JP2011038549A - Fastener with mechanism for preventing looseness of screw - Google Patents

Abstract

Provided is a fastener with a screw locking mechanism that has a sufficient strength and nevertheless exhibits a greater locking effect than conventional products while achieving a significant weight reduction.
SOLUTION: A taper-shaped convex portion 10 is provided on a lower nut 4 and a taper-shaped concave portion 15 that can be engaged with the taper-shaped convex portion is formed on the inner and lower portions of the upper nut 5. It protrudes on the inclined upper surface 9 above the nut 4 so that its center line Y3 is inclined with respect to the center line Y1 of the fastening bolt 2, and on the lower seating surface 6 of the lower nut 4 in a bottom view. A concave groove portion 12 is formed by cutting away the four corner portions 11 when viewed, and the area in contact with the fastened member 1 is reduced.
[Selection] Figure 6

Description

  The present invention relates to an improvement in a fastener that has a male screw portion and a female screw portion that are screwed together to provide a mechanism that does not loosen even when subjected to vibration or impact. In particular, the present invention relates to a fastener suitable for use in a vehicle such as a space rocket, an aircraft, a bullet train, etc., or in a machine / electricity / architecture or other place where it is desired to eliminate loosening of a screw portion even if vibration or impact is applied after fastening.

  In the above space rockets, aircraft, bullet trains, etc., loosening of the screw part of the fastener will lead to a serious accident. For this reason, there is an increasing need for fasteners that do not loosen even when subjected to vibration or impact after fastening, and various types of fasteners have been proposed, and some of them are mass-produced. .

The following is an example that is relatively close to the present invention.
B) As a first type, a tapered convex portion and a concave portion that can be engaged with each other are formed between two or more nuts that are screwed into a fastening bolt, and one nut is engaged by tightening the upper nut. The female screw part is pressed against the male screw part of the bolt to prevent loosening.
Japanese Patent Publication No. 03-526 JP-A-10-286649 Japanese Patent Laid-Open No. 11-6516 JP 2002-89533 A JP 2002-195236 A JP 2005-48807 A JP 2008-38947 A JP 2008-51269 A

5b) As the second type, an inclined surface is formed to deform the axis.
Japanese Utility Model Publication No. 37-29322 Japanese Patent Laid-Open No. 53-110765 Japanese Examined Patent Publication No. 63-53402 Japanese Patent Laid-Open No. 5-39807 Japanese Utility Model Publication No. 6-18719 Japanese Patent Laid-Open No. 10-68409 JP 2003-148438 A JP 2004-156737 A JP 2006-10054 A JP 2008-298264 A

C) The third type uses other structures.
Japanese Patent No. 27776792 JP 2001-59514 A Japanese Patent Laid-Open No. 2003-156022 Japanese Utility Model Publication No. 32-006125

However, the above conventional ones have the following problems.
a) The thing of the said patent document 1 is a double nut type which uses two general nuts as a locking nut. In addition to the tapered concave and convex portions, one nut has an eccentric structure. However, since the entire seating surface of the lower nut comes into contact with the member to be fastened, the contact area between the two nuts is wide. This increases the frictional force, and the frictional torque due to the vibration of the fastened member causes the lower nut to rotate in response to the loosening direction, which may cause the lower nut and the upper nut to rotate together. is there. In addition, since the weight is equivalent to two nuts, there are cases where the intended use and location of use are limited due to inappropriate use on an aircraft, for example.

  b) The above-mentioned patent document 2 is intended to facilitate the reduction of diameter by forming longitudinal grooves at a plurality of locations on the peripheral portion of the tapered upper convex portion of the lower nut, but only a slight amount of reduction occurs. As in the case of the above cited reference 1, the seat surface is wide and the frictional force is large. Therefore, the lower nut is loosened due to the vibration of the fastened member, etc. There is also the possibility of co-surrounding. In addition, the weight is equivalent to two nuts, and there are cases where the usage and location of use are limited.

  c) In the above-mentioned Patent Document 3, in addition to the tapered concave / convex portion, one nut is also provided with an eccentric structure. Since it is wide and has a large frictional force, the lower nut may be loosened due to vibration of the fastened member, and the lower nut and the upper nut may co-rotate. Moreover, since the weight is also equivalent to two nuts, there are cases where the intended use and use location are limited.

  d) The thing of the said patent document 4 is not a double nut type but a triple nut type using three nuts. Each nut has an eccentric structure in addition to the tapered concave / convex portion, but the cost is high because it has three nuts, and it is difficult to reduce the weight. In addition, since there is a height corresponding to three nuts, the working space and usable locations are limited, and the mounting work requires fastening by tightening the three nuts, which increases the work time.

