Abstract:
The present invention pertains to a screw essentially comprising a plurality of bulges disposed on threads of the screw and unengaged with a shank; whereby a consecutive extrusion path is formed between the bulges and the shank. Herein, while the bulges facilitate the screw threads to efficiently chop fibers of the object into debris and render the screw to easy drill into the object, the extrusion path smoothly guides and extrudes the debris therealong. Thus, the present invention conduces to decrease the drilling torque resulting in a speedily screwing; moreover, the bulges also allow the unsevered fibers hugging therearound to enhance the screw firmness inside the object.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a screw, in particular to a screw that assists in decreasing the drilling torque to increase the screwing speed as well as promoting the firm screwing. 
         [0003]    2. Description of the Related Art 
         [0004]    A conventional screw  1  shown in  FIG. 1  generally comprises a head  11 , a shank  12  outwardly extended from the head  11 , a plurality of threads  13  spiraling round the shank  12 , a drilling portion  14  disposed on the shank  12  and located opposite to the head  11 , and a plurality of bulges  15  disposed at regular intervals on the threads  13 . Wherein, each of the threads  13  has two flanks  131  extending from the outer periphery of the shank  12  as well as a thread peak  132  defined where the flanks  131  congregate. The bulges  15  are further outwardly extended from the shank  12  toward the thread peak  132  and correspondingly protruded on the flanks  131  of the threads  13 . 
         [0005]    Further referring to  FIGS. 1 and 2 , while driving the screw  1  into an object  2 , the bulges  15  forms an enlarged bore for allowing the threads  13  to follow the bore track and enter into the object  2  and helps the object fibers to be cut into debris. However, in view of the confinement of the bulges  15  protruded from the shank  12  to the peak  132 , a room  21  formed between any two of the threads  13  for receiving debris is relatively restricted. Although the debris just fills with the limited room  21  and surrounds the shank  12 , it still cannot attain a favorable screwing firmness of the screw  1  into the object  2  as the room  21  cannot accommodate enough amount of the debris. Furthermore, the forced entwining of the unsevered fibers round the shank  12  would also incur a large drilling torque in time of incessantly drilling the screw  1  into the object  2  since the threads  13  of the screw  1  would not fully chop all the fibers. 
         [0006]    Besides, as arrowed in  FIG. 3 , when the cutting debris travels along the threads  13 , it is difficult to smoothly extrude the debris as the configuration of the bulges  15  is an obstacle to the debris, namely the debris would be obstructed and adversely piled up between the bulges  15 , which however results in the debris unable to travel therethrough and guide out of the object  2  until the later debris attains at a certain amount to forcedly push the afore debris moving forward. Therefore, the jam and the accumulation of the debris within the room  21  generates an reverse resistance and results of the increment of the drilling torque as well as the decrease of the screwing speed and drilling efficiency, even to crack the object  2  while screwing. 
       SUMMARY OF THE INVENTION 
       [0007]    The object of the present invention is to provide a screw to achieve a speedy screwing and a decreased drilling torque so as to increase the screwing efficiency. 
         [0008]    The screw in accordance with the present invention mainly comprises a head, a shank outwardly extended from the head, a plurality of threads spiraling round the shank, and a drilling portion disposed on the shank, opposite to the head. Wherein, each thread has two flanks and either of which has a plurality of bulges placed apart thereon; said bulges are not engaged with the shank, so that a consecutive extrusion path is defined between the bulges and the shank. Therefore, in the preliminary drilling, the bulges assist the threads in chopping fibers of an object and render the screw to easily enter into the object; further, the redundant debris can untrammelledly and smoothly pass along the extrusion path to be ejected out of the object even it is obstructed by the bulges. Thus, the screw is capable of reducing its drilling torque to raise the screwing speed. The remained non-chopped fibers along with the remained debris would also firmly gather and entwine around the bulges to promote the screwing firmness after screwing. 
