BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a screw and relates particularly to a wood screw provided with an enlarged cutting area of drilling portion to facilitate a cutting capability.
2. Description of the Related. Art
Referring to FIG. 1, a conventional fastener 1 comprises a head 11, a shank 12 extending downwards from the head 11, a drilling portion 13 connected to an end of the shank 12 and tapering off to a tip 131, and a plurality of threads 14 spirally disposed on the shank 12 and the drilling portion 13. The screwing operation of the conventional fastener 1 begins with rendering the tip 131 of the drilling portion 13 to be against a surface of an object 2. Then, the rotation force is applied to the head 11 to drive the threads 14 to cut the object 2 and further thread the drilling portion 13 and the shank 12 into the object 2, thereby completing the screwing operation of the conventional fastener 1.
However, the conventional fastener 1 still has problems. First, fibers contained in the object 2 are broken ineffectively by the threads 14 at the beginning of the screwing operation to result in an entanglement of the fibers around the shank 12 and increase the screwing resistance of the conventional fastener 1. Hence, the larger rotation force is required to thread the conventional fastener 1 into the object 2 to cause the enhanced use inconvenience.
Second, the entanglement of the fibers around the shank 12 causes that the cut chips resulted from the cutting operation of the threads 14 are excluded ineffectively and accumulate in the object 2 . Further, the object 2 may crack when the conventional fastener 1 keeps screwing downwards and squeezing the accumulated cut chips. Thus, the conventional fastener 1 still needs to be improved.
SUMMARY OF THE INVENTION
The object of this invention is to provide a wood screw with an enlarged cutting area of drilling portion to increase the cutting efficiency, exclude cut chips quickly, reduce the screwing resistance effectively, and attain the stable, fast and effort-saving screwing effect.
The wood screw of this invention comprises a head, a shank extending downwards therefrom, a drilling portion connected to an end of the shank and opposite to the head, a plurality of threads spirally disposed around the shank and the drilling portion, and at least two first ribs formed on the drilling portion between two adjacent thread convolutions of the threads. The first ribs extend upwards toward an extension direction different from a screwing direction. Each first rib has two first surfaces extending outwards from the shank and converging at a first edge which is positioned in the screwing direction. Hence, the first ribs projecting outwards from the drilling portion increase the cutting area of the drilling portion that helps a cutting capability, thereby enhancing the cutting effect, severing fibers of an object effectively to prevent the entanglement of the fibers, and reducing the resistance derived during the screwing operation. Further, the first ribs and the thread convolution work to form three cutting points in cross section, thereby attaining the fast cutting effect and accelerated evacuation of the cut chips. Therefore, the stable, fast and effort-saving screwing effect is completed.
Preferably, the first rib has at least one end separated from at least one thread convolution of the threads to form a space.
Preferably, two ends of each first rib connect the thread convolutions of the threads.
Preferably, the shank includes a plurality of second ribs spirally disposed thereon and situated between the threads. The second ribs have a helical direction different from the extension direction of the first ribs.
Preferably, at least one second rib spirally extends toward the drilling portion and terminates at a second end. At least one first rib extends upwards toward the shank and terminates at a first end. The second end is situated relative to the first end.
Preferably, each second rib has two second surfaces extending outwards from the shank and converging at a second edge which is positioned in the screwing direction.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view showing a conventional fastener;
FIG. 2 is a schematic view showing a first preferred embodiment of this invention;
FIG. 2A is an enlarged view showing a partial element of FIG. 2;
FIG. 3 is a top plan view as seen along the line A-A of FIG. 2;
FIG. 4 is a schematic view showing a simulation when the first preferred embodiment screws into an object; and
FIG. 5 is an enlarged view showing a second preferred embodiment of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 2, a first preferred embodiment of a wood screw 3 of this invention is disclosed. The wood screw 3 includes a head 31, a shank 32 extending downwards from the head 31, a drilling portion 33 fitted at an end of the shank 32 and opposite to the head 31, a plurality of threads 34 spiraled on the shank 32 and the drilling portion 33, and at least two first ribs 35 formed on the drilling portion 33 between two abutting thread convolutions of the threads 34. The drilling portion 33 gradually tapers off to a tip 331. Referring to FIG. 2 and FIG. 2A, in this preferred embodiment, the shank 32 includes a plurality of second ribs 36 spirally disposed thereon and situated between the threads 34. The first ribs 35 and the second ribs 36 are formed by directly stamping materials, namely by single-stage stamping, when forming the wood screw 3. Therefore, no waste material is generated. Hence, the wood screw 3 is provided with the enhanced structure strength andpreferable screwing torsion resistance.
