JPS6242166B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is used by inserting a bolt rod into a mounting hole formed in a resin part such as a resin lamp, and driving the bolt head into the resin part and fixing it. This invention relates to a resin stud bolt.

<Prior art> As shown in Fig. 1, this type of conventional bolt has an oval-shaped bolt head, so there is a risk that the bolt may rotate in the threaded direction after being attached to a resin component. However, during manufacturing, the bolt head, which had been formed into a circular shape, had to be cut off (shearing), which was a time-consuming process, and it also had the disadvantage of poor workability because it created a directional problem when driving. Moreover, after the bolt is press-fitted into the mounting hole C of the resin component B, the claw D must be placed over the top surface of the bolt head A and swaged, which increases the number of installation steps and requires the use of resin Since the bending exceeds the elastic (plastic) limit of In addition, by press-fitting the bolt into the mounting hole C of the resin part B, a certain degree of waterproofing effect can be obtained, but there are many irregularities, and a sufficient waterproofing effect cannot be expected. When formed, there were problems such as cracking of the resin parts and galling phenomenon when the bolts were press-fitted.

<Problems to be Solved by the Invention> The present invention has been made in view of the inconveniences and shortcomings of the conventional products, and it can be mounted on resin parts in one step and has high rigidity in the direction of screw rotation. It is an object of the present invention to provide a resin stud bolt that has a high attachment force and a high pull-out strength in the axial direction, and also provides a high waterproof effect between the resin parts and the resin parts.

<Means for Solving the Problems> The resin stud bolt of the present invention which achieves the above object has a flat slit along the axial direction formed on the circumferential surface of the bolt head, and a flat slit along the axial direction in the bottom surface of the bolt head. It is characterized by forming a substantially arcuate concave portion extending from the circumferential edge to the bolt rod, and by curving the circumferential edge of the bottom portion inward.

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

The bolt 1 is composed of a bolt rod 5 that is inserted and projected into a mounting hole 13 of a resin component 8, and a head 2 that is driven into the resin component 8. A flat slit 3 is formed, and a concave portion 6 is formed in the bottom surface of the head 2, extending from the circumferential edge 4 to the bolt rod 5 and recessed in a substantially arc shape, and the circumferential edge 4 of the bottom surface portion is curved inward. Let it form.

The flat slit 3 formed on the circumferential surface of the bolt head 2 is intended to make it easier to cut and press fit the bolt head 2 into the resin part 8 when driving it into the resin part 8, and at the same time to obtain a high fixing force in the direction of screw rotation. The bolt 2 is formed by the rolling dies 9a and 9b.
The thread 10 is formed along the axial direction of the bolt rod 5 at the same time as the thread 10 is formed on the bolt rod 5.

The circumferential edge 4 of the bottom surface of the bolt head 2 is for enclosing the resin when the bolt head 2 is driven into the resin part 8 and obtaining high pullout strength in the axial direction. The bolt rod is curved in 5 directions, and is formed into a substantially elongated mouth shape in cross-sectional view.

Then, a concave portion 6 is formed in the bottom surface of the bolt head 2 to continue with the circumferential edge 4 and extend to the bolt rod 5 in a substantially circular arc shape, so that the resin trapped by the circumferential edge 4 of the bolt head 2 is formed. Try to keep it full.

When manufacturing such a resin stud bolt, first, a solid rod 7 as shown in FIG. 3 is subjected to header processing to form a circular bolt head 2 and bolt rod 5 as shown in FIG. 4. At this time, a recess 6 is formed in the bottom surface of the bolt head 2. Next, rolling mold 9
slit forming portions 14a, 1 using
4b and the thread forming parts 15a and 15b form a flat slit 3 along the axial direction on the peripheral surface of the bolt head 2, and a thread 10 is formed on the bolt rod 5. At this time, the circumferential edge 4 of the bottom surface of the bottle head 2 is curved inward as the flat slit 3 is rolled, and is formed into a substantially eagle-mouth shape in cross-section. As the bolt 10 is rolled, a hammer neck portion 11 is formed between the bolt head 2 and the bottom surface.
In addition, the circumferential surface of the bolt head 2 should be slightly widened in advance.
Due to this, as the flat slit 3 is rolled, the peripheral end 4 is further curved inward, and the cross section has an undercut shape.

