that are used in a stacked state, The first member has a slope portion, and the slope of the slope portion is a linear, constant-angle upward plane from the lowest point to the highest point. The upward direction of the upward plane is opposite to the tightening rotation direction of the nut. The second member has a first surface, Tightening rotation direction of the nutthe first member has a second surface that contacts the first surface of the nut and is formed to correspond to the slope of the first surface of the first member along the fixed angle, and when the first surface and the second surface are stacked one on the other so that they mesh with each other without any gaps, the outer shapes of the first and second members are formed to match in the circumferential direction, and the slope of the slope portion has a portion that exhibits an anti-loosening effect according to the fixed angle.

[0019] Claim 9 The invention is Claim 8 a step of using a tool having an engaging portion that engages with an outer periphery of a bolt head or nut, and a washer, and a gripping portion connected to the engaging portion, engaging the engaging portion of the tool with the bolt head or nut, and a member of the first and second members that is on the bolt head or nut side, and rotating the bolt head or nut and the member on the bolt head or nut side in a tightening rotation direction to bring the outer shapes of the first and second members into agreement in the circumferential direction, and a step of, subsequent to the step, engaging the engaging portion of the tool with the bolt head or nut and the first and second members, and rotating the bolt head or nut and the first and second members in a loosening direction. Effect of the Invention

[0020] The present invention utilizes a sloping portion that extends in the circumferential direction and forms a slope of a specified shape to form the contact surface of the bolt head or nut and the contact surface of the washer.The action of the sloping portion prevents loosening even when subjected to severe vibration, and when it is desired to release the fastening, the bolt head, nut, etc. can be easily loosened. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2A is a diagram showing a fastening structure according to the present invention, which is formed by combining a nut and a washer, and FIG. 2B is a diagram showing only the nut and the washer. [Diagram 2]3A and 3B show a nut used in the fastening structure (fastening structure having two inclined surfaces), in which FIG. 3A is a perspective view seen from above, and FIG. 3B is a perspective view seen from below. [Diagram 3] FIG. 13 is an explanatory diagram of a nut having one inclined surface portion. [Figure 4] 1A and 1B show a nut used in the fastening structure (fastening structure having three inclined surface portions), in which (a) is a perspective view seen from above, and (b) is a perspective view seen from below. [Diagram 5] 1A and 1B show a washer used in the fastening structure (fastening structure having two inclined portions), in which (a) is a perspective view seen from above, and (b) is a perspective view seen from below. [Figure 6] 1A and 1B show a washer used in the fastening structure (fastening structure having three inclined surface portions), in which (a) is a perspective view seen from above, and (b) is a perspective view seen from below. [Figure 7] Fig. 7(a)(b) shows an embodiment (fastening structure with two inclined surfaces) in which a rounded edge (disk portion) is provided at the bottom of the washer, and Fig. 7(a)(b) is a view similar to Fig. 5(a)(b). [Figure 8] Fig. 8(a)(b) shows an embodiment (fastening structure with three inclined surfaces) in which a rounded edge (disk portion) is provided at the bottom of the washer, and Fig. 8(a)(b) is a view similar to Fig. 5(a)(b). [Figure 9] FIG. 11 is a perspective view for explaining how the washer is less likely to loosen due to a change in position caused by rotation when the number of inclined surfaces is two, and is also a logical explanatory diagram of FIG. [Figure 10] 11A and 11B are diagrams showing position changes in the resistance to loosening of a washer used in the fastening structure. [Figure 11] FIG. 1 is a perspective view showing an example of a fastening structure using two washers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1(a) shows a fastening structure according to the present invention, which is formed by combining a nut and a washer, FIG. 1(b) shows only the nut and the washer, and FIG. 2 shows a nut used in the fastening structure (fastening structure having two inclined portions), where FIG. 2(a) is an oblique view seen from above and FIG. 2(b) is an oblique view seen from below.

[0023] As shown in Figures 1(a) and (b), one example of the fastening structure of the present invention is a structure in which a threaded rod 12 (e.g., the threaded rod portion of a bolt) extending from a member to be attached 13 is passed through a mounting hole in the member to be attached 11 so that a tip portion (tip threaded rod portion) of the threaded rod 12 protrudes from a surface 11a of the member to be attached 11 (the surface opposite to the surface that contacts the member to be attached 13), and a nut 1 is applied to the tip portion with a washer 2 sandwiched therebetween to fix the member to be attached 11 to the member to be attached 13.