  e) Although the thing of the said patent document 5 has a contact part so that the lower end part of a clamping tool may not be engaged with a lower nut at the time of the tightening operation | work in addition to a taper-shaped concave and convex part, Processing is not easy and the cost is high. Further, as in the above cited reference 1, since the seat surface of the lower nut is wide and the frictional force is large, the lower nut is loosened due to vibration of the fastened member, and the lower nut and the upper nut are rotated together. There is a possibility. Since the weight is also equivalent to two nuts, there are cases where the usage and location of use are limited.

  f) Although the thing of the said patent document 6 has an eccentric structure in addition to a taper-shaped concave / convex part, like the said cited reference 1, this also has a wider seat surface of a lower nut and is frictional. Since the force is large, the lower nut may be loosened due to vibration of the fastened member, and the lower nut and the upper nut may be rotated together. In addition, the weight is equivalent to two nuts, and there are cases where the usage and location of use are limited.

  g) In the above-mentioned Patent Document 7, a slit is formed in the taper convex portion to increase the pressure contact with the male screw portion of the fastening bolt, but it is plastically deformed while biting into the male screw portion. As a result, the nut may be difficult to remove, and as in the case of Patent Document 1, the seat surface of the lower bolt is wide, so the frictional force is large, and the lower nut is loosened due to the vibration of the member to be fastened. There is also a possibility of it.

  h) The above-mentioned Patent Document 8 has been put into practical use and is still commercially available. It is an integrated type of double nuts with tapered concave and convex parts, which are separated by screwing into bolts and tightening, and the convex part side engages with the concave part side. However, the tightening torque is not always constant when a person manually tightens, and once tightened and fastened, it is separated into upper and lower parts, so that it is not suitable for re-fastening or repeated use. Moreover, the manufacture is not easy, and the problem that the cost becomes high remains. One similar to this is described in Utility Model Registration No. 3018706.

  i) The thing of the said patent document 9 forms an inclined surface between a washer and a nut, and the force to the direction which the centerline inclines with respect to a volt | bolt is acted with respect to a volt | bolt by tightening a nut. In order to prevent loosening, the internal thread portion of the nut and the external thread portion of the bolt are brought into pressure contact with each other by the stress (reaction force). However, since the seating surface of the washer below the nut is wider, the frictional force with the fastened member is large, and the force acts in the direction that the lower nut is loosened by the frictional torque due to vibration of the fastened member, etc. Is considered small.

  j) In Patent Document 10 described above, an inclined surface is formed between the upper and lower nuts, and the weight can be reduced by reducing the thickness of one of the nuts. May also be hooked on the other nut, resulting in a co-tightened state. Also, the frictional force is large on the wide seating surface of the lower nut, and there is a possibility that the force acts in the direction of loosening the nut and loosens it.

  k) Although the thing of the said patent document 11 forms the lower surface of the upper nut in the inclined surface, since the seat surface of the lower nut which contact | connects a fastening member is also wide and a frictional force is large, the vibration of a fastening member is a nut. May be induced, and the weight of two nuts may limit the usage and location.

  l) In the above-mentioned Patent Document 12, the upper nut is inclined with respect to the upper surface of the lower nut by providing a protrusion on a part of the lower surface of the upper nut. In the case of the same 15, the lower surface of the upper nut is inclined. In the same manner as in the above Patent 8, the force is applied in the direction in which the center line of the bolt is inclined by tightening the nut, and the stress of the bolt is received as a reaction force to press-contact between the female screw portion of the nut and the male screw portion of the bolt. It is intended to be in a state of being loosened.

  However, these also have a wide seating surface of the lower nut in contact with the fastening member and a large frictional force, so the vibration of the fastening member may induce loosening of the nut, and the weight of two nuts, Usage and location may be restricted.

  m) The thing of the said patent document 16 is a single nut type which uses one nut, and is one of what is marketed now. A slit is provided from the side of the nut, and the seating surface is an inclined surface. This is because when the nut is tightened to the bolt, a strong tightening force is required to bring the seat surface into close contact with the member to be fastened, and over-torque is required at the time of tightening, making it difficult to remove the nut later. There is a possibility. Furthermore, as in each of the above cases, the nut seat surface is wide and the frictional force is large. There is also a possibility that the stopping effect is hindered.

  n) The thing of the said patent document 17 is a double nut type integral type, and made the seat surface into the inclined surface, and is supposed to exhibit the same tightening force as a double nut. However, the structure that divides the nut into the upper and lower parts is not suitable for repeated use, so it is restricted in its intended use and is difficult to remove. Moreover, the difficulty of processing is high, leading to an increase in cost.

