JP2002327723A - Screw used for steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent poor connection caused by destruction of a screw hole in screwing works of a thin steel sheet. SOLUTION: A trumpet portion 3 provided between a parallel thread portion 4 and screwhead 2 of a screw 1 used for a steel sheet is formed that the diameter in a lower end is equal to the root diameter of the parallel thread portion and that the diameter in an upper end is smaller than the diameter of the screwhead. Thus, the thread with the same peak-to-peak diameter of the thread is formed from the parallel thread portion to the vicinity of the upper end of the trumpet portion. The thin steel sheet is always engaged with the thread portion of the screw without exceeding the starting position of the thread, and completion for tightening of the screw can be surely detected by increasing fastening torque so that a flat portion in the peripheral edge of the undersurface of the screwhead is kept in pressed contact with the thin steel sheet. Consequently, any possibility of destructing the screw hole by excessive rotation of the screw can be eliminated, and occurrence of poor connection is also prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw for a steel plate, and more particularly, to a screw for a steel plate with an improved joining force.

[0002]

2. Description of the Related Art In recent years,
Houses using thin steel sheets having a thickness of about 0.4 mm to 0.5 mm as building structural materials are increasing. This type of house is constructed by a method of joining thin steel plate structural members with a self-tapping type steel plate screw, and an electric screwdriver is used to tighten the screw. There are various types of screws for steel plates, but in general, a screw with a shape that increases in diameter from the parallel threaded portion to the screw head in a tapered or trumpet shape is used to strengthen the joining force and prevent loosening. Have been.

However, in this type of steel sheet screw, when the screw is tightened into a thin steel sheet, the starting position of the thread of the parallel thread portion (the upper end position of the screw thread) passes through the thin steel sheet, and the screw runs idle or penetrates. If not, only a part of the steel plate may be in a state of being threaded. In such a state, the tightening torque is reduced, so that the torque limiter mechanism of the electric screwdriver that operates according to the tightening torque does not function, and even when the driver is turned by hand, the completion of screw tightening cannot be detected. In any case, in many cases, the screw is further rotated to break the screw hole, so that the screw is idle and the joining force is often significantly reduced.

[0004] Therefore, there arises a technical problem to be solved in order to prevent the above-mentioned destruction of the screw hole and the idle rotation of the screw so as to ensure a predetermined joining force. Aims to solve the above problems.

[0005]

SUMMARY OF THE INVENTION The present invention proposes to achieve the above-mentioned object. The present invention proposes a parallel screw portion and a taper screw at the tip from a screw head having a flat lower surface via a taper portion or trumpet portion. The diameter of the upper end of the tapered part or trumpet part is smaller than the diameter of the screw head, and the diameter of the lower end of the tapered part or trumpet part is equal to the root diameter of the parallel screw part. The present invention provides a screw for a steel plate, wherein a thread having the same diameter is formed in a tapered portion or a trumpet portion and a parallel thread portion, and a thread is provided up to near the upper end of the tapered portion or the trumpet portion.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a screw 1 for a steel plate, 2 is a flat round screw head, 3 is a trumpet part, 4 is a parallel screw part,
Reference numeral 5 denotes a tapered screw portion at the tip, and a cross hole 6 is formed in the screw head 2. Screw 1 for steel plate shown in the figure is a screw head
2, trumpet part 3, parallel screw part 4, and taper screw part 5
The diameter φ2 of the upper end of the trumpet part 3 is smaller than the diameter φ1 of the screw head 2 and the diameter φ3 of the lower end of the trumpet part 3 is equal to the root diameter φ4 of the parallel screw part 4. I have.

[0007] The thread is continuous from the tip to the trumpet part 3, and the thread having the same thread is formed from the parallel thread part 4 to the trumpet part 3. The screw thread is cut to the vicinity of the upper end of the trumpet part 3, and the distance from the lower surface of the screw head 2 to the screw start position is almost zero.

When a screw 1 for a steel sheet is screwed into two thin steel sheets using a driver, the screw holes are tapped into the thin steel sheet by the tapered screw portion 5 and the parallel screw portion 4 at the tip and penetrate. The two thin steel sheets advance toward the screw head 2, and the trumpet part 3 enters the screw hole while expanding the screw hole, and the thin steel sheet contacts the lower surface of the screw head 2.

At this time, as shown in FIG.
Screw holes of the trumpet portion 3 are meshed with the thread of the trumpet portion 3, and when the screw 1 for the steel plate is further rotated, the lower surface of the screw head 2 is pressed against the thin steel plates S1 and S2 by the screw thrust of the trumpet portion 3, and the screw 1 for the steel plate Tightening torque rises sharply. Thus, in the case of both the electric screwdriver and the hand-held screwdriver, the operator senses the increase in the tightening torque and completes the screw tightening.

At the time of completion of screw tightening, at least the screw holes of the lower thin steel plate S2 are engaged with the threads of the trumpet part 3, and the screw head 2 is in close contact with the upper steel plate S1, so that two steel plates Since S1 and S2 are strongly tightened, and the trumpet portion 3 is in close contact with the screw hole and there is no play in the screw 1 for the steel plate and the screw hole, the screw 1 for the steel plate does not loosen.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible within the technical scope of the present invention, and it goes without saying that the present invention extends to those modifications. is there.

[0012]

As described above, the screw for a steel plate of the present invention is provided with a screw thread up to the vicinity of the upper end of the taper portion or the trumpet portion connecting the screw head and the parallel screw portion. Unlike a conventional screw having an interval between the screws, the thin steel plate does not disengage from the screw thread beyond the start position of the screw when the screw tightening is completed. Therefore,
When the screw tightening is completed, the tightening torque does not decrease,
In addition, since the flat part of the lower surface of the screw head is pressed against the thin steel plate and the tightening torque increases, the completion of screw tightening can be sensed reliably. This eliminates the possibility that the screw hole will be destroyed, and prevents the occurrence of poor connection.

[Brief description of the drawings]

1 shows an embodiment of the present invention, wherein (a) is a plan view of a screw for a steel plate, and (b) is a side view.

FIG. 2 is a sectional view of a screw head portion of a screw for a steel plate.

FIG. 3 is a cross-sectional view illustrating a screwed state of the steel plate screw.

[Explanation of symbols]

 1 Screw for thin steel plate 2 Screw head 3 Trumpet part 4 Parallel screw part 5 Tapered screw part 6 Cross hole S1, S2 Thin steel plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Mitsuhisa Machida, Inventor 6-6, Hakozakicho, Nihonbashi, Chuo-ku, Tokyo Inside Max Co., Ltd. No. KM Seiko Co., Ltd.

Claims (1)

[Claims] 1. A screw for a steel plate having a shape from a screw head having a flat lower surface to a parallel screw portion and a tapered screw portion at a tip end via a tapered portion or trumpet portion, wherein a diameter of an upper end of the tapered portion or trumpet portion is provided. Is smaller than the diameter of the screw head, the diameter of the lower end of the tapered part or trumpet part is equal to the root diameter of the parallel screw part, and the taper part or trumpet part and the parallel screw part are formed with the same diameter screw thread, A screw for a steel plate, wherein a screw thread is provided near the upper end of a tapered portion or a trumpet portion.