JPS6340966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to bolts, and more particularly to resin stud bolts (resin-embedded bolts) used for fastening vehicle bodies and lamp bodies.

As shown in Fig. 1, resin stud bolts are used by embedding and integrating the head 2 of the bolt 1 into a resin component such as a lamp rim. It will be concluded in Natsutoni through.

<Prior Art> In conventional bolts of this type, twill knurling a is carved on the surface of the bolt head 2, and the bolt is driven into a resin part while being heated to be integrated. In this conventional bolt, when viewed from the driving direction, the knurling peaks overlap to form an almost circular shape, so when driving the bolt, the molten resin is pushed toward the tip of the bolt head, and the resin is deposited in the valley of the knurl. was not sufficiently distributed, and therefore the rotational torque and pull-out strength were weak. Moreover, it is extremely difficult to control the temperature during driving, which poses a problem in ensuring quality.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 50-85756, it was proposed that a large diameter portion sandwiching an annular groove be formed with a large number of grooves diagonally in opposite directions with respect to the axial direction. It was done. This type has higher rotational torque and pull-out strength than the twilled knurling because the resin is pushed into the annular groove, but when viewed from the driving direction, there are many Since the grooves overlap to form a nearly circular shape, the actual problem is that the resin does not spread sufficiently into the valleys of each groove, resulting in no significant improvement in rotational torque or pull-out strength, and when cold driving at room temperature ( When press-fitting), there is a risk that excessive force will be applied to the resin parts, causing them to become distorted or broken, and there is a problem that the quality stability will not improve much.

<Problems to be Solved by the Invention> The present invention has been made in view of the problems of conventional products, and can significantly improve rotational torque and pull-out strength compared to conventional products, as well as improve cold (normal temperature)
The purpose of the present invention is to provide a bolt that can be driven (press-fitted) and has improved quality stability.

<Means for Solving the Problems> The bolt of the present invention that achieves the above object has a plurality of flat slits formed in the bolt head in the shape of a triangular wave with acute angle peaks and valleys along the axial direction. A boundary recess is formed between the flat slits, and the bolt head is formed so that the crest of the lower flat slit can be seen from the valley of the upper flat slit when viewed from above, and the tip of the upper flat slit is formed. The lower flat slit is formed in a tapered shape, and the upper end of the lower flat slit is formed in a horizontal shape.

<Example> Hereinafter, an example of implementing the present invention will be described based on the drawings.

In the figure, reference numeral 1 denotes a bolt 1, in which flat slits 3 in the shape of a triangular wave with acute angle peaks and valleys are formed along the axial direction in two or more stages, and each A boundary depression 4 is formed between the flat slits 3a and 3b.

The flat slits 3a, 3b are formed along the axial direction of the bolt 1, and their cross-sectional shape is such that the peaks 6a, 6b and the valleys 5a, 5b form an acute triangular wave shape as shown in the illustrated example. Along with forming
The tip 3a'' of the upper flat slit 3a is formed in a downwardly tapered shape, and the upper end 3b' of the lower flat slit 3b is formed horizontally.

Also, each flat slit 3a, 3b is connected to the bolt head 2.
The valley part 5a of the upper sole slit 3a when viewed from the plane
The pitches of the lower flat slits 3b are shifted from each other in the circumferential direction so that the peaks 6b of the lower flat slits 3b can be seen, and the pitches and outer diameters of the slits are also different. That is, in the embodiment shown in FIGS. 2 and 3, the outer diameters of the upper flat slit 3a and the lower flat slit 3b are formed to be the same size, and the lower flat slit 3b is formed with the same pitch as the upper flat slit 3a. 3b is formed by shifting the pitch by half in the circumferential direction, and in the embodiment shown in FIGS. 4 and 5, the outer diameter of the upper flat slit 3a is the same as the outer diameter of the lower flat slit 3b. It is formed to have a slightly larger diameter, and the pitch of the upper flat slits 3a is made larger (approximately twice the pitch) than the pitch of the lower flat slits 3b. By forming the flat slits 3a and 3b in this manner, when the bolt head 2 is driven into a resin part, the resin in the portion where the trough 5a of the upper flat slit 3a has passed is transferred to the crest of the lower flat slit 3b. With the portion 6b, it is possible to reliably push and fill the inside of the boundary recessed portion 4 and the valley portion 5a of the upper flat slit 3a.

The concave portion 4 is formed between each of the flat slits 3a and 3b to have an appropriate width and a diameter smaller than the outer diameter of the flat slit.

The bolt of the present invention explained above is formed by a rolling method. That is, as shown in FIGS. 6, 7, and 9, a plurality of flat slit forming portions 8a, 8b are formed in the rolling molds 7A, 7B, and a gap between each flat slit forming portion 8a, 8b is formed. In order to prevent the flesh 2' of the bolt head 2 from flowing into the boundary recessed part 4 during rolling, the control plate 12 is arranged so as to be the same as or slightly protrude from the flat slit forming parts 8a and 8b. , a solid bolt head 2 is formed with a plurality of flat slits 3a, 3b and a boundary recess 4. In the figure, 9 is a peak formed in the flat slit forming portion 8 of the rolling die, and 10 is a trough.

