JPH0113846Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Objective" (Industrial Technical Field) This invention relates to a stud bolt having a torque transmission part between both threaded parts.

(Prior Art) A conventional stud bolt, as shown in FIGS. 1 and 2, for example, includes a threaded part 1 on the implant side, a shaft part 2 having an outer diameter approximately equal to the outer diameter of the threaded part 1, and a shaft part 2 with a diameter smaller than the outer diameter of the threaded part 1 on the implant side. It consists of a nut side threaded part 3. The reason why the outer diameter of the threaded part 1 on the implant side is made larger than the outer diameter of the threaded part 3 on the nut side is that a bending moment is generated in the bolt due to an external force acting on the nut side, which causes fatigue in the threaded part 1 on the implant side. This is to prevent destruction from occurring.

3 and 4 show an embodiment of a conventional stud bolt having an inner collar 4 on the shaft portion 2. As shown in FIG. Nakatsuba 4
The implant side threaded portion 1 is brought into contact with the mating surface into which it is screwed to bear the bending moment.

However, in such conventional stud bolts, when tightening the stud side thread part into the female thread, a double nut is screwed into the nut side thread part, the required tightening torque is applied to the double nut, and then The procedure involved removing the darb nut, which made the work less efficient, and as shown in Figures 3 and 4, the tightening torque was large for stud bolts with a central flange, so the torque was applied to the threaded part on the nut side. When adding
Since the nut-side threaded portion was smaller than the implant-side threaded portion, there was a fatal defect in that the nut-side threaded portion could be threaded off.

Another conventional example is a bolt with a hexagonal inner brim (Utility Model Publication No. 52-53906).
The material does not spread to the diagonal of the corner, resulting in an accurate hexagonal shape and poor fit with the tightening tool.In order to form an even more accurate hexagonal shape, if you use hexagonal punching, a large amount of material will be lost. There was a drawback that it appeared.

On the other hand, as shown in FIG. 12, the stud bolt B that screws into the center of the carburetor 10 and attaches the air cleaner 12 has a hexagonal protrusion on the middle flange, so that the intake air is It had the drawback of causing disturbances.

Further, when the shaft portion 2 of the stud bolt serves to position the object to be fastened, no inner flange can be provided, and naturally a torque transmitting portion cannot be formed in that portion. In the figure, numeral 14 indicates an air cleaner cap, and numeral 16 indicates a wing nut.

(Problems to be solved by the invention) This invention eliminates the complexity of tightening the stud bolt and prevents damage to the threaded part on the nut side during tightening. To provide a stud bolt with good precision, less material loss, excellent cold workability, and a torque transmitting part that is not affected by the presence or absence of a center flange.

(Means for Solving the Problems) This invention aims to eliminate the above-mentioned drawbacks, and its gist is that a stud bolt or a stud bolt with an outer diameter of the threaded part on the nut side smaller than the outer diameter of the threaded part on the implanted side In a stud bolt having a shaft portion extending between both threaded portions, the circumscribed circle dimension of the shaft portion extending between the cylindrical portion and the threaded portion on the nut side is This is a stud bolt characterized in that it is constituted by a hexagonal torque transmitting portion whose inscribed circle diameter is smaller than the diameter of the hexagonal torque transmitting portion and whose inscribed circle diameter is larger than the outer diameter of the threaded portion on the nut side.

"Structure" (Example) An example of this invention will be described with reference to FIGS. 5 to 8. In the embodiment shown in FIG. 5, an implant-side threaded portion 1, a shaft portion 2, and a nut-side threaded portion 3 having an outer diameter smaller than the outer diameter of the implant-side threaded portion 1 are provided on the same axis. The shaft portion 2 is provided at a terminal end in the direction of the nut-side threaded portion 3, continuing from the columnar portion 2a.
The torque transmitting portion 2b has a hexagonal cross section.

Further, the circumscribed circle of the hexagonal cross section is smaller than the outer diameter of the cylindrical part 2, and the inscribed circle is made larger than the outer diameter of the nut side threaded part 3. Note that the diameter of the cylindrical portion 2a is generally approximately equal to the outer diameter of the threaded portion 1 on the implanted side in order to prevent the threaded portion 1 on the implanted side from entering too far into the female thread, and also to serve the role of positioning the object to be tightened. It is true.

7 and 8 show a bolt in which the inner flange 4 is provided on the implantation side of the shaft portion 2 shown in FIGS. 5 and 6. The purpose of providing the middle flange 4 is to prevent fatigue failure of the threaded portion on the implantation side by causing the middle flange to bear the bending moment as described above. Therefore, a large stress is generated in the upper columnar part 2a of the inner collar 4 due to the bending moment, so the shaft diameter must be large enough to withstand this stress.

Therefore, the diameter of the shaft part 2 should be within 30% of the outer diameter of the threaded part 1 on the implantation side in terms of cross-sectional reduction rate (reduction in diameter to the pitch of the thread, for example, M10 x 1.25). If it is a screw, it is generally about φ8.75).