[0024] 2(a) and (b), the nut 1 has two inclined surface portions 1Aa, 1Aa formed along the circumferential direction on the surface 1A (first surface) that overlaps and contacts the washer 2 so that the height gradually decreases toward the tightening rotation direction of the nut 1. Each inclined surface portion 1Aa forms one inclined surface.

[0025] The two sloped surface portions 1Aa, 1Aa have the same slope inclination angle and slope area, and are out of phase with each other in the circumferential direction, but have the same shape. In other words, half of the entire surface 1A of the nut 1 is formed as sloped surface portions 1Aa, 1Aa, each having a straight slope with a slope angle. The two sloped surface portions 1Aa, 1Aa have the same shape, but the shapes are relative to each other, and the lowest point of one slope (slope portion 1Aa) is the highest point of the other slope.

[0026] When there are two inclined surface portions 1Aa, there are two boundaries (boundaries) between the inclined surface portions 1Aa, and therefore two steps are formed. The height and shape of the two steps are the same. Therefore, for example, the same surfaces 1A (first surfaces) of two nuts 1 can be brought into contact with each other so that they overlap perfectly with no gaps.

[0027] 2(b), further explaining based on the slope portion 1Aa formed on the front half of the nut 1, part A is at the lowest position of the slope (of the slope portion 1Aa), and part B is at the highest position of the slope. The slope starts at the exact center of the opposite parallel sides of the hexagonal cross section, but as long as each half of the entire face 1A of the nut 1 is a slope portion 1Aa, 1Aa of the same shape with a straight slope at an inclination angle, the slope of the slope portions 1Aa, 1Aa may start at a position other than that shown in FIG. 2(b).

[0028] The inclination angle (=α°) of the slope from part A to part B is set so that the average height difference between parts A and B is always greater than 1 / 2 (1 / 1 (=1) when there is one slope, 1 / 3 when there are three, and 1 / 6 when there are six) of the thread pitch of the threaded rod 12. Strictly speaking, the average height difference means the average value, since there is a slight difference in height between the step on the inner circumference side and the step on the outer circumference side of the slope part 1Aa.

[0029] In the above embodiment, the slope of the slope portion 1Aa is formed as a linear, constant-angle ascending plane from portion A to portion B, but the slope may be formed in a spiral shape while maintaining the same inclination angle along the circumferential direction (arc direction) around the axis of the threaded rod 12. In this case, the slope of the slope portion becomes a curved surface along the circumferential direction. Nuts and washers having such a slope shape can be manufactured using, for example, a 3D printer.

[0030] Furthermore, the number of inclined surfaces is not limited to two, and in the case of a hexagonal nut, for example, any number that divides 6 may be used, such as one, three, or six. In the case of one inclined surface, for example in Fig. 2(b), a step is formed at part B, but as shown in Fig. 3, by lowering part B parallel to the surface 1Ab of the nut 1' so that it is flush while keeping the inclination angle of the inclined surface constant over the entire surface, the step at part B can be almost completely eliminated.

[0031] In other words, the inclined surface portions 1Aa, 1Aa in Fig. 2(b) are uniformly connected to each other at portion B, and as a result, it appears as if there is only one inclined surface portion 1Ab with the inclined surface continuing along the circumferential direction, as shown in Fig. 3. In this specification, this case is referred to as "the number of inclined surface portions is one" on surface 1A'.

[0032] When there is one sloped surface, the step height t of part A is twice the step when there are two sloped surfaces (see Fig. 2(b)). In Fig. 3, part D is taller than part C, so the thickness of the nut is thicker at part D than at part C. In contrast, in the case of Fig. 2(b) which has two sloped surfaces 1Aa, 1Aa, parts D and C are the same height (the nut has the same thickness).

[0033] 4(a) and (b) show a nut 21 having three inclined surface portions. The nut 21 has three inclined surfaces 21Aa, 21Aa, 21Aa on its surface 21A.

[0034] On the other hand, as shown in Fig. 5(a), the washer 2 also has two inclined surfaces 2Aa, 2Aa formed on the surface (second surface) that comes into contact with the nut 1, which have exactly the same shape and the same inclination angle as the contact side of the nut 1. In relation to the external shape of the hexagonal cross section, the inclination start position of the inclined surfaces 2Aa, 2Aa is also the same as the inclined surfaces 1Aa, 1Aa on the nut 1 side. Therefore, when the inclined surfaces 1Aa, 1Aa, 2Aa, 2Aa of the nut 1 and the washer 2 are brought into contact with each other and overlapped, the nut 1 and the washer 2 overlap with no gaps. This is because the positions of the inclined surfaces 1Aa, 1Aa, 2Aa, 2Aa are aligned in phase between the nut 1 and the washer 2.

