Patent Publication Number: US-2021190120-A1

Title: Wing-Shaped Thrust Screw

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a screw and, more particularly, to a wing-shaped thrust screw (or self-tapping screw). 
     2. Description of the Related Art 
     A conventional anchor for masonry veneer walls was disclosed in the U.S. Pat. No. 4,764,069. The tail end of the wall anchor is provided with an internally threaded hole for locking a headless screw, so that the headless screw can be locked and fixed in the internally threaded hole of the wall anchor. The headless screw has a tail provided with a drill tip. The outer diameter of the tail end of the wall anchor is larger than that of the thread of the headless screw, thereby forming a thrust part to prevent a further screwing motion of the headless screw. The wall anchor and the headless screw are produced individually. The wall anchor and the headless screw are made the zinc alloy which is cast and then tapped to form the thread, and finally the headless screw is locked in the internal thread hole of the wall anchor. However, the wall anchor and the headless screw are not formed integrally, and have a complicated working process, thereby increasing the cost of fabrication. 
     A conventional fastener for logs and fastening technique therefor was disclosed in the U.S. Pat. No. 6,050,765. The fastener is provided with two enlarged portions which are mainly used for hole expansion and chip removal during cutting. The two enlarged portions do not have a thrust function and cannot prevent a further screwing motion of the external thread. 
     A conventional stainless steel self-tapping screw was disclosed in the Taiwanese Patent Publication No. M311788. The stainless steel screw has a top provided with an enlarged cap portion, a middle provided with a screw body, and a bottom provided with a drill blade. The screw body is provided with a thread section and two convex fin portions. When the self-tapping screw is used to lock a non-metal plate and a metal skeleton, the two convex fin portions enlarge the bore of the non-metal plate, so that a space is kept between the screw body and the non-metal plate, to provide an expansion space when heat expansion occurs. Each of the two convex fin portions is a thin plate, such that when the two convex fin portions pass through the non-metal plate and touch the metal skeleton, the two convex fin portions are broken and detached from the screw body, and will not affect the metal skeleton. Thus, the screw body and the metal skeleton are connected steadily. However, the two convex fin portions do not have a thrust function, and cannot stop a further screwing motion of the thread section. 
     A conventional self-tapping screw  40  in accordance with the prior art shown in  FIGS. 1-3  comprises a head  41 , a first shank  43 , a second shank  44 , and a drilling member  42 . The head  41  is provided with a restriction portion  411  which is provided with a rotation portion  412  which is provided with a through hole  413 . The drilling member  42  includes a pointed portion  421 . Thus, the rotation portion  412  is driven and rotated by a driving tool to rotate the self-tapping screw  40 . The second shank  44  is provided with an external thread  441 . A thrust member  45  is formed between the first shank  43  and the external thread  441 . The thrust member  45  includes a stop ring  452  and a groove  451 . A washer  50  is mounted on the bottom of the stop ring  452 , and a resilient washer  51  is mounted on the bottom of the washer  50 . A perforation  52  is formed in the washer  50  and the resilient washer  51 . In fabrication, the thrust member  45  is formed by extrusion, such that a material for forming the groove  451  is squeezed downward to form the stop ring  452 . Thus, the stop ring  452  has a diameter slightly greater than that of the external thread  441 . In operation, the rotation portion  412  is driven and rotated by the driving tool to rotate the self-tapping screw  40 , such that the pointed portion  421  is drilled through a cement  1 , and the external thread  441  is screwed into the cement  1 . When the stop ring  452  touches the washer  50 , the self-tapping screw  40  stops rotating. However, when the self-tapping screw  40  is deflected from the washer  50 , the stop ring  452  easily passes through the perforation  52 , such that the stop ring  452  is deformed or broken by the washer  50 , and the thrust member  45  cannot stop a further movement of the external thread  441 . 
     BRIEF SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a wing-shaped thrust screw that stops rotation during a preset distance. 
     In accordance with the present invention, there is provided a thrust screw comprising a head, a first shank, a second shank, and a drilling member. The first shank and the second shank are arranged between the head and the drilling member. The second shank is provided with an external thread. The first shank is provided with a thrust member corresponding to the external thread. The thrust member includes two wing-shaped stop pieces and two flat portions. The two flat portions are formed on the two wing-shaped stop pieces respectively and correspond to the external thread. The two flat portions have an outer diameter greater than that of the external thread. The two flat portions of the thrust member stop a further screwing motion of the external thread. The first shank is worked by a first molding process to form the thrust member with the two wing-shaped stop pieces, and the thrust member is worked by a second molding process to form the two flat portions on the two wing-shaped stop pieces respectively. 