         [0009]    The advantages of the present invention over the known prior arts will become more apparent to those of ordinary skilled in the art by reading the following descriptions with the relating drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a plan view showing a conventional screw; 
           [0011]      FIG. 2  is a schematic view showing the conventional screw screwed among an object; 
           [0012]      FIG. 3  is a schematic view showing the motion of the debris of the conventional screw while screwing; 
           [0013]      FIG. 4  is a perspective view showing a first preferred embodiment of the present invention; 
           [0014]      FIG. 5  is a cross-sectional view showing the A-A section in  FIG. 4 ; 
           [0015]      FIG. 6  is schematic view showing a second preferred embodiment of the present invention; 
           [0016]      FIG. 7  is a schematic view showing the first preferred embodiment screwed among an object; 
           [0017]      FIG. 8  is a schematic view showing the motion of the debris of the present invention while screwing; 
           [0018]      FIG. 9  is a perspective view showing a third preferred embodiment of the present invention; 
           [0019]      FIG. 9A  is a partial enlarged view of  FIG. 9 ; 
           [0020]      FIG. 9B  is a partial enlarged view showing a fourth preferred embodiment of the present invention; 
           [0021]      FIG. 10  is a schematic view showing of  FIG. 9  screwed among an object; 
           [0022]      FIG. 11  is a schematic view showing a fifth preferred embodiment of the present invention; and 
           [0023]      FIG. 12  is a bottom view showing of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Before describing in greater detail, it should note that the like elements are denoted by the similar reference numerals throughout the disclosure. 
         [0025]    Referring to  FIGS. 4 and 5 , a screw  3  of a first preferred embodiment comprises a head  31 , a shank  32  outwardly extended from the head  31  and forming a drilling portion  34  with a pointed tip  341  to be disposed opposite to the head  31 , and a plurality of threads  33  spiraling round the shank  32  and incessantly distributing over the drilling portion  34 . Wherein, each of the threads  33  has two flanks  331  respectively extending from the outer periphery of the shank  32 , and a thread peak  332  is defined at the convergence of the two flanks  331 . Further, a plurality of bulges  35  are disposed on either flank  331 ; each bulge  35  provides with one end thereof to disconnect from the shank  32  and with other end thereof to contact with the thread peak  332  so as to form a consecutive extrusion path  351  between the shank  32  and the bulges  35 . 
         [0026]    Particularly, the bulges  35  can be merely disposed on one flank  331 , for instance of being on the upper flank  331  of the thread  33  in  FIG. 4 , or can be correspondingly disposed on both flanks  331  as shown in  FIG. 6 . It should be noted that the following configuration will be particularly described basing on the first preferred embodiment in consideration of the bulges  35  being disposed on either one flank  331  which achieves the same manipulations and competences as the elements on both flanks  331 . 
         [0027]    Referring to  FIGS. 4 and 7 , in operation, a force is initially imparted upon the head  31  to rotate the drilling portion  34  as well as the threads  33  drilling into an object  4  with wooden fiber. Further, the threads  33  accompanying the bulges  35  expand a drilling bore on the object  4  and simultaneously sever the fibers into debris, so that the attendant threads  33  are capable of rapidly entering into the object  4  by following the expanded bore track to decrease the drilling torque. When the drilling and cutting of the threads  33  and the bulges  35  keep working, the redundant debris is capable of being smoothly extruded out of the object  2  along the extrusion path  351 . As plainly arrowed in  FIG. 8 , by means of the existing of the extrusion path  351 , the debris would in turn to be pushed toward the extrusion path  351  and be progressively guided out of the object  4  when it is impeded by the bulges  35 , and which accordingly facilitates decreasing the drilling torque and achieving a speedy screwing as well as avoids the broken of the object  4  by the guidance of the extrusion path  351  that prevents the occurrence of excessively accumulating debris and of the forced jam of the debris within the threads  33 . 
         [0028]    Still referring to  FIG. 7 , after screwing the screw  3  into the object  4 , the remain debris (shown by the dots) which is not extruded out of the object  4  distributively and consecutively fills with the threads  33 , namely among the extrusion path  351  and the bulges  35 , so that the screw  3  can achieve a preferable firmness within the object  4  as the installation of the bulges  35  would not affect the amount of the remained debris accommodating between the threads  33 . Moreover, the unsevered fibers (shown by irregular solid lines) with the elasticity would also tightly wrap around the bulges  35  and further congregate with the debris within the threads  33 . Therefore, the screw  3  can steadily prevent itself from loosening while being subjected to an external force. 