The processing method for the hexagonal torque transmission section 2b is as follows.
In a final step or a separate step during the cold forging process of a stud bolt having a conventional shape, the bolt having a conventional shape is inserted into a hexagonal drawing die and the shaft portion is drawn. At this time, the cylindrical portion 2a serves to facilitate the drawing process by preventing the material from flowing toward the mouth of the drawing die. During drawing, the material stretches in the axial direction due to the reduction in cross section, so bolts that are shorter than conventional products must be used accordingly. Also, during insertion during this drawing process, the shaft portion 2 formed in the previous process and the plank of the implanted side threaded portion 1 (cylindrical material before thread rolling (not shown)) do not swell due to the pressure during insertion. Therefore, the reduction rate must be within 30% (reduction rate of cross-sectional area).

When the screw is tightened until it breaks, the breaking torque is approximately the same as the simple torsional strength of the screw, based on conventional tests. Therefore, when it is necessary to ensure that the breaking strength of the torque transmitting part 2b is greater than the breaking torque of the screw described above, it is sufficient to make the cross-sectional area of the hexagonal torque transmitting part 2b the same as that of the implant-side threaded part 1. .

To be more specific, if the circumscribed circle of the shaft part 2, which has the same diameter as the outer diameter of the implanted threaded part 1, is equal to the diameter of the cylindrical part, the cross-sectional area of the hexagonal torque transmission part 2b will be equal to the thread pitch. Although it depends, in general it will be approximately the same cross-sectional area as the screw. (For example, M10×1.25
The cross-sectional area of the screw is 61.2 mm ² , and the cross-sectional area of the hexagon with a circumscribed circle diameter of 10 is 65.0 mm ² ).

Generally, the tightening torque is about 1/2 of the breaking torque, and if the above-mentioned level of transmission torque is not required, the hexagonal torque transmission part 2b is used within the above-mentioned narrowing ratio of 30%. You can make it thinner.

Figures 9 and 10 show the shape of the torque transmission part 2c (commonly known as 12 points), and the processing method is the same as that of the bolt described above, except that the drawing die is dodecagonal. be.

Tightening of the bolt into the internal thread of the threaded part 1 on the implantation side according to this invention is carried out by meshing a parallel spanner and a socket wrench with the hexagonal torque transmitting part 2b and applying the required torque to the wrench.

"Effects" (1) Since the torque transmission section is provided at the end of the shaft,
It is extremely easy to fit with tightening tools and has excellent workability.

(2) Since the nut side screws are not used during tightening, there is no damage to the nut side screws during tightening as in conventional methods.

(3) Also, when a torque transmission part is provided in the middle flange, problems such as disturbing air flow will not occur.

(4) The diameter of the inscribed circle of the torque transmitting part is larger than that of the threaded part on the nut side, so even when using a socket wrench, it can engage with the torque transmitting part without interfering with the threaded part on the nut side, improving work efficiency. is further improved.

(5) Since the shaft part is composed of a cylindrical part and a torque transmitting part continuous to the cylindrical part, and the diameter of the circumscribed circle of the torque transmitting part is made smaller than the diameter of the cylindrical part, the torque transmitting part can be drawn into an accurate shape by drawing. Furthermore, there is no loss of material due to the drawing process.

(6) Since the same cylindrical part as the conventional one remains, various effects such as being able to withstand bending moments can be obtained.

Also, by using a 12-point torque transmission section, the number of engagement surfaces is 12, so the socket
It becomes easier to engage with the wrench (dodecagonal), the transmitted torque is doubled, and its large cross-sectional area increases the torsional strength against torque, the drawing ratio is reduced, the workability is improved, and the internal Since the circle diameter is large, it can be used even when the threaded part on the nut side is large.

As mentioned above, this invention solves problems such as the complexity of tightening and damage to the threaded part on the nut side without sacrificing the advantages of conventional bolts, and is extremely suitable for mass production. A tightening part can also be formed.

[Brief explanation of the drawing]

Fig. 1 is a schematic front view of a conventional stud bolt, Fig. 2 is a right side view of Fig. 1, and Fig. 3 is a schematic front view of the stud bolt shown in Fig. 1 with an inner flange provided on the bolt shaft. , FIG. 4 is a right side view of FIG. 3, and FIG. 5 is a right side view of FIG.
FIG. 6 is a schematic front view of the stud bolt according to this invention, and FIG. 7 is a right side view of FIG. 5, and FIG. 7 is a schematic front view of the stud bolt shown in FIG. 7 is a right side view of FIG. 7, FIG. 9 is a schematic front view of an embodiment in which the torque transmitting portion of the stud in FIG. 7 is dodecagonal, and FIG. 10 is a right side view of FIG. 9. FIG. 11 is an enlarged view of FIG. 9, and FIG. 12 is a schematic partial cross-sectional view of the carburetor with the air cleaner attached via the stud B of this invention. 1... Implant side threaded part, 2... Shaft part, 3... Nut side threaded part, 4... Middle flange, 2b... Torque transmission part.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a stud bolt having an outer diameter of the threaded portion on the nut side smaller than the outer diameter of the threaded portion on the studding side or a stud bolt with a middle flange, the shaft portion extending between both threaded portions. The outer diameter of the circumscribed circle is smaller than the outer diameter of the cylindrical part, and the diameter of the inscribed circle is smaller than the outer diameter of the nut-side threaded part. A stud bolt characterized by being composed of a larger hexagonal torque transmission part. (2) The stud bolt according to claim (1), wherein the torque transmitting portion has a dodecagonal shape.