Patent Publication Number: US-2016223008-A1

Title: Screw

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a screw and relates particularly to a screw for fastening a wood board to a metal floor structure of a container or for fastening any wood board to a metal board. 
     2. Description of the Related Art 
     A container, e.g. a shipping container, a cargo container and a container house, is usually constructed by a metal floor board, and a wooden board is usually laid on and secured to the metal board of the container. Generally, a container screw is a wood-metal screw whereby the boards are fastened together, so the container screw should be able to cut both the wooden board and the metal board to suit the demand. For example,  FIG. 1  and  FIG. 2  show a conventional container screw  1  including a head  11 , a shank  12  extending downwards from the head  12 , a threaded section  13  spirally disposed on the shank  12 , a drill  14  installed at an end of the shank  12 , and two wings  15  disposed on the drill  14 . The end of the shank  12  forms a slot  121  where a top part of the drill  14  is embedded. The drill  14  has two opposite flat surfaces so that the drill  14  can have a flat shape. A thickness  14 D between the two opposite flat surfaces of the drill  14  is less than ⅕ times a diameter  12 D of the shank  12 . During the manufacturing process, the top part of the flat drill  14  is directly inserted into the slot  121 , and then the end of the shank  12  is compressed with a tool (not shown) to lodge the top part of the drill  14  into the slot  121 . In use, the drill  14  is rotated to bore a hole on a wooden board and a metal board of a container (not shown). During the drilling action, the threaded section  13  keeps drilling into the boards while the wings  15  are reaming the hole. Thus, the wooden board is fastened to the metal board by the screw  1 . 
     Generally, a method of making the screw  1  comprises steps of forming the shank  12  and the drill  14  respectively, embedding the drill  14  into the slot  121  and lodging the top part of the drill  14  in the slot  121  by gripping and compressing the end of the shank  12  with a tool. Such method requires many detailed steps and takes time, so the manufacturing cost is high. Further, the thickness  14 D less than ⅕ the diameter  12 D may render the drill  14  thinner to take more wood chips, but the hardness and strength of the drill  14  may not be good enough to overcome the drilling resistance. Therefore, the material of the drill  14  must be limited to one with the higher hardness, and the material cost may be increased inevitably. 
       FIG. 3  and  FIG. 4  show another conventional container screw  2  which includes a head  21 , a shank  22  extending downwards from the head  21 , a threaded section  23  spirally disposed on the shank  22 , an elliptical drill  24  with two opposite grooves  241  disposed at an end of the shank  22 , and two wings  25  disposed on the shank  22  and between the threaded section  23  and the drill  24 . When the drill  24  enters a wooden board  31  which is laid on a metal floor panel  32  of a container  3  and cuts wood fibers of the board  31  into wood chips, the chips accumulate between the drill  24  and the wings  25  easily because of lack of a proper means for removing chips. This causes the container screw  2  unable to remove the chips from the drill  24  effectively. Further, the accumulation of too many chips around the drill  24  incurs an over large drilling resistance and renders the container screw  2  unable to drill into the wooden board  31  successfully. It is also possible that the screw  2  snaps under the over large drilling resistance. Thus, the conventional screws should be improved. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a screw which increases the strength of the drilling portion and attains the preferable effect of cutting, removing and accommodating chips. 
     The screw in accordance with this invention comprises a head, a shank extending downwards from the head, a threaded section spirally disposed on the shank, and a drilling portion connected to the shank. The drilling portion includes a flat first body with a point and a second body with a conical surface or in a shape of a conical frustum disposed between the first body and the shank. The first body has two opposite first surfaces, two second surfaces respectively extending from the first surfaces, and two third surfaces respectively connected to the first surfaces and the second surfaces and sloping down from the second surfaces to the point. Each first surface is a flat surface and has a groove recessedly formed thereon. Each groove extends upwards from the point by an extended length and intersects with the second and the third surface along a cutting edge. A distance between the two opposite first surfaces is ¼˜¾ times a diameter of the shank. Therefore, the distance between the two flat first surfaces can be set at least ¼ times the diameter of the shank with the aid of the groove formed on each first surface in order to provide an increased thickness whereby the strength of the entire first body is promoted. The first body having the flat shape and the grooves also helps increase the space for removing and receiving the cut chips. The chips leaving each groove are moved along the second body and then removed from the wooden workpiece, thereby attaining a smooth and labor-saving operation. 