When fixing the bolt 1 to the resin part 8, the bolt rod 5 is inserted and protruded into the mounting hole 13 formed in the resin part 8, and the bolt head 2 is then
into the resin part 8. Then, the flat slit 3 of the bolt head 2 press-fits into the resin part 8 while cutting it, and at the same time, the pushed resin flows from the circumferential end 4 of the bolt head 2, which has a roughly eagle-shaped cross section, to the bolt rod 5. The bolt head 2 is fixed to the resin component 8 by filling the concave portion 6 leading to the pincer neck portion 11 .
At this time, on the edge of the mounting hole 13 formed in the resin part 8, the embodiment shown in FIGS.
As in the embodiment shown in FIGS. 0 and 11, the recessed part 16 may be formed so that the bolt head 2 does not protrude from the surface of the resin component 8, or as in the embodiment shown in FIGS.
The convex portion 17 may be formed as in the embodiment shown in FIG. The inner diameter of the concave portion 16 and the outer diameter of the convex portion 17 are formed to be slightly smaller than the outer diameter of the bolt head 2.
Further, as in the embodiment shown in FIGS. 7 to 9, a ring-shaped protrusion 1 is provided on the rim of the mounting hole 13 of the resin component 8.
2 may be provided in a protruding manner so that the resin of the protruding portion 12 is actively filled into the recess 6 of the bolt head 2.

<Effects of the Invention> Since the resin stud bolt of the present invention is constructed in this manner, when the bolt head is driven into the resin part, the flat slit of the bolt head is press-fitted into the resin part while being cut into the resin part, and is inserted into the valley of the flat slit. The resin bites in, and at the same time, the pushed resin comes to fill and adhere tightly to the recess that extends from the circumferential end of the bolt head to the neck of the bolt rod, which is formed to have an approximately eagle-shaped cross section.
As a result, high fixing force in the direction of screw rotation,
A high pull-out strength in the axial direction can be obtained, and a high waterproofing effect between resin parts can be obtained.

Moreover, when driving the bolt head, the flat slit of the bolt head is press-fitted while cutting into the resin part, and in addition, the circumferential edge of the bolt head is curved inward, so the resin may get caught during driving. Smooth driving is possible with no occurrence of cracks, and the driving load and stress applied to the resin parts are small, eliminating the risk of breaking the resin parts (occurrence of cracks).

Furthermore, in the case of the resin stud bolt of the present invention, as a result of the bolt head being press-fitted tightly into the resin part, even if the inner diameter of the mounting hole formed in the resin part is sufficiently larger than the outside diameter of the bolt rod, the bolt head is press-fitted tightly into the resin part. Since it does not affect the adhesion performance or waterproof performance, there is no need to press fit the bolt rod into the mounting hole of the resin part as with conventional products, and the driving load and stress on the resin part are further reduced. There is no need to worry about cracking or galling of resin parts during driving.

Furthermore, by providing a ring-shaped protrusion 12 protruding from the mounting hole edge of the resin component 8 as in the embodiment shown in FIG. It is easier to adhere to the neck of the rod, and at the same time it is easier to fill the undercut-shaped part at the peripheral end, which has a roughly eagle-shaped cross section.
Higher pull-out strength and waterproofing effects can be expected.

In addition, since the bolt head can be formed into a circular shape, there is no directionality during installation, and it can be installed on the resin part 8 with a single drive, making installation work much easier than with conventional products. By forming a convex portion 17 on the surface of the resin part 8 as shown in FIG. 12, it becomes possible to firmly press-fit and fix even a thin resin part.

Thus, the intended purpose can be achieved.

[Brief explanation of the drawing]

1A and 1B are a sectional view and a perspective view showing a conventional example, FIG. 2 is a front view of a stud bolt for resin according to the present invention, and FIGS. 3 to 5 show a method for manufacturing a stud bolt for resin according to the present invention. 6 is a sectional view taken along the line 6-6 in FIG. 5 in the bolt manufacturing process; FIGS. 7 to 9 are sectional views illustrating the order of driving and fixing the bolt of the present invention into a resin part; 1st
0 and 11 are cross-sectional views showing other embodiments of resin parts for fixing bolts of the present invention, and FIG. 12 and 1
FIG. 3 is a sectional view showing still another embodiment of the resin part. In the figure, 1 is a bolt, 2 is a head, 3 is a flat slit, 4 is a peripheral end, 5 is a bolt rod, and 6 is a recess.

Claims (1)

[Claims] 1. A flat slit extending along the axial direction is formed on the circumferential surface of the bolt head, and a substantially arcuate concave portion extending from the circumferential end to the bolt rod is formed on the bottom surface of the bolt head. A press-fit bolt characterized by an inwardly curved peripheral edge of the bottom surface.