According to the rolling dies 7A and 7B, the flesh 2' of the bolt head 2 pushed away during rolling is prevented from flowing into the boundary recess 4 by the control plate 12, and as a result, Lower end 3 of upper sole slit 3a
a' and the upper end 3b' of the lower flat slit 3b can be formed horizontally and at an acute angle (right angle), and at the same time can be formed into the ideal external shape shown by the imaginary line in FIG. It becomes like this.

<Effects of the Invention> Since the bolt of the present invention is configured in this way, when the bolt head is press-fitted into a resin part and fixedly integrated, when the bolt head is driven into the resin part, the upper flat slit cuts the lower part. The flat slit allows the resin to be pushed into the boundary recess and into the trough of the upper flat slit to fill it. That is, when the bolt head is driven and press-fitted into a resin part with the upper flat slit side as the top, the tapered tip of the upper flat slit first cuts into the resin part while the upper flat slit presses into the resin part. At that time, the resin in the area where the peak of the upper flat slit has passed is pushed toward the valley, increasing the density of the resin in the valley, and causing the resin to be strongly pressed against the valley of the upper flat slit. becomes. Then, when the bolt head is further driven and press-fitted into the resin part, when the bolt head is viewed from above, the peak of the lower flat slit faces from the valley of the upper flat slit, and the upper end of the lower flat slit is horizontal. Because it is formed in a shape, the resin in the part where the valley of the upper flat slit passes is also cut by the peak of the lower flat slit and is forcibly pushed into the boundary recess and into the valley of the upper flat slit.
Therefore, the density of the resin within the boundary recess or the valley of the upper flat slit becomes even higher, increasing the pressure.
The tightening force against the bolt head increases, and as a result, the bolt head is firmly fixed and integrated with the resin part.
High-strength quality with significantly improved rotational torque and pull-out strength compared to conventional products can be obtained.

Moreover, when driving, the tapered tip of the upper flat slit cuts into the resin part and press-fits it, so it is possible to press-fit with low pressure, and by instantaneous driving, the required strength can be secured only by the elastic force of the resin. Therefore, unlike conventional products, there is no need for heating when driving, and cold (room temperature) driving (press-fitting) is possible.As a result, there is less variation in quality, and quality stability is greatly improved.
Workability can be improved and it can be provided at low cost.

In addition, by forming the pitch of the upper flat slits to be larger than the pitch of the lower flat slits, the upper flat slits can make large cuts into resin parts.
Since the resin is pushed into the boundary recessed part and the valley of the upper flat slit with a small pitch, the resin is more reliably pushed into the area through which the upper flat slit has passed, filling it and increasing its strength. At the same time, it is possible to alleviate the strain on the resin parts during press-fitting. That is, since the resin part is cut with the upper flat slit of large pitch, excessive force is not applied to the resin part, and the resin in the part where the valley of the upper flat slit passes is pushed through the lower flat slit of small pitch. Therefore, in general, excessive force is not applied to the resin parts, the bolt head and the resin parts are fixedly integrated with each other, and the strain on the resin parts can be alleviated.

Furthermore, by forming the outer diameter of the upper flat slit to be the same as or slightly larger than the outer diameter of the lower flat slit, when the resin in the portion that has passed through the upper flat slit is pushed up by the lower flat slit, the flow of the resin is reduced. Since there is a margin, excessive force is not applied to the resin parts, which can alleviate the strain on the resin parts and prevent them from breaking, as well as prevent them from separating from the bolt head, making them even stronger. It is possible to integrate the bolt head and resin parts.

Therefore, the intended purpose can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view illustrating a conventional product, Fig. 2 is a front view of the bolt of the present invention, and Fig. 3 is a perspective view of the main parts.
Fig. 4 is a front view showing another embodiment of the present invention, Fig. 5 is a perspective view of the main part, Fig. 6 is a perspective view explaining the bolt manufacturing method, and Fig. 7 is a plan view of the main part. , 8th
The figure is a front view of a bolt head manufactured by a conventional manufacturing method, and FIG. 9 is a front view of a bolt head illustrating the method of manufacturing a bolt of the present invention. In the figure, 1 is a bolt, 2 is a bolt head, 3a is an upper flat slit, 3a'' is its tip, 3b is a lower flat slit, 3b' is its upper end, 4 is a boundary recess, 5a and 5b are Flat slit valley, 6a, 6
b is the peak of the flat slit.

Claims (1)

[Claims] 1. A plurality of flat slits having a triangular wave shape with acute angle peaks and valleys are formed in the bolt head in multiple stages along the axial direction, and boundary recesses are formed between each flat slit, and the bolt head is flattened. The slits are formed so that the peaks of the lower flat slits can be seen from the valleys of the upper flat slits when viewed from above, and the tips of the upper flat slits are tapered, and the upper ends of the lower flat slits are horizontal. A bolt characterized by the fact that it is formed.