[0035] Both the nut 1 and the washer 2 have a hexagonal cross section and the same external dimensions, but the washer 2 has a cylindrical engagement portion 2A having inclined surfaces 2Aa, 2Aa provided on a washer body 2B having a hexagonal cross section. The engagement portion 2A forming the mating surface (contact surface) with the nut 1 is cylindrical with an outer diameter r that is the same as the parallel opposite side width AF of the washer 2, and rises from the washer body 2B near the lowest position of the inclined surface 2Aa (see FIG. 5(a)).

[0036] The outer peripheral surface of the portion where the inclined portion is formed is machined into a cylindrical round shape to form a curved surface, but the outer peripheral surface of the portion where the inclined portion 1Aa on the nut 1 side is formed rather than the washer 2 side may be machined into a curved surface, or the outer peripheral surfaces of both the portions where the inclined portions on the washer 2 side and the nut 1 side are formed may be machined into a curved surface.

[0037] The back surface 2Ba of the washer 2 is not a flat surface, but has a gradually tapered recessed shape from the outer periphery of the washer 2 toward the center, that is, a conical recessed shape, as shown in FIG. 5(b).

[0038] In other words, the rear surface 2Ba is slightly recessed toward the center. Therefore, for example, when the washer 2 is placed on a horizontal surface, only the outer periphery comes into contact with the horizontal surface, and the center portion is floating above the horizontal surface and does not come into contact with the horizontal surface.

[0039] The size of such a recess on the back surface 2Ba gradually becomes smaller as the nut 1 is rotated and tightened, being pushed against the underside of the nut, but it is desirable to set it so that it finally becomes zero (= the entire surface of the washer 2, including the central portion, comes into contact with a horizontal surface) when the nut 1 reaches the specified tightening force against the threaded rod 12 (bolt).

[0040] 6(a) and (b) show a washer 22 having three inclined portions. The inclined portions correspond to the three nuts 21 shown in Fig. 4(a) and (b), and the engaging portion 22A has three inclined portions 22Aa, 22Aa, 22Aa. The engaging portion 22A is provided on the upper side of the washer body 22B.

[0041] The size of the taper angle that forms such a recess is determined taking into consideration the thickness and material of the washer 2. For example, if the washer is for M16, is made of hardened carbon steel, and is 4 mm thick, the taper angle is only about 0.5°. This is a size that can be felt by hand.

[0042] In addition, the washer 2 has the engagement portion 2A provided on the washer body 2B, but as in the washer 23 shown in Figures 7(a) and (b), a rounded edge, i.e., an annular disk portion 23C, which is integral with the washer 22, can be attached to the lower part of the washer body 22B, which has a hexagonal cross-section, and a recess 23Ca, which is a conical recess-shaped depression, can be formed on the underside of this disk portion 23C.

[0043] In this way, when the nut is tightened, the outer shape of the washer is larger than that of a hexagonal cross section, and the surface of the object to which the washer (disk portion 23C) comes into contact is less likely to be damaged. This has been confirmed by experiments. The diameter of the disk portion 23C is set to be equal to or greater than the distance between the corners of the nut 1, i.e., the washer 2. FIGS. 8(a) and 8(b) show a washer 24 having a structure similar to that of the washer 23 shown in FIGS. 7(a) and 7(b), in which the engagement portion 24A has three inclined portions 24Aa, 24Aa, and 24Aa. The engagement portion 24A is provided on the upper side of the washer body 24B, and includes a disk portion 24C having a recess 24Ca.

[0044] Next, the principle of preventing the nut from loosening in the fastening structure will be described. As shown in FIG. 1, when vibration is applied to a nut 1 and a washer 2 fastened together, the threaded rod 12 does not rotate, and the nut 1 rotates (counterclockwise) to loosen.

[0045] The nut 1 and washer 2 are assembled and integrated as shown in Figure 1, so if the nut 1 and washer 2 were to rotate together, the anti-loosening effect would not be achieved. However, with the fastening structure shown in Figure 1, the washer 2 would not rotate, and only the nut 1 would try to rotate.

