JP2003194031A - Lock nut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lock nut for fastening equivalent to a double nut. <P>SOLUTION: At the time of using the lock nut 1, a bolt 2 is screwed in an internal thread 6 of an outer nut 5 from a bolt insertion end 5b side. The outer nut 5 is turned with a universal tool so that an inner nut 4 is pulled into the inside of a receiving hole 8 of the outer nut 5 along a taper and received therein and the receiving hole 8 of the outer nut 5 with a taperedly reduced diameter in an insertion direction of the inner nut compresses the inner nut 4 in a direction of an axial center. As the inner nut 4 is compressed and reduced in diameter according to advancing into the receiving hole 8, the bolt 2 is strongly clamped from its entire periphery. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock nut that can be tightened with a tightening force that is about the same as when a bolt fastened to a fastening target is fastened with a double nut.

[0002]

2. Description of the Related Art A fastening mechanism using bolts and nuts is shown in FIG.
As shown in 3, a proper fastening target member (22) in which the bolt (20) and the nut (21) are screwed and sandwiched between the bolt (20) and the nut (21)
Is to tighten.

When the conventional bolt (20) and nut (21) are tightened, the screw surface (23) on one side of the bolt (20) and nut (21) is tightened.
A) is strongly contacted by the fastening force and frictional force is generated. Due to this frictional force, the bolt (20) and the nut (21) are fixed without loosening. However, if a large rotational force that cancels this frictional force is generated due to vibration, etc., the bolt
(20) and nut (21) will gradually loosen.

Therefore, a so-called double nut is generally used in which two nuts are stacked to prevent loosening. In this method, each nut has a screw surface on the opposite side (in FIG. 13, if one screw surface is the surface on the (23a) side, the other screw surface is the surface on the (23b) side). Since it abuts on the thread surface of the male thread of the bolt, even if a large rotational force that overcomes the frictional force generated on the screw surface (23a) on one side is generated, the rotational force is applied in a direction that loosens the nut. Even in other cases, since the other nut is in contact with the male thread of the bolt on the thread surface (23b) on the opposite side, the rotational force becomes the rotational force in the direction of tightening the other nut, and as a result, With a double nut, the nut will not loosen even if vibration is applied.

However, this method requires not only one extra nut but also a complicated tightening process.

Further, when excessive tightening torque is applied to suppress loosening, there are problems such as breakage of the bolt and damage of the screw thread.

[0007]

Therefore, the object of the present invention is to realize a fastening force equivalent to a double nut with a single nut, prevent loosening of the bolt even when vibration occurs, and perform a simple fastening operation. Is to provide nuts.

[0008]

The invention described in claim 1 is an inner nut (4) having a female screw (6), and an inner nut.
A lock nut (1) comprising an outer nut (5) having a housing hole (8) for housing (4), wherein the outer peripheral surface of a cross section perpendicular to the axial direction is formed into a non-circular shape, and the outer surface (4a) is tapered, and the outer surface (4a) or the inner surface of the female screw (6)
An inner nut (4) having a groove (7) for reducing the diameter formed in at least one of (6a) along the axial direction, and a storage hole (8).
The inner peripheral shape of the cross section perpendicular to the axial direction of is formed in a non-circular shape to match the outer peripheral shape of the inner nut (4), and the inner surface (8a) of the storage hole (8) is the outer surface ( 4a) and an outer nut (5) that is formed in a taper shape such that the diameter gradually decreases from the inner nut insertion end surface (5a) side toward the insertion direction. It is (1).

When the inner nut (4) rotates together with the outer nut (5), the inner nut (4) is drawn along the taper into the accommodation hole (8) of the outer nut (5) for storage. At the same time, the accommodating hole (8) tapered in the insertion direction of the inner nut of the outer nut (5) tightens the inner nut (4) toward the center of the shaft. The inner nut (4) has a groove (7) for reducing its diameter.
This enables deformation in the direction of reducing the groove width, and the groove bottom portion (7a) of the diameter reducing groove (7) of the inner nut (4) is compressed and plastically deformed to reduce the diameter. In this way, the inner nut (4) fits into the storage hole (8).
The bolt (2) can be strongly tightened from the entire circumference because it is compressed and reduced in diameter as it enters. In other words, the female threads (6) of the inner nut (4) and the male threads (2a) of the bolt (2) are in strong contact with each other at the same time. Can be concluded.