  o) The above-mentioned Patent Document 18 is a single nut type, in which an inclined surface is not formed on the upper or lower surface of the nut, but is formed so that the female screw hole of the nut is inclined. This is the same as that having an inclined surface. However, this nut has a problem that it is difficult to form a female screw hole, and the labor and cost of manufacturing are increased.

  p) The thing of the said patent document 19 is a structure different from said each case. Screw a plate-shaped nut locking device with a disk shape and a special shape from the top of a normal nut, loosen by bending against the top surface of the nut and the rough surface of the inner periphery biting into the male thread of the bolt. Is to stop. However, this locking device has a complicated shape, so it is not easy to manufacture and is expensive.It is not considered for repeated use, and there are problems in terms of maintainability and repair costs. is there.

  q) The structure disclosed in Patent Document 20 has a different structure from the above cases. The coil spring is slightly screwed into the male threaded portion of the bolt so that the coil spring fits into the threaded valley portion. To do. However, this is not a normal bolt and nut as defined by JIS, and it is necessary to make the screw trough a special screw deep in the radial direction, which increases the cost.

r) The thing of the said patent document 21 is a single nut type, and while making the bottom face of the skirt-like washer part provided in the nut into a shallow concave shape, and forming a concave groove on the slightly upper outer periphery of the washer part, the washer part The nut can be elastically deformed in the direction in which the bottom surface becomes flat. When the nut is screwed into the bolt and tightened, a large internal stress is applied between the female screw portion and the male screw portion to prevent loosening. However, this requires a considerably large tightening torque when screwing and tightening the nut, and since the contact area between the seat surface and the member to be fastened is wide and the frictional force is large, the vibration from the member to be fastened is received. It is easy to loosen, and once it begins to loosen, it is difficult to suppress it .

s) In the above-mentioned Patent Document 22, the upper and lower nuts have a tapered concave portion and a tapered convex portion, and an inclined surface below the lower nut. This is because when a vertical groove is formed on the side of the lower nut and both nuts are tightened, one end of the inclined surface at the bottom of the lower nut is in contact with the fastened member, The spring action is generated so that the thread portion between the bolt and the nut is strongly engaged. However, there is a limit to the spring action, and since there is a difference in the spring action depending on the tightening method, there is a problem that a forceful screw loosening force is not always produced.

  The conventional ones still have the problems and issues described above, so that it is hoped that fasteners with a simple structure will be lighter and have sufficient strength, but also have a stronger locking force. It was rare. An object of the present invention is to solve the problems of the conventional fastener with a screw locking mechanism. That is, the object of the present invention is a relatively simple structure, which is lighter than the conventional one, has sufficient strength, and has a screw locking mechanism that has a stronger locking effect. It is to provide a fastener.

The fastener with a screw locking mechanism according to the present invention is:
A double nut type screwing the lower nut 4 to the male screw portion 3 of the fastening bolt 2 inserted through the member 1 to be fastened and screwing and fixing the upper nut 5
The lower nut 4 has a female screw portion 7 in the vertical direction, and the upper surface of the lower half portion 8 having a substantially quadrangular shape when viewed from above is an inclined upper surface having a slight inclination angle α with respect to the seat surface 6. 9 to form
A trapezoidal taper-shaped convex portion 10 having a smaller diameter toward the top and a trapezoidal taper-like convex portion 10 as seen in a side view is formed on the upper portion of the inclined upper surface 9 with the side line portion perpendicular to the inclined upper surface 9 as a center line Y3.
Further, the seat surface 6 of the lower half portion 8 is cut out from each edge to form a cross-shaped concave groove portion 12 so that the four corner portions 11 as seen in the bottom view are left to be applied to the fastened member 1. The contact part,
On the other hand, the outer shape of the upper nut 5 is a hexagonal nut shape . The upper nut 5 has a female screw portion 14 in the vertical direction in the upper half portion, and the upper nut 5 extends upward from the lower side surface 13 in the lower half portion. A tapered concave portion 15 that can be engaged from above is formed corresponding to the tapered convex portion 10;
When the upper nut 5 is engaged with the lower nut 4 from above and screwed to the fastening bolt 2, the lower side surface 13 of the upper nut 5 is pressed against the side portion of the inclined upper surface 9 of the lower nut 4. It is a thing.

