JPH0437289B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Field of Industrial Application] The present invention relates to a stud bolt having threads formed at both ends of a bar.

[Conventional technology] Conventionally, stud bolts, which are round bars with threads cut on both ends, are made by first implanting one end into the fuselage, making a hole in the part to be fixed, inserting it together with the seat, and tightening it with a nut. I am using it.

[Problems to be Solved by the Invention] However, the stud bolts used in this manner are becoming lighter and lighter as machines become lighter, especially parts used in transportation machines such as automobiles. , a product with a high manufacturing yield was desired. A possible stud bolt to improve this point is one in which the cylindrical portion sandwiched between the threaded portions at both ends is a triangular prism, and the diameter of the circumscribed circle of the triangular prism is equal to the nominal diameter of the stud bolt. However, when such a stud bolt is used, if a strong tightening torque is applied, both ends of the triangular prism will dig into the object, resulting in a lack of strength.

The present invention was made to solve the above problems, and proposes a stud bolt that also maintains strength resistance.

Structure of the Invention The structure of the present invention that achieves the above object will be explained below.

[Means for Solving the Problems] The stud bolt of the present invention is a stud bolt in which threads are formed at both ends of a bar material, and includes a threaded portion at both ends and a rod-shaped portion sandwiched between the threaded portions. Annular locking protrusions larger than the root diameter of the screw are formed approximately at the boundary along the outer circumference of the boundary, and rod-shaped portions other than the boundary have an outer diameter that is equal to the outer diameter of the screw. The gist is that a smaller part was formed.

[Function] The stud bolt of the present invention having the above configuration has the following features:
Since locking protrusions each having an outer diameter larger than the root diameter of the screw are formed at the boundary between the thread forming part and the rod-shaped part, it can be used in the same manner as a conventional stud bolt. Moreover, since the stud bolt of the present invention has a portion on the rod-shaped portion whose outer diameter is smaller than the outer diameter of the screw, the overall weight of the stud bolt can be reduced.

[Examples] In order to further clarify the configuration of the present invention described above, preferred embodiments of the present invention will be described next. The stud bolt 1 according to the first embodiment of the present invention is as follows:
As shown in the front view of FIG. 1A and the side view of FIG. 1B, it consists of threaded portions 3a, 3b at both ends and a cylindrical portion 5 at the center. The central cylindrical part 5 is the threaded part 3
The threaded portions 3 at both ends are thinner than the outer diameters of a and 3b.
a, 3b, a collar-shaped annular protrusion band 7a, 7 having the same diameter and having a predetermined diameter larger than the nominal diameter of the stud bolt perpendicular to the axis along its outer periphery.
b are provided respectively. The stud bolt 1 of the first embodiment is made of a round wire rod by cold heading, with both ends chamfered, and a blank made by reducing both ends and the center part to a predetermined diameter, and a plate is attached to this blank. Threads are processed and formed by thread rolling.

The stud bolt 1 of the first embodiment processed and formed in this way has one threaded portion 3a implanted in the fuselage body 29 in advance as shown in FIG. support tool 35
The other threaded portion 3b is tightened with a nut 37 and fixed. Therefore, when screwed into the body 29, the annular protrusion 7a provided at the boundary between the threaded portion 3a and the cylindrical portion 5 acts to lock onto the body 29. Therefore, the stud bolt 1 of the first embodiment has the excellent effect that the cylindrical portion 5 does not dig into the body 29. Moreover, the annular protrusion 7
Since the stud bolt a does not dig into the fuselage 29, the stud bolt 1 of the first embodiment has the advantage of being lighter than conventional stud bolts because the columnar portion 5 can be formed to be thinner than the outer diameter of the threaded portion 3a. Also,
Each annular protrusion 7a, 7b of the first embodiment
is larger than the outer diameter of the threaded parts 3a and 3b, and has the same outer diameter, so when it is screwed into the body of the fuselage, etc., which has a hole with the same inner diameter, the respective annular protrusions located on both sides The difference in dimensions between the holes 7a and 7b and the holes is small, and the annular protrusions 7a and 7b serve as guides to prevent the stud bolt 1 from wobbling laterally in the holes. Furthermore, the stud bolt 1 of the first embodiment can be easily processed and formed with high precision, so that it has the effect of increasing the yield in product manufacturing.

The stud bolt 11 of the second embodiment of the present invention is
As shown in the front view of FIG. 2A and the side view of FIG. 2B, the stud bolt 1 is composed of threaded portions 13a, 13b and a cylindrical portion 15, similar to the stud bolt 1 of the first embodiment.
The central cylindrical portion 15 is thinner than the outer diameter of the threaded portions 13a, 13b, and has an arbitrary number of collar-shaped annular protrusions 17 formed on its outer peripheral surface at right angles to the axis. The outer diameter of the annular protruding band 17 is a predetermined diameter larger than the nominal diameter of the stud bolt 11, and the respective diameters are all the same.

The stud bolt 11 of the second embodiment is processed and formed in the same manner as the stud bolt 1 of the first embodiment. The stud bolt 11 of the second embodiment processed and formed in this manner has an arbitrary number of rib-shaped annular protrusions 17 formed on the outer peripheral surface of the cylindrical portion 15 at right angles to the axis. Therefore, in addition to exhibiting the same functions and effects as the stud bolt 1 of the first embodiment, the object inserted into the cylindrical portion 15 does not move. As a result, there is an effect that the object is firmly held. It should be noted that the present invention is open to various improvements without departing from the gist thereof. For example, the outer diameters of the respective annular protrusions may not be the same, but may be different diameters from each other.

Effects of the Invention As detailed above, in the stud bolt of the present invention, annular locking protrusions larger than the root diameter of the screw are formed along the outer periphery of the boundary at approximately the boundary between the threaded part and the rod-shaped part. The rod-shaped portion other than the locking protrusion has a portion whose outer diameter is smaller than the outer diameter of the screw. Therefore, the rod-shaped portion does not bite into the object screwed onto the screw, and has the advantage of having high strength, fixing the object, and reducing the weight of the product. Furthermore, there is an effect that the yield of the product can be ensured well.

[Brief explanation of drawings]

1A and 1B are diagrams showing a stud bolt according to the first embodiment of the present invention, FIG. 2 is a diagram showing an application example of the stud bolt according to the same embodiment, and FIG. 3 is a diagram showing a stud bolt according to the second embodiment. It is a figure showing a stud bolt. 1, 11... Stud bolt, 3a, 3b, 13
a, 13b...Threaded part, 5, 15... Cylindrical part, 7a,
7b, 17...Protrusion belt.

Claims (1)

[Scope of Claims] 1. A stud bolt in which threads are formed at both ends of a bar, wherein a valley of the thread is provided at the approximate boundary between the thread forming portions at both ends and the rod-shaped portion sandwiched between the thread forming portions. A stud bolt, wherein annular locking protrusions larger than the diameter are formed along the outer periphery of the boundary portion, and a portion whose outer diameter is smaller than the outer diameter of the screw is formed on the rod-shaped portion other than the boundary portion.