The invention described in claim 2 is the same as claim 1.
In a modified example, an inner nut (4) having a female screw (6) and an outer nut having a storage hole (8) for storing the inner nut (4).
(5) is a lock nut (1) composed of, the outer peripheral shape of the cross section perpendicular to the axial direction is formed in a circle, the outer surface (4a) is formed in a tapered shape, the outer surface (4a) Engagement protrusion (10a)
A groove (7) for reducing the diameter in at least one of the outer side surface (4a) or the inner side surface (6a) of the female screw (6).
The inner nut (4) formed along the axial direction
And an inner peripheral shape of a cross section perpendicular to the axial direction of the storage hole (8) is formed in a circular shape in accordance with the outer peripheral shape of the inner nut (4), and the inner surface of the storage hole (8) is the inner nut. It is formed in a taper shape such that the diameter gradually decreases from the inner nut insertion end surface side (5a) toward the insertion direction according to the outer surface (4a) of (4), and engages with the engagement projection (10a). The engagement concave portion (10b) is constituted by the outer nut (5) formed on the inner side surface (8a) of the housing hole (8).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Lock nut (1) according to the present invention
There are first to sixth embodiments (1-1) to (1-6), which will be sequentially described below with reference to the drawings. The present invention is described in the first embodiment.
(1-1) is a representative example, and in the second and subsequent embodiments (1-2) (1-3) ... To avoid complexity of description, common parts are omitted and only different parts are explained. And

The lock nut (1-1) of the first embodiment is shown in FIG.
As shown in Fig. 3, tighten the appropriate fastening target member (3) (Fig. 3) that is screwed into the bolt (2) (Fig. 3) and sandwiched between the lock nut (1) and the bolt (2). And inner nuts (4)
And outer nut (5).

The inner nut (4) is for screwing the bolt (2) (FIG. 3), and the inner nut (4) has a female screw at the center thereof.
(6) is bored in the axial direction.

The outer peripheral surface (4a) of the inner nut (4) is tapered so that the outer nut (5) can be tightened by pulling the inner nut (4) into the accommodation hole (8). Has been formed.

The outer peripheral shape of the cross section perpendicular to the axial direction of the inner nut (4) is hexagonal, and the outer shape is a hexagonal truncated cone shape. However, the outer peripheral shape is not limited to the hexagonal shape, and may be, for example, a polygonal shape such as a triangular shape or a quadrangular shape, an elliptical shape, or a non-circular shape in the first embodiment. It's enough.

The outer surface (4a) of the inner nut (4) is provided with a groove (7) for reducing the diameter from the large diameter end surface (4b) to the small diameter end surface (4c) along the axial direction. The inner nut (4) is arranged substantially at the center of the side between the corners of the outer surface (4a) so that the diameter of the inner nut (4) can be easily reduced. Here, "engraved along the axial direction" does not only mean that it is engraved in parallel with the axis of the female screw (6), but is engraved obliquely with respect to the axial direction. Including the case of being done.

When the inner nut (4) is hexagonal, the number of the grooves (7) is plural (for example, three) so that the diameter can be uniformly reduced.
It is carved.

The length of the groove (7) varies from the large diameter end surface (4b) of the outer surface (4a) of the inner nut (4) to the small diameter end surface (4c) so that the entire inner nut (4) can be uniformly reduced in diameter. It is engraved over. However, one or both ends may not reach the end of the outer side surface (4a).

The width and depth of the groove (7) are appropriately set depending on the shape and material of the inner nut (4).

Although not shown, the groove (7) is a female screw.
It may be similarly engraved on the inner surface (6a) of (6).

Further, in order that the lock nut (1) can be tightened while visually confirming the position where the tightening is completed, an inner nut such as a black circle (not shown) or a horizontal bar (not shown) can be used. An indication indicating the tightening completion position of (4) may be marked on the outer surface (4a) of the inner nut (4).

