JP4977178B2 - Fastener, bolt and nut manufacturing method, and fastener fastening method - Google Patents

Description

  The present invention relates to a fastener having a function of preventing loosening, a method of manufacturing bolts and nuts used therein, and a method of fastening a fastener.

Usually, a plurality of bolts are used at the same location, and it is hardly considered that they are damaged during use unless they are loosened. In addition, the bolt has an excellent feature that the taper effect (wedge effect) of the screw enables powerful tightening even with thick members and can be easily loosened with a simple tool even when tightened. ing. On the other hand, even if it is tightened, the nut or bolt rotates backward during a long period of use, causing the phenomenon of “loosening”. Once loosening occurs, the repeated stress will continue until the part is retightened. As a result, an excessive stress is applied to the bolt, and the bolt is easily broken.
In particular, in screw fasteners (mainly bolts and nuts) used for moving parts or joints of members that receive vibration from the outside, even if they are properly tightened at the beginning, It was inevitable that the bolts were loosened by stress, and it was necessary to retighten them during the period of use.
Therefore, in order to solve these problems, various bolts having a function of preventing loosening and methods for manufacturing the same have been researched and developed in recent years.
For example, as a kind of double nuts and bolts, as in (Patent Document 1), coarse and fine screws are machined in the same place, and the coarse nuts are fitted inside and the fine nuts are fitted to the outside. Therefore, a bolt and nut fastening system that is extremely difficult to loosen has been proposed.
Such a double nut / bolt fastening system has the advantage that the screw fastening part does not loosen when a repeated load is applied, but at least two types of nuts must be used. In this respect, the user is not always satisfied sufficiently. In addition, since the bolt itself is not applied with a measure to improve fatigue strength, there are cases in which it is not possible to expect benefits such as reducing the number of bolts or securing more safety than current screw fasteners. It has also been desired to improve the fatigue strength of the bolt.
However, there are very few effective measures for improving the fatigue strength of bolts, and screw fasteners that have both a loosening prevention function and a measure for improving fatigue strength have not been studied.
In other words, although the bolt does not loosen, but the bolt is not strong enough, or even if it has sufficient strength, it is difficult to reduce the number of bolts and dimensions, etc. In addition, there is a problem that the size is likely to increase, the degree of freedom in design is lacking, and man-hours are required for drilling and bolt tightening.

Therefore, as a result of earnest research to solve these problems, the applicant of the present application has found that "a male screw portion of pitch p _b formed on at least the tip end side of the bolt shaft portion and a bolt head side of the male screw portion. Alternatively, a part of the top of the screw thread on the bolt cylindrical part side is removed, and a taper part in which the screw thread outer diameter is reduced toward the bolt head side or the bolt cylindrical part side, and the bolt head side from the minimum diameter part of the taper part or a and an incomplete thread removing unit formed by expanded slowly in an arc shape toward the bolt cylindrical portion, a female fastened screwed with pitch p _b and a male screw portion of the male threaded portion A bolt having a relationship of a screw pitch _pn of 0.003 ≦ (p _n −p _b ) / p _b ≦ 0.05 ”was filed as“ Patent Document 2 ”.
(Patent Document 2) is a single nut that not only has an excellent anti-loosening function and fastening force that is difficult to loosen even when subjected to repeated load (vibration), but also has a significantly improved fatigue strength, In addition to providing bolts with superior safety and reliability that could not be obtained with screw fasteners, the use of these bolts has a simple structure, a small number of parts, and a large number of bolts and nuts used and dimensions. To reduce the product size and weight, significantly reduce the man-hours required for drilling and tightening bolts, etc., and reduce the cost of the product. Product design flexibility and assembly workability The present invention provides a fastener with excellent practicality capable of remarkably improving the resistance.

Japanese Patent No. 3770320 Japanese Patent Application No. 2008-10975

However, as a result of further research, the invention described in the above (Patent Document 2) was found to have the following problems.
(1) (Patent Document 2), the pitch _{p b} of the male screw portion, the pitch _{p n} of the female screw which is fastened screwed with the male screw portion, 0.003 ≦ _(p n _-p b) / The male screw portion or female screw (nut) of the bolt must be formed so as to satisfy the relationship of p _b ≦ 0.05, but the pitch of the normal bolt or nut itself is the same over the entire length, When processing these, it is necessary to manufacture bolts or nuts from scratch using dedicated rolling dies or cutting taps with slightly different pitches, and ready-made bolts and nuts cannot be used, Productivity is lacking.
(2) Since it is necessary to provide a very slight pitch difference in conjunction with the pitch of bolts or nuts that should always be fitted, special rolling dies or cutting taps must be produced on order. Management is complicated and lacks in workability and mass productivity.

  The present invention solves the above-mentioned conventional problems, has a reliable loosening prevention function, can greatly improve fatigue strength, and has excellent safety that could not be obtained with conventional screw fasteners, Realizing reliability, drastically reducing the number and size of bolts and nuts used to reduce the size and weight of the product, as well as reducing the man-hours required for drilling and tightening bolts. Product cost can be reduced, product design flexibility, assembly workability, mass production can be significantly improved by providing a fastener with excellent practicality, and by simply processing bolts and nuts, Providing a bolt and nut manufacturing method that does not loosen even when subjected to repeated loads (vibration), has excellent fastening force, is low cost and has excellent mass productivity, and has a fatigue prevention strength, as well as a ready-made bolt Bolts and nuts can be firmly fixed by applying simple processing after screwing the nut, and it will not loosen even when subjected to repeated loads (vibration), and achieves excellent fastening force It aims at providing the fastening method of the fastener excellent in the safety | security which can be performed, and reliability.

In order to solve the above-described conventional problems, the fastener, bolt and nut manufacturing method and fastener fastening method of the present invention have the following configurations.
The fastener according to claim 1 of the present invention is a fastener having a bolt and a nut screwed to the bolt, and the bolt is formed on at least the tip end side of the bolt shaft portion. a male screw portion of the pitch p _b, the male threaded portion the bolt head side or a portion of the top of the bolt cylindrical portion of the thread is removed the bolt head side or thread outer diameter toward the bolt cylindrical portion of A taper portion having a reduced diameter, and an incomplete screw removing portion formed by gradually expanding in a circular arc shape from the minimum diameter portion of the taper portion toward the bolt head side or the bolt cylindrical portion side. and, wherein the nut has a female screw portion of the pitch p _n, at least (a) said bolt, the axial position of the top of the threads at least part of the thread of the male screw portion by plastically deforming a plastic deformation male screw portion which gave displaced in the direction, the plastic deformation The positional deviation amount d _{bp in} the axial direction of the screw thread of the male screw part and the pitch p _b of the male screw part have a relationship of 0.003 ≦ d _bp / p _b ≦ 0.05 or (b) The nut plastically deforms at least a part of the screw thread at the peripheral edge of the screw hole on the end surface, thereby shifting the position of the top of the screw thread in at least one of the radial direction and the axial direction of the screw hole. and plastic deformation has a female screw portion, and the positional deviation amount d _np of the axial thread of the plastic deformation female thread portion, the pitch p _n of the female screw _{portion, 0.003 ≦ d np / p n} ≦ It has the structure which is 0.05 relationship .
With this configuration, the following effects can be obtained.
(1) Plasticity in which the male screw part formed on at least the tip end side of the bolt shaft part and at least a part of the screw thread of the male screw part are plastically deformed so that the position of the top part of the screw thread is displaced in the axial direction. By using a bolt having a deformed male screw portion, when the nut corresponding to the male screw portion formed at a standard pitch is screwed, the plastic deformation male screw portion of the bolt and the female screw portion of the nut Appropriate frictional force is generated between screw threads to enable strong screwing and tightening, as well as to provide a large resistance in the loosening direction, providing an excellent anti-loosening function even when fluctuating stress is applied from the outside. Can be maintained. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability.
(2) Plastic deformation in which at least a part of the screw thread at the peripheral edge of the screw hole on the end surface is plastically deformed so that the position of the top of the screw thread is displaced in at least one of the radial direction and the axial direction of the screw hole. By using a nut having a female screw part, when an off-the-shelf bolt corresponding to the standard pitch of the nut is screwed, an appropriate frictional force is generated between the screw thread of the plastic deformation female screw part of the nut and the male screw part of the bolt. This makes it possible to provide strong screwing and tightening, and to impart a large resistance in the loosening direction, and to maintain an excellent anti-loosening function even when fluctuating stress is applied from the outside. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability.
(3) The axial displacement amount of the screw thread in the plastic deformation male screw portion of the bolt (position displacement amount of the screw thread tip) d _bp and the pitch p _b of the male screw portion of the bolt are 0.003 ≦ d _bp / P _b ≦ 0.05, so that an appropriate frictional force is generated between the screw thread of the plastic deformation male screw portion of the bolt and the female screw portion of the nut, thereby enabling strong screwing and tightening. A large resistance in the loosening direction can be imparted, and an excellent anti-loosening function can be maintained even when fluctuating stress is applied from the outside. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability. Due to the displacement of the screw thread of the plastic deformation male screw part, the top of the screw thread is displaced compared to the bottom of the screw valley, so that the pitch of the female screw part of the nut becomes larger than the pitch of the plastic deformation male screw part. A moderate frictional force is generated between the plastic deformation male screw portion and the screw thread of the nut based on the force to increase the distance between the screw threads of the plastic deformation male screw portion in the combined state and the force against the force. Can do.
(4) the positional displacement amount d _np of the axial thread of the plastic deformation female screw portion of the nut, the pitch p _n of the female screw portion of the nut, the _{0.003 ≦ d np / p n ≦} 0.05 relation As a result, an appropriate frictional force is generated between the male screw portion of the bolt and the plastic deformation female screw portion of the nut, enabling strong screwing and tightening and giving a large resistance in the loosening direction. It is possible to maintain an excellent loosening prevention function even when a fluctuating stress is applied from the outside. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability.
(5) A taper in which a screw thread outer diameter (nominal diameter) is reduced toward the bolt head side or the bolt cylindrical part side by removing a part of the top of the screw thread on the bolt head side or the bolt cylindrical part side of the male screw part. Since the height of each screw thread of the taper part screwed with the female screw part of the nut gradually decreases in inverse proportion to the surface pressure to be shared, the load of each screw thread of the taper part When the sharing is uniform and the nuts are screwed together, tension and bending stresses can be reduced from concentrating on the bottom of the threaded valley of the taper near the bolt head side or bolt cylindrical part side (inner side). The fatigue strength of can be greatly improved.
(6) Normally, stress concentration is likely to occur in the incomplete screw portion formed at the beginning of the male screw portion, but the circle gradually increases from the minimum diameter portion of the taper portion toward the bolt head side or the bolt cylindrical portion side. By forming the incomplete screw removal part by expanding the diameter in an arc shape, even if the taper part is formed, stress concentration hardly occurs in the incomplete screw removal part, and the fatigue strength improvement effect by the taper part can be maintained. it can.
(7) The action of the taper portion does not significantly increase the stress concentration of tension or bending at the bottom of the screw valley near the end surface inside the nut , but the pitch becomes smaller than the pitch p _b of the male screw portion of the bolt. deforming the plastically deformed male screw portion of the bolt, pitch than p _b of the male screw portion of either, or bolt pitch p _n of the female screw portion of the nut is set to be larger than the pitch of the plastic deformation male threaded portion If the plastic deformation female screw part of the nut is deformed in the direction in which it increases, in the normal (stationary) state, compressive stress is generated on the plastic deformation male screw part of the bolt or the screw valley bottom of the male screw part. Even if tensile stress is applied, this tensile stress and compressive stress cancel each other out, and the influence of external stress can be reliably suppressed, and the resistance to repeated fluctuating stress, which is the primary cause of fatigue failure, is greatly enhanced. Can be improved, it is possible to combine the fatigue strength and excellent anti-loosening feature.

Here, as the bolts, there are hexagon bolts, square bolts, eye bolts, round head bolts, flat head bolts, butterfly bolts, foundation bolts, hexagon socket head cap bolts, etc. having bolt heads, Examples of the male screw portion formed without the bolt head include an implanted bolt and a U bolt.
Regarding the material of bolts and nuts, the concept can be applied to metals or non-metals that can be plastically deformed. However, particularly effective are considered to be steel materials, soft metals such as copper, aluminum, titanium and magnesium, and alloys thereof.
Examples of the cross-sectional shape of the screw thread of the male screw part include a triangular screw, a trapezoidal screw, a square screw, a saw blade screw, and a round screw.