[0046] The reason is that the maximum diameter of the contact surface between nut 1 and washer 2 is r, as shown in Figure 5(a). On the other hand, the maximum diameter of the surface (back surface) where washer 2 comes into contact with object 11 to be attached is R. Whether nut 1 rotates first relative to washer 2 or washer 2 rotates first relative to the surface due to vibration depends on the size of their respective effective friction diameters, provided that the friction coefficients are the same.

[0047] In this embodiment, since R>r, the force of washer 2 clinging to the surface (i.e., not slipping or rotating) prevails, so washer 2 does not slip or rotate, and nut 1 rotates first.

[0048] Furthermore, the back surface of washer 2 tapers gradually toward the center, forming a conical recess shape with a small inclination angle, so when the tightening force of nut 1 is small, only the six corners of washer 2, which has a hexagonal cross section, come into contact with the surface. As it is tightened with a stronger force, the entire back surface of washer 2 gradually comes into contact with the surface, and when this happens, the effective friction diameter of the back surface becomes approximately the average value of dimensions R and r. On the other hand, the effective friction diameter of the side of washer 2 that comes into contact with nut 1 is the average value of dimensions r and the washer inner diameter, so the former value is also larger. In other words, washer 2 does not slide around.

[0049] 5, the relationship R>r is utilized under the condition that the coefficient of friction is almost the same on the front surface (slope portion 2Aa) and the back surface 2Ba of the washer 2. However, by performing a surface treatment (for example, by baking or applying a fluororesin) only on the front surface side that makes the coefficient of friction much smaller than that of the back surface 2Ba, it is possible to eliminate the annular processing for forming the engagement portion 2A and form the slope portion directly on the washer body 2B, as in the case of the nuts shown in FIGS. 2 to 4. However, the surface treatment tends to peel off if the washer is tightened with a strong force.

[0050] Furthermore, because the back surface of the washer is concave, if it is made of iron, the washer will be elastic, and the pressing force on the outer periphery of washer 1 will contact the surface stronger than the pressing force on the inner diameter. This has the effect of relatively increasing the effective friction diameter (= roughly the average value of dimension R and the inner diameter of the washer) of the back surface, calculated geometrically above, and further increases the frictional force that holds washer 1 to the surface to prevent it from turning. This has been confirmed by testing an M16 nut, which shows that the washer will not turn.

[0051] If washer 2 does not rotate, nut 1 will rotate in a direction that loosens it from the washer surface (counterclockwise) due to vibration, etc., but when nut 1 tries to rotate, the inclined surface of nut 1 and washer 2 presses washer 2 strongly against the surface. In other words, it has the same effect as tightening a threaded rod (bolt) even more strongly than when it is tightened. Therefore, nut 1 will not loosen.

[0052] A prototype for M16 was manufactured, and in a vibration test in which the nut was tightened with a torque of 30 Nm, it was confirmed that while a normal nut would loosen after being subjected to approximately several thousand vibrations, the product of the present invention did not loosen at all even after approximately one million vibrations in a test under the same conditions. Furthermore, when loosening, it could be easily loosened with a torque of around 25 to 40 Nm.

[0053] When nut 1 is tightened, the contact surface between nut 1 and washer 2 exerts the same uniform pressure force on all surfaces. However, once nut 2 begins to loosen due to vibration, the direction of the contact slope of both the nut and washer rises in a straight line from part A to part B, whereas the direction of the rotation of the nut trying to loosen is always tangent to the arc, so the relative angle at which the nut and washer slide against each other on their contact surfaces will differ depending on the contact position.

[0054] For example, as shown in Figure 9, at the lowest position where the slope begins (θ=0° in Figure 9), the inclination angle in the tangent direction to the arc is 0°, so it does not contribute to the difficulty of loosening. On the other hand, at the position of θ=90°, the tangent direction and the direction of the slope are the same, so the inclination angle of this part is at its maximum, α°. In other words, it is the slope that is most difficult to loosen.

[0055] Figure 10 shows a theoretical calculation of the change in position that affects the resistance of a washer to loosening when there are two inclined surfaces, with the lowest point of the inclination (part A in Figure 2(b)) set to 0° and the highest point (part B in Figure 2(b)) set to 180°, for an M16 (thread pitch 2 mm) washer with a slope angle of 3.5°.