The outer nut (5) is for accommodating the inner nut (4) and integrally rotating the inner nut (4) using a general-purpose tool, and its outer shape is, for example, a hexagonal column shape. There is. A housing hole (8) for housing the inner nut (4) is axially formed in the center of the outer nut (5).

The inner peripheral shape of the storage hole (8) in a cross section perpendicular to the axial direction is appropriately selected according to the outer peripheral shape of the inner nut (4) so that the inner nut (4) can be housed and rotated integrally. Is set. For example, when the outer peripheral shape of the inner nut (4) is hexagonal, the inner peripheral shape of the storage hole (8) is also set to hexagonal.

The inner surface (8a) of the housing hole (8) is gradually tapered with respect to the inserting direction of the inner nut (4) so that the inner nut inserting end surface (5a) side has a large diameter. Is set according to the taper angle of the outer surface (4a) of the inner nut (4).

Here, the taper angles of the outer side surface (4a) of the inner nut (4) and the inner side surface (8a) of the housing hole (8) of the outer nut (5) are not less than 3 degrees and not more than 8 degrees. It is preferable that the angle is 4 degrees or more and 6 degrees or less.

When the taper angle is 3 degrees or less, the inner nut (4) has a large moving distance to reduce its diameter, and the outer nut (5) becomes longer than necessary. On the other hand, if the angle is greater than 8 degrees, the frictional force between the inner nut (4) and the outer nut (5) in the direction of the slope decreases, and the inner nut (4) easily separates from the outer nut (5) due to vibration. turn into.

The size of the storage hole 8 is determined by the moving distance d required for the inner nut 4 to be sufficiently reduced in diameter, as can be seen from FIG. That is, the small diameter end face when the inner nut (4) before reducing the diameter contacts the outer nut (5)
A surface distance H between the bolt (4c) and the bolt insertion end surface (5b) of the outer nut (5) is set to be equal to or more than the above-mentioned moving distance d.

A ring-shaped excessive tightening prevention portion (9) for preventing excessive tightening of the inner nut (4) is provided at the end portion of the inner surface (8a) of the housing hole (8) on which the bolt is inserted. There is.

The overtightening prevention portion (9) has a ring-shaped outer shape, and the surface in contact with the inner nut (4) is the inner nut.
It is provided at a position separated from the small-diameter end surface (4c) of (4) by a movement distance d. A hole (9a) larger than the outer diameter of the foot of the bolt (2) is formed in the center of the excessive tightening prevention portion (9).

The inner nut (4) is a storage hole for the outer nut (5)
(8) When the inner nut (4) is pulled in by a distance d, the small diameter end face (4c) of the inner nut (4) abuts against the excessive tightening prevention portion (9) to prevent excessive tightening of the inner nut (4). it can. The excessive tightening prevention portion (9) is not limited to the ring-shaped member, and may be a simple protrusion-shaped member.

When the overtightening prevention part (9) comes into contact with the inner nut (4), the external force received by the inner nut (4) from the bolt (2) is passed through the overtightening prevention part (9) to the outer nut.
It will be transmitted to (5). Therefore, since the inner nut (4) and the outer nut (5) integrally receive the external force from the bolt (2), the contact area with the fastening target member (3) can be increased, Tighten the lock nut (1).

If the function of preventing excessive tightening is not necessary, the excessive tightening preventing portion (9) can be omitted.

When using the lock nut (1), see FIG.
As shown in (4), after the bolt (2) is screwed into the female screw (6) from the small diameter end face (4c) side of the inner nut (4), the outer nut (5) is rotated by a general-purpose tool or the like.

As described above, since the outer peripheral shape of the inner nut (4) and the inner peripheral shape of the housing hole (8) of the outer nut (5) are each hexagonal, the inner nut (4) is replaced by the outer nut. (Five)
The respective vertices can engage when stored in (FIG. 4). Therefore, the inner nut (4) is
It can rotate integrally without spinning against (5).

When the outer nut (5) begins to rotate, the bolt
The inner nut (4) screwed to (2) is pulled into the inside of the storage hole (8) along the taper, and the taper of the storage hole (8) causes the outer nut (5) to move to the inner nut (4). Tighten 4) toward the center of the shaft. The inner nut (4) has its outer surface (4
Since the force is concentrated on the groove bottom portion (7a) of the groove (7) engraved in a), the diameter is reduced as a whole due to compression plastic deformation.