The plastically deformed male screw part may be formed by plastically deforming at least a part of the screw thread of the male screw part and shifting the position of the top of the screw thread in the axial direction. It should be noted that the displacement amount and the displacement direction of the top of each screw thread in the plastic deformation male screw portion need not be uniform or the same. Further, the positional deviation amount and the positional deviation direction need not be uniform or continuous in the circumferential direction, and may be intermittently or partially deformed.
The plastically deformed female screw portion plastically deforms at least a part of the screw thread at the peripheral edge of the screw hole on the end face, and the position of the top of the screw thread is displaced in at least one of the radial direction and the axial direction of the screw hole. You can do it. It should be noted that the displacement amount and displacement direction of the top of the thread of the plastic deformation female screw portion need not be uniform or continuous along the peripheral edge of the end surface of the screw hole, and may be intermittently or partially deformed. May be.

Here, it is preferable that the ratio of the amount of axial displacement d _{bp in} the axial direction of the top of the thread of the plastic deformation male screw portion to the pitch p _b of the male screw portion is 0.3% to 5%. As this ratio becomes smaller than 0.3%, the force to increase the distance between the screw threads of the relatively narrow pitch and the frictional force generated between the screw threads of the bolt and nut are reduced, and the looseness is prevented. There is a tendency that the function tends to be lowered, and as it becomes larger than 5%, the galling between the bolt and the nut is likely to occur, the tightening torque required for fastening is increased, and the workability is easily lowered. There is a tendency and neither is preferable.
Further, the positional deviation amount and the positional deviation direction of the top of the screw thread of the plastic deformation male screw part do not have to be uniform over the entire region, and the absolute value of the positional deviation amount is partially (partially) as described above. It suffices if it falls within the range (however, if there is a portion exceeding the upper limit, it will cause galling, which is not preferable).

Here, the ratio of the pitch p _n of the female screw portion in the axial direction of the displacement amount d _np of threads of the plastic deformation female screw portion is preferably 0.3% to 5%. As this ratio becomes smaller than 0.3%, the frictional force generated between the plastic deformation female screw portion of the nut and the screw thread of the male screw portion of the bolt tends to decrease, and the loosening prevention function tends to decrease. As it becomes larger than 5%, galling is likely to occur between the bolt and the nut, the tightening torque required for fastening increases, and the workability tends to be lowered, which is not preferable. Although threads of the plastic deformation female screw portion positional deviation in the radial direction is generated, the positional displacement amount d _na, the position displacement amount d _np and comparable axial thread of the plastic deformation female screw portion It is preferable that When the ratio to the pitch p _n of either parameter female screw portion of the displacement amount d _np of radial position deviation amount d _na and axially more than 5%, tends galling occurs, but not preferred, Even if the positional deviation amount _{dna in the} radial direction is smaller than 0.3%, if the partial positional deviation amount _{dnp in the} axial direction is within the above range, a good locking effect can be obtained.
Further, the amount of displacement and the displacement direction of the top of the thread of the plastically deformed female thread need not be uniform over the entire circumference of the thread, and may be partially within the above range ( However, the presence of a portion exceeding the upper limit is not preferable because it causes galling.)

The invention according to claim 2, a fastener according to claim 1, have a configuration in which at least a portion of the female screw portion of the nut is fastened screwed with the tapered portion of the bolt is doing.
With this configuration, in addition to the operation obtained in the first aspect , the following operation can be obtained.
(1) At least a part of the female screw portion of the nut is screwed to and tightened with the taper portion of the bolt, so that the screw thread of the taper portion of the end face on the bolt head side or the bolt cylindrical portion side (inner side) of the nut On the other hand, contact is made only at the tip of the screw thread of the nut, which is easy to bend, and the contact area is reduced. It is possible to improve the fatigue limit of the bolt.

Here, as described above, the material of the nut is preferably used as the bolt, but when a part of the hard metal is used, it is assumed that both the bolt and the nut are the same hard. In some cases, it is desirable to make the material of the nut that is difficult to break somewhat soft. Specifically, the relationship between Vickers hardness Hv _n Vickers hardness Hv _b and the nut of the bolt are preferably used those _{0.4 ≦ Hv n / Hv b ≦} 0.9. Positional displacement amount in the axial direction of the plastic deformation the male screw portion of the bolt d _bp or positional deviation amount d _np axial plastic deformation female screw portion of the nut, the male screw portion of the pitch p _n or bolts of the female screw portion of the nut smaller relative of p _b, the difference in hardness of the bolt and the nut can also be reduced, positional deviation amount d _bp, depending on d _np, each hardness Hv _b, range Hv _n described above You can choose from.

The invention according to claim 3 is the fastener according to claim 2 , wherein the nut is screwed to the taper portion of the bolt within a range of 50% to 80% of the total length of the female screw portion. It has the composition which is.
With this configuration, in addition to the operation obtained in the second aspect , the following operation can be obtained.
(1) When the nut is screwed with the taper portion of the bolt within a range of 50% to 80% of the total length of the female screw portion, the bottom of the screw taper portion on the inner end face side of the nut, which is a dangerous cross section, Therefore, the load sharing can be made uniform and the stress concentration of tension and bending can be alleviated and the contact per piece can be alleviated reliably and efficiently, and the fatigue strength is highly reliable.

Here, the nut is preferably screwed to the taper portion of the bolt within a range of 50% to 80% of the total length of the female screw portion. As the taper portion included in the fitting portion between the female screw portion of the nut and the male screw portion or the plastic deformation male screw portion of the bolt becomes less than 50% of the total length of the female screw portion, the fatigue strength is improved by the taper portion. As the amount exceeds 80%, the effect of improving the fatigue strength by the taper portion decreases, and the engagement between the female screw portion and the male screw portion or the plastic deformation male screw portion decreases, and the tightening force is reduced. There is a tendency to be lowered easily, and neither is preferable.
In addition, in order to make the position of the nut an optimum position, the length of the bolt shaft portion of the bolt is selected according to the thickness of the fastened body, but if necessary, the position of the nut can be adjusted by using a washer. A good fastening state can be obtained by adjusting, and an excellent fatigue strength and a loosening prevention function can be realized.

Invention of Claim 4 is a fastener of Claim 2 or 3 , Comprising: The said bolt of the said bolt which fits the screw thread of the said bolt head side or the said bolt cylindrical part side end of the said nut. The height of the thread of the taper portion is 10% to 75% of the height of the thread of the nut.
With this configuration, in addition to the operation obtained in the second or third aspect , the following operation can be obtained.
(1) The height of the thread of the taper portion that fits with the thread on the bolt head side or the end of the bolt cylindrical portion of the nut is 10% to 75% of the height of the nut thread. As a result, a sufficient tightening force can be secured and a reduction in safety can be prevented.

  Here, the height of the thread of the taper portion that fits into the thread on the bolt head side or the end of the bolt cylindrical portion of the nut is 10% to 75% of the height of the nut thread. It is preferable. As the height of the thread of the tapered portion that fits into the thread of the nut on the inner end face side of the nut, which is a dangerous cross section, becomes lower than 10% of the height of the thread of the nut, it may bear a tensile load. There is a tendency that it becomes difficult to obtain a sufficient fatigue strength improving effect, and as it becomes higher than 75%, there is a tendency that a fatigue strength improving action by the tapered portion is difficult to be obtained.

The bolt manufacturing method according to claim 5 of the present invention is the bolt manufacturing method according to any one of claims 1 to 4, wherein the bolt head side of the bolt shaft portion or the bolt cylinder. The incomplete screw removing portion that gradually decreases in a circular arc shape from the portion side toward the tip end side of the bolt shaft portion and the minimum diameter portion of the incomplete screw removing portion toward the tip end side of the bolt shaft portion a drawing step of forming a tapered portion which threads outside diameter is enlarged, the male thread portion formation step of forming by rolling or cutting the male screw portion of the pitch p _b at least front end portion of the bolt shank A male screw portion plastic deformation step of plastically deforming at least a part of the screw thread portion of the male screw portion to form a plastic deformation male screw portion in which the position of the top portion of the screw thread is displaced in the axial direction. , Axial position of the thread of the plastic deformation male screw part A displacement amount d _bp, pitch p _b of the male screw portion has a configuration is the relationship _{0.003 ≦ d bp / p b ≦} 0.05.
With this configuration, the following effects can be obtained.
(1) An incomplete screw removing portion and an incomplete screw removing portion that gradually reduce in diameter in an arc shape from the bolt head side or the bolt cylindrical portion side of the bolt shaft portion toward the tip end side of the bolt shaft portion in the drawing process. By forming a taper portion where the outer diameter of the screw thread (nominal diameter) increases from the minimum diameter portion toward the tip end side of the bolt shaft portion, almost no stress concentration occurs in the incomplete screw removal portion, Furthermore, the height of each screw thread of the taper portion screwed with the nut can be gradually decreased in inverse proportion to the surface pressure to be shared, and the load sharing of each screw thread of the taper portion is made uniform, and the nut Manufactures bolts that can significantly improve fatigue strength by mitigating the concentration of tensile and bending stresses on the bottom of the threaded portion of the taper section near the end face of the bolt head side or bolt cylinder side (inner side) can do.
(2) After forming the incomplete screw removal portion and the taper portion in the drawing process, the male screw portion and the plastic deformation male screw portion can be formed in the male screw portion forming step and the male screw portion plastic deformation step. It can be mass-produced at a low cost and has excellent productivity.
(3) A male screw part forming step of forming a male screw part by rolling or cutting at least on the tip end side of the bolt shaft part, and plastically deforming at least a part of the screw thread of the male screw part to Since there is a male screw part plastic deformation process that forms a plastically deformed male screw part whose position is shifted in the axial direction, the male screw part is formed at a standard pitch p _b in accordance with the standard as usual in the male screw part forming process. After that, in the male screw part plastic deformation process, the desired position of the screw thread of the male screw part is selectively (partially) plastically deformed in the axial direction according to the length of the bolt shaft part and the thickness of the fastened body. Thus, the plastically deformed male screw portion can be formed, and the productivity is excellent.
(4) By simply adding one male screw plastic deformation process to the normal male screw part forming process, it is possible to easily and reliably add a loosening prevention function, and to make effective use of existing bolts. Excellent in resource and resource saving.

Here, the bolt material is as described in claim 1. In order to form the bolt shaft portion, it is possible to use a metal, synthetic resin, or the like formed in a columnar shape or a conical shape.
Even when the male screw portion forming step is performed by rolling, it is not necessary to use a specially processed rolling die (round die or flat die), and the mass productivity is excellent.
The male screw part plastic deformation process may be any process that can be plastically deformed by shifting the position of at least a part of the screw thread of the male screw part in the axial direction.

Invention of Claim 6 is a manufacturing method of the volt | bolt of Claim 5 , Comprising: The said male screw part plastic deformation process makes a projection material collide with at least one part of the screw thread of the said male screw part. It has the structure provided with any one or more of the blasting process, the high pressure water injection process which injects high pressure water, and the pressing process which presses a pressing tool.
With this configuration, in addition to the operation obtained in the fifth aspect , the following operation can be obtained.
(1) The male screw part plastic deformation process may be any of a blasting process for causing a projection material to collide with at least a part of a screw thread of the male screw part, a high-pressure water jetting process for jetting high-pressure water, and a pressing process for pressing a pressing tool. By having one or more, the desired position of the male screw portion can be plastically deformed by a desired amount to easily add a loosening prevention function, and the mass productivity is excellent.

