JPH07197924A - Lock bolt - Google Patents

Abstract

PURPOSE:To obtain a sufficient looseness preventing effect so as to realize repeated use many times by forming both side surfaces of a ridge forming portion into a different and asymmetric shape, and forming a slit having an arcuate bottom surface on a lock ridge. CONSTITUTION:A lock bolt comprises a screw 3 having a lock ridge 2 and a hexagonal head integrally formed at one end of the screw 3. An inclined slit 6 having both side surfaces 2a, 2b each formed into an arcuate shape and a bottom surface 5 formed at the center thereof into an arcuate shape to thus obtain a different and asymmetric shape is formed in the lock ridge 2. In the thus formed lock bolt, the lock ridge 2 is screwed with a ridge 8 of a nut 7 in such a manner as to form a small clearance of the slit 6 in the upper portion, thereby imparting elastic force on the lock ridge 2 so as to prevent looseness. Since both side surfaces of the ridge are formed into a different and asymmetric shape, the tip of the lock screw ridge is formed into a shape difficult to be damaged, thus efficiently inhibiting biting into the nut.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock bolt having a screw thread formed with a slit for preventing loosening.

[0002]

2. Description of the Prior Art The shape and function of a lock bolt having a wedge-shaped slit formed in the radial direction from the top of a screw thread so as to prevent the loosening and its function are described in Japanese Patent Application No.
In No. 117605, the ribs are discontinuous and the cross section is substantially a quadrilateral, so there is little elastic deformation, which causes galling accidents and slip-in accidents, frictional wear with the side surface of the internal thread is easy, and elastic deformation is also local. However, the self-locking function is low. In Japanese Patent Application No. 52-131527, at the start of screwing, the screw crest corner portion is fixed at a screwing fixed position, and the acute angle projection portion of the screw crest corner portion is line screwed at the screwing fixed position. Therefore, there is a drawback in that, even after screwing, a galling phenomenon occurs to continuously damage the female screw side surface screwing portion, causing a slipping accident and failing to perform the original screw screwing function. Even after the screwing is completed, the contact portion with the side surface of the internal thread is line-threaded due to the fixed position of the acute-angled protrusion-shaped portion, so elastic deformation of the thread side surface in an unreasonable state causes plastic deformation due to age hardening of the metal structure. In addition, there is a drawback that the stress is diffused due to the deformation, and the slit from the top of the wedge-shaped screw thread to the shaft center has a drawback that the bottom end becomes a hindrance due to the plastic work rolling with a pitch of two threads at one thread. At the start of screwing and during screwing, elastic deformation stress of the screw threads may concentrate on the tip of the bottom of the slit, causing a hair crack accident or a fracture accident reaching the shaft center. If the resistance at the screw fixed position point specified at the screw crest corner portion at the start of screwing is large, this slit causes an accident of being embedded in the side surface of the female screw before elastic deformation occurs. Therefore, the function of the shape of the screw thread and the wedge-shaped slit shape of the screw crest has a disadvantage that the frictional resistance is too large and the apparent torque value increases, but the self-locking function cannot be performed. Japanese Patent Application No. 56-124652
No. 52-131527, it is said that the number of flank angles was increased to two to eliminate the galling phenomenon at the tip of the thread, but at the start of screwing the intersection angle of two flank angles. There is no improvement in comparison with Japanese Patent Application No. 52-131527 in that it is fixed at a fixed position from the time when the screwing is completed to the fixed position. Since the shaft is located from the axial center, elastic deformation is less likely to occur in screwing at a fixed fixed position (line contact at a fixed fixed position in three dimensions), and frictional resistance during screwing is extremely reduced. It causes the workability to deteriorate, and the frictional wear between the specific fixing corner of the screwed part and the side surface of the internal thread causes severe frictional wear.When the screwing is completed, the self-lock torque value is attenuated, and this effect is repeated. The disadvantage is that it cannot be used effectively. The wedge-shaped slit at the top of the screw thread has not been improved, and the tip of the wedge-shaped slit facing the axial direction has a sharp edge, which makes elastic deformation of the screw thread difficult to occur and it is impossible when screwing. There is a drawback that the elastic deformation load stress of the screw thread concentrates on the tip of the bottom slit and a hair crack accident easily occurs, leading to a fracture accident toward the axis. The function based on the shape with such a problem has many drawbacks as a shape that performs the self-locking function, and is difficult to improve.