     According to the primary advantage of the present invention, the thrust screw is formed integrally with the thrust member, such that the external thread is not screwed or locked too deeply due to a defective working or assembling process or due to an improper operation of the user, thereby preventing the thrust screw from being broken or worn out during rotation. Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is a perspective view of a conventional self-tapping screw in accordance with the prior art. 
         FIG. 2  is a schematic operational view showing a screwing operation of the conventional self-tapping screw. 
         FIG. 3  is a schematic operational view showing finish of the screwing operation of the conventional self-tapping screw. 
         FIG. 4  is a perspective view of a thrust screw in accordance with the first preferred embodiment of the present invention. 
         FIG. 5  is a front view of the thrust screw as shown in  FIG. 4 . 
         FIG. 6  is a cross-sectional view of the thrust screw taken along line E-E as shown in  FIG. 5 . 
         FIG. 7  is a schematic operational view showing a screwing operation of the thrust screw in accordance with the first preferred embodiment of the present invention. 
         FIG. 8  is a schematic operational view of the thrust screw as shown in  FIG. 7 . 
         FIG. 9  is a perspective view of a thrust screw in accordance with the second preferred embodiment of the present invention. 
         FIG. 10  is a front view of the thrust screw as shown in  FIG. 9 . 
         FIG. 11  is a cross-sectional view of the thrust screw taken along line F-F as shown in  FIG. 10 . 
         FIG. 12  is a schematic operational view showing a screwing operation of the thrust screw in accordance with the second preferred embodiment of the present invention. 
         FIG. 13  is a schematic operational view of the thrust screw as shown in  FIG. 12 . 
         FIG. 14  is a schematic operational view of a thrust screw in accordance with the third preferred embodiment of the present invention. 
         FIG. 15  is a schematic operational view of a thrust screw in accordance with the fourth preferred embodiment of the present invention. 
         FIG. 16  is a perspective view of a thrust screw in accordance with the fifth preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and initially to  FIGS. 4-6 , a thrust screw  10  in accordance with the preferred embodiment of the present invention comprises a head  11 , a first shank  13 , a second shank  14 , and a drilling member  12 . 
     The first shank  13  and the second shank  14  are arranged between the head  11  and the drilling member  12 . The second shank  14  is provided with an external thread  141 . The first shank  13  is provided with a thrust member (or stop member)  15  corresponding to the external thread  141 . The thrust member  15  is connected with the external thread  141  of the second shank  14  and includes two wing-shaped (or fin-shaped) stop pieces  151  and two flat portions  152 . The two wing-shaped stop pieces  151  are formed on and protrude outward from the first shank  13 . The two flat portions  152  are formed on the two wing-shaped stop pieces  151  respectively and correspond to the external thread  141 . The two flat portions  152  have an outer diameter (or a dimension) greater than that of the external thread  141  and greater than that of the first shank  13 . Thus, the two flat portions  152  of the thrust member  15  stop a further movement of the external thread  141  and prevent a further screwing motion of the external thread  141 . 
     In fabrication, the first shank  13  is worked by a first molding process to form the thrust member  15  with the two wing-shaped stop pieces  151 , and the thrust member  15  is worked by a second molding process to form the two flat portions  152  on the two wing-shaped stop pieces  151  respectively. Preferably, the two wing-shaped stop pieces  151  are formed integrally on the first shank  13  by stamping, punching or pressing, and the two flat portions  152  are formed on the two wing-shaped stop pieces  151  respectively by turning or cutting. 
     In the preferred embodiment of the present invention, the drilling member  12  includes a pointed (or conic or tapered) portion  121 . 
     In the preferred embodiment of the present invention, the head  11  is provided with a circular restriction portion  111  disposed horizontally. The restriction portion  111  is provided with a rotation portion  112  disposed vertically. Thus, the rotation portion  112  is driven and rotated by a driving tool to rotate the thrust screw  10 . 
     In the preferred embodiment of the present invention, the rotation portion  112  is a sheet plate. 