  In the above configuration, the expression of the lower nut 4 and the upper nut 5 means that the fastening bolt 2 is inserted from the lower side of the fastened member 1 and the two nuts 4, 5 are inserted into the male screw portion 3 of the bolt 2 protruding upward. This means the positional relationship when screwing. Even when the upper / lower positional relationship is reversed, the lower nut 4 is indicated as being screwed into the fastening bolt 2 first, and the upper nut 5 is indicated as being screwed and locked later. Therefore, the lower half portion 8 of the lower nut 4 means a portion on the fastened member 1 side in the lower nut 4.

  When the lower nut 4 is viewed in a side view, the upper surface of the lower half portion 8 is formed on an inclined upper surface 9 having a slight inclination angle α with respect to the seating surface 6 of the lower nut 4, and the inclination angle α is Usually about 1.5 to 3.5 degrees is desirable.

  The tapered convex portion 10 on the inclined upper surface 9 has a smaller diameter toward the top and has a trapezoidal shape as seen in a side view, that is, a truncated cone shape, and a line perpendicular to the inclined upper surface 9 is formed as a center line Y3. . The center line Y3 is inclined with respect to the center line Y2 of the lower nut 4 and the center line Y1 of the fastening bolt 2. The inclination angle is the same as the inclination angle α of the inclined upper surface 9 and is about 1.5 to 3.5 degrees.

  The seat surface 6 of the lower half portion 8 of the lower nut 4 is cut out from each edge, leaving four corners as seen in the bottom view, and is formed in a concave groove portion 12 having a cross shape with the female screw hole interposed therebetween. It is. Here, the cross section of the recessed groove portion 12 may be a shallow quadrangular shape or an arch shape.

The tapered recess 15 of the upper nut 5 corresponds to the tapered protrusion 10 of the lower nut 4 and can be engaged therewith from above, and has a tapered recess, that is, a hollow frustoconical shape with a smaller diameter toward the top. ing.

  According to the fastener with the screw locking mechanism according to the present invention, while having a relatively simple structure, it has sufficient strength as compared with the conventional one, can be reduced in weight, and is even stronger. Can be used to prevent loosening.

The reason will be described.
The first reason is that the taper-shaped convex portion 10 protruding from the upper part of the lower nut 4 is not formed with the center line Y2 of the lower nut 4 or the center line Y1 of the fastening bolt 2 as the center line, A line perpendicular to the inclined upper surface 9 is formed as a center line Y3 on the upper surface of the inclined upper surface 9 having the inclination angle α. That is, the center line Y3 of the tapered convex portion 10 is inclined with respect to the center line Y2 of the lower nut 4 and the center line Y1 of the fastening bolt 2.

Therefore, after the lower nut 4 is screwed onto the fastening bolt 2 inserted through the member 1 to be fastened, when the upper nut 5 is screwed from above, the upper nut 5 is initially along the center line Y1 of the bolt 2. And are screwed together (see, for example, FIG. 1). However, the tapered recess 15 of the upper nut 5 begins to engage from above in a taper-shaped convex portion 10 of the lower nut 4, it will engage along the tapered shaped convex portion 10 which center line Y3 inclined, the bolt 2 There is no threading along the center line Y1.

Subsequently, the screwing of the upper nut 5 to the bolt 2 is advanced, and the center line Y3 of the tapered convex portion 10 becomes the center of the bolt 2 as described above, as the tapered concave portion 15 is further engaged with the tapered convex portion 10. Under the influence of being inclined with respect to the line Y1, the upper nut 5 is screwed while exerting a force in the direction of bending the bolt 2 into a "<" shape. After a part of the lower side surface 13 of the upper nut 5 comes into contact with a part of the inclined upper surface 9 of the lower nut 4, when the upper nut 5 is further screwed together, the lower side surface 13 of the upper nut 5 Comes into contact with the inclined upper surface 9 of the lower nut 4 (see, for example, FIGS. 2 and 6).

  In this state, the force of the strong reaction force from the bolt 2 on the anti-inclined side (for example, the left side in FIG. 6) due to the stress of the bolt 2 that is to bend against the female screw portion 14 of the upper nut 5. Will be added. Therefore, the female threaded portion 14 of the upper nut 5 bites into the male threaded portion 3 of the bolt 2 on the anti-inclined side to be in a strong pressure contact state and has a large pressure contact area (explained in examples described later) And for example, see FIG.

  The biting pressure contact state and the pressure contact area are larger on the side opposite to the upper end edge of the female threaded portion 14 of the upper nut 5 (see, for example, FIG. 6). A strong stress from the male screw part is received, and a strong locking force is acting on the upper nut 5.