Here, as a blasting process, a granular projection material formed of a material such as cast iron, aluminum, zinc or the like, ceramic such as alumina or silicon carbide, synthetic resin such as polycarbonate, glass or the like is sprayed on the surface of the screw thread. The shot blasting that causes collision is preferably used. The material of the projection material can be appropriately selected according to the material of the bolt. Moreover, although the hardness of a projection material changes also with the material etc. of a volt | bolt, Hv = 800-1200 is preferable. As the hardness Hv of the projection material becomes smaller than 800, the amount of displacement of the screw thread in the axial direction becomes insufficient, and the initial purpose tends to be difficult to achieve. As the projection material becomes larger than 1200, the toughness of the projection material decreases. The durability tends to decrease, the projection material cannot be used repeatedly, and there is a tendency to lack resource saving, which is not preferable. The particle diameter of the projection material varies depending on the material and nominal diameter of the bolt, but the diameter φ is preferably 0.5 mm to 3 mm. As the diameter φ of the projection material becomes smaller than 0.5 mm, it becomes necessary to collide the projection material at a higher projection speed, and depending on the equipment, a sufficient projection speed cannot be obtained and the initial purpose tends to be difficult to achieve. Yes, as it becomes larger than 3 mm, the roughness of the surface with which the projection material collides becomes rough, and there is a tendency that the commercial value is lowered or the effect of improving the fatigue strength is hindered. Although the projection speed of a projection material changes also with the material of a bolt, a nominal diameter, etc., the projection speed v = 50m / s-200m / s is preferable. As the projection speed v of the projection material becomes slower than 50 m / s, it takes time to process, and the mass productivity tends to decrease. As the projection speed v becomes faster than 200 m / s, the amount of axial displacement of the screw thread increases. It becomes too large and tends to be galling at the time of fitting with a nut, which is not preferable.
The injection speed and the injection diameter of the high-pressure water in the high-pressure water injection process can be appropriately selected depending on the material and nominal diameter of the bolt. Moreover, a metal roller etc. are used suitably as a pressing tool used at a press process.

Method for producing a nut according to claim 7 of the present invention, there is provided a nut manufacturing method for the fastener according to any one of claims 1 to 4, a nut having a female screw portion of the pitch p _n A plastic deformation in which at least a part of the screw thread at the peripheral edge of the screw hole on the end face of the screw is plastically deformed so that the position of the top of the screw thread is displaced in at least one of the radial direction and the axial direction of the screw hole. includes a female threaded portion plastically deformed to form a female screw portion, and the positional deviation amount d _np of the axial thread of the plastic deformation female thread portion, the pitch p _n of the female screw portion, 0.003 ≦ d _The structure has a relationship of _np / p _n ≦ 0.05 .
With this configuration, the following effects can be obtained.
(1) Plastic deformation by plastically deforming at least a part of the screw thread at the peripheral edge of the end face of the screw hole and shifting the position of the top of the screw thread in at least one of the radial direction and the axial direction of the screw hole. Since it has a female screw part plastic deformation process for forming the female screw part, it is possible to easily add a loosening prevention function to the existing nut in the female screw plastic deformation process, and to effectively use the existing nut. It is excellent in mass productivity and resource saving.

Here, the nut material is as described in claim 1. The female thread plastic deformation step is plastically deformed so that at least a part of the thread on the peripheral edge of the end surface of the screw hole of the nut is displaced in at least one of the radial direction and the axial direction of the screw hole. Anything is acceptable. The plastically deformed female screw portion has a plurality of protrusions formed radially from the screw thread over the entire circumference of the peripheral edge of the screw hole, or a screw thread at the peripheral edge of the screw hole. Those that are displaced in the direction are preferably used. This is because the tightening force can be kept substantially uniform and a stable locking function can be maintained. When a plurality of protrusions are formed as the plastic deformation female screw portion, the distance (projection amount of the protrusion) from the top of the original screw thread of the female screw to the tip of the protrusion is the amount of the screw thread in the plastic deformation female screw portion. This corresponds to a positional deviation amount d _na in the radial direction.

Invention of Claim 8 is a manufacturing method of the nut of Claim 7 , Comprising: The said female screw part plastic deformation process collides a projection material with the peripheral part of the said screw hole of the said end surface of the said nut. A blasting process, a high-pressure water jetting process for jetting high-pressure water, and a pressing process for pressing the pressing tool.
With this configuration, in addition to the operation obtained in the seventh aspect , the following operation can be obtained.
(1) The female screw part plastic deformation process is any one or more of a blasting process in which the projection material collides with the peripheral part of the screw hole on the end face, a high-pressure water injection process for injecting high-pressure water, and a pressing process for pressing the pressing tool. Therefore, the peripheral portion of the screw hole on the end face can be plastically deformed by a desired amount to easily add a loosening prevention function, which is excellent in mass productivity.
Here, since the blasting process, the high-pressure water injection process, and the pressing process are the same as in the sixth aspect , the description thereof is omitted.

A fastener fastening method according to a ninth aspect of the present invention is the fastener fastening method according to any one of the first to fourth aspects, wherein the fastener is fastened on at least the tip end side of the bolt shaft portion. A portion of the male screw portion of the pitch p _b and the top of the screw thread on the bolt head side or the bolt cylindrical part side of the male screw part is removed, and the screw thread outside toward the bolt head side or the bolt cylindrical part side. A tapered portion having a reduced diameter, and an incomplete screw removing portion formed by gradually expanding in a circular arc shape from the minimum diameter portion of the tapered portion toward the bolt head side or the bolt cylindrical portion side, screwed step of screwing the nut having a female screw portion of the pitch p _n to bolt having plastic deformation step of plastically deforming at least a portion of the threads of the male screw portion of the bolt around the end face of the nut and The plastic deformation formed in the plastic deformation step The positional deviation amount d _{bp in} the axial direction of the screw thread of the male screw part and the pitch p _b of the male screw part have a relationship of 0.003 ≦ d _bp / p _b ≦ 0.05 . .
With this configuration, the following effects can be obtained.
(1) screwed step of screwing the nut to the bolt, Runode and a plastic deformation step of plastically deforming at least a portion of the threads of the male threaded portion of the bolt around the end face of the nut, in engagement step After screwing the bolt and nut formed according to the standard as usual, in the plastic deformation process, it is only necessary to plastically deform at least a part of the thread of the male screw part of the bolt around the end face of the nut. The anti-loosening function can be realized, the occurrence of loosening due to external force can be reliably suppressed throughout the period of use, troubles associated with loosening can be prevented, and workability, reliability, and maintainability are excellent.
(2) By simply adding one plastic deformation step to the normal screwing step, it is possible to easily and surely prevent loosening, and existing bolts and nuts can be used effectively, resulting in excellent mass productivity and resource saving.

The invention according to claim 10 is the fastening method of the fastener according to claim 9 , wherein the plastic deformation step collides a projection material with at least a part of a screw thread of the male screw portion of the bolt. A blasting process, a high-pressure water jetting process for jetting high-pressure water, and a pressing process for pressing the pressing tool.
With this configuration, in addition to the operation obtained in the ninth aspect , the following operation can be obtained.
(1) The plastic deformation process is any one of a blasting process in which a projection material collides with at least a part of a screw thread of a male screw part of a bolt, a high-pressure water injection process for injecting high-pressure water, and a pressing process for pressing a pressing tool. By having one or more, the screwed bolt can be plastically deformed by a desired amount at the peripheral edge of the screw hole on the end face of the nut, and a loosening prevention function can be easily added. Excellent.
Here, since the blasting process, the high-pressure water injection process, and the pressing process are the same as in the sixth aspect , the description thereof is omitted.
A fastening method for a fastener according to an eleventh aspect of the present invention is the fastening method for a fastener according to any one of the first to fourth aspects, wherein the fastener is formed at least on a tip end side of the bolt shaft portion. A portion of the male screw portion of the pitch p _b and the top of the screw thread on the bolt head side or the bolt cylindrical part side of the male screw part is removed, and the screw thread outside toward the bolt head side or the bolt cylindrical part side. A tapered portion having a reduced diameter, and an incomplete screw removing portion formed by gradually expanding in a circular arc shape from the minimum diameter portion of the tapered portion toward the bolt head side or the bolt cylindrical portion side, screwed step of screwing the nut on the bolt with a female screw portion of the pitch p _n, plastic deformation step of plastically deforming at least a portion of the threads of the peripheral portion of the screw hole of the nut around the end face of the nut And plasticity formed by the plastic deformation step A positional displacement amount d _np of the axial thread deformation female screw portion, the pitch p _n of the female screw portion, has a configuration is the relationship _{0.003 ≦ d np / p n ≦} 0.05 Yes.
With this configuration, the following effects can be obtained.
(1) A screwing step comprising: a screwing step of screwing a nut into a bolt; and a plastic deformation step of plastically deforming at least a part of a screw thread at a peripheral portion of a screw hole of the nut around the end surface of the nut. After screwing together the bolts and nuts formed in accordance with the standard as usual, in the plastic deformation process, just plastically deform at least a part of the screw thread at the periphery of the screw hole of the nut around the end face of the nut. It is possible to realize an excellent anti-loosening function, to reliably suppress the occurrence of loosening due to external force throughout the period of use, to prevent troubles associated with loosening, and to be excellent in workability, reliability and maintainability.
(2) By simply adding one plastic deformation step to the normal screwing step, it is possible to easily and surely prevent loosening, and existing bolts and nuts can be used effectively, resulting in excellent mass productivity and resource saving.
Invention of Claim 12 is the fastening method of the fastener of Claim 11, Comprising: The said plastic deformation process makes the projection material collide with the said peripheral part of the said screw hole of the said nut, It has the structure provided with any one or more of the high pressure water injection process which injects high pressure water, and the press process which presses a pressing tool.
With this configuration, in addition to the operation obtained in the eleventh aspect, the following operation can be obtained.
(1) The plastic deformation step has at least one of a blasting step for colliding the projection material with a peripheral portion of the screw hole of the nut, a high-pressure water injection step for injecting high-pressure water, and a pressing step for pressing the pressing tool. Thus, the screwed nut can be plastically deformed by a desired amount at the peripheral portion of the screw hole on the end face of the nut to easily add a loosening prevention function, which is excellent in workability and labor saving.
Here, since the blasting process, the high-pressure water injection process, and the pressing process are the same as in the sixth aspect, the description thereof is omitted.

As described above, according to the fastener, bolt and nut manufacturing method, and fastener fastening method of the present invention, the following advantageous effects can be obtained.
According to the first aspect of the invention, the following advantageous effects can be obtained.
(1) The bolt is formed at a standard pitch by having a plastic deformation male screw portion in which at least a part of the screw thread of the male screw portion is plastically deformed and the top portion of the screw thread is displaced in the axial direction. When a nut corresponding to the male screw part is screwed, an appropriate frictional force is generated between the screw thread of the plastic deformation male screw part of the bolt and the female screw part of the nut, enabling strong screwing and tightening In addition, a large resistance in the direction of loosening can be applied, and an excellent anti-loosening function can be maintained even when fluctuating stress is applied from the outside, ensuring the occurrence of loosening due to external force over a long period of use. It is possible to provide a fastener that can be suppressed and has excellent reliability and maintainability that can prevent troubles associated with looseness.
(2) The nut plastically deforms at least a part of the screw thread at the peripheral edge of the screw hole at the end face, thereby shifting the position of the top of the screw thread in at least one of the radial direction and the axial direction of the screw hole. By having a plastically deformed female screw part, when a ready-made bolt corresponding to the standard pitch of the nut is screwed, an appropriate frictional force is provided between the screw thread of the plastically deformed female screw part of the nut and the male screw part of the bolt. It can be generated, firmly screwed and tightened, can be given a large resistance in the loosening direction, and can maintain an excellent anti-loosening function even when fluctuating stress is applied from the outside. Thus, it is possible to reliably suppress the occurrence of loosening due to an external force throughout the period of use, and it is possible to provide a fastener with excellent reliability and maintainability that can prevent troubles associated with loosening.
(3) The axial displacement amount of the screw thread in the plastic deformation male screw portion of the bolt (position displacement amount of the screw thread tip) d _bp and the pitch p _b of the male screw portion of the bolt are 0.003 ≦ d _bp / P _b ≦ 0.05, a sufficient frictional force is generated between the screw thread of the plastic deformation male screw part of the bolt and the female screw part of the nut, enabling strong screwing and tightening, and loosening A large resistance in the direction can be applied to maintain an excellent anti-loosening function even when fluctuating stress is applied from the outside, and it is difficult to cause galling between the bolt and nut, and tightening required for fastening Torque does not become excessively large, and a fastener excellent in workability can be provided.
(4) the positional displacement amount d _np of the axial thread of the plastic deformation female screw portion of the nut, the pitch p _n of the female screw portion of the nut, the _{0.003 ≦ d np / p n ≦} 0.05 relation By generating a sufficient frictional force between the male screw part of the bolt and the plastic deformation female screw part of the nut, it is possible to perform strong screwing and tightening, and give a large resistance in the loosening direction, Excellent anti-loosening function can be maintained even when fluctuating stress is applied from the outside, and it is difficult for galling to occur between the bolt and nut, and the tightening torque required for fastening does not become excessive, making the workability It is possible to provide an excellent fastener.
(5) than the pitch p _b of the male thread portion of the bolt is deformed plastically deformed male screw portion of the bolt in the direction in which the pitch is smaller, than the pitch the pitch p _n is plastically deformed male screw portion of the female screw portion of the nut larger way or, or by than the pitch p _b of the male thread portion of the bolt deforming the plastically deformed female screw portion of the nut in the direction in which the pitch is large, usually (still) bolt plastic deformation male thread of a state Even if compressive stress is generated at the bottom of the thread valley of the thread or male thread, and tensile stress is applied to the bolt from the outside, this tensile stress and compressive stress cancel each other, and the influence of the external stress can be reliably suppressed, resulting in fatigue failure. Thus, it is possible to provide a fastener that has an excellent anti-loosening function and fatigue strength by greatly improving the resistance to repeated fluctuating stress that is the primary cause of the above.