     In the preferred embodiment of the present invention, the rotation portion  112  is provided with a through hole  113 . 
     In the preferred embodiment of the present invention, the thrust member  15  has a height that is adjusted according to the thickness of a workpiece. 
     In operation, referring to  FIGS. 7 and 8  with reference to  FIGS. 4-6 , a first article  2  is placed on a cement (or concrete)  1 . When the rotation portion  112  is driven and rotated by the driving tool, the thrust screw  10  is rotated, such that the pointed portion  121  of the drilling member  12  is drilled through the first article  2  into the cement  1 , and the external thread  141  is screwed through the first article  2  into the cement  1  as shown in  FIG. 7 . When the two flat portions  152  of the thrust member  15  touch the cement  1 , and the restriction portion  111  of the head  11  touches the first article  2  as shown in  FIG. 8 , the thrust screw  10  stops rotating. 
     Referring to  FIGS. 9-13 , the drilling member  12  includes a drill tip  122 . The thrust member  15  is spaced from the external thread  141 , and the thrust screw  10  further comprises a third shank  16  located between the thrust member  15  and the external thread  141 , a washer  20  mounted on the first shank  13  and located under the head  11 , and an elastic cushion (or pad or spacer or washer)  21  mounted on the first shank  13  and located under the washer  20 . The washer  20  rests on a bottom of the restriction portion  111  of the head  11 . The elastic cushion  21  rests on a bottom of the washer  20 . 
     In operation, referring to  FIGS. 12 and 13  with reference to  FIGS. 9-11 , a second article  3  is placed on the cement  1 , and a plurality of third articles  4  are placed on the second article  3 . When the rotation portion  112  is driven and rotated by the driving tool, the thrust screw  10  is rotated, such that the drill tip  122  of the drilling member  12  is drilled through the third articles  4 , and the second article  3  into the cement  1 , and the external thread  141  is screwed through the third articles  4 , and the second article  3  into the cement  1  as shown in  FIG. 12 . When the two flat portions  152  of the thrust member  15  touch the second article  3 , and the elastic cushion  21  touches the uppermost one of the third articles  4  as shown in  FIG. 13 , the thrust screw  10  stops rotating. In such a manner, the washer  20  and the elastic cushion  21  separate the head  11  from the third articles  4  to prevent the head  11  from pressing the third articles  4  directly. In addition, the elastic cushion  21  has a resilient feature to enhance the screwing and locking force of the external thread  141 , such that the washer  20  and the elastic cushion  21  rest on the third articles  4  smoothly and evenly. 
     Referring to  FIG. 14 , the restriction portion  111  is provided with a rotation portion  114  disposed vertically. Preferably, the rotation portion  114  is a hexagonal nut. Thus, the rotation portion  114  is driven and rotated by a driving tool, such as a socket wrench, to rotate the thrust screw  10 . 
     In operation, when the rotation portion  114  is driven and rotated by the driving tool, the thrust screw  10  is rotated, such that the pointed portion  121  of the drilling member  12  is drilled into a wood element  5 , and the external thread  141  is screwed into the wood element  5 . When the two flat portions  152  of the thrust member  15  touch the wood element  5 , the thrust screw  10  stops rotating. Then, a cement  6  is poured to the wood element  5 . The height of the cement  6  increases gradually until the cement  6  touches the restriction portion  111  of the head  11 . 
     Referring to  FIG. 15  with reference to  FIG. 14 , the pointed portion  121  is replaced by the drill tip  122 . 
     Referring to  FIG. 16 , the head  11  is directly provided with a rotation portion  115 . The rotation portion  115  has a tapered (or conic) shape and is provided with a driving slot. Preferably, the driving slot has a flat shape or a cross shape. Thus, the rotation portion  112  is driven and rotated by a driving tool, such as a screwdriver, to rotate the thrust screw  10 . 
     Accordingly, the thrust screw  10  is formed integrally with the thrust member  15 , such that the external thread  141  is not screwed or locked too deeply due to a defective working or assembling process or due to an improper operation of the user, thereby preventing the thrust screw  10  from being broken or worn out during rotation. In addition, the two flat portions  152  have an outer diameter greater than that of the external thread  141 , to stop a further screwing motion of the external thread  141 . 
     Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the scope of the invention.