JPS6242166Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a hexagonal bolt with an upset type flange, and more particularly to a hexagonal bolt with an upset type flange that can easily form a perfect hexagonal diagonal.

Examples of conventional upset-type flanged hexagonal bolts include those shown in FIGS. 1 to 6, and FIGS. 1 and 2 show a general flanged hexagonal bolt b. Figures 3 and 4 show the shape of the bolt b in Figures 1 and 2 before the flange rounding process;
This shows a state in which the material protrudes from the outer periphery of the flange 2, making it easier to form a hexagonal shape.

Figures 5 and 6 show a known hexagonal bolt b in which a protrusion 6 is annularly provided on the lower surface of the flange 2. With this shape, the hexagonal part shape can be easily formed and the round cutting process described above can be omitted. There is.

Next, the reason for the shape of the bolt b shown in FIGS. 3, 4, and 5 and 6 will be explained based on the flow of the material when forming the head of the bolt b. FIG. 7 shows a state in which the head of bolt b is cold forged by header h.
Note that 15 represents an ejector pin provided within the die 14.

The material of the preformed bolt b held in the die 14 is heated by the hexagonal nib 9 approaching toward the die.
Inside, the nib is formed by a hexagonal punch 13 and begins to swell into the shape of the nib, but in order to spread the material around the diagonal part of the hexagon and swell into a complete hexagonal shape,
As the required molding pressure becomes considerably large, the material begins to flow toward the outer circumference of the flange 2, causing the material to overhang the outer circumference of the flange 2 to a greater extent than the outer diameter of the flange after the bolt is completed, or causing the material to flow toward the outer circumference of the flange. In order to prevent the flow of water, an annular projection 6 must be provided at the bottom of the flange 2.

As mentioned above, in such a conventional hexagonal bolt with an upset type flange, it was necessary to round out the outer periphery of the flange 2 and to provide an annular projection 6 on the lower surface of the flange. There were defects in that the axial force of the bolt decreased due to the occurrence of cracks or caving in the object to be fastened, which caused the bolt to loosen, resulting in poor quality and productivity.

Also, in order to avoid rounding in the next process, there are some products in which the outer diameter of the flange is expanded only to the final shape.
In this case, the material does not sufficiently spread to the diagonal portions of the hexagon, resulting in an incomplete hexagonal shape with "sag". Therefore, in order to obtain a perfect hexagonal shape, a round cutting process is necessary.

This invention eliminates the aforementioned defects by forming one or more annular protrusions on the upper surface of the flange of a hexagonal bolt with an upset type flange, concentrically with the bolt axis, thereby creating a perfect hexagonal diagonal part. To provide a hexagonal bolt with an upset type flange that can be easily formed.

Next, an embodiment of this invention will be described with reference to the drawings. In FIGS. 8 and 9, the bolt b has a shaft portion 1,
It consists of a flange 2 and a hexagonal head 3, a recess 5 is formed at the top of the head, and one or more annular protrusions 7 are formed on the upper surface of the flange in a circular shape concentric with the axis. Note that 4 represents a hexagonal diagonal portion of the head 3.

The annular projection 7 may be positioned anywhere on the upper surface of the flange 2, and its size is not particularly limited. Further, the annular recessed surface 7a formed between the annular protrusions 7, 7 matches the shape of the upper surface of the conventional flange 2.

During cold forging, the material of the bolt b is compressed within the hexagonal nib 9 by the hexagonal punch 13 and begins to swell into the shape of the nib. A part of the bolt b material also begins to flow into the gap between the mouth of the nib 9 and the die 14, but in order to form the annular protrusion 7 on the upper surface of the bolt flange 2, it flows into the annular concave surface 7a provided on the nib 9. A portion of the bolt material will fit in, blocking the flow of the material, and more forming pressure will be consumed to form the hexagonal portion. Therefore, the flange 2 of the material
Since the flow in this direction is prevented, the material can be sufficiently distributed to the hexagonal diagonal portion 4.

Therefore, it is possible to reduce the flow of the material B to the outer circumference of the flange 2 and inflate the material to the hexagonal diagonal, omit the process of rounding out the flange, and provide a protrusion 6 on the lower surface of the flange. It has a superior anti-loosening effect and is easier to manufacture.

Furthermore, the flange strength of the bolt of this invention is not reduced at all compared to bolts of conventional shape.

[Brief explanation of the drawing]

Fig. 1 is a front view of a conventional upset-type bolt, Fig. 2 is a partially transparent side view of Fig. 1, and Fig. 3 shows the shape before the flange rounding process, with the bolt material overhanging the flange outer circumference. Front view of the state where
FIG. 4 is a partially transparent side view of FIG. 3, and FIG. 5 is a partially transparent side view of FIG.
A partially transparent, cutaway side view of another embodiment of a conventional upset-type bolt, FIG. 6 is a right side view of FIG. 5,
Fig. 7 is a partial sectional view of the header in a state where the bolt head is cold forged, Fig. 8 is a front view of the upset type hexagonal bolt according to this invention, and Fig. 9 is
FIG. 8 is a partially transparent, enlarged cutaway side view, and FIG. 10 is a partially enlarged cross-sectional view of FIG. 9. 1...Shaft portion, 2...Flange, 3...Head, 5
... recess, 7 ... annular projection, 7a ... annular recess surface.

Claims (1)

[Scope of utility model registration request] 1 on the top surface of flange 2 concentrically with the bolt axis
A hex bolt with an upset type flange, which is provided with one or more annular protrusions 7.