According to the invention described in claim 2 , in addition to the effect described in claim 1 , the following advantageous effects can be obtained.
(1) At least a part of the female screw portion of the nut is screwed to and tightened with the taper portion of the bolt, so that the screw thread of the taper portion of the end face on the bolt head side or the bolt cylindrical portion side (inner side) of the nut On the other hand, contact is made only at the tip of the screw thread of the nut, which is easy to bend, and the contact area is reduced to reduce contact, and the stress at the bottom of the thread valley of the tapered part close to the dangerous section is greatly reduced to prevent breakage. In addition, it is possible to provide a fastener that can improve the fatigue limit of the bolt and is excellent in durability and long life.

According to the invention described in claim 3 , in addition to the effect described in claim 2 , the following advantageous effects can be obtained.
(1) When the nut is screwed with the taper portion of the bolt within a range of 50% to 80% of the total length of the female screw portion, the bottom of the screw taper portion on the inner end face side of the nut, which is a dangerous cross section, Thus, it is possible to provide a fastener with excellent fatigue strength reliability that can achieve uniform load sharing, relaxation of stress concentration during tension and bending, and relaxation per piece reliably and efficiently.

According to the invention described in claim 4 , in addition to the effect described in claim 2 or 3 , the following advantageous effect can be obtained.
(1) The height of the thread of the taper portion that fits with the thread on the bolt head side or the end of the bolt cylindrical portion of the nut is 10% to 75% of the height of the nut thread. As a result, it is possible to provide a fastener with excellent durability and reliability that can secure a sufficient tightening force and prevent a decrease in safety.

According to the fifth aspect of the invention, the following advantageous effects can be obtained.
(1) After forming the male screw portion with a standard pitch p _b in accordance with the standard as usual in the male screw portion forming step, in the male screw portion plastic deformation step, depending on the length of the bolt shaft portion and the thickness of the fastened body In addition, a highly productive bolt manufacturing method capable of forming a plastically deformed male screw portion by selectively (partially) plastically deforming a desired position of a screw thread of the male screw portion in the axial direction is provided. be able to.
(2) By forming the incomplete screw removal part and the taper part in the drawing process, the occurrence of stress concentration is suppressed, the load sharing of each screw thread is made uniform, and the bolt head side or the bolt cylindrical part side of the nut It is possible to provide a bolt manufacturing method that can relieve the concentration of tensile and bending stresses on the bottom of the thread valley of the tapered portion in the vicinity of the (inner side) end face and can greatly improve the fatigue strength.

According to the invention described in claim 6 , in addition to the effect described in claim 5 , the following advantageous effect is obtained.
(1) As a male screw part plastic deformation process, by performing any one or more of a blast process, a high-pressure water injection process, and a pressing process, the desired position of the male screw part is plastically deformed by a desired amount and is easily loosened. It is possible to provide a method for manufacturing a bolt that is capable of adding a prevention function and is excellent in mass productivity.

According to the seventh aspect of the invention, the following advantageous effects can be obtained.
(1) By forming the plastic deformation female screw part in the plastic deformation part plastic deformation process, it can be used effectively by simply adding an anti-loosening function to an existing nut. A method for manufacturing a nut can be provided.

According to the invention described in claim 8 , in addition to the effect described in claim 7 , the following advantageous effect can be obtained.
(1) By performing one or more of a blasting process, a high-pressure water jetting process, and a pressing process as the female thread plastic deformation process, the peripheral part of the screw hole on the end surface is plastically deformed by a desired amount and loosened easily. It is possible to provide a method for manufacturing a nut capable of adding a prevention function and excellent in mass productivity.

According to the invention described in claim 9 , the following advantageous effects can be obtained.
(1) After screwing a bolt and a nut formed in accordance with the standard in a screwing process as usual, in a plastic deformation process, at least a part of a screw thread of a male screw part of the bolt around the end face of the nut An excellent anti-loosening function can be realized simply by plastic deformation, and it is possible to reliably prevent the occurrence of loosening due to external force throughout the period of use and to prevent troubles caused by loosening. A fastener fastening method can be provided.

According to the invention described in claim 10 , in addition to the effect described in claim 9 , the following advantageous effects can be obtained.
(1) As a plastic deformation process, by performing any one or more of a blast process, a high-pressure water injection process, and a pressing process, the screwed bolt is plasticized by a desired amount at the peripheral portion of the screw hole on the end surface of the nut. It is possible to provide a fastener fastening method excellent in workability and labor saving that can be easily deformed and added with a loosening prevention function.
According to the invention described in claim 11, the following advantageous effects can be obtained.
(1) After screwing a bolt and a nut formed according to the standard as usual in the screwing step, in the plastic deformation step, at least a part of the screw thread at the peripheral edge of the screw hole of the nut is only plastically deformed. This is a fastening method with excellent workability, reliability, and maintainability that can realize an excellent anti-loosening function, reliably suppress the occurrence of loosening due to external force throughout the period of use, and prevent troubles associated with loosening. Can be provided.
According to the invention described in claim 12, in addition to the effect described in claim 11, the following advantageous effect is obtained.
(1) As a plastic deformation process, any one or more of a blasting process, a high-pressure water injection process, and a pressing process are performed, so that the screwed nut is plasticized by a desired amount at the peripheral portion of the screw hole on the end surface of the nut. It is possible to provide a fastener fastening method excellent in workability and labor saving that can be easily deformed and added with a loosening prevention function.

Side view of main part of bolt used in fastener of embodiment 1 (A) Enlarged schematic cross-sectional side view before the male screw part plastic deformation process in part A in FIG. 1 (b) Enlarged schematic cross-sectional side view after the male screw part plastic deformation process in part A of FIG. Schematic cross-sectional side view of an essential part showing a use state of a fastener using the bolt of the first embodiment Main part schematic cross-sectional side view showing a modification of the male thread plastic deformation step in the method of manufacturing a bolt used in the fastener of the first embodiment (A) An enlarged schematic cross-sectional side view before a plastic deformation step of a female screw part in a method for manufacturing a nut used in the fastener of the second embodiment (b) A female screw part in a method of manufacturing a nut used for the fastener of the second embodiment Enlarged schematic cross-sectional side view after plastic deformation process Schematic cross-sectional side view of an essential part showing a use state of a fastener using the nut of the second embodiment The principal part schematic cross section side view which shows the modification of the internal thread part plastic deformation process in the manufacturing method of the nut used for the fastener of Embodiment 2. FIG. The expanded schematic cross section side view which shows the fastening method of the fastener of Embodiment 3.

Hereinafter, a method of manufacturing a fastener, a bolt and a nut, and a method of fastening a fastener according to an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a side view of a main part of a bolt used in the fastener of the first embodiment.
In FIG. 1, 1 is a bolt in the fastener of the first embodiment, 2 is a bolt shaft portion of the bolt 1, 3 is a bolt head of the bolt 1 formed by cold forging or the like, and 4 is a bolt shaft by cutting or rolling. This is a male screw part of the bolt 1 formed from the tip part of the part 2 to a predetermined part.
Next, the detailed shape of the bolt used for the fastener of Embodiment 1 will be described based on the manufacturing method.
2A is an enlarged schematic cross-sectional side view of the A part of FIG. 1 before the male thread plastic deformation step, and FIG. 2B is an enlarged schematic view of the male screw part plastic deformation process of the A part of FIG. It is a cross-sectional side view.
In FIG. 2 (a), 1a is a drawing bolt that has not undergone the plastic deformation process of the male screw part, 4a is the top of the screw thread of the male screw part 4, 4b is the bottom of the valley of the male screw part 4, and 4c is the male screw part. The flank 4 and 5 are drawn bolts 1a in which a part of the top of the screw thread on the bolt head 3 side of the male screw part 4 is removed and the outer diameter (nominal diameter) of the screw thread is reduced toward the bolt head 3 side. The taper portion 6 is an incomplete screw removal of the drawn bolt 1a formed by gradually increasing the outer diameter (nominal diameter) of the screw thread in a circular arc shape from the minimum diameter portion of the taper portion 5 toward the bolt head 3 side. Part.

In order to manufacture the bolt 1 used for the fastener of the first embodiment, first, the incomplete screw removing portion 6 and the taper portion 5 are formed in the bolt material in the drawing process.
Next, in the male screw portion forming step, the male screw portion 4 is formed by rolling or cutting at least on the tip end side of the bolt shaft portion, and the drawn bolt 1a not subjected to the male screw portion plastic deformation step is obtained. In this case, the pitch of the male screw portion 4 of the drawing bolt 1a is p _b.
Next, a male screw part plastic deformation process is performed.
FIG. 2A shows a case where a blast process is performed as the plastic deformation process of the male screw part.
As a blasting process, a part of the male screw portion 4 of the drawn bolt 1a is made of a material such as a cast iron, a metal such as aluminum or zinc, a ceramic such as alumina or silicon carbide, a synthetic resin such as polycarbonate, or glass. Shot blasting was used in which the formed granular projection material 30 was blown against the surface of the screw thread and collided. Thus, the bolt 1 used for the fastener of the first embodiment is obtained.

In FIG. 2B, 4A is a plastically deformed male screw portion formed by plastically deforming a part of the screw _{threads of the} male screw portion 4 and shifting the position of the top portion of the screw _{thread in the} axial direction, d _{bp1 to} d _bp6 is an axial displacement amount of each screw _thread of the plastic deformation male screw portion 4A.
By performing the male screw portion plastic deformation step, as shown in FIG. 2B, a plastically deformed male screw portion 4A in which the position of the top of a part of the screw thread of the male screw portion 4 is displaced in the axial direction is obtained. Can be formed.
In the present embodiment, as shown in FIG. 2A, the projecting material 30 is sprayed from the diagonally upper side opposite to the bolt head 3 side toward the flank 4c of the screw thread to form the plastically deformed male screw portion 4A. However, if the drawing bolt 1a is suspended with the bolt head 3 up, the drawing bolt 1a is moved while being rotated, and the projection material 30 is sprayed, a large amount of drawing bolt 1a can be obtained in a short time. On the other hand, the male screw part plastic deformation process can be performed, and the mass productivity is excellent.
When d _bp collectively positional displacement amount in the axial direction of each of the threads d _bp1 to d _bp6, the positional deviation amount d _bp of the axial top of threads of the plastic deformation male screw portion 4A of the male screw portion 4 proportion to the pitch _{p b} is preferably 0.3% to 5%. As this ratio becomes smaller than 0.3%, the force to increase the distance between the screw threads of the relatively narrow pitch and the frictional force generated between the screw threads of the bolt and nut are reduced, and the looseness is prevented. There is a tendency that the function tends to be lowered, and as it becomes larger than 5%, the galling between the bolt and the nut is likely to occur, the tightening torque required for fastening is increased, and the workability is easily lowered. This is because it was found that there was a tendency.
It should be noted that the positional deviation amounts d _{bp1 to} d _bp6 and the positional deviation direction of the top of the _{thread of} the plastic deformation male screw part 4A need not be uniform over the entire region. Moreover, it is not necessary that all of the displacement amount d _bp1 to d _bp6 has entered all the above range, the absolute value of the part (partial) even that position deviation amount, it is sufficient within the range of the (However, if there is a portion exceeding the above range, it is not preferable because it causes galling.)