[0003]

In the conventional lock bolt, the slit formed in the radial direction from the top of the screw thread is almost impossible to be machined for the narrow width and depth of the slit. Although it may be possible to manufacture it by a rolling method, the slits are narrow and deep, so the durability of the slit-forming projections formed on the rolling die is poor, and it is almost impossible to economically roll. was there. Furthermore, since the flanks of the thread with the slits have one or two flank angles, the side surface of the nut and the threaded portion is in a line contact state that is fixed by the protruding portion to form the slit. Because the elastic deformation of the screw thread is hard to occur and the function is biased or it changes to plastic deformation, it diffuses and the locking effect and the loosening prevention critical value are low, or it makes a line contact at a specific fixed protrusion part. There is a problem in the stress concentration of, the excessive resistance value deteriorates the workability, and the extreme friction and wear of the screwed part lowers the lock effect and damages it, and also causes the occurrence of hair cracks and breakage accidents. However, it had the drawback of being unreliable.

In view of the above-mentioned conventional drawbacks, the present invention has been made.
It is an object of the present invention to provide a lock bolt which is easy to manufacture, has a sufficient effect of preventing loosening, and can be repeatedly used any number of times.

The above and other objects and novel characteristics of the present invention will become more fully apparent when the following description is read in view of the accompanying drawings. However, the drawings are for explanation only and do not limit the scope of the present invention.

[0006]

In order to achieve the above-mentioned object, the present invention provides a bolt body and both side surfaces formed at a thread forming portion of the bolt body are asymmetrical and asymmetrical.
A lock screw is formed with a lock screw thread having a bottom surface formed with an arcuate slit.

[0007]

The lock bolt constructed as described above is usually formed lower than the thread, and the bottom formed on the lock thread has an arcuate slit to impart sufficient elasticity to the thread. In addition, since both side surfaces of the screw thread are formed asymmetrically and asymmetrically, the tip of the lock screw thread is difficult to be damaged, and it is possible to efficiently prevent biting into the nut.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings.

In the first embodiment of the present invention shown in FIGS. 1 to 7, reference numeral 1 is a lock bolt of the present invention. The lock bolt 1 has a screw portion 3 having a lock screw thread 2, and the screw portion 3. And a hexagonal head 4 integrally formed at one end of the.

The lock screw thread 2 is, as shown in FIG.
Both side surfaces 2a, 2b are arcuate, and a slanted slit 6 is formed in which the bottom surface 5 is arcuately formed at the center so that it is asymmetrical.

As shown in FIG. 4, the lock bolt 1 constructed as described above is screwed into the screw thread 8 of the nut 7 so that the lock screw thread 2 is screwed so that the gap between the upper slits 6 becomes small. Since the elastic force is applied to the lock screw threads 2, it is possible to prevent loosening.

The lock bolt 1 is manufactured using a rolling die 9 for manufacturing a lock bolt shown in FIG. The rolling dies 9 for producing lock bolts are composed of a pair of rolling dies 9 and 9 of substantially the same shape which are fixed to a fixed base 11 and a movable base 12 of a flat rolling machine 10, respectively. As shown in FIGS. 6 and 7, the rolling dies 9 and 9 include a plate-shaped rolling die main body 13 and a bolt main body 14 formed at a portion near the upstream portion of the rolling die main body 13. One of the thread forming portion 16, the slit forming portion 17, for forming the original shape of the lock screw thread 2 in the thread forming portion 15;
The other thread forming part 18 and the thread groove forming part 19, and one thread forming part 16A and slit forming part 17 for forming the finished shape of the lock bolt thread 2 in the downstream portion.
A, the other thread forming portion 18A and the thread groove forming portion 19
It is composed of A and.

[0013]

Different Embodiments of the Present Invention Next, different embodiments of the present invention shown in FIGS. 8 to 16 will be described. In the description of these different embodiments of the present invention, the same components as those of the first embodiment of the present invention will be designated by the same reference numerals and redundant description will be omitted.