[0056] In Figure 10, the "loosening difficulty ratio" is the theoretical step H of the slope that occurs when the nut goes around a circle while maintaining the slope angle at that position, divided by the thread pitch P (=H / P). When this value is 1.0, the step is equivalent to the thread pitch, so that position becomes the boundary between whether the nut will loosen or not.

[0057] If the value is below 1.0, the anti-loosening effect is not exerted at the contact surface. Looking at Figure 10, from the start position to around 30°, and from the maximum position of 180° to around 150°, the value is below 1.0, so it does not contribute to the anti-loosening effect, but from 30° to around 150° the multiplier is over 1.0, so it does have an anti-loosening effect, and at the 90° position the multiplier is close to 2.0, providing the best anti-loosening effect.

[0058] Incidentally, when tightening the nut 1, a general tool, such as a hexagonal wrench (or a twelve-sided wrench) having an engagement portion that engages with the outer periphery of the bolt head or nut and washer, and a gripping portion that is connected to the engagement portion, can be used to rotate the nut 1 in the tightening rotation direction.

[0059] It is the same as tightening a normal nut. Because there is a step between nut 1 and washer 2, when you rotate only nut 1, washer 2 also rotates automatically and is tightened. Because they overlap, it is also possible to use a wrench on both nut 1 and washer 2 to rotate them together.

[0060] When loosening, simply rotating nut 1 will not loosen it. It is necessary to use a wrench on both nut 1 and washer 2 and rotate them simultaneously in the loosening direction. When initially tightened, nut 1 and washer 2 are aligned, but if vibrations cause the nut 1 and washer 2 to shift in the circumferential direction over time, it is possible that the wrench will fit on nut 1 but not on washer 2. In this state, it will not be possible to loosen the nut.

[0061] In such a case, you can use a wrench to turn the nut 1 in the tightening direction, and then align the outer shape of the washer 2 with the outer shape of the nut 1. The wrench will then drop and catch on both the nut 1 and the washer 2, and you can then turn the nut 1 and the washer 2 together in the loosening direction. In other words, you need to take a two-step procedure: turn the nut 2 in the tightening direction once, and then loosen it again.

[0062] In this way, by rotating the nut 1 and the washer 2 together, the threaded rod, nut, washer, etc. can be loosened without damaging them, and the fastened state can be easily released, so that the components such as the threaded rod, nut, and washer can be reused.

[0063] In the above-mentioned embodiment, the fastening structure is a combination of a nut having a sloping portion and a washer, but the present invention is not limited to this, and the same effect can be obtained when two washers having a sloping portion (see FIG. 5) are combined to form a flat washer and used in the same way as a normal flat washer, as shown in FIG. 11. 13 is a normal nut.

[0064] That is, by making two washers 2, 2 as shown in Fig. 5 and fitting them together so that the surfaces (second surfaces) on which the inclined portions 2Aa, 2Aa are formed are brought into contact with each other, a pair of washers with an external shape having a hexagonal cross section is produced. If an adhesive is applied to the inclined portions 2Aa, they become one and can be treated as a single washer (the washer of the present invention).

[0065] In this way, by placing the present invention under the head of a commercially available normal hexagonal nut or hexagonal bolt, the effect of preventing the nut or bolt from loosening can be obtained in the same way as in the above-mentioned embodiment. Note that the back surface of the washer on the side that comes into contact with the bolt head or nut can be a flat surface instead of a conical recessed surface with a central portion.

[0066] Then, when tightening the nut, the nut and washer are aligned and tightened together with a tool such as a wrench. Even if the nut becomes misaligned due to vibration, it can be loosened as a unit by tightening the nut back down and aligning it with the washer. [Explanation of symbols]

[0067] 1,1,13,21 Nut 1A,1A',21A side 1Aa, 1Ab, 21Aa Slope 2,22,23,24 Washers 2A,22A,23A,24A Engagement part 2Aa,22Aa,23Aa,24Aa Slope section 2B, 22B, 23B, 24B Washer body 23C, 24C Disc Section 2Ba,23Ca,24Ca Back side 11 Mounting object 11a surface 12 Threaded rod 13 Mounting member