The material and particle size of the projection material 30 can be selected as appropriate according to the material and nominal diameter of the drawing bolt 1a. Although the hardness of the projecting material 30 varies depending on the material of the drawn bolt 1a and the like, a material with Hv = 800 to 1200 was used. Further, the particle diameter of the projection material 30 varies depending on the material of the drawn bolt 1a, the nominal diameter, and the like, but the diameter φ = 0.5 mm to 3 mm is used.
As the hardness Hv of the projection material 30 is smaller than 800 or the diameter φ is smaller than 0.5 mm, the amount of plastic deformation by each projection material 30 is reduced, and the tendency to decrease the loosening prevention effect is seen. As the hardness Hv is greater than 1200 or the diameter φ is greater than 3 mm, the amount of plastic deformation by each projection material 30 increases, the screw thread shape collapses and the engagement with the female screw decreases, and the fastening force This is because it has been found that there is a tendency that a decrease in the axial direction of the screw thread increases and a large tightening torque is required at the time of fastening, and a tendency to cause galling easily occurs.
The projection speed of the projection material 30 varies depending on the material and the nominal diameter of the drawing bolt 1a, but is set to a projection speed v = 50 m / s to 200 m / s. As the projection speed v of the projecting material 30 becomes slower than 50 m / s, it takes time to process, and the mass productivity tends to decrease. As it becomes faster than 200 m / s, large plastic deformation occurs in a short time. This is because it has been found that there is a tendency that variation in deformation amount and galling at the time of fitting tend to occur.
In the male screw part plastic deformation process, the same processing can be performed not only by a blasting process using shot blasting but also by a high-pressure water injection process for injecting high-pressure water.

FIG. 3 is a schematic cross-sectional side view of an essential part showing a usage state of a fastener using the bolt of the first embodiment.
In FIG. 3, reference numeral 10 _denotes a nut having a pitch pn, which is fastened by a part of the bolt head 3 side screwed with the plastic deformation male screw portion 4 _</ b _{> A} of the bolt 1 in the fastener using the bolt 1 of the first embodiment. the end surface of 10a is nut 10, 20 is fastened member is fastened by fasteners with bolts of the first embodiment, h _n is thread height of the nut 10, the bolt head 3 side of the h _t nut 10 the total length of the central height of the thread of the bolt 1 of the tapered portion 5 which threads mate with the end portion (referred to as the minimum thread height of the tapered portion 5 fitted to the nut 10.), l _n is the nut 10, l _t is the length of the portion of the taper portion 5 of the bolt 1 to be screwed with the nut 10.

As described with reference to FIG. 2B, when 0.003 ≦ d _bp / p _b ≦ 0.05, resistance is generated when the bolt 1 and the nut 10 are screwed together. Since d _{bp1 to} d _bp6 are small and are in a range that can be absorbed by elastic deformation of the screw _thread , it can be easily fastened only with a commonly used tool, and exhibits a loosening prevention effect after fastening. Can do.
In addition, regarding the material of the bolt 1 and the nut 10, a metal or a non-metal that can be plastically deformed can be used. However, from the viewpoint of the effect, soft materials such as steel materials, copper, aluminum, titanium, and magnesium and alloys thereof Are preferred. If some of the hard metals are used, if both the bolt 1 and the nut 10 are similarly hard, there is a risk of biting at the time of fitting. In this case, the nut 10 that is hard to break is used. It is desirable to make the material of the material somewhat soft. Specifically, the relationship between the Vickers hardness Hv _{b of the} bolt 1 and the Vickers hardness Hv _n of the nut 10 is preferably 0.5 ≦ Hv _n / Hv _b <0.9. The positional deviation amount d _bp axial plastic deformation male thread portion 4A of the bolt 1 is smaller relative to the pitch p _n of the female screw portion of the nut 10 is made smaller the difference in hardness of the bolt 1 and the nut 10 Therefore, the respective hardnesses Hv _b and Hv _n can be selected from the above-mentioned range according to the positional deviation amount d _bp .

Also, the total length l _n of the nut 10, the relationship between length l _t of the nut 10 and screwed in part of the tapered portion 5 including the plastic deformation male screw portion 4A of the bolt 1, 0.5 ≦ l _t / L _n ≦ 0.8. As the tapered portion 5 contained in the fitting portion of the nut 10 and the male screw portion 4 bolt 1 (including plastic deformation male screw portion 4A on at least a part) is less than 50% of the total length l _n of the nut 10, tapered There is a tendency that the fatigue strength improving action by the portion 5 tends to be reduced, and as it exceeds 80%, the fatigue strength improving action by the tapered portion 5 is lowered and the hooking between the nut 10 and the plastic deformation male screw portion 4A is reduced. This is because it has been found that the tightening force by the nut 10 tends to decrease.
The height h _t of the threads of the tapered portion 5 which threads mate with the end portion of the bolt head 3 side of the nut 10, the relationship between the height h _n of the threads of the nut 10, 0.1 ≦ h _t / H _n ≦ 0.75. As the height h _t of the threaded portion of the taper portion 5 fitted to the thread of the nut 10 on the inner end face side of the nut 10, which is a dangerous section, becomes lower than 10% of the height h _n of the thread 10 of the nut 10. The fatigue strength is reduced, the hooking of each screw thread in the taper portion 5 is reduced, the burden of the remaining screw thread is increased, the stress concentration is likely to occur, and the dimensional accuracy is increased. Fluctuation is likely to occur, and fluctuations in fatigue strength are likely to occur due to the influence thereof, and the fastening stability tends to be lowered. As it becomes higher than 75%, the effect of improving the fatigue strength by the tapered portion 5 tends to become difficult to obtain. It is because I understood.

In FIG. 3, when tightening is completed at a predetermined position, when viewed from the nut 10 side, the position of the top 4 a of the screw thread of the plastic deformation male screw portion 4 _</ b _> A of the bolt 1 is brought close to the pitch pn of the nut 10. The force to try, that is, the force to return the screw thread of the plastic deformation male screw portion 4A to the original position is acting.
On the other hand, when viewed from the bolt 1 side, a force that resists the force of returning the thread of the plastic deformation male thread portion 4A to its original position is generated, and an appropriate frictional force is generated between the thread of the bolt 1 and the nut 10. It is produced and it is in the state which is hard to loosen.
The position deviation amount d _bp1 to d _bp6 of each thread of the plastic deformation male screw portion 4A need not be uniform as described above, since also varies in the circumferential direction, the position of the nut 10 is If it changes, the fitting state of each screw thread of the bolt 1 and the nut 10 will change, and the magnitude | size of the working force will also change in connection with it.

In a normal combination of bolts and nuts having the same pitch, tensile stress is generated at the bottom of the screw valley of the bolt in use, and compressive stress is generated at the nut side. Since the diameter of the screw valley bottom is larger on the nut side than on the bolt side, in general, breakage easily occurs from the bolt side. When the bolt breaks down due to fatigue, the breakage generally occurs from the inner end face side of the nut to be screwed in due to tensile stress.
Plastic deformation male screw portion 4A of the bolt 1 is deformed in the axial direction, if as the pitch p _n of the female screw portion of the nut 10 is greater than the pitch of the plastic deformation male screw portion 4A, the normal (stationary) state Then, since the compressive stress is generated at the plastic deformation male screw portion 4A of the bolt 1 or the screw valley bottom of the male screw portion 4, even if a tensile stress is applied to the bolt 1 from the outside, the tensile stress and the compressive stress cancel each other. Can be reliably suppressed, and resistance to fluctuating stress can be greatly improved.
Further, by gradually reducing the height of each screw thread of the taper portion 5 screwed with the nut 10 so as to be inversely proportional to the surface pressure shared by the screw thread, the load of each screw thread of the taper portion 5 is reduced. The load is made uniform, and the tension and bending stress are concentrated on the bottom of the thread valley of the taper portion 5 near the inner end face of the nut 10, and a part of the nut 10 is screwed with the taper portion 5 of the bolt 1. By fastening, it can be brought into contact with the screw thread of the taper portion 5 on the inner end face of the nut 10 only at the tip end side of the screw thread of the nut 10 which is easily bent, the contact area can be reduced, The stress at the thread valley bottom of the taper portion 5 close to the dangerous section is greatly reduced.
Due to these synergistic effects, the fatigue strength of the bolt 1 can be dramatically improved in addition to the loosening prevention function.
The bolt 1 can also be used as an embedded bolt, and is screwed not only with a normal nut 10 but also with a female screw member embedded in the joint portion or a female screw portion formed in the joint portion. It can also be used.

Next, a modification of the male screw part plastic deformation process will be described.
FIG. 4 is a schematic cross-sectional side view of an essential part showing a modification of the male screw plastic deformation step in the method of manufacturing a bolt used in the fastener of the first embodiment.
In FIG. 4, reference numeral 40 denotes a pressing tool pressed against the flank 4 c of the screw thread to be plastically deformed in the male screw portion 4, 41 is a rotating shaft of the pressing tool 40, and 42 is fixed to the rotating shaft 41 of the pressing tool 40. The abacus-shaped roller 42a is an inclined surface of the roller 42 that abuts the thread flank 4c, α is an angle of the valley bottom 4b, and β is an angle formed by the inclined surface 42a of the roller 42.
In FIG. 4, the male screw part plastic deformation process of the modified example is different from that of the first embodiment in that a pressing process of pressing the pressing tool 40 against a part of the screw thread of the male screw part 4 is performed instead of the blasting process. Is a point.
The angle β formed by the inclined surface 42a of the roller 42 of the pressing tool 40 is formed slightly larger than the angle α of the valley bottom 4b, and the pressing thread 40 is pressed against the thread flank 4c while rotating the pressing tool 40. It is possible to form a plastically deformed male screw portion 4A similar to that of FIG. 2B by deforming and shifting the position of the top of the screw thread in the axial direction.

According to the fastener of the first embodiment of the present invention as described above, the following operation is obtained.
(1) Plasticity in which the male screw part formed on at least the tip end side of the bolt shaft part and at least a part of the screw thread of the male screw part are plastically deformed so that the position of the top part of the screw thread is displaced in the axial direction. By using a bolt having a deformed male screw portion, when the nut corresponding to the male screw portion formed at a standard pitch is screwed, the plastic deformation male screw portion of the bolt and the female screw portion of the nut Appropriate frictional force is generated between screw threads to enable strong screwing and tightening, as well as to provide a large resistance in the loosening direction, providing an excellent anti-loosening function even when fluctuating stress is applied from the outside. Can be maintained. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability.
(2) The relationship between the axial displacement d _bp of the screw thread of the plastic deformation male screw portion of the bolt and the pitch p _b of the male screw portion of the bolt is 0.003 ≦ d _bp / p _b ≦ 0.05. As a result, an appropriate frictional force is generated between the screw thread of the plastic deformation male screw part of the bolt and the female screw part of the nut, enabling strong screwing and tightening and giving a large resistance in the loosening direction. Even if fluctuating stress is applied from the outside, an excellent locking function can be maintained. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability. Due to the displacement of the screw thread of the plastic deformation male screw part, the top of the screw thread is displaced compared to the bottom of the screw valley, so that the pitch of the female screw part of the nut becomes larger than the pitch of the plastic deformation male screw part. A moderate frictional force is generated between the plastic deformation male screw portion and the screw thread of the nut based on the force to increase the distance between the screw threads of the plastic deformation male screw portion in the combined state and the force against the force. Can do.
(3) A part of the top of the screw thread on the bolt head side of the male screw part is removed, and the screw thread of the nut is provided with a tapered part whose outer diameter (nominal diameter) is reduced toward the bolt head side. Since the height of each screw thread of the taper part screwed with the taper gradually decreases in inverse proportion to the surface pressure to be shared, the load sharing of each screw thread of the taper part becomes uniform, and the nut is screwed. At this time, it is possible to alleviate the concentration of tension or bending stress on the bottom of the threaded portion of the taper portion near the end face on the bolt head side (inner side) of the nut, and the fatigue strength of the bolt can be greatly improved.
(4) Usually, stress concentration is likely to occur in the incomplete screw portion formed at the beginning of the male screw portion, but the circle gradually increases from the smallest diameter portion of the taper portion toward the bolt head side or the bolt cylindrical portion side. By forming the incomplete screw removal part by expanding the diameter in an arc shape, even if the taper part is formed, stress concentration hardly occurs in the incomplete screw removal part, and the fatigue strength improvement effect by the taper part can be maintained. it can.
(5) The action of the taper portion does not significantly increase the stress concentration of tension or bending at the bottom of the screw valley near the end face inside the nut, but the pitch is smaller than the pitch p _b of the male screw portion of the bolt. deforming the plastically deformed male screw portion of the bolt, if as the pitch p _n of the female screw portion of the nut is greater than the pitch of the plastic deformation male screw portion, usually (still) bolt plastic deformation male thread of a state Compressive stress is generated at the bottom of the screw or the male thread, so even if a tensile stress is applied to the bolt from the outside, the tensile stress and the compressive stress cancel each other, and the influence of the external stress can be reliably suppressed. The resistance to repetitive fluctuating stress, which is the primary cause of fracture, can be greatly improved, and it can have both an excellent loosening prevention function and fatigue strength.
(6) When at least a part of the female screw portion of the nut is screwed and fastened with the taper portion of the bolt, the screw thread of the taper portion of the end face on the bolt head side or the bolt cylindrical portion side (inner side) of the nut On the other hand, contact is made only at the tip of the screw thread of the nut, which is easy to bend, and the contact area is reduced. It is possible to improve the fatigue limit of the bolt.
(7) When the nut is screwed to the taper portion of the bolt in the range of 50% to 80% of the total length of the female screw portion, the bottom of the screw taper portion on the inner end face side of the nut, which is a dangerous cross section, Therefore, the load sharing can be made uniform and the stress concentration of tension and bending can be alleviated and the contact per piece can be alleviated reliably and efficiently, and the fatigue strength is highly reliable.
(8) The height of the thread of the taper portion that fits into the thread on the bolt head side end of the nut is 10% to 75% of the height of the thread of the nut. A sufficient tightening force can be secured, and a reduction in safety can be prevented.