     Preferably, at lease one wing can protrude from the first body or the shank. In one preferred embodiment, two wings are formed on the second surface of the first body. In another preferred embodiment, two wings are formed on the shank and located close to the second body. 
     Preferably, the threaded section spirally disposed on the shank further extends to the conical surface of the second body. 
     Preferably, at least one chip clearance recess is formed on the second body. 
     Preferably, a neck is disposed between the second body and the first body. A maximum diameter of the neck is less than the diameter of the shank. 
     The advantages of this invention are more apparent to those skilled in the art upon reading following descriptions in conjunction with accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a first conventional screw; 
         FIG. 2  is a bottom plan view of  FIG. 1 ; 
         FIG. 3  is a schematic view showing a second conventional screw; 
         FIG. 4  is a bottom plan view of  FIG. 3 ; 
         FIG. 5  is a perspective view showing a first preferred embodiment of this invention; 
         FIG. 6  is a bottom plan view of  FIG. 5 ; 
         FIG. 7  is a schematic view showing the front elevation of  FIG. 5  in use; 
         FIG. 8  is a schematic view showing the side elevation of  FIG. 5  in use; 
         FIG. 9  is a perspective view showing a second preferred embodiment of this invention; and 
         FIG. 10  is a perspective view showing a third preferred embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 5  and  FIG. 6 , a screw  3  of a first preferred embodiment of this invention comprises a head  50 , a shank  51  extending downwards from the head  50 , a threaded section  52  spirally disposed on the shank  51 , and a drilling portion  53  connected to the shank  51 . The drilling portion  53  includes a first body  531  having a point  533  and a second body  532  having a conical surface. The first body  531  is formed into a flat and elongated design. Specifically, two oppositely-disposed first surfaces  5311  are provided in opposite sides of the first body  531 . Two second surfaces  5312  are respectively provided in the opposite sides of the first body  531 . Herein, each second surface  5312  extends from each first surface  5311 , and preferably extends rearwards from each first surface  5311  to suit a screwing direction. Two third surfaces  5313  are also provided in the opposite sides of the first body  531 . Each third surface  5313  is connected to the first surface  5311  and the second surface  5312  and slopes down from the second surface  5312  to the point  533 . Therefore, the two opposite third surfaces  5313  meet at the point  533 . Further, each of the first surfaces  5311  is flat, and a groove  5314  is recessedly formed on each of the first surfaces  5311 . The groove  5314  extends upwards and slantingly from the point  533  by an extended length and meets each of the second surfaces  5312  and each of the third surfaces  5313  along a cutting edge  5315 . In addition, a distance  5311 D between the two opposite first surfaces  5311  is ¼˜¾ times a diameter  51 D of the shank  51 . With respect to the second body  532 , the second body  532  is disposed between the first body  531  and the shank  51  and has a shape of a conical frustum. Specifically, the second body  532  has a decreasing diameter from a part connected to the shank  51  to a part connected to a top portion of the first body  531  or connected to a neck  534  which will be described as follows. 
     In the preferred embodiment, a neck  534  can be preferably disposed between the second body  532  and the first body  531 , and a maximum diameter  534 D of the neck  534  is less than the diameter  51 D of the shank  51 . Furthermore, at lease one wing  54  can be provided. For example, the first body  531 , as shown in  FIG. 5 , has two wings  54  protruding from the second surface  5312 . It is possible that the groove  5314  extends to where the wings  54  are located. Alternatively,  FIG. 9  shows a second preferred embodiment, the wings  54  of which protrude from the shank  51  and located close to the second body  532 . Herein, the structure that two wings  54  are respectively disposed on the second surfaces  5312  is described as an example. 
