JPH10131931A - Drill tapping screw for metal thin plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill tapping screw whereby a workpiece of thin metal plate can be surely fixed in adhesion by relatively low screwing torque. SOLUTION: In a leg part 3, a barrel part 10 of the same diameter having a section of almost triangular shape and a thread ridge is formed, in a tip end of the barrel part 10, a drill part 20 formed by an almost triangular large diametric part 22 almost equal to an effective diameter of a thread ridge 11 is formed through a shaft part 21 equal to a bottom diameter of the thread ridge 11, this drill part 20 is formed in a shape having a tip sharpened cutting edge 24, by obtaining a metal thin plate use drill tapping screw with a length L of the shaft part 21 between the large diametric part 22 and the thread ridge 11 a little longer than a thickness T of a workpiece 4, 5, without the shaft part into contact with a prepared hole during work, by relatively low screwing torque, work can be performed, a low output driver can be used. Since the thread ridge comes into contact with the prepared hole in almost three points, to mold an internal thread, relating to the thin plate-shaped workpiece, it is made in adhesion without generating a space between the workpieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-tapping screw which can be continuously screwed into a work without forming a pre-drilled hole in the work in advance and forming a female screw in the work itself. And a drill tapping screw suitable for a thin metal plate.

[0002]

2. Description of the Related Art Conventionally, when a tapping screw is screwed into a thin metal work, a prepared hole into which the screw is screwed using a tool such as a drill is formed in advance in the thin metal work. By screwing a self-tapping screw into the prepared hole, a female screw is formed and screwed into the work by itself. In such a case, a tapping screw in which the thread is formed up to the tip of the leg, and the tip is tapered so that the tip becomes smaller in diameter from the tip to the tip, is used. The screw is adapted to be screwed into a prepared hole smaller than the thread diameter, for example, of an effective diameter or less.

When such a tapping screw is used, it is necessary to drill a pilot hole in the work as a preliminary operation before screwing the tapping screw into a predetermined position of the work into which the screw is screwed. For this reason, the operation time and man-hours are long, and it is not suitable for a large amount of screw tightening work.

In order to solve this problem, as shown in FIG. 3, a drill portion 120 having a cutting blade 124 is integrally formed at the tip of a thread 111 of a leg portion 103, and this drill portion 1 is formed.
Drill tapping screw 1 having a pair of blades 125 having a height equal to the outer diameter of the screw thread at the rear part of the shaft 20 at symmetrical positions with respect to the axis.
01 is used. However, the drill tapping screw 101 has been developed for use when the work 104 on the mounting side is relatively softer than the work 105 on the fixed side.
4, a through hole larger than the drill diameter is drilled by the pair of blades 125.
5, the blade 125 is cut, and the drill portion 120 is cut.
, A pilot hole 106 having a diameter of
For this reason, when fixing a work having the same hardness as that of the fixed-side work, the screws cannot be used because the blades are not cut even when the fixed-side work is hit.
Also, in the production of such tapping screws, the number of steps for producing the blades increases, and thus there is a problem that the production cost inevitably increases.

In order to solve such a problem and fix two relatively thin plate-like works to each other, FIG.
And a drill tapping screw 201 as shown in FIG. 5 is used. This is a drill screw disclosed in Japanese Utility Model Laid-Open Publication No. 57-165810.
1 are formed in a triangular shape on the tip side, and two cylindrical drill-shaped blades 2 having substantially the same diameter as the root diameter of the screw thread 211 are formed on the tip.
24, a drill hole 206 is drilled in the works 204, 205 by stacking two works 204, 205, and then screwing the drill screw 201 while pressing the work, thereby continuing the drilling work. Thread 2
At 11, the female screw 207 is formed.

[0006]

However, when such a drill tapping screw is used, a pilot hole is made in this drill portion, but since the drill portion is cylindrical, the outer periphery of the drill portion is formed in this hole. Are constantly in contact with each other, so that a screwing torque is relatively high and a high-output driver is required. Also, since the thread is formed following the drill, the thread will bite into the pilot hole during the drilling operation.Thus, if the work is thin, the work on the mounting side will be screwed in. Since the screw is lifted up from the fixed-side work and the screw is screwed in this state, there is a problem that the two works cannot be brought into close contact with each other.

SUMMARY OF THE INVENTION An object of the present invention is to provide a drill tapping screw which can solve the above-mentioned problems and which can securely fix thin metal plate works to each other with a relatively low screwing torque.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a leg 3
And a head 2 integrally formed at one end of the leg 3 with a diameter larger than the diameter of the leg, and having the same diameter as the leg 3 continuous from the head 2 and perpendicular to the axis. The cross section is substantially triangular and forms a body 10 having a thread 11. The effective diameter of the thread 11 is substantially equal to the tip of the body 10 via a shaft 21 having a root diameter equal to the root diameter of the thread 11. A drill portion 20 having a substantially triangular large-diameter portion is formed.
And the large-diameter portion 22 and the trunk 10
The length L of the shaft 21 between the thread 11 and the thread 11 is achieved by providing a drill tapping screw for a thin metal plate slightly longer than the thickness T of the workpieces 4 and 5 into which the tapping screw is screwed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 1 denotes a drill tapping screw including a head 2 and a leg 3, and a head 2 having a diameter larger than the diameter of the leg is integrally formed at one end of the leg 3. On the head side of the leg 3 is formed a parallel trunk 10 having the same leg diameter and having a substantially triangular cross section across the axis. The body 10 has a substantially triangular screw thread 11 whose valleys and crests follow the cross-sectional shape of the body 10.
When screwed into the work, the three substantially triangular points come into contact with the female threads 7 of the works 4 and 5.

