Abstract:
A structure of a knife includes an arcuate main body combined with two corresponding housings, an extension and a subordinate housing, a blade rack capable of holding different kind of blades releasably secured in the front end, a blade chamber in a middle portion with a slender magnet disposed thereunder to prevent the stored blades from sticky together, a roller and a press plate disposed at rear end for respectively making a track on the carpet being cut and to get ride the crepes in the carpet.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to cutting tools and more particularly to a structure of a knife which is adapted to cut the carpet and capable of storing and assembling different kind of blades. 
   Generally, a heavy duty artistic knife or other cutting means adapted to cut the carpet requires different blade. However, there are cutting tools can only suit to one or two kinds of blades. But the cutting of carpet requires many kind of blades to cope with different cutting conditions. Thus the operator has to prepare a lot of knives of different blades that causes great inconvenience to the operator. 
   Besides, many of these knives have blade chamber to store the spare blades which have always been applied with the lubricating oil for rust-proof. But one is difficult to pick up the spare blade on one by one basis due to the sticky of the oil and the thin of the blade. Therefore, some of the producers embeds a magnet in the wall of the chamber. Because of the magnetic attraction, that causes more difficult to pick up a single blade from the chamber. 
   Further, the operator needs a pressing means to press the carpet when it becomes crepe or beside a wall so that is a wearisome job for an operator to repeatedly change the tools. 
   SUMMARY OF THE PRESENT INVENTION 
   The present invention has a main object to provide a structure of a knife which is capable of coupling with different blade available in the market such that the operator uses only one kind of the knife to perform different cutting requirement of the carpet. 
   Another object of the present invention is to provide a structure of a knife in which a blade chamber is provided to store different kind of blades, each of the storing blade has a small gap therebetween to facilitate the operator to pick up a blade on one by one basis. 
   Further object of the present invention is to provide a structure of a knife which has a press plate at rear end which presses the turning point or the crepe of the carpet or twists the carpet for 90 degrees without using other tools. 
   Accordingly, the structure of a knife of the present invention comprises general a main body or handle which is combined with two corresponding arcuate housings. The front inner side of the first housing has a pair of positioning rods, a stop wall and a circular magnet. A blade chamber in a middle portion stores different kind of the spare blades. A slender magnet disposes under the chamber which provide the magnetic rays parallel to the blades for preventing the stored blades from sticky together. A slant extension on the rear end has a roller and a concave for disposing a spring biased catch which has a projection at front end. An inverse trapezoid blade rack is fixed to the front end for disposing a blade of front or back side. A second housing rotatably combines with the first housing by screw having a check depression in rear end releasably checked by the catch. A subordinate housing connects the slant extension with a soft pad and a roller disposed therebetween. The subordinate housing further has a press plate projected outward from a rear end thereof for preventing the carpet from a crepe. 
   The present invention will become more fully understood by reference to the following detailed description thereof when read in conjunction with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of the preferred embodiment of the knife according to present invention, 
       FIG. 2  is a perspective view of the assembly of  FIG. 1 , 
       FIG. 3  is a plane view indicating that the second housing is rotated for about 90 degrees, 
       FIG. 4  is a plane view indicating that the second housing is rotated to facilitate the blade to assemble to the blade rack, 
       FIG. 5  is a perspective to show the front and the back sides of the blade rack, 
       FIG. 6  is a plane view indicating that the back side of the blade rack is toward outside during the second housing being rotated for about 90 degrees, 
       FIG. 7  is a plane view indicating that a double-edge blade assembled to the blade rack, 
       FIG. 8  is a top view and partially sectional view indicating that the blades inside the blade chamber are separated from each other, 
       FIG. 9  is a plane view indicating that the knife of the present invention is cutting a carpet, and 
       FIG. 10  is a plane view indicating that the press plate is pressing the crepes of the carpet at a corner. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to  FIGS. 1 ,  2  and  3  of the drawings, the structure of a knife of the present invention comprises a main body or handle  1  which is combined with a first and a second corresponding housing  10  and  30 , an inverse trapezoid blade rack  20 , a subordinate housing  40  and a blade  50 . 
   In the first corresponding housing  10 , there is an extension  11  projected downward from the rear end, a circular magnet  12  disposed in a circular protrudent cavity  121  which is provided to attract the blade rack  20 , a first positioning groove  101  in the top of the front end, a second positioning groove  102  in a top apart from the first positioning groove  101 , a first positioning rod  103  on a middle portion between the positioning grooves  101  and  102 , a second positioning rod  104  on a middle portion beneath the second positioning groove  102 , a stop partition  105  beneath the second positioning rod  104 , a first protrudent through hole  106  on a middle portion aside the circular cavity  121 , a blade chamber  13  in a rear portion for storing different kind of spare blades  50  and  51  therein (as shown in  FIGS. 3 and 6 ), a slender cavity  14  beneath the blade chamber  13  for disposing a slender magnet  15  therein, a second protrudent through hole  107  and a rectangular concave spacedly formed in the rear end thereof. The extension  11  has a reinforced axial hole  111  on an inner side adjacent the lower end made engageable with the central bore  1121  of a roller  112 , and a serrated side wall  113 . 