Referring to FIG. 2A and FIG. 3 , the first ribs 35 extend upwards and head in an extension direction dissimilar from a screwing direction of the wood screw 3, namely the first ribs 35 extend in a levorotary direction. Each. first rib 35 has two first surfaces 352 extending outwards from the shank 32 and a first edge 353 formed at a convergence of the first surfaces 352. The first edges 353 are positioned in the screwing direction of the wood screw 3. Therefore, the first ribs 35 enlarge a cutting area of the drilling portion 33 which assists with a cutting capability. In this preferred embodiment, two ends of each first rib 35 connect the thread convolutions of the threads 34. Meanwhile, the second ribs 36 have a helical direction dissimilar from the extension direction of the first ribs 35. Each second rib 36 has two second surfaces 362 extending outwards from the shank 32 and a second edge 363 formed at a convergence of the second surfaces 362. The second edges 363 of the second ribs 36 are orientated in the screwing direction. Further, at least one first rib 35 extends upwards toward the shank 32 and terminates at a first end 351. At least one second rib 36 spirally extends toward the drilling portion 33 and terminates at a second end 361. The second end 361 is positioned relative to the first end 351, as shown in FIG. 2A.
Referring to FIG. 2 and FIG. 4, during a screwing operation of the wood screw 3, the tip 331 of the drilling portion 33 is positioned against to an object 4 firstly. Then, the head 31 receives the rotation force from a driving tool (not shown) to render the tip 331 to press and move downwards into the object 4 and synchronously carry out the screwing actions of the threads 34 and the first ribs 35 that are formed on the drilling portion 33. Hence, the wood screw 3 gradually threads into the object 4 during the screwing operation. Because the first ribs 35 projecting outwards from the drilling portion 33 enlarge a cutting area of the drilling portion 33, the enlarged cutting area assists in reaming the object 4. Further, the first ribs 35 and. the thread convolution of the threads 34 constitutes three cutting points in cross section. In other words, the first surfaces 352 of the first ribs 35 which extend in the direction different from the screwing direction excavate the object 4 first. After that, the first edges 353 which are orientated in the screwing direction assist in breaking cut chips and severing fibers entangled around the drilling portion 33 at the beginning of the screwing operation. Therefore, the reaming operation by scraping the objects 4 and breaking the cut chips provides the wood screw 3 with the stable screwing effect. Meanwhile, the resistance derived from the friction is effectively reduced and the screwing torsion caused by pressing the cut chips and the entanglement of the fibers is decreased at the beginning of the screwing operation. Further, the cut chips are evacuated along the first ribs 35 and the threads 34 to the outside because the first ribs 35 connect the thread convolutions of the threads 34. Therefore, the stable, speedy and effort-saving screwing effect is attained at the beginning of the screwing operation. Besides, the rotation force for threading the wood screw 3 into the object 4 is reduced and the screwing speed is accelerated to facilitate the following threading operation of the threads 34 into the object 4. Moreover, when the cut chips generated during the cutting operation of the threads 34 are evacuated to the outside and the shank 32 gradually threads into the object 4, the second surfaces 362 of the second ribs 36 can push the cut chips near the shank 32 and the second edges 363 further sever the entangled fibers, thereby attaining the smooth threading operation of the shank 32 and increasing the screwing efficiency effectively. Thus, the first ribs 35 and the second ribs 36 assist in the screwing operation of the wood screw 3, thereby enhancing the cutting effect, reducing the friction between the wood screw 3 and the object 4, saving the rotation force and operation time for screwing the wood screw 3 into the object 4, and achieving the screwing and positioning effects quickly.