In the conventional bolt / nut fastening mechanism, only the screw surface (23a) (FIG. 13) on one side of the bolt (20) and the nut (21) abut, but the inner nut (4) is reduced in diameter. As a result, the screw surfaces (11a), (11b) (FIG. 3) on both sides can be brought into contact at the same time. Therefore, one nut can achieve the same effect as the double nut, and can prevent loosening.

Further, the bolt (2) is tightened by the frictional force between the outer surface (4a) of the inner nut (4) and the inner surface (8a) of the storage hole (8) provided in the outer nut (5). , The lock nut (1) will not loosen unless this frictional force is released.

When removing the lock nut (1), the outer nut (5) is rotated in the direction of loosening. At this time, the inner nut (4)
Retains the state of being housed in the outer nut (5) as shown in FIG. 5, and the bolt (2) is still fastened to the lock nut (1). In this state, when a striking force is applied to the bolt insertion end surface (5a) of the outer nut (5) in the inner nut insertion direction, the outer nut (5) separates from the inner nut (4). Since the inner nut (4) is released from the compression force from the outer nut (5), the frictional force on the screw surface is reduced and the bolt
It is easy to remove from (2).

In the lock nut (1-2) of the second embodiment, the outer peripheral shape of the cross section of the inner nut (4) perpendicular to the axial direction is formed in a perfect circle shape. In this case, there is no part that can be engaged, so rotating the outer nut (5) will cause the inner nut (4) to rotate.
Will spin idle. Therefore, for example, as shown in FIG. 6, a pin-shaped engaging projection (10a) is formed on the outer diameter surface (4b) side of the outer surface (4a).
The inner nut insertion end surface of the inner surface (8a) of the storage hole (8)
An engaging recess (10b) that engages with the engaging protrusion (10a) may be provided on the (5a) side. In this case, the engagement protrusion (10a) and the engagement recess (10a
By engaging with b), the inner nut (4) and the outer nut (5) can rotate integrally.

Next, the lock nut (1-3) of the third embodiment will be described. Inner nut in the first and second embodiments described above
The outer surface (4a) of (4) has a groove (7) for reducing the diameter, but as shown in FIG. 7, the outer surface (4a) 'of the inner nut (4)' is provided in the axial direction. The inner nut (4) 'may be divided into a plurality of inner nut divided bodies (13) by dividing the inner nut (4)' by a plurality of divided grooves (12).

Next, the lock nut (1-4) of the fourth embodiment will be described. For example, as shown in FIG.
The inner nut insertion end surface of the outer nut (5) is provided with a cap-shaped fall prevention part (14) that prevents the inner nut (4) housed in (8) from coming off the housing hole (8) due to vibration or the like. (Five
a) It may be provided above.

The lower end portion (14a) of the drop-out prevention portion (14) is connected (welded or adhered) to the inner nut insertion end surface (5a) of the outer nut (5). A through hole (14c) larger than the outer diameter of the foot of the bolt (2) and smaller than the maximum outer diameter of the inner nut (4) is provided in the center of the ceiling (14b) of the captive prevention unit (14). Since it is provided, the foot of the bolt (2) can be inserted into the through hole (14c). In addition, the through hole (14c) does not necessarily have to be provided in the central portion of the ceiling (14b) of the fall prevention unit (14),
The ceiling (14b) may be integrally formed without a break. Here, the "maximum outer diameter of the inner nut" refers to the distance between the opposite corners of the outer peripheral shape (= hexagonal shape) of the inner nut (4).
In this case, it is possible to prevent the inner nut (4) from coming off from the outer nut (5) and dropping off when not in use or being transported.

Next, the lock nut (1-5) of the fifth embodiment will be described. In the above-mentioned fourth embodiment, in order to prevent the inner nut (4) from falling off, the cap-shaped fall prevention portion (14) is provided on the inner nut insertion end surface (5a) of the outer nut (5). For example, as shown in FIG. 9, a collar (or a protrusion) (15) may be formed on the inner side surface (8a) 'of the storage hole (8)' and used as the fall prevention portion (14) '.