According to the bolt manufacturing method used for the fastener of the first embodiment of the present invention as described above, the following operation is obtained.
(1) A male screw part forming step of forming a male screw part by rolling or cutting at least on the tip end side of the bolt shaft part, and plastically deforming at least a part of the screw thread of the male screw part to Since there is a male screw part plastic deformation process for forming a plastic deformation male screw part whose position is shifted in the axial direction, the male screw part is formed at a standard pitch p _b in accordance with the standard as usual in the male screw part formation process. After that, in the male screw part plastic deformation process, the desired position of the screw thread of the male screw part is selectively (partially) plastically deformed in the axial direction according to the length of the bolt shaft part and the thickness of the fastened body. Thus, the plastically deformed male screw portion can be formed, and the productivity is excellent.
(2) By simply adding one male screw plastic deformation process to the normal male screw part forming process, it is possible to easily and reliably add a loosening prevention function, and to make effective use of existing bolts. Excellent in resource and resource saving.
(3) The incomplete screw removing portion and the incomplete screw removing portion that gradually reduce in diameter in an arc shape from the bolt head side or the bolt cylindrical portion side of the bolt shaft portion toward the tip end side of the bolt shaft portion in the drawing process. By forming a taper portion where the outer diameter of the screw thread (nominal diameter) increases from the minimum diameter portion toward the tip end side of the bolt shaft portion, almost no stress concentration occurs in the incomplete screw removal portion, Furthermore, the height of each screw thread of the taper portion screwed with the nut can be gradually decreased in inverse proportion to the surface pressure to be shared, and the load sharing of each screw thread of the taper portion is made uniform, and the nut Manufactures bolts that can significantly improve fatigue strength by mitigating the concentration of tensile and bending stresses on the bottom of the threaded portion of the taper section near the end face of the bolt head side or bolt cylinder side (inner side) can do.
(4) After forming the incomplete screw removal portion and the taper portion in the drawing step, the male screw portion and the plastic deformation male screw portion can be formed in the male screw portion forming step and the male screw portion plastic deformation step. It can be mass-produced at a low cost and has excellent productivity.
(5) The male screw part plastic deformation process may be any of a blasting process for causing the projection material to collide with at least a part of the thread of the male screw part, a high-pressure water jetting process for jetting high-pressure water, and a pressing process for pressing the pressing tool. By having one or more, the desired position of the male screw portion can be plastically deformed by a desired amount to easily add a loosening prevention function, and the mass productivity is excellent.

(Embodiment 2)
FIG. 5 (a) is an enlarged schematic cross-sectional side view before the female thread plastic deformation step in the method of manufacturing a nut used in the fastener of the second embodiment, and FIG. 5 (b) is a diagram of the fastener of the second embodiment. It is an expansion schematic cross section side view after the female screw part plastic deformation process in the manufacturing method of the nut to be used. In addition, the same code | symbol is attached | subjected to the thing similar to Embodiment 1, and description is abbreviate | omitted.
In FIG. 5 (a), 10A is an unprocessed nut that has not been subjected to the female screw portion plastic deformation step, 10b is a screw hole of the unprocessed nut 10A, and in FIG. 5 (b), 10B is a female screw portion plastic deformation step. The nut used for the fastener of the second embodiment to which 11 is applied, 11 is a matte-like uneven portion of the nut 10B formed in the peripheral portion of the screw hole 10b of the end face 10a by the female screw portion plastic deformation step, and 12 is the female screw. The nut 10B is formed by plastically deforming at least a part of the screw thread at the peripheral edge of the screw hole 10b of the end face 10a by the partial plastic deformation process, thereby shifting the position of the top of the screw thread in the radial direction and axial direction of the screw hole 10b. The plastic deformation female screw portion, d _np is the axial displacement amount of the screw _thread of the plastic deformation female screw portion 12, and d _na is the radial displacement amount of the screw thread of the plastic deformation female screw portion 12.

In order to manufacture the nut 10B used for the fastener according to the second embodiment, as shown in FIG. 5A, first, an unprocessed nut 10A manufactured so as to conform to dimensional standards such as ISO and JIS is prepared. To do.
Next, a female screw part plastic deformation process is performed.
FIG. 5A shows a case where a blast process is performed as the female screw plastic deformation process.
By performing a female screw portion plastic deformation process on the unprocessed nut 10A, as shown in FIG. 5B, at least a part of the screw thread at the peripheral portion of the screw hole 10b of the end face 10a is plastically deformed to form a screw. A nut 10B having a plastically deformed female screw portion 12 in which the position of the top of the mountain is displaced in the radial direction and the axial direction of the screw hole 10b is obtained.
In the present embodiment, as shown in FIG. 5A, projection is performed from an obliquely upper side opposite to the bolt head side of the raw nut 10A toward the peripheral portion of the screw hole 10b of the end surface 10a of the raw nut 10A. The plastic deformation male screw part 12 was formed by spraying the material 30.
Proportion to the pitch _{p n} of the female screw portion of the displacement amount _{d np} of the axial thread of the plastic deformation male screw portion 12 of the nut 10B is preferably 0.3% to 5%. As this ratio becomes smaller than 0.3%, the frictional force generated between the plastically deformed female screw portion 12 of the nut 10B and the screw thread of the male screw portion of the bolt decreases, and the loosening prevention function tends to decrease. As it becomes larger than 5%, it is found that galling is likely to occur between the bolt and the nut 10B, the tightening torque necessary for fastening increases, and the workability tends to decrease. This is because.

The positional deviation amount _dnp and the positional deviation direction of the top of the thread of the plastic deformation male screw part 12 need not be uniform over the entire circumference of the thread. Further, it is not necessary for the positional deviation amount d _np to be in the above range over the entire circumference, and the absolute value of the positional deviation amount only needs to be in the above range even in part (partial) ( However, the presence of a portion exceeding the above range is not preferable because it causes galling.)
Moreover, it is preferable that the positional deviation amount d _{na in} the radial direction of the screw _thread of the plastic deformation female screw part 12 is substantially the same as the positional deviation quantity d _{np in} the axial direction of the screw thread of the plastic deformation female screw part 12. When the ratio to the pitch p _n of either parameter female screw portion of the displacement amount d _np of radial position deviation amount d _na and axially more than 5%, tends galling occurs, but not preferred, Even if the positional deviation amount _{dna in the} radial direction is smaller than 0.3%, if the partial positional deviation amount _{dnp in the} axial direction is within the above range, a good locking effect can be obtained.
In this blasting process, the processing target is simply changed from the pre-processing bolt 1a of Embodiment 1 to the pre-processing nut 10A, and the processing conditions such as the material, particle size, hardness, and projection speed of the projection material 30 are as follows. Since it is the same as that of Embodiment 1, description is abbreviate | omitted.
Further, in the female screw part plastic deformation process, the same as the male screw part plastic deformation process described in the first embodiment, in addition to the blasting process using shot blasting, the same applies to the high-pressure water injection process for injecting high-pressure water. Processing can be performed.

FIG. 6 is a schematic cross-sectional side view of an essential part showing a use state of a fastener using the nut of the second embodiment.
In the present embodiment, the nut 10B of the second embodiment is screwed into the drawing bolt 1a that does not have the plastic deformation male screw portion 4A described in the first embodiment.
As described in FIG. 5B, when 0.003 ≦ d _np / p _n ≦ 0.05, resistance is generated when the drawn bolt 1a and the nut 10B are screwed together. Since the shift amount _dnp is small and can be absorbed by elastic deformation of the screw thread, it can be easily fastened only with a commonly used tool and can exhibit a loosening prevention effect after fastening. it can.
In FIG. 6, when the clamping is completed in a predetermined position, close to the diaphragm when viewed from the machining bolt 1a side, fit the pitch p _b of machining bolt aperture 1a the position of the top of the thread of the plastic deformation female screw portion 12 The force which tries to return, that is, the force which tries to return the screw thread of the plastic deformation female screw part 12 to the original position is acting.
On the other hand, when viewed from the nut 10B side, a force that resists the force to return the thread of the plastic deformation female screw portion 12 to its original position is generated, and the drawn bolt 1a and the nut 10B are formed on the end face 10a of the nut 10B. Appropriate frictional force is generated between the screw threads, and it is difficult to loosen.
Note that the screw _thread misalignment amount _dnp of the plastically deformed female screw portion 12 varies in the circumferential direction as described above, and a uniform frictional force is not generated over the entire circumference. Further, if the position of the nut 10A changes, the fitting state of the drawing bolt 1a and the nut 10B changes, and the magnitude of the working force changes accordingly.

Full length _{l n} of the nut 10B, the relationship of length _{l t} of the nut 10B threadably engaged in part of the tapered portion 5 of the drawing bolt 1a is a _{0.5 ≦ l t / l n ≦} 0.8 so as to the point, the height h _t of the threads of the tapered portion 5 which threads mate with the end portion of the bolt head 3 side of the nut 10B, the relationship between the height h _n of the threads of the nut 10B, The point where 0.1 ≦ h _t / h _n ≦ 0.75 is the same as in the first embodiment, and the functions and effects obtained thereby are also the same, so the description thereof is omitted.

Next, a modification of the female screw plastic deformation process will be described.
FIG. 7 is a schematic cross-sectional side view of an essential part showing a modification of the female thread plastic deformation step in the method of manufacturing a nut used in the fastener of the second embodiment.
In FIG. 7, reference numeral 50 denotes a pressing tool pressed against a portion of the threaded portion of the peripheral edge of the screw hole 10 b of the end face 10 a of the unprocessed nut 10 </ b> A, 51 a rotating shaft of the pressing tool 50, and 52 a pressing tool 50. A conical abutting portion 52a formed at the tip of the rotating shaft 51 is an inclined surface of the abutting portion 52 that abuts against a thread on the peripheral edge of the screw hole 10b.
In FIG. 7, the female screw part plastic deformation process of the modified example is different from that of the second embodiment in that, instead of the blasting process, the pressing tool 50 is applied to the screw thread at the peripheral edge of the screw hole 10 b of the end face 10 a of the unprocessed nut 10 </ b> A. It is a point which performs the press process which presses.
When the pressing tool 50 is rotated and pressed against the peripheral edge of the screw hole 10b, the screw thread of the end face 10a is plastically deformed, and the position of the top of the screw thread is displaced in the axial direction or the radial direction. The nut 10B having the same plastic deformation female screw portion 12 as in FIG.