         [0029]    Referring to  FIG. 9 , a screw  3  of a third preferred embodiment still comprises a head  31 , a shank  32 , threads  33 , and a drilling portion  34 . Different from the first preferred embodiment that each bulge  35  with its other end to just contact with the thread peak  332 , the bulge  35  of this embodiment disposed on either flank  331  particularly projects out of the thread peaks  332  as well as concomitantly has an extending surface  352  connecting with the thread peaks  332  (see  FIG. 9A ). Accordingly, the projected bulges  35  substantially create an enlarged bore  41  while drilling the screw  3  into the object  4  and permit the succeeding threads  33  to follow the track of the bore  41  for an easy and rapid entry, so that the redundant debris can be extruded out of the object  4  along the extrusion path  351  and the space between the bore  41  and the threads  33  as more clearly shown in  FIG. 10 . Hence the drilling torque is relatively decreased. Concurrently, the extrusion path  351  also applies to congregate the remained debris therein, and the unsevered wooden fibers would also tightly wrap around the bulges  35  basing on their elasticity, which hence prevent the problem of loosening from the object  4  and achieves a tighter and firmer screwing efficiency. 
         [0030]    Besides, further referring to  FIG. 9B  showing a fourth preferred embodiment of the present invention, the bulges  35  are disposed on both the flanks  331  integrally project out of the thread peaks  332  so as to perform in a hugging statement. Still referring to  FIG. 10 , the integral bulges  35  on the threads  33  can also generate an enlarged bore  41  whereby the succeeding threads  33  are capable of efficiently traveling therein to decrease the drilling torque. In this manner, the debris can further gather within the extrusion path  351 ; in addition, the resilient wooden fiber will tightly embrace the integral bulges  35 , which results in filling with the extrusion path  351  and the thread peaks  332  to enhance the screwing firmness. 
         [0031]    Besides the aforementioned embodiments, the screw  3  can also have another embodiment for more strengthening the screwing capability.  FIGS. 11 and 12  showing a fifth preferred embodiment comprises a head  31 , a shank  32  extended from the head  31 , threads  33  spiraling round the shank  32 , and bulges  35  instanced to be disposed on both upper and lower flanks  331  as the same as the second embodiment to define an extrusion path  351 . Especially, a drilling portion  34 , over which the threads  33  continuously distributing, is outwardly extended from the shank  32  and located opposite to the head  31 . The drilling portion  34  has a pointed tip  341  at its distal end. At least three drilling ridges  342  radiate from a pointed tip  341  and incline to a central axis “α” of the shank  32 , and four drilling ridges  342  are preferably adopted in this embodiment. Between any two drilling ridges  342  further forms a drilling surface  343 . More explicitly, one end of each drilling ridge  342  connects to the pointed tip  341 , the other end of which connects to the joint of the shank  32  and the drilling portion  34 . 
         [0032]    Still referring to  FIGS. 11 and 12 , while the threads  33  on the drilling portion  34  keep drilling into an object (not shown), the drilling ridges  342  and the drilling surfaces  343  progressively sever and shatter the wooden fibers into debris to overcome the occurrence of the entwining of the fibers around the shank  32  and further to decrease the drilling torque. The screwing speed hence can be promoted. In addition, a bore (not shown) expansively created via the drilling ridges  342  not only makes an easy entry into the object but also renders the debris to be further promptly extruded through the extrusion path  351  and the space between the enlarged bore and the thread  33 . Thus, the screw  3  requires lower drilling torque and substantially save the labor imparted thereon. Such drilling portion  34  readily chops the fibers and cooperates with the bulges  35  and the extrusion path  351  to eject the redundant debris so as to avoid the destruction of the object during the introduction of drilling and to more promote the afore performance of the screw  3  and the using convenience. 
         [0033]    To sum up, the present invention takes advantage of a plurality of bulges on threads disconnected from the screw shank and a formation of a consecutive extrusion path to efficiently chop wooden fibers into debris, readily drive the screw into the object, and allow a free motion of the debris along the extrusion path, thereby the decreasing drilling torque for the purpose of increment of the screwing speed as well as avoiding cracking object due to the jam of the debris. The unsevered fibers would also tightly hug round the bulges to promote the screwing firmness. Besides, a drilling portion of the present invention can alternatively have its drilling portion to provide with sloping drilling ridges along with a drilling surface formed therebetween so as to enhance the chopping capability of the screw, which hence more prevents the object from destruction and decreases the drilling torque as well as increases the screwing speed. 
         [0034]    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.