The inner size of the collar (or protrusion) (15) is smaller than the outer diameter of the large-diameter end surface (4b) of the inner nut (4) so as to prevent the inner nut (4) from falling off. Is set.

Further, when the inner nut (4) is accommodated in the outer nut (5), the accommodation hole (8) 'is located at the position of the large diameter end surface (4b) of the inner nut (4) in the outer nut (5). Inner nut insertion end face (5
It is formed so as to be on the smaller diameter end face (4c) side than the position of a).

The inner nut (4) 'may be used instead of the inner nut (4) in the above-mentioned fourth and fifth embodiments.

Next, the lock nut (1-6) of the sixth embodiment shown in FIG. 10 will be described. In this case, the inner nut (4) '
Is divided into a plurality of inner nut divided bodies (13), and the inner nut (4) 'that is the assembly is a storage hole for the outer nut (5).
It is stored in (8). And, the inner nut insertion end surface (5a) of the outer nut (5) is provided with a captive prevention part (14), and the inner nut (4) 'is placed inside the captive prevention part (14). A pressing member (17) for pressing and urging in the nut insertion direction is provided.

The pressing member (17) has an inner nut (4) 'at one end.
Is connected to the large-diameter end surface (4b) 'and the other end is connected to the surface of the bottom surface (14b) of the cap (14) opposite to the inner nut (4)'. At this time, the pressing member (17) is housed in the drop-out preventing portion (14) while being compressed to some extent.

As the pressing member (17), an elastic body (for example, a coil spring having shape elasticity) is used. The elastic body is not limited to the coil spring, and a leaf spring may be used, or a volume elastic body such as rubber may be used.

Since the pressing member (17) is housed in the fall prevention portion (14) in a state of being compressed to some extent, the pressing member (1)
The inner nut (4) 'is pressed in the inner nut insertion direction by the restoring force of 7), and the inner nut (4)' is fixed in the state where it is stored in the storage hole (8) of the outer nut (5). It

In this state, when the bolt (2) is inserted from the small-diameter end surface (4c) 'side of the inner nut (4)', the diameter of the female screw (6) 'of the inner nut (4)' is initially determined by the dividing groove. The male screw (2
The diameter is smaller than the diameter of a), and the end surface of the male screw (2a) contacts the small diameter end surface (4c) ′ of the inner nut (4) ′. When the inner nut (4) 'is pushed in from the small diameter end face (4c)' side toward the large diameter end face (4b) 'side, the pressing member (17) is compressed and the inner nut (4)' follows the taper. The movement starts from the small diameter end surface (4c) 'side toward the large diameter end surface (4b)' side. At this time, the inner nut split body (13) moves along the taper,
The diameter of (6) 'gradually increases. Then, at the moment when the diameter of the female screw (6) 'becomes larger than the diameter of the male screw (2a) of the bolt (2), the inner nut (4)' is moved in the inner nut inserting direction by the restoring force of the pressing member (17). And the tip of the male screw (2a) enters the inside of the female screw (6) ', the female screw (6)' is reduced in diameter and the male screw (2a) is screwed (Fig. 11).

In this case, since the tip of the male screw (2a) is screwed into the female screw (6) 'simply by inserting the bolt (2), the tightening work can be easily performed.

[0053]

According to the present invention, the lock nut is composed of the inner nut and the outer nut, and the contact surface between the inner nut and the outer nut is formed in a tapered shape. Can be stored inside the storage hole provided. Further, since the inner nut is provided with a groove for reducing the diameter, the inner nut can enter the inside of the accommodation hole of the outer nut and the inner nut can be reduced in diameter by receiving the compressive force from the outer nut. . Since the inner nut can firmly tighten the bolt from the entire circumference, the inner nut and the bolt come into close contact with each other on both sides of the screw surface, and a single nut provides a fastening force similar to that of a double nut.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a first embodiment.

FIG. 3 is a cross-sectional view showing a usage state of the first embodiment.

FIG. 4 is a plan view of the first embodiment.

FIG. 5 is a cross-sectional view showing another usage state of the first embodiment.

FIG. 6 is a sectional view showing a second embodiment.

FIG. 7 is an exploded perspective view showing a third embodiment.