Claims

1. A fastening structure in which a threaded rod for attaching an object to be attached is inserted into a mounting hole in a workpiece to protrude a tip portion of the threaded rod, and a washer is sandwiched between the tip portion and a nut is applied to fix the object to the workpiece, The nut has a slope portion, the slope portion being a linear, constant-angle ascending plane from the lowest point to the highest point, and the ascending direction of the ascending plane is opposite to the tightening rotation direction of the nut. The washer has a second surface having a slope portion formed in correspondence with the slope portion of the first surface of the nut along a tightening rotation direction of the nut, The washer and the nut are attached by being stacked one on top of the other so that the inclined surface of the first surface and the inclined surface of the second surface are engaged with each other, The outer shapes of the nut and the washer are formed to match in the circumferential direction when they are stacked one on the other so that the inclined surface of the first surface and the inclined surface of the second surface mesh with each other without any gaps, The inclined surface of the inclined surface portion has a portion that exerts an anti-loosening effect according to the fixed angle. A fastening structure characterized by:

2. 2. The fastening structure according to claim 1, wherein the first surface and the second surface each have one, two, three or six inclined surfaces of the same shape.

3. 3. The fastening structure according to claim 1, wherein the nut and the washer have a hexagonal cross section and have the same external dimensions.

4. The fastening structure according to any one of claims 1 to 3, wherein the washer has a surface opposite to the second surface formed into a conical recess shape that is gradually recessed toward a center portion.

5. The outer peripheral surface of the inclined portion of one or both of the washer and the nut is a curved surface having a diameter equal to the width of the parallel opposite sides of the washer or the nut, The fastening structure according to any one of claims 1 to 4, wherein the curved surface rises from near the lowest position of the inclined surface portion.

6. A method for releasing the fastening structure according to any one of claims 1 to 5, comprising the steps of: A tool having an engagement portion that engages with the outer periphery of the nut and the washer and a grip portion that is connected to the engagement portion is used, a step of engaging an engagement portion of the tool with an outer periphery of the nut and rotating the nut in a tightening rotation direction so that the outer shapes of the nut and the washer coincide with each other in the circumferential direction; A method for releasing a fastening fastener, comprising, subsequent to the above step, a step of engaging an engagement portion of the tool with the washer in addition to the nut, and rotating the nut and the washer together in a loosening direction.

7. A washer that is provided between a bolt head or a nut and an object to be attached when the object to be attached is attached to a workpiece using a bolt or a nut, The device comprises first and second members that are used in a stacked state, The first member has a slope portion, and the slope of the slope portion is a linear, constant-angle ascending plane from the lowest position to the highest position, and the ascending direction of the ascending plane is opposite to the tightening rotation direction of the nut. The second member has a second surface having a slope portion formed in correspondence with the slope portion of the first surface of the first member along a tightening rotation direction of the nut, the first and second members are formed so that their outer shapes coincide with each other in a circumferential direction when the first and second members are stacked one on the other so that the inclined surface portion of the first surface and the inclined surface portion of the second surface mesh with each other without any gaps; The inclined surface of the inclined surface portion has a portion that exerts an anti-loosening effect according to the fixed angle. A washer characterized by the above.

8. A fastening structure in which a washer is provided between a bolt head or a nut and an object to be attached when the object to be attached is attached to a workpiece using the bolt or the nut, The washer includes first and second members that are used in a stacked state, The first member has a slope portion, and the slope of the slope portion is a linear, constant-angle ascending plane from the lowest position to the highest position, and the ascending direction of the ascending plane is opposite to the tightening rotation direction of the nut. The second member has a second surface that is in contact with the first surface of the nut and has a slope portion formed in a tightening rotation direction of the nut in correspondence with the slope of the first surface of the first member, When the first surface and the second surface are stacked one on the other so as to mesh with each other without any gap, the outer shapes of the first and second members are formed to coincide with each other in the circumferential direction, The inclined surface of the inclined surface portion has a portion that exerts an anti-loosening effect according to the fixed angle. A fastening structure characterized by:

9. A method for releasing the fastening structure according to claim 8, comprising the steps of: A tool having an engagement portion that engages with the outer periphery of the bolt head or nut and washer, and a grip portion that is connected to the engagement portion is used, a step of engaging an engagement portion of the tool with the bolt head or nut and one of the first and second members that is located on the bolt head or nut side, and rotating the bolt head or nut and the member located on the bolt head or nut side in a tightening rotation direction to make the outer shapes of the first and second members coincide with each other in the circumferential direction; A method for releasing fastening, comprising, following the above step, a step of engaging an engagement portion of the tool with the bolt head or nut and the first and second members, and rotating the bolt head or nut and the first and second members in a loosening direction.

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