The lower nut 4 also has a tapered convex portion 10 that presses against the inner surface of the tapered concave portion 15 of the upper nut 5 on the inclined side (right side in FIG. 6). Since it is also in a pressure contact state with the male screw portion 3 of the bolt 2 and the pressure contact area is large, it contributes as a loosening prevention force for the lower nut 4. In addition thereto the present invention, when the fastening state of the by engagement, by the lower surface 13 of the upper nut 5 is pressed against the side edge portion on the inclined upper surface 9 of the lower nut 4, between the upper nut 5 and the lower nut 4 Are in close contact with each other, so that they are integrated with each other.

  The reason 2 is that the bottom bearing surface 6 of the lower nut 4 is notched from each edge except for the four corners 11 as seen in the bottom view, and is recessed so as to have a cross shape with the female screw hole interposed therebetween. That is, the groove 12 is formed. Thus, the area where the seat surface 6 of the lower nut 4 is in contact with the fastened member 1 is a small area of only the four corners 11 (see, for example, FIGS. 3 and 10).

  This is based on the idea of reversal. That is, conventionally, in order to increase the frictional area with the fastened member 1 and increase the frictional force to prevent the nut from loosening, a nut with a flange, a disc spring nut, or a flat washer is interposed.

  However, the frictional torque caused by vibration or impact generated on the fastened member 1 side does not act on the lower nut 4 that is screwed into the bolt 2 and fastened to tighten the fastening state. Acts as a force in the direction to loosen the state. The greater the frictional force between the fastened member 1 and the seat surface 6 of the lower nut 4, the greater the frictional torque and the easier the screw will loosen.

  On the other hand, in the present invention, the concave groove portion 12 is formed in the seat surface 6 of the lower nut 4 as described above, and the area where the seat surface 6 of the lower nut 4 contacts the fastened member 1 is limited to the four corner portions 11. The friction area is a small area that is a fraction of that of the entire rectangular seating surface.

  Therefore, the frictional force between the lower nut 4 and the member 1 to be fastened is small, and the force in the loosening direction and the friction torque received by the lower nut 4 due to vibration / impact of the member 1 to be fastened are also small. As a result, it acts as a loosening force of the lower nut 4.

  In addition, the fastener with a screw locking mechanism according to the present invention has a conventional grooved portion 12 formed on the lower side surface of the lower nut 4 in addition to the above-described locking effect. The lower nut 4 has a square shape when viewed from the top, so that it can be used as a jig when machining internal thread holes and inclined surfaces in the manufacturing process. It is easy to fix and has a shape that can be flowed to the processing line, and also has an effect that it is easy to improve accuracy and processing efficiency.

  As described above, the fastener with the screw locking mechanism according to the present invention can exhibit a large locking effect while further reducing the weight. This point is specifically described in the Examples section below, and the “H-1 type M12 P1.75 SS400” manufactured by Company A, which has gained a high reputation worldwide for its high locking effect (for example, FIG. 7 This is explained in comparison with FIG.

FIG. 5 is a schematic side view showing a state where the upper nut is screwed onto the fastening bolt in the fastener with the screw loosening prevention mechanism according to the present invention. In those shown in FIG. 1 is a schematic side view showing a state in which the tapered recess screwed on nut almost completely engaged into the tapered shaped convex portions of the lower nut. It is a perspective view from the lower part of the lower nut used with what was shown in FIG. It is a partial vertical side view of the lower nut used by what was shown in FIG. It is a partial vertical side view of the upper nut used by what was shown in FIG. FIG. 3 is a partially longitudinal side view for showing a pressure contact area ratio between upper and lower nuts and a fastening bolt in the state shown in FIG. 2. It is a schematic side view which shows the state in which the upper nut is screwed to a fastening bolt with the fastener made from A company as a prior art example. In those shown in FIG. 7 is a schematic side view showing a state in which the tapered recess screwed on nut almost completely engaged into the tapered shaped convex portions of the lower nut. In the state shown in FIG. 8, it is a partial longitudinal side view which imaged the press-contact area between each upper and lower nuts and fastening bolts manufactured by the company A. It is a figure of the calculation formula explaining that the frictional torque by the seat surface of a lower nut is small with the fastener with a screw loosening prevention mechanism which concerns on this invention. It is a figure which shows the strength test data of the fastener with a screw locking mechanism which concerns on this invention. The guaranteed load value based on the strength test data shown in FIG. 11 is displayed in comparison with the guaranteed load value specified by JIS. It is a figure which shows the result of having done the Junker-type screw loosening test in order to compare the locking effect of the fastener with a screw locking mechanism which concerns on this invention with the thing made from said A company. It is a figure which shows the result of having confirmed the loosening prevention effect of the fastener with a screw loosening prevention mechanism which concerns on this invention by the NAS type | mold vibration test.