FIG. 8 is a sectional view showing a fourth embodiment.

FIG. 9 is a sectional view showing a fifth embodiment.

FIG. 10 is a sectional view showing a sixth embodiment.

FIG. 11 is a cross-sectional view showing a usage state of the sixth embodiment.

FIG. 12 is a cross-sectional view showing another usage state of the sixth embodiment.

FIG. 13 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

(1) ... Lock nut (2) ... bolt (3)… Parts to be fastened (4)… Inner nut (5)… Outer nut (6)… female screw (7) ... Groove for diameter reduction (8) ... Storing hole

Claims (9)

[Claims] 1. A lock nut comprising an inner nut having a female screw and an outer nut having a housing hole for housing the inner nut, wherein the outer peripheral shape of a cross section perpendicular to the axial direction is non-circular. The outer nut is tapered, and the inner nut is formed with a groove for reducing the diameter along at least one of the outer surface and the inner surface of the female screw in the axial direction; The inner peripheral shape of the cross section perpendicular to the axial direction of the is formed in a non-circular shape in conformity with the outer peripheral shape of the inner nut, and the inner side surface of the housing hole is inserted from the inner nut insertion end surface side in conformity with the outer side surface of the inner nut. A lock nut comprising the outer nut formed in a tapered shape such that the diameter gradually decreases in the direction. 2. A lock nut comprising an inner nut having a female screw and an outer nut having a housing hole for housing the inner nut, wherein the outer peripheral shape of a cross section perpendicular to the axial direction is circular. The outer surface is formed in a taper shape, the engaging projection is formed on the outer surface, and a groove for reducing the diameter is formed along at least one of the outer surface and the inner surface of the female screw along the axial direction. The inner nut and the inner peripheral shape of a cross section perpendicular to the axial direction of the accommodation hole are formed in a circular shape in accordance with the outer peripheral shape of the inner nut, and the inner surface of the accommodation hole is the outer surface of the inner nut. In accordance with the above, the engagement recess is formed in a tapered shape such that the diameter gradually decreases from the inner nut insertion end face side in the insertion direction, and the engagement recess that engages with the engagement protrusion is formed on the inner side surface of the accommodation hole. Composed with the outer nut Lock nut, characterized in that it has been. 3. The lock nut according to claim 1, wherein an excessive tightening preventing portion that engages with the inner nut when screwed in is provided so as to project from an inner surface of the housing hole. 4. The lock nut according to claim 1, wherein an indication showing a tightening completion position of the inner nut is marked on an outer surface of the inner nut. 5. The cap-shaped fall-out preventing portion is provided on the inner nut insertion end surface side of the outer nut so as to cover the nut insertion side opening of the housing hole. The lock nut on the crab. 6. The lock nut according to claim 1, wherein a collar-shaped drop-out preventing portion is provided so as to project on an inner side surface of the housing hole. 7. The lock nut according to claim 1, wherein the diameter reducing groove provided in the inner nut is a dividing groove that divides the inner nut into a plurality of divided bodies. 8. An inner nut having a female screw, an outer nut having a housing hole for housing the inner nut, and an inner nut provided on the inner nut insertion end side of the outer nut so as to cover the housing hole. A lock nut composed of a cap-shaped drop-prevention portion that prevents the drop-out and a pressing member that is interposed between the inner nut and the drop-prevention portion and presses the inner nut in the inserting direction of the inner nut. There, the inner nut is an assembly of a plurality of divided bodies divided by a plurality of dividing grooves provided in the axial direction, the outer peripheral shape of the cross section perpendicular to the axial direction is formed non-circular, The side surface is formed in a tapered shape, and the storage hole provided in the outer nut is formed such that the inner peripheral shape of the cross section perpendicular to the axial direction thereof is formed in a non-circular shape in conformity with the outer peripheral shape of the inner nut. Of the hole Lock nut characterized in that the side surface is formed in a tapered shape such that diameter gradually from the inside toward the nut insertion end face in the insertion direction in accordance with the outer surface of the inner nut. 9. The lock nut according to claim 1, wherein a taper angle formed on the inner nut and the outer nut is 3 degrees or more and 8 degrees or less.