Referring to FIG. 5 shows a second preferred embodiment of the wood screw 3 of this invention. The correlated elements and the concatenation of elements, the operation and objectives of the second preferred embodiment are the same as those of the first preferred embodiment. This embodiment is characterized in that the first rib 35 has at least one end disconnected with at least one thread convolution of the threads 34 to form a space 37. Certainly, two ends of each first rib 35 can be disconnected with the thread convolutions of the threads 34 to form two spaces 37 (not shown) . Here takes an example that an end of the first rib 35 is separated from the thread convolution of the threads 34 to form the space 37. Therefore, when the first ribs 35 help the drilling portion 33 ream the object 4 (not shown) , the first edges 353 assist the threads 34 formed around the drilling portion 33 in severing the fibers entangled around the drilling portion 33 to position the wood screw 3 quickly. Meanwhile, the cut chips occurred at the beginning of the screwing operation can be excluded through the space 37 along the threads 34 to the outside, thereby preventing the threads 34 which are disposed around the drilling portion 33 from being pressed by the cut chips and preventing the screwing speed from slowing down. Thus, the screwing efficiency becomes smooth, the rotation force for screwing the wood screw 3 into the object 4 is reduced greatly, and the fast screwing and positioning effect is attained effectively.
Therefore, the wood screw 3 of this invention compared with the conventional fastener 1 is provided with advanced advantages and effects. First, the first ribs 35 formed on the drilling portion 33 extend the cutting area to facilitate the cutting capability and ream the object 4 firstly. Meanwhile, the first ribs 35 and the thread convolution cooperate to form three cutting points in cross section. Therefore, the first surfaces 352 of the first ribs 35 which extend, in the direction different from the screwing direction excavate the cut chips, and thence the first edges 353 which are orientated in the screwing direction break the cut chips and the fibers, thereby reducing the resistance derived from the entanglement of the fibers during the screwing operation, increasing the screwing efficiency, facilitating the following threading operation of the threads 34, saving the rotation force for screwing the wood screw 3 into the object 4, and attaining the stable, fast and effort-saving screwing and positioning effects.
Second, the second ribs 36 disposed between the threads 34 can timely push the cut chips which press the shank 32 when the shank 32 keeps threading into the object 4. Meanwhile, the second edges 363 assist in breaking the cut chips and severing the fibers to allow the shank 32 to thread into the object 4 smoothly. Further, the cut chips are pushed by the second ribs 36 properly to be evacuated to the outside smoothly, thereby preventing the cut chips from accumulating in the object 4, preventing the object 4 from cracking caused when the wood screw 3 keeps pressing the accumulated cut chips, reducing the friction between the wood screw 3 and the object 4 during the screwing operation, decreasing the screwing torsion and resistance, and increasing the screwing speed.
To sum up, the wood screw of this invention takes advantages of the two first ribs formed on the drilling position between two thread convolutions of the threads to enlarge the cutting area of the drilling portion, thereby attaining the stable reaming effect. Further, the first surfaces of the first ribs which head in the extension direction different from a screwing direction can shovel the object, and thence the first edges which are orientated in the screwing direction can break the shoveled cut chips and sever the fibers entangled around the drilling portion, thereby reducing the screwing resistance at the beginning of the screwing operation. Meanwhile, the second ribs disposed between the threads properly push the cut chips which press the shank, thereby smoothing the screwing effect, decreasing the screwing resistance between the wood screw and the object, and achieving the steady, speedy and effort-saving screwing effect.
While the embodiments of this invention are shown and described, it is understood that further variations and modifications may be made without departing from the scope of this invention.
Patent Application
20190113066