     This screw  5  is used to fasten a wooden workpiece  61  to a metal workpiece  62  of a container  6 , the use of which is explained with the aid of  FIG. 7  and  FIG. 8 . Referring to  FIG. 7 , a user puts the point  533  on the wooden workpiece  61  and rotates the head  50  by a screwing direction to drill the first body  531  into the wooden workpiece  61 . Therefore, the two opposite cutting edges  5313  bore a hole  611  in the wooden workpiece  61  and cut wood fibers. During the cutting action, the first body  531  with the flat shape and the grooves  5314 , the neck  534  and the second body  532  increase the space for removing and receiving chips. In other words, a room A, as shown in  FIG. 8 , is formed around the first body  531  between the first surfaces  5311  which are flat and the hole  611 , and a channel B communicating with the room A is also formed around the neck  534  and the second body  532  within the hole  611 . The room A and the channel B allow the chips to be accommodated therein. When each cutting edge  5313  cuts the wood fibers into chips, the chips travel along each groove  5314  and enter the room A and the channel B directly because of the slantingly extending groove  5314 . Thus, the cut chips are moved from each groove  5314  to the room A and the channel B quickly, and then part of the chips, as arrowed in the figures, keep moving along the second body  532  whereby the chips are expelled from the wooden workpiece  61  easily and quickly. This prevents too many chips from accumulating in the hole  611  and obstructing the drilling action of the drilling portion  53 . The drilling resistance is reduced to attain a smooth and labor-saving drilling action, and the conventional snapping problem under the over large resistance is also prevented. After the screw  5  subjects the wooden workpiece  61  to the aforementioned cutting and removing action, a proper amount of remaining chips stay in the grooves  5314 , the room A and the channel B, and then the cutting edges  5315  and the wings  54  continue cutting the metal workpiece  62  and reaming. Thus, the threaded section  52  can be firmly positioned into the metal workpiece  62 , and the two workpieces  61 ,  62  are firmly fastened together with the screw  5 . 
     By designing the flat first body  531  with grooves  5314 , the second body  532  and the neck  534 , the room A and the channel B between the drilling portion  53  and the hole  611  can be largely increased to promote the effect of removing and accommodating chips and facilitate a smooth and labor-saving operation. The grooves  5314  allow the distance  5311 D between the two opposite first surfaces  5311  to be set at least ¼ times the shank diameter  51 D, so the strength of the first body  531  is increased. By comparison with the conventional drill  14  of  FIG. 1 , the material of the first body  531  is not limited. Thus, the selection of the material of this invention is flexible, and the cost of the material is correspondingly reduced. 
     Referring to  FIG. 10 , a screw  3  of a third preferred embodiment of this invention still comprises a head  50 , a shank  51 , a threaded section  52  and a drilling portion  53 . The concatenation of correlated elements is the same as the first preferred embodiment and herein is omitted. This preferred embodiment is characterized in that the threaded section  52  spirally disposed on the shank  51  further extends to the conical surface of the second body  532 . Preferably, the second body  532  can have one or more chip clearance recesses  5321  formed thereon. Accordingly, the extension of the threaded section  52  to the second body  532  helps the drilling action and allows the screw  5  to be straight and smoothly drilled into the workpiece. The chip clearance recess  5321  also helps remove the chips along the second body  532  quickly, thereby increasing the drilling effect and operating more smoothly. 
     To sum up, this invention takes advantage of the groove formed on each first surface of the first body and extending upwards from the point to set the distance between the two opposite first surfaces at ¼˜¾ times the diameter of the shank, thereby increasing the strength of the first body. The first body having the flat first surface with the groove in cooperation with the second body or in cooperation with the second body and the neck helps increase the space for removing and accommodating the chips. The second body also helps the quick removal of the chips when the chips leave the grooves in order to facilitate a smooth and labor-saving operation. 
     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.