SCREW FOR USE IN NONMETAL OBJECTS

VIS POUR UTILISATION DANS DES OBJETS NON METALLIQUES

English Abstract

The present invention pertains to a screw (3) for use in nonmetal objects comprising a plurality of cut-aiding portions (311) formed by the longer (312) and shorter (313) cutting surfaces inclined toward an opposite direction. Further, a cutting edge (314) formed by the junction of any two adjacent cutting surfaces (312,313) presents in a fastening direction of the screw. Thus, the cutting edge assists the threads (33) to thoroughly severe and to shatter the wood fibers and debris of the objects, which can also be accommodated into the cut-aiding portions. Also, the ridge (317) of the longer cutting surface (312) aids in cutting fibers and further guides the debris out. In this manner, the present invention facilitates to enhance cutting capability with less screwing resistance, prevent the destruction of the object and increase the screwing speed.

French Abstract

Vis (3) pour objets non métalliques comportant une multitude de portions aidant à la coupe (311) formées par des surfaces coupantes longues (312) et courtes (313) inclinées dans des directions opposées. De plus, un bord coupant (314) formé par la jonction de deux surfaces coupantes adjacentes (312, 313) se présente dans la direction du mouvement de la vis. Ainsi, le bord coupant aide le filet (33) à couper complètement et à briser les fibres de bois et les débris des objets, avec l'assistance des portions aidant à la coupe. De plus, l'arête (317) de la surface coupante longue (312) aide à couper les fibres et guide les débris vers l'extérieur. Ainsi, la vis permet l'amélioration de la capacité de coupe tout en diminuant la résistance pendant le vissage, ce qui empêche la destruction de l'objet et accélère le vissage.

Claims

I CLAIM:
1. A screw for use in nonmetal objects comprising:
a screw head;
a shank longitudinally extending from said screw head along a
shank axis;
a drilling portion disposed on a distal end of said shank,
opposite to said screw head; and
a plurality of threads disposed on said shank;
wherein a plurality of cut-aiding portions being disposed on
said shank and located between any of said two threads, and said
cut-aiding portions being adjacent to each other; each of said
cut-aiding portions consisting of a longer cutting surface and a
shorter cutting surface joined thereto; said longer cutting surface
and said shorter cutting surface being positioned toward opposite
directions; a cutting edge being formed at an intersect of said
shorter cutting surface and said longer cutting surface, which are
respectively located in any of said two adjacent cut-aiding
portions, whereby said cutting edge being presented in a fastening
direction of said screw; said longer cutting surface comprising
a first raked face and a second raked face with different slopes
disposed thereon, thus forming a ridge where said first raked face
and said second raked face meet; said ridge transversely extending
to said shorter cutting surface of said cut-aiding portion.
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2. The screw as claimed in claim 1, wherein each of said threads has
a notch disposed on an outer edge thereof; said notches on said
threads are sequentially connected for being arranged as a state
of a single helix around said shank, started from an initial notch
located adjacent to said drilling portion and terminated at a final
notch located adjacent to said screw head; said initial notch and
said final notch are disposed at relative positions, so that said
initial notch is exactly aligned with said final notch by an
imaginary line.
3. The screw as claimed in claim 1, wherein said shorter cutting
surface is parallel to said shank axis.
4. The screw as claimed in claim 1, wherein said shorter cutting
surface is inclined with respect to said shank axis by an angle.
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Description