In the second embodiment of the present invention shown in FIGS. 8 to 10, the main difference from the first embodiment of the present invention is the lock screw thread 2A, which is located closer to the center than the central portion. The slit 6A is formed in a direction perpendicular to the axial direction of the threaded portion 3 by being shifted. Even if the lock screw thread 2A thus formed is formed on the threaded portion 3 of the lock bolt 1A, the same operation and effect as those of the first embodiment of the present invention can be obtained.

In the third embodiment of the present invention shown in FIGS. 11 to 13, the main difference from the first embodiment of the present invention is a lock screw thread 2B, and both sides of the lock screw thread 2B are different. A plurality of flanks, three flanks in this embodiment, are formed. Even with the lock bolt 1B formed on the lock screw thread 2B in this manner, the same operational effects as those of the first embodiment of the present invention can be obtained.

In the fourth embodiment of the present invention shown in FIGS. 14 to 16, the main difference from the second embodiment of the present invention is a lock screw thread 2C, and both sides of the lock screw thread 2C are different. A plurality of flanks, three flanks in this embodiment, are formed. Even with the lock bolt 1C formed on the lock screw thread 2C in this manner, the same effect as that of the second embodiment of the present invention can be obtained.

[0017]

As is apparent from the above description, the following effects can be obtained in the present invention.

(1) A bolt main body and a lock screw thread whose bottom surface is formed with an arcuate slit so that both side surfaces formed at the thread forming portion of the bolt main body are asymmetrical. Therefore, a sufficient elastic force can be applied to the thread by the slit having the arcuate bottom surface. Therefore, a sufficient relaxation preventing effect can be obtained.

(2) According to the above (1), a part of the screw thread of the nut is brought into contact with and screwed, so that the contact area is smaller than in the conventional case, and the screwing work can be performed like an ordinary bolt. .

(3) According to the above (1), the elastic region of the thread can be made larger than the conventional one by the slit having the arc-shaped bottom surface. Therefore, it can always be used in the elastic region,
It can be used over and over again with almost no damping of the locking effect.

(4) According to the above (1), since the bottom surface is formed with arcuate slits so that both side surfaces are not asymmetrical, threads are formed. It is possible to prevent sharp angles. Therefore,
It is possible to reliably prevent the tip of the thread from being damaged or being injured at the tip of the thread.

(5) Claims 2 and 3 also have the above (1) to (4).
The same effect as can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of the present invention.

FIG. 2 is a bottom view showing the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a screw thread.

FIG. 4 is an explanatory diagram of a state in which the nut is screwed together.

FIG. 5 is an explanatory view of a rolling die for manufacturing a lock bolt.

FIG. 6 is a plan view of a rolling die.

FIG. 7 is a side view of a rolling die.

8 to 10 are explanatory views showing a second embodiment of the present invention.

11 to 13 are explanatory views showing a third embodiment of the present invention.

14 to 16 are explanatory views showing a fourth embodiment of the present invention.

[Description of Reference Signs] 1, 1A, 1B, 1C: Lock bolt, 2, 2A, 2B, 2C: Lock screw thread, 3: Threaded portion, 4: Head portion, 5: Bottom surface, 6, 6A: Slit,
7: Nut, 8: Thread, 9:
Rolling dies for rock bolt manufacturing, 10: Flat rolling machine,
11: fixed base, 12: movable base, 1
3: Rolling die body, 14: Bolt body,
15: screw thread forming portion, 16 and 16A: one screw thread forming portion, 17 and 17A: slit forming portion,
18, 18A: The other thread forming portion, 19, 19A:
Thread groove forming part.

Claims (3)

[Claims] 1. A bolt main body and a lock screw thread having a bottom surface formed with arcuate slits so that both side surfaces formed at the thread forming portion of the bolt main body are asymmetrical. Rock bolt to do. 2. A bolt main body and a lock screw thread having an arc-shaped bottom formed so that both side surfaces formed at a thread forming portion of the bolt main body are arcuate and asymmetrical. Rock bolt characterized by. 3. A lock screw having a bottom formed with an arcuate slit so that the bolt main body and a plurality of flank angles formed on the thread forming portion of the bolt main body are different and asymmetrical with different flank angles. A rock bolt characterized by being composed of mountains.