JP3909371B2 - Simple fastening nut - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a simple fastening nut, that is, a nut that can easily perform a fastening operation, and relates to a nut that is fitted into a screw thread from a side of a bolt and can be attached to a fastening position.
[0002]
[Prior art]
Ordinary nuts need to be screwed onto the thread from the tip of the bolt. The fastening force of the nut is transmitted to the bolt through a plurality of screw threads, and the fastening force causes a compressive stress to act on the nut and a tensile stress to the bolt. Due to the elastic deformation of the nut, the largest force is applied to the thread closest to the fastening surface of the nut (the surface on which the fastening force acts).
[0003]
Since a normal nut is inserted into the bolt from the tip of the bolt, if the bolt is long, the nut must be rotated many times to move the nut to the fastening position. It takes a lot of work. If there is an obstacle at the tip of the bolt, it is impossible to attach the nut to the middle of the bolt.
[0004]
Therefore, a simple fastening nut is proposed in which a nut is cut in the axial direction or divided into two in the axial direction. A nut with an axial notch is disclosed in, for example, Japanese Patent Laid-Open No. 3-61709. As shown in FIG. 5, the nut is inserted into the screw hole 31 of the nut so that the nut can be inserted from the side of the bolt. The upper nut 1 is provided with a series of notches 32 and the lower nut 2 is provided with a similar notch 33. The upper nut 1 and the lower nut 2 are fitted by a groove 34 and a projection 35 concentric with a screw hole formed in the mating surfaces of the two nuts 1 and a relative deviation in the direction perpendicular to the axis does not occur. The upper nut 1 and the lower nut 2 are formed such that when the notches 32 and 33 are in the same direction, the thread is shifted by a half lead.
[0005]
In the simple fastening nut shown in FIG. 5, with the notches 32 and 33 aligned, the upper nut 1 and the lower nut 2 are fitted into the bolt from the side of the bolt, and the upper nut 1 is rotated 180 degrees in the fastening direction. After that, fastening is performed by rotating both 1 and 2 simultaneously.
[0006]
An example of splitting the nut in the axial direction is shown in, for example, Japanese Utility Model Publication No. 5-83434. As shown in FIG. 6, split pieces 40a and 40b divided in the axial direction are mounted from the side of the bolt. Then, the ring-shaped cap 41 is put on it and the divided pieces 40a and 40b are to be integrated. Since this structure requires the cap 41 to be inserted from the tip of the bolt, it cannot be used when there is an obstacle at the tip of the bolt.
[0007]
As another structure for dividing the nut in the axial direction, there is a structure in which the divided pieces are coupled to each other with a hinge pin or a lock pin (for example, Japanese Utility Model Application No. 1-27677). However, this structure is troublesome especially when the screw diameter is small, and it is troublesome to connect the ends of the two split pieces with a lock pin after fitting the nut into the bolt. There are troubles such as having to prevent the lock pin from coming off.
[0008]
[Problems to be solved by the invention]
Therefore, the structure shown in FIG. 5 is excellent in that the nut can be quickly fitted into the intermediate position of the bolt and the fastening operation after fitting is easy. However, according to the result of the stress analysis performed by the inventor of the present application using the nut of FIG. 5, when the nut is fastened, both the upper nut 1 and the lower nut 2 have a large local stress on the thread on the fastening surface side. It was found to occur.
[0009]
In the structure as shown in FIG. 5, even if the screw thread of the bolt is screwed with the nut only half of the circumference, and the entire circumference of the bolt is screwed with the upper and lower nuts, Due to the elastic deformation of the nut, the load that should be handled by the remaining half of the screw thread is concentrated on the part where the screw thread of the nut on the side close to the fastening surface is cut off. Concentrates and causes permanent deformation in the thread.
[0010]
Based on the above knowledge, the present invention has a simple structure and can be easily manufactured even with a small-diameter nut, and can be easily attached and fastened to the intermediate portion of the bolt. It is an object of the present invention to obtain a simple fastening nut in which the threads are screwed together over their entire circumference, and thus do not cause local stress concentration in the thread.
[0011]
[Means for Solving the Problems]
The simple fastening nut of the present invention includes an upper nut 1 and a lower nut 2 that are each divided into two in the screw axis direction, and includes four divided pieces 1a, 1b, 2a, and 2b. On the abutting surface of the upper nut 1 and the lower nut 2, a convex strip 4 concentric with the screw shaft is provided on one side 12, and a concave groove 5 is provided on the other side 13. The thread 18 of the upper nut 1 and the thread 19 of the lower nut 2 are configured such that a quarter lead phase is shifted when the split surfaces 9 and 10 are in the same direction. The height of the ridges 4 is preferably higher than a quarter of the lead of the screw, and the inner and outer circumferences of the ridges 4 are fitted into the concave grooves 5 with a fitting relationship as accurate as possible.
[0012]
[Action]
The simple fastening nut having the above-described structure can be obtained by fitting the protrusions 4 and the grooves 5 with the split surfaces 9 and 10 of the upper nut and the lower nut aligned with each other. Can be inserted into the bolt. When the nut thread fits into the bolt thread, the upper nut split pieces 1a, 1b are separated from the lower nut split pieces 2a, 2b by a quarter lead of the screw. In this state, when the upper nut 1 is rotated by a quarter in the fastening direction, the butted surfaces of the upper and lower nuts come into contact with each other, and the divided surfaces 9 and 10 of the upper and lower nuts are orthogonal to each other. In this state, the threads of the upper and lower nuts 1 and 2 are screwed into the bolt threads with the same phase.
[0013]