CA 02607377 2007-10-23
SCREW FOR USE IN NONMETAL OBJECTS
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a screw, in particular a screw
for use in nonmetal objects.
2. Description of the Related Art
Referring to Fig. 1, a conventional screw 1 comprises a screw
head 10, a shank 11 extending from the head 10, a drilling portion
12 disposed at the distal end of the shank 11, and a plurality of
threads 13 disposed on the shank 11; wherein a plurality of slots
14 are disposed on the surface of the shank 11, which results of the
slight concavities in cross section " I " of Fig. 1 separately presented
around the periphery of the shank 11, as shown in Fig. 2. In operation,
the screw 1 is rotated into the wood object 2 by exerting the slots
14 to cut the fibers and accommodate the debris.
Generally, in regard to the resilience of the wood fibers and
the expeditious rotation, the fibers would not be thoroughly received
into the slots 14 with smaller spaces, thus rendering part of fibers
to be severed into debris and the remaining part to be unsevered.
Furthermore, due to the configuration of the slots 14, the debris
is hardly guided out of the object 2 and is continuously accumulated
therein; simultaneously, the unsevered and unbroken fibers are
twisted round the shank 11. In this manner, the aforementioned debris
and the fibers facilely make a larger screwing resistance and further
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CA 02607377 2007-10-23
cause the burden of the operators and the destruction of the object
2 while rotating the screw 1, thus affecting the screwing efficiency.
SUNMARY OF THE INVENTION
Therefore, the objects of the present invention are to provide
a screw which is conducive to enhance cutting capability, reduce the
screwing resistance for a higher screwing speed and prevent the
destruction of the object.
The screw relating to the present invention comprises a screw
head, a shank, a drilling portion and a plurality of threads; wherein
a plurality of cut-aiding portions are located between any of two
threads, and each of which consists of a longer cutting surface and
a shorter cutting surface positioned toward opposite directions. A
cutting edge formed by two adjacent cutting surfaces in any of the
two adjacent cut-aiding portions presents in a fastening direction.
Further, a ridge defined by the raked faces with different slopes
on the longer cutting surface also extends to the shorter cutting
surface. According to the aforementioned configurations, the cutting
edge assists the threads to thoroughly sever and shatter the fibers
and the debris, which can be received into the cut-aiding portions
with larger spaces, and further accompanying with the assistance of
the ridge to cut and smoothly guide the debris out, thereby decreasing
the screwing resistance and improving the problem of the destruction
to the object.
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The advantages of the present invention over the known prior
art will become more apparent to those of ordinary skilled in the
art upon reading the following descriptions in junction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic view showing a conventional screw to be screwed
into the object;
Fig. 2 is a cross-sectional view showing the portion of the
conventional screw;
Fig. 3 is a perspective view of a first preferred embodiment of the
present invention;
Fig. 4 is a schematic view of a second preferred embodiment of the
present invention;
Fig. 5 is a cross-sectional view showing the portion "II" of Fig. 3;
Fig. 6 is a transverse sectional view showing the shank of Fig. 3;
Fig. 7 is a schematic view showing the first embodiment of Fig. 3
to be screwed into the object;
Fig. 8 is a perspective view of a third preferred embodiment of the
present invention; and
Fig. 9 is a schematic view showing the third embodiment of Fig. 6
to be screwed into the object.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before the present invention is described in greater detail,
it should be noted that the like elements are denoted by the same
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reference numerals throughout the disclosure.
Referring to Fig. 3, a screw 3 of a first preferred embodiment
comprises a screw head 30, a shank 31 longitudinally extending from
the screw head 30 along a shank axis "a", a drilling portion 32
disposed on the distal end of the shank 31, opposite to the screw
head 30, and a plurality of threads 33 disposed on the shank 31; wherein
a plurality of cut-aiding portions 311 disposed on the shank 31 and
located between any of the two threads 33. The cut-aiding portions
311 are adjacent to each other. Each of the cut-aiding portions 311
consists of a longer cutting surface 312 and a shorter cutting surface
313 joined thereto, which are positioned toward opposite directions.
The shorter cutting surface 313 can be parallel to (shown in Fig.
4) or inclined to (shown in Fig. 3) the shank axis "a", and it is
adopted to be inclined with respect to the shank axis "a" by an angle
"0" in Fig. 3 or be slanted as a triangular shape shown in Fig. 5
presenting the cross section " II " of Fig. 3. The angle " 9" in
particular permits 8 to 20 degrees applied to the preferred
embodiments of the present invention. Still referring to Fig. 3 and
5, a cutting edge 314 is defined at an intersect of the shorter cutting
surface 313 and the longer cutting surface 312, which are respectively
located in any of the two adjacent cut-aiding portions 311, whereby
the cutting edges 314 present in a fastening direction of the screw
3, for instance of a tendency toward a clockwise direction.
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Further referring to Fig. 3 and 6, the longer cutting surface
312 comprises a first raked face 315 and a second raked face 316 with
different slopes disposed thereon, thereby forming a ridge 317 where
the first raked face 315 and the second raked face 316 meet; the ridge
317 transversely extends to the shorter cutting surface 313 of the
cut-aiding portion 311.
Referring to Fig. 7, in manipulation, the screw 3 is initially
drilled into a object 4 (for instance of a wood object) by the drilling
portion 32 and the threads 33; further, the cutting edge 314 and the
ridge 317 of the cut-aiding portion 311 assist to sequentially sever
and shatter the fibers of the object 4 into smaller debris, so as
to lower the screwing resistance and preventing the unsevered fibers
from being twisted round the shank 31. Simultaneously, the debris
thus can be received into the cut-aiding portions 311 between any
of two threads 33, and the ridge 317 aids in smoothly guiding the
debris out of the surface of the object 4, so as to prevent the fibers
and debris from being constantly accumulated in the object 4. As a
result, the present invention effectively enhances the cutting
capability for a lower screwing resistance and reduces the destruction
of the object, thus increasing the screwing efficiency.
Referring to Fig. 8, a screw 3 of a third preferred embodiment
comprises the similar configurations as the first preferred
embodiment. Particularly, a notch 331 is disposed on an outer edge
of each of the threads 33 and can be formed in V-shaped, U-shaped,
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semicircle-shaped, etc. Two V-shaped notches 331 are especially
applied to this preferred embodiment of the present invention. Further,
the notches 331 on the threads 33 are sequentially connected to be
arranged as a state of a single helix around the shank 31, started
from an initial notch 332 located adjacent to the drilling portion
32 and terminated at a final notch 333 located adjacent to the screw
head 30. The initial notch 332 and the final notch 333 are disposed
at relative positions, whereby the initial notch 332 is exactly
aligned with the final notch 333 by an imaginary line ",8 ".
Further referring to Fig. 9, the screw 3 thoroughly and
sequentially severs and shatters the fibers into smaller debris and
guide the debris out of the surface of the object 4 through the
cut-aiding portions 311 and the notches 331, so as to effectively
reduce the screwing resistance for a higher screw speed and prevent
from damaging the object 4.
To sum up, the present invention takes advantages of the
cut-aiding portions on the shank having the longer and shorter cutting
surfaces, thereby defining a cutting edge for cooperating with threads
to sever and shatter the fibers and a ridge for assisting to cut and
smoothly guide the debris out of the surface of the object. As a result,
the present invention would be conducive to reduce the screwing
resistance and avoid the destruction of the object by improving the
problem of the unsevered fibers and the unbroken debris being twisted
round the shank and continuously accumulated in the object.
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While we have shown and described the embodiment in accordance
with the present invention, it should be clear to those skilled in
the art that further embodiments may be made without departing from
the scope of the present invention.
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Representative Drawing