GB2304849A

GB2304849A - A screw structure

Info

Publication number: GB2304849A
Application number: GB9613342A
Authority: GB
Inventors: Kuo-Tai Hsu
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-08-24
Filing date: 1996-06-26
Publication date: 1997-03-26
Anticipated expiration: 2016-06-26
Also published as: GB9613342D0; FR2740516B3; DE29513571U1; GB2304849B; FR2740516A3

Description

2304849 A SCREW STRUCTURE

BACKGROUND OF THE INVENTION

The present invention relates to an improved screw structure which can be more quickly and securely screwed into a wooden work piece without causing crack thereof.

Nowadays, wooden materials are very widely used in construction. Also, a variety of furnitures and decorations are manufactured from wooden members. In order to connect the wooden members, screws are often utilized. Among various kinds of screws, the wood screws are most widely used. The conventional wood screws can be subdivided into two types, that is, twinfast wood screw and coarse thread wood screw. The above two types of wood screws both have a common shortcoming that the wooden member is subject to break when the screw is screwed into the wooden member. This may cause great loss, especially with respect to a high class wood material. In addition, the above screws have the shortcomings as follows:

1. The conventional wood screw has a tip section and a thread section behind the tip section, which enables the screw to continuously screw into the work piece. In the beginning of screwing operation, the tip section of the wooden screw substantially contacts with the the work piece on a plane surface so that the screw is usually difficult to be preliminarily forced and implanted into the work piece. Moreover, the screw is generally secured into the work piece in a perpendicular direction without any other support. Therefore, the screw often can be hardly stably and accurately screwed into the work piece.

2. After the screw is preliminarily screwed into the work piece, the worker must exert a considerably great screwing force onto the screw so as to continuously shear/cut the internal wooden tissue of the wooden work piece and entirely secure the screw thereinto. In the case that the work piece has a relatively dense and hard tissue, it will be difficult to effectively screw the conventional wood screw with simple thread design into such work piece. Therefore, the working efficiency will be apparently reduced and the working cost will be increased. Furthermore, the poor screwing work will lead to crack and damage of the work piece.

3. After the wood screw is completely screwed -into the work piece, in order to keep the outer surf ace of the work piece tidy and avoid possible scratch, the head of the screw must be imbedded in the work piece.

is Conventionally, this can be only achieved by previously drilling a fisheye hole on the surface of the work piece with another tool. Accordingly, the working procedure is complicated. In addition, the bottom face of the head of the screw is smooth so that the head of the screw may be over-imbedded into the work piece and damage the drilled surface thereof.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide an improved screw structure which can be more quickly and securely screwed into a wooden work piece without causing crack thereof. The screw structure includes a tip section, a core section having a thread and a head section. The tip section is f ormed with a cutting channel def ined by two cutting f aces, whereby at the preliminary stage of the screwing operation, one of the cutting faces exerts a shearing/cutting force on the work piece to drill a hole by itself, quickly locating the tip section and enabling the same to drill into the work piece. The core section is formed with multiple inclined convex cutting stripes between the thread, whereby when the screw is further twisted into the work piece, the cutting stripes scrape the peripheral wall of the drilled hole of the work piece so as to expand the drilled hole and reduce the frictional force against the drilling operation. The convex cutting stripes also serve to fully and evenly grind the wooden tissue of the work piece and exhaust the wooden powder from the clearance between the cutting stripes. Therefore, the work piece is prevented from cracking during the screwing operation. The bottom face of the head section is formed with cutting ribs which serve to facilitate the imbedding of the head section into the surface of the work piece and thus make the head section flush with the drilled surface and keep the appearance thereof plane and tidy.

The present invention can be best understood through the following description and accompanying drawing, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.

invention; Fig. 2 is a side view showing the screwing operation of the present invention at a first stage; Fig. 3 is a side view showing the screwing operation of the present invention at a second stage; and Fig. 4 is a side view showing the screwing operation of the present invention at a third stage.

1 is a perspective view of the present DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer to Fig. 1. The screw structure of the present invention includes a tip section, a core section having a thread 2 and a head section 3. The tip section is formed with a cutting channel 1. The core section is f ormed with multiple convex cutting stripes 21 between the thread. The bottom f ace of the head section 3 is formed with cutting ribs 31.

Please ref er to Fig. 2. The cutting channel 1 is longitudinally cut along the core section and extended upward f rom the tip section. The cutting channel 1 is thus defined by two lateral cutting faces 11. At a preliminary stage of the screwing operation, the tip of the screw is perpendicularly positioned on the surf ace of a work piece 4 and the screw is twisted into thereinto, in cooperation with the screwing f orce and direction of the thread 2, one of the cutting f aces 11 exerts a shear ing/cutting f orce on the work piece 4 to drill a hole by itself, quickly locating the tip section and enabling the same to drill into the work piece 4. Therefore, the stability and efficiency of the screwing operation is enhanced and the screw can be fast secured into the work piece 4. Referring to Fig. 3, the cutting stripes 21 are parallelly inclinedly arranged around the core section of the screw by a 20 degrees cutting angle. When the screw is further twisted into the work piece 4, the cutting stripes contact with the peripheral wall of the drilled hole of the work piece 4 and scrape the wall so as to expand the drilled hole and reduce the frictional force against the drilling operation. Therefore, the drilling operation is speeded. It should be noted that the difference between the full diameter and core diameter of the present wood screw is designed to be within 1.1mm to 2.1mm ( depending on the dimension of the screw), while each cutting stripe 21 only has a height within 0.1mm to 0.35mm. Therefore, although the cutting stripes 21 will expand the drilled hole, the thread 20 still has a sufficient depth for firmly engaging with the work piece 4 without affecting the binding strength. Moreover, the convex cutting stripes 21 serve to fully and evenly grind the wooden tissue of the work piece and exhaust the wooden powder from the clearance between the cutting stripes 21. Also, due to the reduction of the frictional resistance, the work piece is prevented from cracking during the screwing operation. Even under a most critical working condition such as the screw is screwed into an edge portion of the work piece, a good securing effect can be still achieved.

Referring to Fig. 4, the cutting ribs 31 are is inclinedly radially arranged on the bottom f ace of the head section 3 of the screw. The inclined direction of the cutting ribs 31 is accorded to the twisting direction of the screw, whereby when the screwing operation of the screw is completed, the cutting ribs 31 serve to facilitate the imbedding of the head section 3 into the surf ace of the work piece 4 and thus make the head section flush with the drilled surface and keep the appearance thereof plane and tidy. In addition, the cutting ribs 31 prevent the head section 3 f rom being over-imbedded into the work piece 4 to cause a depression thereon.

It is to be understood that the above description and drawings are only used for illustrating one embodiment of the present invention, not intended to limit the scope thereof. Any variation and derivation from the above description and drawings should be included in the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1 - A screw structure comprising a tip section, a core section having a thread and a head section, wherein a cutting channel is f ormed on the tip section, multiple convex cutting stripes are f ormed on the core section between the thread, and multiple cutting ribs are formed on a bottom f ace of the head section, the cutting channel being longitudinally cut along the core section and extended upward f rom the tip section and thus defined by two lateral cutting faces, the cutting stripes being parallelly inclinedly arranged around the core section, the cutting ribs being inclinedly radially arranged on the bottom face of the head section with inclined direction of the cutting ribs accorded to twisting direction of the screw.

2. A screw structure as claimed in claim 1, wherein the cutting stripes are parallelly inclinedly arranged around the core section of the screw by a 20 degrees cutting angle.