JP2002039134A - Tapping screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve discharging effect of chips and to reduce fastening torque of the screw. SOLUTION: A shaft part 3 extending from a head part 2 is provided with a first screw part 4 comprising screw threads 10 with a reference first pitch P1, and a second screw part 5 that comprises screw threads 11 with a second pitch P2 larger than the first pitch P1 and disposed on the head part side of the first screw part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can reduce the tightening torque of a screw by smoothly discharging chips to the rear side, thereby suppressing damage to the screw itself or the screw tightening machine, and insufficient tightening of the screw. The present invention relates to a tapping screw that can prevent the occurrence of a tapping screw.

[0002]

2. Description of the Related Art As shown in FIG. 5A, in the construction of a house or the like, a hard base material A such as a lightweight shaped steel material is compared with a hard base material A such as wood or lightweight concrete. Screw B having a drill part c1 at the tip when fixing the object B such as a soft soft face material
Is often used. In the same figure, the base material A of the channel steel is shown.
Next, a case where a cement board B1 forming a floor panel is fixed via a wooden bar B2 for heat insulation is illustrated, and the base material A and the wooden bar B2 are fixed via an adhesive.

As shown in FIG. 5 (B), a tapping screw c of this type is generally formed by a screw having a constant pitch on a shaft c3 extending from a head c2 and having the drill c1 at the tip. A portion c4 is formed. Then, the screw portion c4 is screwed into the prepared hole D of the attachment B formed by the rotation of the drill portion c1 sequentially, so that a pushing force is applied to the drill portion c1 and the prepared hole D is further formed. While being dug down, the threaded portion c4 is screwed into the base material penetrating portion D1 of the prepared hole D, so that the attachment B is firmly fixed to the base material A.

[0004] At this time, the chips in the prepared hole D generated by the drill portion c1 are normally discharged to the rear side through the space between the prepared hole D and the shaft portion c3.

On the other hand, in the cement board B1 and the like,
In recent years, in order to increase the surface strength, a long fiber compound board reinforced by including long fibers (about 20 mm in length) made of synthetic resin such as polypropylene has appeared.

However, when a conventional tapping screw c is used for such a long fiber-containing board, the long fiber is easily entangled with the screw portion c4, and an eye by the cutting powder is formed in the prepared hole D. The tightening torque of the screw is significantly increased, for example, due to clogging. As a result, the mounting object B itself may be damaged, such as cracking, the screw tightening machine may fail due to excessive torque, or a groove, for example, a cross-shaped driver engaging groove provided on the head c2 of the screw. There are many problems such as deformation such as crushing, and insufficient tightening of the screws, resulting in improper fixing (tightening failure) to the object B.

In view of the above, the present invention is directed to a method of manufacturing a semiconductor device, comprising: a first thread portion having a first reference pitch thread; and a second pitch thread portion disposed behind and having a second pitch larger than the first pitch. Based on the fact that it is composed of a second threaded portion consisting of: a long fiber can be cut and the cutting powder discharge effect can be greatly improved, and the torque is excessive without impairing the basic performance of the tapping screw. It is an object of the present invention to provide a tapping screw that can solve the above-mentioned various problems.

[0008]

According to a first aspect of the present invention, there is provided a tapping screw according to the present invention, wherein a shaft portion extending from a head has a first thread having a first reference pitch.
And a second screw portion comprising a screw thread of a second pitch larger than the first pitch and arranged on the head side of the first screw portion. .

In the invention of claim 2, the shaft portion has a drill portion at a tip.

According to the third aspect of the present invention, the second pitch is 1.5 to 2.5 times the first pitch, and the first pitch and the second pitch are smoothly formed. It is characterized by being connected.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described.
This will be described together with the illustrated example. FIG. 1 is a side view of a tapping screw of the present invention, FIGS. 2A and 2B are a side view and a bottom view showing an enlarged drill portion at a tip, and FIG. It is sectional drawing which shows the state fixed to the material.

In FIG. 1, a tapping screw 1 has a shaft portion 3 extending from a head portion 2 and a first screw portion 4 and a second screw portion 5 on the head side (rear end side) of the same. It is formed incorrectly.