Since the split surfaces 9 and 10 of the upper and lower nuts 1 and 2 are orthogonal to each other by 90 degrees, the lower nut is prevented from being split by the upper nut by the fitting of the ridges 4 and the concave grooves 5, Splitting of the nut is suppressed by the lower nut. Since this restraining force acts on the abutting surfaces of the upper and lower nuts, the divided pieces of the upper and lower nuts cannot be integrated completely. However, when the nut is tightened with the upper nut and the lower nut splitting at 90 degrees perpendicular to each other, the lower nut 2 is sandwiched between the upper nut and the fastened member, and the upper nut Since the nut 1 is given a moment in the direction in which the split surfaces of the split pieces are brought into close contact with each other, the split pieces of the upper and lower nuts cannot be tilted and are provided as integrated nuts. All the screw threads are screwed with the screw threads of the bolt over the entire circumference.
[0014]
The phase difference between the screw threads of the upper and lower nuts has been described as a quarter lead. However, in reality, the fastening force also acts on the abutting surfaces of the upper and lower nuts, and the nut and bolt are deformed by the fastening force. Therefore, it is more preferable that the phase difference is obtained by subtracting the phase difference due to the deformation to a quarter lead. Further, since the upper nut 1 also functions as a detent nut for the lower nut 2, when such a function is positively given, the phase difference between the threads of the upper nut 1 and the lower nut 2 is further increased. It is effective to make it smaller.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show a first embodiment of the present invention. The simple fastening nut according to the present invention includes an upper nut 1 and a lower nut 2, and the upper nut 1 and the lower nut 2 each include two divided pieces 1 a, 1 b, and 2 on a plane including the central axis of the screw hole 3. It is divided into 2a and 2b. On the upper surface of the lower nut 2, a ridge 4 concentric with the central axis of the screw hole is integrally formed. The cross section of the ridge 4 is square and the corner 11 on the tip side is chamfered small. On the lower surface of the upper nut 1, a groove 5 having a groove width into which the protrusion 4 is just fitted is formed. The height of the ridge 4 is higher than a quarter of the lead of the screw 6 provided on the nut, and the groove 5 has a depth that allows the ridge 4 to be completely accommodated.
[0016]
One split piece 1a and 2a of the upper and lower nuts 1 and 2 is combined in a state in which the protruding strip 4 is fitted in the concave groove 5, and the other split piece 1b and 2b is similarly combined with the convex strip 4 into the concave groove 5. The two combined bodies are mounted from both sides so that the bolts 7 are sandwiched by combining them in a fitted state. Since the screw threads of the upper nut 1 and the lower nut 2 are shifted by a quarter of the lead, when the bolt 7 is sandwiched between the two combinations, the upper nut 1 and the lower nut 2 are A 1/4 lead gap is left in the screw. In this state, when the upper nut 1 is rotated by a quarter in the fastening direction, the butted surfaces of the upper and lower nuts (the lower surface of the upper nut and the upper surface of the lower nut) are brought into close contact with each other, and the phases of the upper and lower nut screws are also matched. . In this state, if the upper and lower nuts 1 and 2 are simultaneously rotated by a single spanner or the like, the upper and lower nuts are united and screwed on the bolt 7 to fasten the fastened object 8.
[0017]
The upper and lower nut split pieces 1a, 1b and 2a, 2b can be manufactured by plastic working such as cutting or die forging. When forming a screw hole by cutting, the upper and lower nuts are fixed to the machine tool in a state where the divided surfaces 9 and 10 are orthogonally crossed (the state at the time of fastening), and the threads of the four divided pieces are Process it at the same time. If the upper and lower nuts are held with axial preload applied and processed, the surface pressure acting between the upper and lower nuts during fastening can be controlled.
[0018]
FIG. 4 is a view showing a second embodiment of the present invention. In the second embodiment, the concave and convex grooves 5 having the same radius and the same width are provided on the abutting surfaces 12 and 13 of the upper and lower nuts, and the rectangular cross section is provided. The ridges 4 are formed by fitting the half-cracked ring 16 into one of the concave grooves 5. In this case, the butt end 17 of the half-breaking ring 16 does not necessarily coincide with the dividing surface of the upper or lower nut.
[0019]
In the second embodiment, all of the four divided pieces are provided with the concave grooves 5, so that the divided pieces 1a and 2a and the upper and lower nuts 1a and 2b and 1b and 2b are manufactured in one mold. Therefore, the die cost can be saved when the nut is manufactured by casting or die forging.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of the first embodiment. FIG. 2 is a combined perspective view of the first embodiment. FIG. 3 is a perspective view of a fastening state of the first embodiment. FIG. 5 is a perspective view showing a conventional example of a simple fastening nut inserted from the side of a bolt. FIG. 6 is a perspective view showing a conventional example of a simple fastening nut divided in the axial direction.
1 Upper nut
1a, 1b Split piece 2 Lower nut
2a, 2b Divided piece 4 Convex strip 5 Concave groove
9,10 Dividing plane
12,13 butt surface
18,19 thread

Claims (1)

An upper nut (1) consisting of an upper divided piece (1a, 1b) divided in two in the screw axis direction and a lower nut (2) consisting of a lower divided piece (2a, 2b) divided in two in the screw axis direction A ridge (4) concentric with the screw shaft is provided on one (12) of the butted surfaces of the upper nut (1) and the lower nut (2), and a concave groove (5) is provided on the other (13). The upper nut (1) thread (18) and the lower nut (2) thread (19) are approximately one quarter when the split surfaces (9, 10) are in the same direction. A simple fastening nut with a lead phase difference.

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