Further, the body 10 having the thread 11 formed thereon is formed.
A shaft 21 having the same diameter as the root of the screw thread 11 is formed continuously at the tip of the screw thread 11.
Large-diameter portion 22 having substantially the same diameter as the effective diameter 1 and having a pointed tip.
Is provided. The shaft portion 21 and the large-diameter portion 22 have a substantially triangular cross section, similarly to the body portion 10. As shown in FIG. 2, the large-diameter portion 22 and the shaft portion 21 have two guide grooves 23 on opposite sides of the shaft center along the axis and gradually have a bottom as the distance from the tip of the screw 1 increases. A cutting edge 24 is formed on the outer edge of the guide groove 23 on the forward side in the screwing direction to form a drill portion 20. Further, the length L of the shaft portion 21 is set to be slightly longer than the thickness T of the workpieces 4 and 5 into which the shaft portion 21 is screwed. Never do.

Using the drill tapping screw 1 obtained in this manner, the drill tapping screw 1 is pressed against a metal sheet-like work 4 or 5 having a thickness T shorter than the length L of the shaft portion 21 of the screw 1. , Head 2 of drill tapping screw 1
In the initial stage of the screwing, the pilot hole 6 is drilled continuously with the workpieces 4 and 5 by the drill portion 20 having the cutting blade 24. After the formation of the pilot hole 6, the thread 11 of the body 10 bites into the pilot hole 6 of the work 4.
The drill tapping screw 1 is screwed in while the female screw is formed by the thread 11 of 0. At this time, the screw thread 11 forms a female screw at approximately three points, and the other screw threads 11
Since there is almost no contact with the female screw, the female screw is formed with low resistance.

As described above, the workpieces 4 and 5 are provided with the drill portions 20.
Since the thread 11 is bitten after drilling the pilot hole 6, the workpieces 4 and 5 on the mounting side and the fixed side are fixed in close contact with each other without separating.

[0013]

As described above, according to the present invention, the leg 3
And a head 2 integrally formed at one end of the leg 3 with a diameter larger than the diameter of the leg, and having the same diameter as the leg 3 continuous from the head 2 and perpendicular to the axis. A body 10 having a substantially triangular cross section and having a thread 11 is formed.
Drill portion 2 comprising a substantially triangular large-diameter portion 22 substantially equal to the effective diameter of screw thread 11 via shaft portion 21 equal to the root diameter of
0, the drill portion 20 has a sharpened tip and a shape having a cutting blade 24, and the length L of the shaft portion 21 between the large diameter portion 22 and the thread 11 of the body portion 10. Is a drill tapping screw for a thin metal plate slightly longer than the thickness T of the workpieces 4 and 5 into which the tapping screw is screwed, so that the shaft does not always contact the hole during the drilling operation in the drill portion. Work with a relatively low screwing torque is possible, and a low-power driver can be used.
Also, since the screw thread contacts the pilot hole at almost three points to form the female screw, the female screw can be formed smoothly, so that there is a gap between the thin plate-like work and the other work. And can be screwed in tightly together without causing cracks. Furthermore, the work of constantly drilling a prepared hole at the position where the screw of the work is screwed becomes unnecessary, and the work time and man-hours are reduced. In addition, even if many screws are used in the product, there is no special work for drilling a pilot hole, which reduces the fatigue of the operator and the screws can bite into the work in a short time. Specific effects such as a decrease in bending and an improvement in the appearance of the product can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is an enlarged bottom view of FIG.

FIG. 3 is a front view showing a use state of a conventional example of the present invention.

FIG. 4 is a front view showing a use state of another conventional example of the present invention.

FIG. 5 is a bottom view of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drill tapping screw 2 Head 3 Leg 4,5 Work 6 Prepared hole 10 Body 11 Thread 20 Drill 21 Shaft 22 Large diameter part 23 Guide groove 24 Cutting blade

Claims (1)

[Claims] 1. A tapping screw comprising a leg 3 and a head 2 integrally formed at one end of the leg 3 with a diameter larger than the diameter of the leg, wherein the diameter of the leg 3 continuous from the head 2 is the same. In addition, a trunk section 10 having a substantially triangular cross section perpendicular to the axis and having a thread 11 is formed, and a tip of the trunk 10 is provided with a shaft section 21 having a root diameter equal to the root diameter of the thread 11. A drill portion 20 having a substantially triangular large-diameter portion 22 substantially equal to the effective diameter of the screw thread 11 is formed, and the drill portion 20 has a shape having a sharpened tip and a cutting blade 24. Part 2
The length L of the shaft 21 between the thread 2 and the thread 11 of the body 10 is the thickness T of the work 4 or 5 into which the tapping screw is screwed.
Drill tapping screw for thin metal sheets characterized by being slightly longer.