JPH071598A - Resin-made component - Google Patents

Abstract

PURPOSE:To provide a resin-made component, wherein the cutting component of a tapping screw can be scrwed along a tapping-screw cutting hole and fastening force is not reduced when the tapping screw is scrwed in again. CONSTITUTION:A bearing surface 10 is formed over 360 deg.. A head part 6a of a blade 6 of a tip part 4a is set so that the head part is in contact along the length of one round of a tapping screw 4. The slant angle of the bearing surface 10 is gradually changed. The slant angle alpha2 at a terminating-end position Y is smaller than the slant angle alpha1 at an initial position X. Thus, a step difference part is formed at this part. The surface of the step difference part becomes a cutting surface 11. The cutting surface 11 is formed at a specified angle with the bearing surface 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin part having a female screw cut by a tapping screw.

[0002]

2. Description of the Related Art Conventionally, as this type, for example, there is one as shown in FIG. In the figure, reference numeral 1 is a resin boss formed on a resin part. A tapping screw cutout hole 2 in which a female screw is cut by a tapping screw 4 is formed in the resin boss 1, and an opening 3 of the hole 2 is A taper surface 5 having an angle substantially matching the angle of the tip portion 4a of the tapping screw 4 is formed.

In order to perform tapping, the tip 4a of the tapping screw 4 is inserted into the tapping screw cut-out hole 2. At this time, the tapered surface 5 guides the tip 4a of the tapping screw 4, Easy to insert. After that, the tapping screw 4 is rotated to be screwed into the tapping screw cut-out hole 2, and a female screw is engraved inside the tapping screw cut-out hole 2 and screwed to join the members.

[0004]

However, in such a conventional device, the tapered surface 5 has only a function of simply guiding and has a function of aligning the axis of the tapping screw 4 with the axis of the tapping screw cutout hole 2. As shown by the angle θ in FIG. 4, the axis of the tapping screw 4 may tilt, and if tapping is performed as it is, the female screw may not be cut properly.

When the tapping screw 4 is attached and detached in such a manner, the position where the resin boss 1 is cut out varies depending on the blade 6 of the tip 4a of the tapping screw 4. When 4 is pulled out and the tapping screw 4 is tried to be screwed into the resin boss 1 again, the resin boss 1 is cut out from a different portion, the previous female screw portion is crushed, and the bonding strength is reduced.

There is also one in which a spiral screw engaging edge portion is formed by using a spring plate material as described in Japanese Patent Publication No. 44-31890, for example, but it is itself tapped. It is different from the above-mentioned resin component, and it cannot be reliably guided and is easily screwed diagonally.

Therefore, the present invention provides a resin component which has a function of aligning the axis of the tapping screw with the axis of the tapping screw cut-out hole when tapping, and there is no fear of reducing the fastening force even when screwing in again. That is the issue.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and tapping with a tapping screw having a spirally formed blade causes a female screw to be formed in a tapping screw cutout hole. Is a resin component to be cut, the seating surface is formed in the opening of the tapping screw cutting hole, the crown top of the blade of the tip of the tapping screw is in contact, the seating surface is at least one revolution of the tapping screw. It is set so that the top of the minute blade comes into contact, and at the end position of the seating surface on the far side of the tapping screw cutout hole, there is a cutout surface that has a certain angle with the seating surface and serves as a cut end for tapping. It is characterized by using resin parts.

[0009]

[Operation] According to such means, when tapping the resin part, the tip of the tapping screw is applied to the opening of the tapping screw cutout hole, and the tapping screw is attached to the seat surface formed in this opening. The crown of the blade at the tip comes into contact over the range of one round of the screw. Therefore, since the tapping screw is guided over the entire circumference and within the range of at least one lead, the axis of the tapping screw and the axis of the tapping screw cutout hole are aligned.

From this state, when the tapping screw is rotated and screwed into the tapping screw cutting hole, the blade at the tip of the tapping screw is cut out from the female thread from the cutting surface formed at the end position of the seat surface.