  The center line Y3 of the tapered convex portion 10 projecting from the upper portion of the lower nut 4 is inclined with respect to the center line Y2 of the lower nut 4 and the center line Y1 of the bolt 2, and on the seat surface 6 of the lower nut 4 By forming the concave groove 12 that is cut out while leaving the four corners 11 when viewed from the bottom view, and the area that contacts the fastened member 1 is a small area of only the four corners 11, the loosening prevention effect is greatly increased.

  I. 1 to 6 show an embodiment of a fastener with a screw locking mechanism according to the present invention, wherein 1 is a member to be fastened, 2 is a fastening bolt, 4 is a lower nut, and 5 is an upper nut. The fastening bolt 2 is inserted into the round hole formed in the fastened member 1 from below, and the lower nut 4 is first screwed onto the bolt 2 with the fastened member 1 in between, and the upper nut 5 from above. Are fastened and fixed.

  The member 1 to be fastened is two plate members to be fastened here, and the fastening bolt 2 used here is a JIS standard M12 bolt made of SCM435.

  Here, the lower nut 4 is made of S55C, and has a square lower half 8 with a corner corner notched as seen in a plan view, and a trapezoidal taper at the upper side as seen in a side view. In this embodiment, the square half of the lower half 8 has a dimension of 17.0 mm and a female threaded portion 7 of JIS standard M12.

  The upper surface of the lower half portion 8 is formed on an inclined upper surface 9 having an inclination angle α of 2.5 degrees with respect to the seating surface 6 as viewed in a side view, and a line perpendicular to the inclined upper surface 9 is formed thereon. A taper-shaped convex portion 10 is projected from the center line Y3. Therefore, the center line Y3 of the tapered convex portion 10 is inclined about 2.5 degrees with respect to the center line Y2 of the lower nut 4 here.

  Further, the lower part of the lower nut 4 is 3.5 mm on the thick side here, and the tapered convex part 10 has a truncated cone shape in which the tapered peripheral surface has an inclination of 12 degrees with respect to the center line Y3. The diameter is 15.6 mm, the upper outer diameter is 14 mm, and the height is 3.8 mm.

On the other hand, the upper nut 5 is made of S55C, has a height of about 10 mm, and has the same outer shape as a normal hexagon nut. An internal thread portion 14 in the vertical direction is formed in the upper portion so as to be able to be screwed to the fastening bolt 2. In the inner and lower portions, a trapezoidal shape as seen from a side view around the center line of the upper nut 5 so as to be engageable with the tapered convex portion 10 from above , in other words, a tapered shape of a hollow frustoconical shape with a smaller diameter toward the upper side. A recess 15 is formed. The tapered recess 15 has a tapered inner peripheral surface having an inclination of 12 degrees with respect to the center line Y4 of the upper nut 5. Here, the lower inner diameter is 15.7 mm, the upper inner diameter is 14 mm, and the height is 4 mm. It is as.

B. The operation and effect of the present invention have been described above, but will be described below in more detail based on examples. a) When this embodiment is used, when the lower nut 4 is screwed onto the fastening bolt 2 inserted through the member 1 to be fastened, and the upper nut 5 is screwed from above, the upper nut 5 is initially Is screwed along the center line Y1 of the bolt 2 (see FIG. 1), and then the tapered recess 15 of the upper nut 5 is inserted into the tapered protrusion 10 of the lower nut 4 inclined from the center line Y3 from above. continue to engage.

When the upper nut 5 continues to be screwed and the engagement of the tapered concave portion 15 with the tapered convex portion 10 proceeds, the upper nut 5 applies a force in a direction to bend the fastening bolt 2 into a so-called “<” shape. Screw together while exerting. As a result, the female threaded portion 14 of the upper nut 5 receives a strong reaction force from the bolt 2 due to the stress that is not bent in the shape of “<”, and is on the anti-inclined side (left side in FIGS. 2 and 6). Thus, it is screwed while receiving a strong force from the bolt 2.

  Thereafter, a part of the lower side surface 13 of the upper nut 5 comes into contact with a part of the inclined upper surface 9 of the lower nut 4, and finally the entire lower surface 13 of the upper nut 5 comes into contact with the inclined upper surface 9 of the lower nut 4. (See, for example, FIGS. 2 and 6).

  In this state, the female screw portion 14 of the upper nut 5 receives the reaction force from the bolt 2 on the side opposite to the inclined side, and bites into the male screw portion 3 strongly, so that it is in a very strong pressure contact state. As a result, the pressure contact area also increases. In addition, the biting pressure contact state and the pressure contact area are particularly large at the upper end edge of the female screw portion 14 of the upper nut 5 on the side opposite to the inclined side.