In this embodiment, the case where the head 2 is formed as a countersunk head having a tapered cone-shaped seating surface 6 is illustrated.
A plurality of edge-shaped projections 6A for cutting the surface of the head 2 (shown in FIG. 3) and embedding substantially the entire head 2 in the object B to be mounted.
Are provided radially. On the outer surface of the head 2, an engagement groove 2A for fitting a driver, for example, having a cross shape, a minus shape, a polygon shape, or the like is formed.

The head 2 is not particularly limited, and various types such as a so-called pan head and hexagonal bolt can be used.

The shaft portion 3 has a straight shaft shape smaller in diameter than the head portion 2, and a drill portion 7 having a tapered surface having a tip angle α of, for example, about 120 degrees is provided at the tip.
As shown in FIGS. 2A and 2B,
It is composed of a pair of guide grooves 9 inclined in the circumferential direction from the front end to the rear, and each of the guide grooves 9 faces on both sides of the axis. The guide groove 9 has a substantially V-shaped cross section, and one edge of the guide groove 9 constitutes a cutting blade 9A. The diameter da of the drill portion 7 is equal to the diameter d of the shaft portion 3.
It is formed to have the same diameter or substantially larger diameter as b.

The shaft 3 is formed with first and second screw portions 4 and 5 having different pitches.

The first screw portion 4 is formed adjacent to the drill portion 7 (a part of the guide groove 9 may extend into the first screw portion 4). First pitch P of
It is constituted by a thread 10 having one. In this example, the case of a single thread having one thread 10 is illustrated.

The first screw portion 4 corresponds to the conventional screw portion c4 shown in FIG. 5B, and is screwed into a pilot hole D formed by the drill portion 7 to thereby The drill hole 7 is dug deeper, and a pushing force required to penetrate the base material A is applied to the drill portion 7.
Further, the first screw portion 4 is firmly fixed to the base material A by being screwed into the base material penetration portion D1 of the prepared hole D.

Therefore, the first screw portion 4 may be formed at a relatively short reference first pitch P1 similar to the conventional tapping screw c in order to secure a sufficient pushing force and screwing force. is important. The first pitch P1 is not particularly limited, but is usually preferably set to a range of 0.45 to 1.0 times the thickness t of the base material A (shown in FIG. 3). = 1.59 mm.

Next, the second thread portion 5 is formed of a thread 11 having a second pitch P2 larger than the first pitch P1, and the head side (rear end side) of the first thread portion 4 is formed. Are arranged next to each other. In the present example, the second screw portion 5 is
Similarly to the screw portion 4 described above, a case of a single thread having one screw thread 11 is illustrated, and in this example, the screw thread 11 is smoothly continuous with the screw thread 10 without interruption.

The second screw portion 5 is mainly used to discharge chips generated by the formation of the prepared hole D by the drill portion 7 to the rear side, and to remove long fibers contained in the long fiber blend board. It functions to cut and prevent entanglement.

That is, by the rotation of the tapping screw 1, a pushing force is also generated from the second screw portion 5, and the drill portion 7
To increase the cutting efficiency. However, at this time, the pushing speed becomes the first
, The screw thread 11 of the second screw part 5 rotates idly and cuts off the peripheral wall of the pilot hole D. As a result, the long fibers are cut, and the inner diameter of the prepared hole D is expanded, so that a large space for discharging chips from the shaft portion 3 can be secured. The screw thread 11 also functions as a screw feeder, and together with the expansion of the discharge space, the cutting chips sent from the first screw portion 4 can be sequentially carried out to the rear end side without stagnation. The effect of discharging from the hole D is greatly improved.

Here, in order to more effectively exert the discharge effect, the second pitch P2 is preferably set to 1.5 to 2.5 times the first pitch P1, and if it is less than 1.5 times. In addition, the emission effect becomes insufficient. On the other hand, if it exceeds 2.5 times, the resistance at the time of scraping the peripheral wall of the prepared hole D becomes large, and the tightening torque may be increased. In this example,
The case where the ratio P2 / P1Ｐ2.0 is more preferable is illustrated.