Since the tapping screw is guided by the seat surface in this way and tapping can always be performed with the axis of the tapping screw and the axis of the tapping screw cut-out hole aligned, even if the tapping screw is screwed in again. Since cutting is performed from the same position, there is no possibility that the previous female screw portion is crushed and the coupling strength is lowered unlike the conventional case.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention. The same or equivalent members as the conventional ones will be described with the same reference numerals.

First, the structure will be described. In the figure, reference numeral 7 is a resin boss formed on a resin part, and a tapping screw 4 having a blade 6 spirally formed on the resin boss 7.
However, a tapping screw cut-out hole 8 to be screwed and connected is formed.

A seating surface 10 for guiding the tip 4a of the tapping screw 4 is formed at the opening 9 of the tapping screw cutout hole 8.

The seating surface 10 is formed over 360 °, and is set so that the top portion 6a of the blade 6 at the tip portion 4a of the seating surface 10 comes into contact with the tapping screw 4 for the length of one round. There is. As shown in FIG. 2, the seat surface 10 has a gradual change in the inclination angle, and the inclination angle α at the initial position x.
The inclination angle α2 of the terminal position Y is smaller than 1. As a result, a step portion is formed in this portion, and the surface of this step portion serves as the cutout surface 11. This cutout surface 1
1 is formed at a constant angle with the seat surface 10.

Next, the operation will be described.

When tapping the resin boss 7, the tip portion 4a of the tapping screw 4 is applied to the opening 9 of the tapping screw cut-out hole 8, and the tapping screw is attached to the seat surface 10 formed in the opening 9. Tip 4
The top portion 6a of the blade 6 of a comes into contact over the range of one round of the screw. Therefore, since the tapping screw 4 is guided over the entire circumference and within a range of at least one lead, the axis of the tapping screw 4 and the axis of the tapping screw cutout hole 8 coincide with each other.

From this state, when the tapping screw 4 is rotated and screwed into the tapping screw cutting hole 8, the blade of the tip 4a of the tapping screw 4 moves from the cutting surface 11 formed at the end position Y of the seat surface to the female screw. It is cut out.

In this way, the tapping screw 4 is guided by the seat surface 10, and the tapping screw 4 is always
Since tapping can be performed with the axis of the tapping screw and the axis of the tapping screw cutting hole 8 aligned, the tapping can be performed from the same position even if the tapping screw 4 is screwed in again. There is no possibility that the portion will be crushed and the bond strength will be reduced.

In this embodiment, the resin boss 7 is used as the resin component in the description, but the resin component is not limited to this, and any resin may be used as long as it has an opening for tapping screw cutout holes, such as a resin housing. It goes without saying that parts may be used.

[0022]

As described above, according to the present invention, the tapping screw is always screwed along the tapping screw cut-out hole while the tapping screw shaft and the tapping screw cut-out hole shaft are aligned with each other. In addition, it is possible to provide a resin component that does not damage the tapping screw cutout hole even when screwing it in again and does not reduce the fastening force.

[Brief description of drawings]

FIG. 1 is a perspective view showing a resin boss according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1, showing a resin boss of the same embodiment.

FIG. 3 is a perspective view showing a resin boss of the same embodiment and an enlarged main part.

FIG. 4 is a sectional view showing a conventional resin boss and corresponding to FIG. 2.

[Explanation of symbols]

 7 Resin boss 8 Tapping screw cutout hole 9 Opening 10 Seating surface 11 Cutting surface Y End position

Claims (1)

[Claims] 1. A resin component in which a female screw is cut in a tapping screw cutout hole by tapping with a tapping screw having a spirally formed blade, wherein an opening of the tapping screw cutout hole is formed. A seating surface is formed on the tip of the tapping screw, which is in contact with the top of the blade, and the seating surface is set so that the top of the blade for at least one round of the tapping screw comes into contact with the tapping of the seating surface. A resin component having a cutting surface which has a certain angle with the seat surface and serves as a cutting end at the time of tapping, at a terminal position on the inner side of the screw cutting hole.