  At the same time, between the lower nut 4 and the fastening bolt 2, the female screw portion 7 on the inclined side of the lower nut 4 is in pressure contact with the male screw portion 3 of the bolt 2, and the pressure contact area also increases here.

  FIG. 6 shows an image of the pressure contact area between the lower nut 4 and the upper nut 5 and the bolt 2 in the pressure contact state. This is an actual size drawing using “AutoCAD 2008” manufactured by Autodesk, and the area of the portion in the pressure contact state is calculated and illustrated. FIG. 9 shows the calculation and illustration of the product manufactured by Company A, which is highly evaluated worldwide for the locking force under the same conditions (the same reference numerals are assigned).

In each figure, S1 and S2 are partially enlarged and surrounded by circles and indicated by hatching.
However, between the lower nut 4 and the upper nut 5 and the fastening bolt 2, the pressure contact area of the screw portion is imaged. The total pressure contact area S1 + S2 is 3.3 mm ² for the company A shown in FIG. 9, whereas it is 3.9 mm ² for this embodiment.

  From this result, the embodiment has a pressure contact area that is about 1.2 times as large as that of the product manufactured by Company A. Therefore, the embodiment is more strongly pressed and has a large loosening force. It can be seen that is acting.

    b) In addition to the effect due to the increase in the pressure contact area, in the present embodiment, the portion where the seat surface 6 of the lower nut 4 is in contact with the fastened member 1 may be a small area of only the four corners 11. Acts as a loosening force. This is based on the idea of reverse rotation as described above, and it is not intended to prevent the nut from loosening by increasing the frictional force by increasing the pressure contact area of the nut or bolt head as in the past. No.

In the embodiment of the present invention, the area where the seat surface 6 of the lower nut 4 contacts the fastened member 1 is a small area of only the four corners 11. The lower nut 4 in the present embodiment has a square seat surface 6 of 17 mm × 17 mm as seen in a plan view, and the area of the entire seat surface is 284.7 mm ² by removing each corner. ing. Since the female screw hole is 95 mm ² , the area where the seat surface 6 excluding it is in contact with the fastened member 1 is 189.7 mm ² .

In the present embodiment, as described above, only the four corner portions 11 of the seat surface 6 are in contact with the fastened member 1 and each area of the four corner portions 11 is 7.7 mm ^2. the actual area of the portion in contact becomes 31.6mm ² in 7.7 mm ² × 4 throughout. Thus, the area ratio when the seat surface on the fastened member 1 is in contact, when compared with those not forming a recessed groove portion 12, pressure area of 189.7mm ² pairs 31.6mm ² becomes, in this example 1/6 It has become.

Next, when this is compared with the standard hexagon nut of M12 (the width of the two faces is 18 mm in JIS), the seating surface area of the hexagon nut is 137 mm ^2. Therefore, when this is compared with the present embodiment, it is 137 mm ² vs. 31. The pressure contact area is about 1/4 at 6 mm ² . Therefore, in this embodiment, since the pressure contact force and the friction force are also small, the loosening force caused by the vibration and impact of the fastened member 1 is difficult to be transmitted to the lower nut 4, and the occurrence of the loosening is reduced.

  Further, what has been verified about the difference in friction torque caused by the seating surface 6 of the lower nut 4 is the “illustration of friction torque” shown in FIG. 10 (this is an explanation based on text and drawings. Because it is difficult to describe inside, it is shown as a drawing). As a result of the verification, the friction torque Tw3 of the seating surface of the lower nut 4 of the present embodiment was 1/6 compared to the friction torque Tw1 in the case of the hexagonal nut. As a result, it can be seen that the force that the vibration and impact of the fastened member 1 acts as a friction torque is small, and the force in the direction of loosening the lower nut 4 can be suppressed to a very low level.

    c) Further, when the weight was measured in order to know the degree of weight reduction in this example, the total weight of the upper nut 5 and the lower nut 4 excluding the fastening bolt 2 was 17.8 g. Since the product made by Company A belonging to 10T, which is an equivalent strength category, was 26.3 g, the lower nut 4 of this example was made as described above, so that the weight could be reduced by about 33%. I found out.

C) The results of a strength test and a test for confirming the screw locking effect of this example are shown.
a) First, FIG. 11 shows the result of the strength test (guaranteed load test) of this example. This was done by requesting the Osaka Prefectural Industrial Technology Research Institute on July 17, 2009. The load is applied and the maximum load is measured. The test result was able to withstand a maximum load of 132.8 kN.