Further, from the viewpoint of the discharge effect, the outer diameter d2 of the screw thread 11 is, for example, 0.2 to 0.2 times smaller than the outer diameter d1 of the screw thread 10.
It is also preferable to set it to be as large as about 0.4 mm. In this example,
The case where the size is increased by 0.3 mm will be exemplified. Note that the ratio d2 / d1
May be set to about 1.02 to 1.06. Further, in order to smoothly carry out the cutting powder, the thread 11 and the thread 10 are smoothly continuous without being interrupted or bent as described above.

Although the length L2 of the second screw portion 5 is not particularly limited, it is usually 1.0 L of the length L1 of the first screw portion 4.
Set to about 3.0 times. At this time, in order to increase the torsional rigidity of the tapping screw 1 and increase the strength, the second
The diameter (corresponding to the valley diameter) of the shaft portion 3 in the screw portion 5 is the diameter (corresponding to the valley diameter) of the shaft portion 3 in the first screw portion 4.
Preferably, the height is increased by about 0.3 mm.

As shown in FIG. 4, for example, as shown in FIG. 4, the thread 11 has an apex angle β of about 60 degrees in order to exhibit the effect of cutting the peripheral wall of the prepared hole D and the effect of cutting the long fiber. Preferably has a triangular cross section. Also, the distance L of the thread crest 11A from the basic chevron J is set to be about 0.125 times the height H of a so-called pointed peak of a normal screw, but is set to 0.05 times or less in this example. ing. As a result, the thread crest 11A is formed to be extremely sharp, and the effect of cutting long fibers is particularly enhanced. In this example, the thread 10 is also formed in the same cross section as the thread 11.

In this embodiment, a pair of fins 20 wider than the outer diameters d1 and d2 of the thread are provided on the drill portion 7.
Can be formed by projecting to both sides. The fin 20 pushes the pilot hole D formed by the drill portion 7 and facilitates the screwing of the tapping screw 1. When the base material A is inserted, the fins 20 are broken and the base material penetrating portion D
A strong screw connection between the first screw portion 4 and the first screw portion 4 is guaranteed.

The tapping screw 1 of the present embodiment can be used for fixing a normal object B containing no long fiber to the base material A in addition to the long fiber blended board. Also, the tightening torque of the screw can be reduced.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment, but may be implemented in various forms.

[0030]

Since the present invention is configured as described above,
Along with cutting long fibers, the effect of discharging chips can be greatly increased, and the screw tightening torque can be reduced without impairing the basic performance of the tapping screw, resulting in excessive torque, for example, screw tightening Failure of the machine, deformation of the screw in the driver engagement groove of the screw itself, and occurrence of poor screw tightening can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view of a tapping screw according to an embodiment of the present invention.

FIGS. 2A and 2B are a side view and a bottom view showing a drill portion in an enlarged manner.

FIG. 3 is a cross-sectional view showing a state in which an object is fixed to a base material.

FIG. 4 is a sectional view showing a screw thread.

FIG. 5A is a cross-sectional view illustrating an example of use of a tapping screw, and FIG. 5B is a side view illustrating a conventional tapping screw.

[Explanation of symbols]

 2 Head part 3 Shaft part 4 First screw part 5 Second screw part 7 Drill part 10, 11 Thread P1 First pitch P2 Second pitch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Nakamura 1-1-4 Shinsenri-Nishimachi, Toyonaka-shi, Osaka National Housing Industry Co., Ltd. (72) Inventor Yoshimichi Yamada 1-1-1, Shinsenri-Nishimachi, Toyonaka-shi, Osaka No.4 Inside the National Housing Industry Co., Ltd. (72) Inventor Norio Nogata 1-10-16 Yoshida Honcho, Higashiosaka City, Osaka KAME Seiko Co., Ltd.

Claims (3)

[Claims] 1. A shaft extending from a head includes a first thread having a first reference pitch thread and a second pitch thread having a second pitch larger than the first pitch. A tapping screw formed with a second screw portion disposed on the head side of the screw portion. 2. The tapping screw according to claim 1, wherein said shaft portion has a drill portion at a tip. 3. The second pitch is 1.5 to 1 of the first pitch.
The screw thread of the first pitch is 2.5 times, and the thread of the first pitch and the thread of the second pitch are smoothly connected.
The described tapping screw.