Patent Publication Number: US-2003235482-A1

Title: Screw

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention is related to an improved screw.  
       [0002] The structure of a screw is varied with the material of a work piece in which the screw is to be screwed. However, it is always required that the screw be quickly, easily and firmly screwed into the work piece. When the screw is screwed to drill the work piece, the smoothness of expulsion of the chips will directly affect the screwing speed and the value of applied torque. In the case that the thread of the screw is such designed as to smoothly expel the chips, the screw can be easily and quickly screwed into the work piece with less torque. Reversely, the resistance will be greater and the screwing speed will be slower and the needed torque will be greater. Therefore, it is necessary to provide a screw structure having better drilling and chip-expelling effect.  
       [0003] In various conventional designs, another cutting/drilling blade or thread is formed between the normal thread of the screw or on a certain section of the screw. That is, the drilling thread and the normal thread are independently formed on the same screw. Accordingly, multiple intersecting angles are contained between the drilling thread (blade) and the normal thread. Such intersecting angles act as resistance points against the expulsion or the chips when drilling the work piece. Therefore, the expulsion of the chips is obstructed and the drilling speed is slowed and the needed screwing torque is increased.  
       SUMMARY OF THE INVENTION  
       [0004] It is therefore a primary object of the present invention to provide an improved screw in which the cutting/drilling and chip-expelling thread is directly formed of the thread of the screw. Therefore, it is unnecessary to additionally design drilling thread (blade). Also, the resistance against the drilling and expulsion of chips caused by the intersecting angles is avoided.  
       [0005] It is a further object of the present invention to provide the above improved screw in which the drilling operation is speeded and the screwing torque is lowered.  
       [0006] The present invention can be best understood through the following description and accompanying drawings wherein: 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is a top view of the screw of the present invention; and  
     [0008]FIG. 2 is a bottom view of the screw of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0009] Please refer to FIGS. 1 and 2. The screw  1  of the present invention includes a screw head  10 , a thread  11  and a conic section  12  at the tail end of the screw  1 . The present invention is characterized in that the thread  11  of the screw  1  spirally extends through the conic section  12  of the screw  1  or to the tip B of the conic section  12  by another guide angle. The thread between the changing point A of the guide angle of the thread  11  and the tip B of the conic section  12  serves as a thread  11 A with cutting/drilling and chip-expelling function. That is, the cutting/drilling and chip-expelling thread  11 A of the screw  1  is directly formed by means of changing the guide angle of the thread  11  of the screw  1 .  
     [0010] The present invention has the following advantages:  
     [0011] 1. The cutting/drilling and chip-expelling thread  11 A is directly formed of the screw&#39;s own thread. Therefore, the drilling and expulsion of the chip are smoothened. The problem caused by the intersecting angles contained by different threads of the conventional screw is avoided.  
     [0012] 2. The remaining chips produced by the cutting thread  11 A are directly upward guided into the successive thread  11  so that the drilling operation is speeded and the resistance is less.  
     [0013] 3. The screw of the present invention has simple structure and better utility.  
     [0014] The above embodiment is only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiment can be made without departing from the spirit of the present invention.