  As a result, in the case of the M12 hexagon nut (metric coarse screw) made of S55C belonging to 10T which is the same strength category as the present embodiment, the guaranteed load is shown in JIS B1052 Annex Table 2 as shown in FIG. Judging from the fact that it is 82.38 kN, it was confirmed that the present example has extremely excellent strength.

b) Next, a Junker type screw loosening test (vibration test) was performed in order to compare the effect of screw loosening with that of the above-mentioned company A.
This was requested on July 22, 2009 by KS Co., Ltd. (in the Uno Building, 2-14-14 Tokuicho, Chuo-ku, Osaka City). Junker) type looseness tester (utility model registration No. 3144492) ”, excitation amplitude ± 0.5 mm, vibration frequency 3.3 Hz, initial tightening axial force 15 kN, measurement time Is a test conducted under conditions of 3 minutes.

  FIG. 13 shows the result. The upper line indicates the loosening force in this example, and the lower line indicates the loosening force of the product manufactured by Company A. Show. As is clear from the test results, it was confirmed that the effect of the present example was greater than that of the above-mentioned company A in that the screw was loosened.

c) Further, another vibration test (NAS type) was also conducted in order to confirm the effect of screw loosening prevention in this example.
This was done on July 31, 2009, by requesting the Shiga Prefectural Industrial Technology Center (Kamitoyama, 232, Ritto City, Shiga Prefecture). Vibration tester VS-200A-140 (made by IMV Corporation) ) Using a torque wrench (manufactured by Nakamura Seisakusho Co., Ltd.), attach the same thing as this example to the shaking table with a tightening torque of 40 Nm with lubricant (KURE CRC 5-56) applied to the sliding surface. In this test, the vibration frequency is 29.7 Hz (1782 rpm), the vibration double amplitude is 11 mm _pp , and the vibration time is 17 minutes (total frequency is 30,000 times).

  The results are shown in FIG. 14. As described in the test result column of the same test report, “the sample did not have any obvious slack such as dropout or rotation (marked on the bolt and nut). The marking was not misaligned) ”.

  As described above, this embodiment has sufficient strength while achieving a significant reduction in weight even when compared with the product manufactured by Company A, which has been highly evaluated worldwide for its large screw locking effect. In addition, it has an even greater loosening effect.

  It should be noted that the numerical values such as the material, dimensions, and angles shown in the above embodiments are merely examples and are not limited thereto.

  In the present invention, a nut is attached to a bolt in a place where it is necessary that the screw of the fastening portion does not loosen even when subjected to vibration or impact, particularly in a vehicle such as a space rocket, aircraft, Shinkansen, machine, electricity, architecture, etc. This is a fastener with a screw loosening prevention mechanism that is suitable for preventing the screw portion from loosening even if vibration, impact, or the like is applied after fastening.

1-fastened member 2-fastening bolt 3-male screw part 4-lower nut 5-upper nut 6-seat surface 7-female screw part 8-lower half part 9-inclined upper surface 10-tapered convex part 11-four corners 12-groove 13-lower side 14-thread 15-tapered recess α-inclination angle Y1-centerline of fastening bolt Y2-lower nut centerline Y3-tapered centerline Y4-upper nut Center line S1-Imaged area of press contact area S2-Imaged area of pressure contact area

Claims (2)

A double nut type screwing the lower nut 4 to the male screw portion 3 of the fastening bolt 2 inserted through the member 1 to be fastened and screwing and fixing the upper nut 5
The lower nut 4 has a female screw portion 7 in the vertical direction, and the upper surface of the lower half portion 8 having a substantially quadrangular shape when viewed from above is an inclined upper surface having a slight inclination angle α with respect to the seat surface 6. 9 to form
A trapezoidal taper-shaped convex portion 10 having a smaller diameter toward the top and a trapezoidal taper-like convex portion 10 as seen in a side view is formed on the upper portion of the inclined upper surface 9 with the side line portion perpendicular to the inclined upper surface 9 as a center line Y3.
And, the seat surface 6 of the lower half 8 is cut out from each edge so as to leave the four corners 11 seen in the bottom view, and formed into a cross-shaped groove 12.
On the other hand, the upper nut 5 is
The outer shape is a hexagonal nut shape, and has an internally threaded portion 14 in the upper half portion in the vertical direction, and corresponds to the tapered convex portion 10 of the lower nut 4 from the lower side surface 13 upward in the lower half portion. A fastener with a screw locking mechanism formed with a tapered recess 15 that can be fitted. The fastener with a screw locking mechanism according to claim 1, wherein the inclined upper surface 9 of the lower nut 4 has an inclination angle α with respect to the seating surface 6 of approximately 1.5 to 3.5 degrees.