According to the fastener of the second embodiment of the present invention as described above, the following operation is obtained.
(1) Plastic deformation by plastically deforming at least a part of the screw thread at the peripheral edge of the screw hole on the end face and shifting the position of the top of the screw thread in at least one of the radial direction and the axial direction of the screw hole. By using a nut having a female screw part, when an off-the-shelf bolt corresponding to the standard pitch of the nut is screwed, an appropriate frictional force is generated between the screw thread of the plastic deformation female screw part of the nut and the male screw part of the bolt. This makes it possible to provide strong screwing and tightening, and to impart a large resistance in the loosening direction, and to maintain an excellent anti-loosening function even when fluctuating stress is applied from the outside. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability.
(2) and the positional deviation amount d _np of the axial thread of the plastic deformation female screw portion of the nut, the pitch p _n of the female screw portion of the nut, the _{0.003 ≦ d np / p n ≦} 0.05 relation As a result, an appropriate frictional force is generated between the male screw portion of the bolt and the plastic deformation female screw portion of the nut, enabling strong screwing and tightening and giving a large resistance in the loosening direction. It is possible to maintain an excellent loosening prevention function even when a fluctuating stress is applied from the outside. As a result, it is possible to reliably suppress the occurrence of loosening due to external force over a long period of use, prevent troubles associated with loosening, and have excellent reliability and maintainability.
(3) A part of the top of the screw thread on the bolt head side of the male screw part is removed, and the screw thread of the nut is provided with a tapered part whose outer diameter (nominal diameter) is reduced toward the bolt head side. Since the height of each screw thread of the taper part screwed with the taper gradually decreases in inverse proportion to the surface pressure to be shared, the load sharing of each screw thread of the taper part becomes uniform, and the nut is screwed. At this time, it is possible to alleviate the concentration of tension or bending stress on the bottom of the threaded portion of the taper portion near the end face on the bolt head side (inner side) of the nut, and the fatigue strength of the bolt can be greatly improved.
(4) Normally, stress concentration tends to occur in the incomplete screw portion formed at the beginning of the male screw portion, but the diameter gradually increases from the minimum diameter portion of the taper portion toward the bolt head side in an arc shape. By forming the incomplete screw removal portion, even if the taper portion is formed, stress concentration hardly occurs in the incomplete screw removal portion, and the effect of improving the fatigue strength by the taper portion can be maintained.
(5) A nut that is easily bent with respect to a thread of a taper portion on an end surface of a bolt head side (inner side) when at least a part of a female screw portion of the nut is screwed and fastened with a taper portion of the bolt. Since the contact area is small and the contact area is small, the contact is reduced, the stress at the bottom of the threaded valley of the taper part close to the dangerous cross section can be greatly reduced, and breakage can be prevented. Can improve the fatigue limit.
(6) When the nut is screwed to the taper portion of the bolt in the range of 50% to 80% of the total length of the female screw portion, the bottom of the screw taper portion on the inner end face side of the nut, which is a dangerous cross section, Therefore, the load sharing can be made uniform and the stress concentration of tension and bending can be alleviated and the contact per piece can be alleviated reliably and efficiently, and the fatigue strength is highly reliable.
(7) The height of the thread of the taper portion that fits into the thread on the bolt head side end of the nut is 10% to 75% of the height of the thread of the nut. A sufficient tightening force can be secured, and a reduction in safety can be prevented.

According to the nut manufacturing method used for the fastener of the second embodiment of the present invention as described above, the following operation is obtained.
(1) Plastic deformation by plastically deforming at least a part of the screw thread at the peripheral edge of the end face of the screw hole and shifting the position of the top of the screw thread in at least one of the radial direction and the axial direction of the screw hole. Since it has a female screw part plastic deformation process for forming the female screw part, it is possible to easily add a loosening prevention function to the existing nut in the female screw plastic deformation process, and to effectively use the existing nut. It is excellent in mass productivity and resource saving.
(2) One or more of the female screw plastic deformation step is any one or more of a blasting step for causing the projection material to collide with the peripheral portion of the screw hole on the end surface, a high-pressure water jetting step for jetting high-pressure water, and a pressing step for pressing the pressing tool. Therefore, the peripheral portion of the screw hole on the end face can be plastically deformed by a desired amount to easily add a loosening prevention function, which is excellent in mass productivity.

  The bolt 1 of the first embodiment and the nut 10B of the second embodiment can be combined and used as a fastener. In that case, a further excellent loosening prevention effect can be realized by the synergistic effect of the loosening prevention effect of the bolt 1 described in the first embodiment and the loosening prevention effect of the nut 10B described in the second embodiment.

(Embodiment 3)
FIG. 8 is an enlarged schematic cross-sectional side view showing a fastening method of the fastener of the third embodiment. In addition, the thing similar to Embodiment 1 or 2 attaches | subjects the same code | symbol, and abbreviate | omits description.
First, in the screwing step, the unprocessed nut described in the second embodiment is screwed into the drawn bolt 1a described in the first embodiment.
Next, in the plastic deformation step, a part of the thread of the peripheral part of the screw hole 10b of the raw nut 10A and a part of the male thread part 4 of the drawn bolt 1a around the end face 10a of the raw nut 10A. Is plastically deformed.
Thereby, the plastic deformation female screw part 12 similar to the nut 10B of the second embodiment shown in FIG. 6 can be formed on the raw nut 10A. In addition, the fitting state of the screw thread of the drawing bolt 1a and the unprocessed nut 10A on the end face 10a changes in the circumferential direction. In the cross section of FIG. 6, since the end face 10a of the unprocessed nut 10A is exposed, the screw thread at the peripheral edge of the screw hole 10b is plastically deformed to form the plastically deformed female thread portion 12, but the end face of the unprocessed nut 10A is formed. In the cross section where the screw thread of the drawing bolt 1a is in contact with the outside of 10a, the screw thread of the drawing bolt 1a is plastically deformed to form a plastically deformed male screw part.
By this fastener fastening method, after drawing the drawn bolt 1a not having the plastic deformation male screw portion 4A and the unprocessed nut 10A not having the plastic deformation female screw portion 12, the plastic deformation step is performed. Only the loosening prevention function and the fatigue strength similar to those of the fastener of the first embodiment or the second embodiment can be realized.
In the plastic deformation process, any one or more of a blast process, a high-pressure water injection process, and a pressing process similar to those in the first and second embodiments can be used.

According to the fastening method of the fastener of the third embodiment of the present invention as described above, the following operation is obtained.
(1) Since there are a screwing process in which a nut is screwed into a bolt and a plastic deformation process in which at least a part of a thread of a male screw part of the bolt is plastically deformed around the end face of the nut, After screwing together the bolts and nuts formed along the screw, in the plastic deformation process, it is possible to achieve excellent locking by simply plastically deforming at least a part of the thread of the male screw part of the bolt around the end face of the nut. The function can be realized, the occurrence of loosening due to external force can be surely suppressed throughout the period of use, troubles associated with loosening can be prevented, and workability, reliability, and maintainability are excellent.
(2) Since there is a screwing process for screwing the nut into the bolt and a plastic deformation process for plastically deforming at least a part of the periphery of the screw hole of the nut around the end face of the nut, After screwing together the bolt and nut formed along, in the plastic deformation process, it is possible to realize an excellent loosening prevention function only by plastically deforming at least a part of the peripheral portion of the screw hole of the nut, Occurrence of loosening due to external force can be reliably suppressed throughout the period of use, troubles associated with loosening can be prevented, and workability, reliability, and maintenance are excellent.
(3) Simple and reliable prevention of loosening can be achieved simply by adding one plastic deformation step to the normal screwing step, and existing bolts and nuts can be used effectively, resulting in excellent mass productivity and resource saving.
(4) The plastic deformation process is any one of a blasting process in which a projection material collides with at least a part of a screw thread of a male screw part of a bolt, a high-pressure water injection process for injecting high-pressure water, and a pressing process for pressing a pressing tool. By having one or more, the screwed bolt can be plastically deformed by a desired amount at the peripheral edge of the screw hole on the end face of the nut, and a loosening prevention function can be easily added. Excellent.
(5) The plastic deformation step has one or more of a blasting step for colliding the projection material with a peripheral portion of the screw hole of the nut, a high-pressure water injection step for injecting high-pressure water, and a pressing step for pressing the pressing tool. Thus, the screwed nut can be plastically deformed by a desired amount at the peripheral portion of the screw hole on the end face of the nut to easily add a loosening prevention function, which is excellent in workability and labor saving.

以上のようにして、振動バーレルに締結した締結具に、ＮＡＳ式高速緩み試験機（米国航空機規格ＮＡＳ３３５０に準じる）を用いて、ボルトの軸方向と直交する方向に振動を繰り返し与える振動試験を１７分間（３００００回）行った。振動数は１７８０ｒｐｍｍ、加振ストロークは１１ｍｍ、インパクトストロークは１９ｍｍとした。
評価の結果、比較例１では、試験後にナットに緩みが発生したが、実施例１〜３については、試験後にナットに緩みが発生しているものはなかった。 Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples.
(Evaluation of axial displacement amount of plastic deformation male screw portion according to Examples 1 to 3 and Comparative Examples 1 and 2)
First, with the M16 coarse nut defined in JIS B 0205-1997 as a reference, a bolt having a plastically deformed male screw portion at the reference pitch p _b of the male screw portion by the bolt manufacturing method described in the first embodiment. 1 was produced.
Table 1 shows the ratio (%) of the maximum amount of displacement d _{bp in} the axial direction of the thread of the plastic deformation male screw portion to the pitch p _b of the male screw portion of the manufactured bolt.
Since the bolt of Comparative Example 2 was galling with the nut, the bolts of Examples 1 to 3 and Comparative Example 1 were inserted into the vibration barrel, and M16 defined in JIS B 0205-1997 was inserted into the male screw portion of the bolt. The nut 10 was screwed and fastened with the same tightening torque (145 N · m).
In order to obtain sufficient fatigue strength, the ratio of the minimum screw thread height of the taper part fitted to the nut (= (h _t / h _n ) × 100 (%)) is 10%, and the taper part length with respect to the entire length of the nut Table 1 shows the results of evaluation with the ratio of (= (l _t / l _n ) × 100 (%)) being 80%.

As described above, using a NAS type high-speed looseness tester (according to US aircraft standard NAS3350) to the fastener fastened to the vibration barrel, a vibration test in which vibration is repeatedly applied in a direction orthogonal to the axial direction of the bolt is performed. For 3 minutes (30000 times). The frequency was 1780 rpm, the excitation stroke was 11 mm, and the impact stroke was 19 mm.
As a result of evaluation, in Comparative Example 1, the nut was loosened after the test, but in Examples 1 to 3, none of the nut was loosened after the test.

Next, fatigue strength tests were performed on the bolts of Examples 1 to 3 and Comparative Example 1.
The bolts of Examples 1 to 3 and Comparative Example 1 are inserted into the jig, and the nut M16 defined in JIS B 0205-1997 is screwed into the male screw portion of the bolt, and the same tightening torque (145 N · m ) The position of the nut is as shown in Table 1.
Using a servo type fatigue tester (± 392 kN), the bolt head and nut were repeatedly pulled in the axial direction of the bolt, and the number of repetitions (time) until failure occurred was counted. The tensile average stress was constant at 176.4 MPa, and the repetition rate was 500 times / minute.
Evaluation was made into a relative value when the fatigue strength of a conventional fastener in which a coarse bolt of M16 and a coarse nut were screwed together was taken as 100%.
As shown in Table 1, the ratio of the maximum amount of positional deviation d _{bp in} the axial direction of the screw thread of the plastic deformation male screw portion to the pitch p _b of the male screw portion of the bolt satisfies the range of 0.3% to 5%. In Examples 1-3, it turned out that it has the fatigue strength more than twice the past.
In Comparative Example 1 in which the ratio of the maximum positional deviation d _{bp in} the axial direction of the thread of the plastic deformation male screw portion to the pitch p _b of the male screw portion of the bolt is smaller than 0.3%, the comparative example 1 is in parallel with the conventional coarse bolt. It was found that there was only a fatigue strength equivalent to that of a fastener screwed with an eye nut, and a fatigue strength improvement effect could not be obtained.

尚、実施例４〜１２、比較例３〜１０のボルトに螺合したナットに嵌合するテーパ部の最小螺子山高さの割合（＝（ｈ_ｔ／ｈ_ｎ）×１００（％））及びナット全長に対するナットが螺着されたテーパ部長さの割合（＝（ｌ_ｔ／ｌ_ｎ）×１００（％））は、それぞれ表２に示した通りである。
振動バーレルに締結した締結具に、ＮＡＳ式高速緩み試験機（米国航空機規格ＮＡＳ３３５０に準じる）を用いて、ボルトの軸方向と直交する方向に振動を繰り返し与える振動試験を１７分間（３００００回）行った。振動数は１７８０ｒｐｍｍ、加振ストロークは１１ｍｍ、インパクトストロークは１９ｍｍとした。
評価の結果、試験後又は試験中にナットに緩みが発生するものはなく、実施例４〜１２、比較例３〜１０の全てが合格となった。 (Evaluation of nut screwing position according to Examples 4 to 12 and Comparative Examples 3 to 10)
In the evaluation of the axial displacement amount of the thread of the plastic deformation male screw portion according to Examples 1 to 3 and Comparative Examples 1 and 2, the displacement amount d _bp of the screw deformation of the plastic deformation male screw portion of the bolt in the axial direction. And the relationship between the pitch p _b of the male screw portion of the bolt and 0.003 ≦ d _bp / p _b ≦ 0.05, it was found that an excellent loosening prevention function can be obtained. The relationship between the axial displacement amount d _bp of the screw thread of the male screw part and the pitch p _b of the male screw part of the bolt is made constant at d _bp / p _b = 0.02 (corresponding to Example 2), and the nut Table 2 shows the results of evaluating the occurrence of looseness and fatigue strength while changing the position.