   The inverse trapezoid blade rack  20  (as shown in  FIG. 5 ) disposes in the front end of the first corresponding housing  10  and has a pair of upper projections  21  and  29  formed spaced apart on the top respectively engaged with the positioning grooves  101  and  102 , a plurality of foreward bent and backward bent pieces  26  and a press plate  27 , a side the upper projections  21  and  29 , a square through hole  22  and a rectangular through hole  23  formed spaced apart in the middle portion thereof respectively engaged with the positioning rods  103  and  104 , a lower projection  24  projected downward from a lower central edge and engaged with the stop partition  105 , a plurality of backward bent pieces  25  aside the lower projection  24  and an additional square through hole  28  formed in a surface beneath the upper projection  29 . Wherein the rectangular through hole  23  has a pair of bent over flanges  231  and both the square through holes  22  and  28  have a bent over flange which is provided to hole the blade  50  thereon. Besides, both of the right side and the back side of blade rack  20  may face upward to serve for different shape of blades (as shown in  FIGS. 4 and 7 ). A detent  16  has a striped outer surface and a catch  162  at front end engaged into the rectangular concave and biased by a spring  161  on the rear end thereof. A soft pad  46  having the coupling grooves  461  in the root of the two square protrusions partially engaged with serrated side wall  113  of the extension  11 . 
   The second corresponding housing  30  combines with the first corresponding housing  10  and has a first depressed through hole  31  engaged with the protrudent through hole  106  and rotatably secured by a bolt  33  and a nut  331  and a check recess  32  in the rear end engaged with the catch  162  of the detent  16  such that the second corresponding housing  30  can be rotated on the bolt  33  and became stable by the detent  16 . 
   The subordinate housing  40  has a second depressed through hole in an upper portion engaged with the second protrudent though hole  107  and secured by a bolt  43  and a nut  431 , a third depressed through hole  42  engaged sequentially with the central bore  1121  of the roller  112  and the reinforced axial hole  111  and secured by a bolt  44  and nut  441 , a receiving space  47  in front end for receiving the striped outer surface of the detent  16  and a press plate  45  extended rearward from the rear wall for pressing the crepes of a carpet. After the subordinate housing  40  engaged with the extension  11 , the roller  112  is able to rotate and the soft pad  46  is secured by an inner wall of the subordinate housing  40  and partially exposes out of the housing  40 . 
   When mounts a trapezoid blade  50  on the blade rack  20 , engage the pair of U-shaped slots  511  in the top of the blade  50  with the press plate  27  of the blade rack  20  and respectively stop the upper edge and the lower edge of the blade  50  against the foreward bent pieces  25  and  26  (as shown in  FIG. 4 ) so that the blade is firmly fixed.  FIGS. 6 and 7  indicate that the blade rack  20  is turned over to have its backside toward outward. However, the upper projections  21  and  29  are still engaged with the positioning grooves  101  and  102 , the rectangular through hole  23  and the square through hole  22  are also engaged with the positioning rods  103  and  104 , and the lower projection  24  stops against the stop partition  105 , too. The turned over blade rack  20  suits to mount a double-edge blade  51  which has a rectangular central hole  511  engaged with the bent over flanges  231  of the rectangular through hole  23 . Further, the structure of this blade rack  20  also suit to mount a single U-shaped slot blade or a blade having an arcuate hooked edge. 
   Referring to  FIGS. 1 and 8 , the blade chamber  13  is provided to store different shapes of blades. Due to the magnetic line of force of the slender magnet  15  that is parallel to these blades and perpendicular to the chamber  13 . So that a small gap is therefore presented between each adjacent blades which are readily picked up without sticky together. 
     FIGS. 9 and 10 , in application, the operator has to skillfully grasps the handle  1  and lets the roller to rotate on a carpet in order to make a track on the surface of the carpet. Then the blade cuts the carpet by following the track. So that the result should be very neat. If a crepe is found on the carpet or that the carpet at a corner between a wall and the floor, the operator can use the press plate  45  to get rid of those problems. 
   When the edge of the blade  50  or  51  is found blunt, pull the detent  16  rearward to have its projection  162  disengaged with the check recess  32  in the rear end of the second corresponding housing  30  which is now set free to rotate for about 90 degrees (as shown in  FIG. 3 ). So that both the blade rack  20  and the blade chamber  13  are exposed out to enable the operator removing the old blade  50  or  51  and picking a new blade  50  or  51  up from the blade chamber  13  and mounting onto the blade rack  20 . Then rotate the second corresponding housing  30  back to its original position and be locked again by the detent  16  in a snap fitting. 
   The feature of the knife of the present invention is set forth as follows: 
   a) the addition of a blade rack  20  enables the handle  1  to suit any kind of blade available in the market and need not to prepare different shape of knives, 
   b) a small gap exist between each adjacent blade  50  or  51  in the blade chamber  13  that enables the operator to readily pick up a blade  50  or  51  from the blade chamber  13 , 
   c) the addition of a press plate  45  facilitates the operator to get rid of the crepes in the carpet, and 
   d) the second corresponding housing  30  is readily to open and automatically to check by a detent. 
   Note that the specification relating to the above embodiment should be construed as an exemplary rather than as a limitative of the present invention, with many variations and modifications being readily attainable by a person of average skill in the art without departing from the spirit or scope thereof as defined by the appended claims and their legal equivalents.