In addition, the ratio (= (h _t / h _n ) × 100 (%)) and nut of the taper portion fitted to the nut screwed to the bolt of Examples 4 to 12 and Comparative Examples 3 to 10 The ratio of the length of the taper portion in which the nut is screwed to the total length (= (l _t / l _n ) × 100 (%)) is as shown in Table 2, respectively.
Using a NAS type high-speed looseness tester (according to the US aircraft standard NAS3350) to the fastener fastened to the vibration barrel, a vibration test is repeatedly applied for 17 minutes (30000 times) in a direction perpendicular to the axial direction of the bolt. It was. The frequency was 1780 rpm, the excitation stroke was 11 mm, and the impact stroke was 19 mm.
As a result of the evaluation, there was no loosening of the nut after the test or during the test, and all of Examples 4 to 12 and Comparative Examples 3 to 10 passed.

Next, fatigue strength tests were performed on the bolts of Examples 4 to 12 and Comparative Examples 3 to 10.
Evaluation was performed in the same manner as in Examples 1 to 3 and Comparative Example 1 except that the position of the nut was different.
As shown in Table 2, the minimum thread height h _t of the tapered portion to be fitted to the nut, with 10% to 75% of the height of the height h _n of the threads of the nut, the nut is, the total length of the nut l It turned out that Examples 4-12 screwed with the taper part of the bolt in the range of 50% to 80% of _n have excellent fatigue strength.
In Comparative Example 4, 6 and 8 were the smallest thread height h _t of the tapered portion to be fitted to the nut 80% of the height h _n of the threads of the nut, the conventional coarse bolt and coarse nut It was found that there was only a fatigue strength equivalent to that of the screwed fastener, and an effect of improving fatigue strength could not be obtained.
Moreover, nut, in Comparative Example 9 was engaged bolt threadedly a tapered portion at 40% of the total length l _n of the nut was found to decrease sharply fatigue strength improvement effect as compared with 50% in Example 4 . Moreover, nut, in Comparative Example 10 was engaged bolt threadedly and the tapered portion of the 90% of the total length l _n of the nut, but it was found that the fatigue strength of conventional 1.5 is obtained, the full length of the nut l _Since most of _n is screwed at the taper portion, there is a possibility that it may be completely pulled out by an external force or the like, and it is not preferable because it is not reliable in fastening.
In Comparative Example 3, 5, 7 to the minimum thread height h _t of the tapered portion was 5% of the height h _n of the threads of the nut to be fitted to the nut, the minimum thread taper portion to be fitted to the nut While the crest height h _t is 50 percent to embodiment 5, 8, 11 almost as fatigue strength of the height h _n of the threads of the nut, the minimum thread height of the tapered portion to be fitted to the nut the h _t as peak example 4, 7, 10, which was 10% of the height _{h n} of the threads of the nut, has decreased rapidly fatigue strength, of 5% to 10% range, little position It can be said that this is an unstable region where the fatigue strength is likely to vary due to the difference. Further, since there is little catching of each screw thread in the taper portion, the burden on the remaining screw thread that is fitted increases, stress concentration is likely to occur, and this is not preferable because it is not practical. Further, if the height of the screw thread is lowered, it is not preferable because it is easily affected by variations in dimensional accuracy, lacks in production stability, tends to cause variations in fatigue strength, and lacks fastening stability.
In this embodiment, a bolt formed in a typical M16 size that is generally used is used, but the same tendency as in Tables 1 and 2 is observed regardless of the bolt size.

  The present invention has a reliable loosening prevention function, can greatly improve fatigue strength, and realizes excellent safety and reliability that cannot be obtained with conventional screw fasteners. Not only can the number and size of nuts be greatly reduced, reducing the size and weight of the product, but also reducing the cost of the product by reducing the number of man-hours required for drilling and tightening bolts. , Provide practical fasteners that can remarkably improve product design flexibility, assembly workability, and mass productivity, and can be easily subjected to repeated loads (vibration) by simply processing bolts and nuts Providing a bolt and nut manufacturing method that has both a loosening prevention function and fatigue strength that is excellent in fastening power, low cost and excellent in mass productivity without loosening, and simple processing after screwing an existing bolt and nut This makes it possible to securely fasten bolts and nuts, and will not loosen even when subjected to repeated loads (vibrations), and can realize excellent fastening force. A fastening method can be provided, and the reliability of movable parts such as various mechanical devices, iron bridges, buildings, construction machines, various transport equipment, electrical products, and glasses, or joints of members that receive vibration from the outside is improved. And the incidence of delayed fracture and stress corrosion cracking can be reduced.

DESCRIPTION OF SYMBOLS 1 Bolt 1a Drawing bolt 2 Bolt shaft part 3 Bolt head 4 Male screw part 4a Top part 4b Valley bottom part 4c Flank 4A Plastic deformation male screw part 5 Taper part 6 Incomplete screw removal part 10 Nut 10a End surface 10A Unprocessed nut 10b Screw hole 10B Nut 11 Concavity and convexity portion 12 Plastic deformation female screw portion 20 Fastened body 30 Projection material 40, 50 Pressing tool 41, 51 Rotating shaft 42 Roller 42a, 52a Inclined surface 52 Abutting portion

Claims (12)

A fastener having a bolt and a nut screwed into the bolt,
The bolt has a male screw portion with a pitch p _b formed on at least the tip end side of the bolt shaft portion, and a part of the top of the screw thread on the bolt head side or the bolt cylindrical portion side of the male screw portion. A taper part with a reduced screw thread outer diameter toward the bolt head side or the bolt cylindrical part side, and a gentle arc from the smallest diameter part of the taper part toward the bolt head side or the bolt cylindrical part side An incomplete screw removing portion formed by expanding the diameter,
The nut has a female screw portion of the pitch p _n,
At least (a) the bolt includes a plastically deformed male screw portion in which at least a part of the screw thread of the male screw portion is plastically deformed to shift the position of the top of the screw thread in the axial direction, and the plastic The positional deviation amount d _{bp in} the axial direction of the screw thread of the deformed male screw part and the pitch p _b of the male screw part have a relationship of 0.003 ≦ d _bp / p _b ≦ 0.05 or (b) The nut plastically deforms at least a part of the screw thread at the peripheral edge of the screw hole on the end surface, thereby shifting the position of the top of the screw thread in at least one of the radial direction and the axial direction of the screw hole. and plastic deformation has a female screw portion, and the positional deviation amount d _np of the axial thread of the plastic deformation female thread portion, the pitch p _n of the female screw _{portion, 0.003 ≦ d np / p n} ≦ A fastener characterized by a 0.05 relationship . Fastener according to claim 1, wherein at least a portion of the female screw portion of the nut is fastened screwed with the tapered portion of the bolt. The fastener according to claim 2 , wherein the nut is screwed to the taper portion of the bolt within a range of 50% to 80% of the total length of the female screw portion. The height of the thread of the taper portion of the bolt that fits into the thread of the bolt head side or the end of the bolt cylindrical portion of the nut is 10% to the height of the thread of the nut. 4. Fastener according to claim 2 or 3 , characterized in that it is 75% high. It is a manufacturing method of the bolt in the fastener according to any one of claims 1 to 4,
From the bolt head side or bolt cylindrical part side of the bolt shaft part to the tip part side of the bolt shaft part, the incomplete screw removing part that gradually reduces in an arc shape and the minimum diameter part of the incomplete screw removing part A drawing process for forming a taper portion whose screw thread outer diameter increases toward the tip end side of the bolt shaft portion, and a male screw portion having a pitch p _b is rolled or formed at least on the tip end side of the bolt shaft portion; A male screw part forming step formed by cutting and a plastically deformed male screw part in which at least a part of the screw thread of the male screw part is plastically deformed and the position of the top of the screw thread is displaced in the axial direction are formed. A male screw portion plastic deformation step , wherein an axial displacement d _{bp of the} plastic deformation male screw portion and a pitch p _b of the male screw portion are 0.003 ≦ d _bp / p _b A method for manufacturing a bolt, wherein the relationship is ≦ 0.05 . The male screw portion plastic deformation step is any one of a blasting step for causing a projection material to collide with at least a part of a screw thread of the male screw portion, a high-pressure water jetting step for jetting high-pressure water, and a pressing step for pressing a pressing tool. The bolt manufacturing method according to claim 5 , comprising one or more. A method for manufacturing a nut in a fastener according to any one of claims 1 to 4,
Pitch p _n at least at least a portion of the threads of the peripheral portion of the screw holes in the end surface of the nut having a female screw portion of the radial or axial direction of the screw hole of the position of the apex of the thread by plastic deformation of one or plastic deformation was allowed displaced in the one direction comprises a female threaded portion plastically deformed to form a female screw portion, and the positional deviation amount d _np of the axial thread of the plastic deformation female threaded portion, of the female screw portion A method for producing a nut, wherein the pitch _pn is in a relationship of 0.003 ≦ d _np / p _n ≦ 0.05 . The female screw portion plastic deformation step, the periphery of the screw hole in the end surface of the nut, blasting step of impinging shot materials, process pressure water injection for injecting high-pressure water, any pressing step of pressing a pressing tool The nut manufacturing method according to claim 7 , comprising at least one of the above. It is the fastening method of the fastener of any one of Claims 1 thru | or 4, Comprising:
A part of the male screw part of pitch p _b formed on at least the tip part side of the bolt shaft part and the top of the screw head on the bolt head side or the bolt cylindrical part side of the male screw part is removed. A taper portion having a reduced screw thread outer diameter toward the bolt cylindrical portion side, and a diameter gradually increasing from the smallest diameter portion of the taper portion toward the bolt head side or the bolt cylindrical portion side in an arc shape. formed and an incomplete thread removing unit, screwed step of screwing the nut having a female screw portion of the pitch p _n to the bolt having, in the threads of the male screw portion of the bolt around the end face of the nut A plastic deformation step of plastically deforming at least a part of the plastic deformation male screw portion formed in the plastic deformation step in the axial direction displacement d _bp of the screw _thread and the pitch p _{b of the} male screw portion. Of 0.003 ≦ d _bp / p _b ≦ 0.05 A fastening method for a fastener, characterized by being a clerk . The plastic deformation step is any one of a blasting step for causing a projection material to collide with at least a part of a screw thread of the male screw portion of the bolt, a high-pressure water injection step for injecting high-pressure water, and a pressing step for pressing a pressing tool. The fastening method of the fastener according to claim 9 , comprising one or more. It is the fastening method of the fastener of any one of Claims 1 thru | or 4, Comprising:
Pitch p formed at least on the tip side of the bolt shaft _b And a part of the top of the screw thread on the bolt head side or the bolt cylinder part side of the male screw part is removed, and the outer diameter of the screw thread is reduced toward the bolt head side or the bolt cylinder part side. A bolt having a tapered portion, and an incomplete screw removing portion formed by gradually expanding in a circular arc shape from the minimum diameter portion of the taper portion toward the bolt head side or the bolt cylindrical portion side. p _n A screwing step of screwing a nut having a female screw part, and a plastic deformation step of plastically deforming at least a part of a screw thread at a peripheral edge portion of the screw hole of the nut around the end surface of the nut, Axial misalignment amount d of screw thread of plastic deformation female screw part formed in plastic deformation process _np And the pitch p of the female screw part _n Is 0.003 ≦ d _np / P _n The fastening method of the fastener characterized by being the relationship of <= 0.05. The plastic deformation step includes one or more of a blasting step for causing a projection material to collide with the peripheral portion of the screw hole of the nut, a high-pressure water injection step for injecting high-pressure water, and a pressing step for pressing a pressing tool. The fastening method of the fastener according to claim 11, wherein:

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