Patent Publication Number: US-2011048209-A1

Title: Cutting Frame of High Cutting Efficiency

Description:
FIELD OF THE INVENTION 
     The present invention relates to a cutting frame of high cutting efficiency, and, more particularly, to a cutting frame including a plurality of cutters for cutting two or more kinds of rectangular unit pieces having relatively small sizes from a rectangular base material at a predetermined inclination, the cutters being mounted or formed in the cutting frame such that the cutters correspond to the rectangular unit pieces, wherein the cutters are formed in the cutting frame in an array structure of the rectangular unit pieces in which largest-sized rectangular unit pieces are arranged at a central part of a base material based on the height of the base material in the longitudinal direction of the base material, and small-sized rectangular unit pieces are arranged above and below the largest-sized rectangular unit pieces. 
     BACKGROUND OF THE INVENTION 
     A technology for cutting a rectangular base material having a relatively large size to manufacture a plurality of rectangular unit pieces having relatively small sizes has been adopted in various fields. For example, a base material sheet having a predetermined width and a long length is repeatedly cut by a cutting frame to simultaneously manufacture a plurality of rectangular unit pieces though a one-time cutting process. 
     Meanwhile, the size (width) of the base material is specified, whereas the size of the rectangular unit pieces may vary as needed, due to various factors, such as the limitation of base material suppliers, the efficiency aspect of the manufacturing process, the fluctuation in demand of rectangular unit pieces, etc. In this case, the cutting efficiency greatly varies depending upon in which structure the cutting frame is constructed, i.e., in which structure cutters for cutting the rectangular unit pieces from the base material are arranged, when cutting a plurality of desired rectangular unit pieces based on the size of the base material. The low cutting efficiency increases the amount of scrap, produced from the base material, which will be disposed of after the cutting process, with the result that eventually, the manufacturing costs of the rectangular unit pieces increase. 
     When the size (width and length) of a base material is in constant proportion to the size (lateral length and longitudinal length) of specific rectangular unit pieces, it is possible to minimize the cutting loss by sequentially arranging the rectangular unit pieces such that the rectangular unit pieces are brought into contact with one another at positions having such constant proportion. However, when such constant proportion is not formed, the cutting loss may vary depending upon the array structure of the rectangular unit pieces. 
     Furthermore, when the rectangular unit pieces are to be cut at a predetermined angle to the longitudinal direction of the base material, a large amount of scrap is inevitably produced. 
     In order to cut the rectangular unit pieces at the predetermined angle, there is generally used an array structure in which cutters (for example, knives) are arranged in the cutting frame such that the rectangular unit pieces corresponding to the cutters are adjacent to one another. 
     In connection with this matter,  FIGS. 1 and 2  typically illustrate a conventional cutting frame in which rectangular unit pieces are located on a base material to construct cutters corresponding to the rectangular unit pieces. For convenience of description, the base material is illustrated to have a predetermined length. 
     Referring to these drawings, a plurality of desired rectangular unit pieces  20  are cut from a base material sheet  10  having a predetermined width and a long length. In a cutting frame  30  are arranged a plurality of cutters  32  corresponding to the rectangular unit pieces  20 . Consequently, the array structure of the rectangular unit pieces  20  is substantially identical to that of the cutters  32 . 
     The cutters  32  are mounted or formed in the cutting frame  30  such that the cutters  32  can cut a predetermined number (six in  FIG. 1  and eight in  FIG. 2 ) of the rectangular unit pieces  20  through a one-time cutting process. Consequently, the base material sheet  10  is cut by the cutting frame  30 , and then the base material sheet  10  is cut again by the cutting frame  30  while the base material sheet  10  is overlapped by a predetermined length s in the longitudinal direction L of the base material sheet  10 . In this way, a series of cutting processes are carried out. 
     Each rectangular unit piece  20  is constructed in a rectangular structure in which a longitudinal side a of each rectangular unit piece  20  is longer than a lateral side b of each rectangular unit piece  20 . Also, each rectangular unit piece  20  is inclined at an angle a of approximately 45 degrees to the longitudinal direction of the base material sheet  10 . When the inclined rectangular unit pieces  20  are arranged on the base material sheet  10 , it is possible to generally consider two array structures of the rectangular unit pieces as shown in  FIGS. 1 and 2 . 
     The first array structure of the rectangular unit pieces is to sequentially arrange the rectangular unit pieces such that the lateral sides b of the respective rectangular unit pieces coincide with one another, as shown in  FIG. 1 . According to this array structure, it is possible to cut a total of 24 rectangular unit pieces  20  from a base material sheet  10  having an effective width W and length L. However, it is not possible to cut a rectangular unit piece  21  located at a position deviating from the effective width W of the base material sheet  10 . 
     In this array structure, only a cutting width D, not the effective width W, of the base material sheet  10  is substantially used, and therefore, the remaining width W-D is disposed of as scrap. Since the rectangular unit pieces  20  are inclined at an angle of approximately 45 degrees, scrap is also inevitably produced at the upper end region of the base material sheet  10 . 
     The second array structure of the rectangular unit pieces is to sequentially arrange the rectangular unit pieces such that the longitudinal sides a of the respective rectangular unit pieces coincide with one another, as shown in  FIG. 2 . According to this array structure, it is possible to cut a total of 19 rectangular unit pieces  20  from a base material sheet  10  having an effective width W and length L. 
     In consideration of the above description, it can be seen that the cutting efficiency may vary according to the array structure of the rectangular unit pieces. However, when the rectangular unit pieces are inclined at a specific angle to the base material sheet, it is not easy to arrange the rectangular unit pieces in various array structures. For this reason, only the array structure of the rectangular unit pieces in which specific sides (longitudinal sides or lateral sides) of the respective rectangular unit pieces coincided with one another as shown in  FIG. 1  or  2  is mainly considered in the conventional art. 
     Furthermore, when two or more kinds of rectangular unit pieces having different sizes are to be cut from the same base material, the array structure of the rectangular unit pieces is very complicated. For this reason, consideration is given to only the array structure of the rectangular unit pieces in which specific sides of the respective rectangular unit pieces coincide with one another or central axes of the respective rectangular unit pieces coincide with one another (see  FIG. 6 ). 
     Consequently, when an array structure of the rectangular unit pieces exhibiting higher cutting efficiency than that of the array structures of the rectangular unit pieces as shown in  FIGS. 1 and 2  is provided, it is possible to lower the cutting loss and eventually reduce the manufacturing costs of products. The improvement of the cutting efficiency is more and more serious especially when the price of the base material is high and/or the rectangular unit pieces are to be manufactured on a large scale. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention has been made to solve the above problems, and other technical problems that have yet to be resolved. 
     As a result of a variety of extensive and intensive studies and experiments on a cutting frame, the inventors of the present invention have found that, when cutters are formed in a specific array structure of rectangular unit pieces, which will be hereinafter described in detail, such that the cutters correspond to the respective rectangular unit pieces, the cutting efficiency is greatly improved as compared with the conventional array structure of the rectangular unit pieces. The present invention has been completed based on these findings. 
     Specifically, it is an object of the present invention to provide a cutting frame including cutters formed to exhibit high cutting efficiency when cutting a plurality of rectangular unit pieces inclined at a predetermined angle to the longitudinal direction of a rectangular base material having a relatively large size from the rectangular base material. 
     It is another object of the present invention to provide a scrap having bores corresponding to the rectangular unit pieces arranged in the array structure of the rectangular unit pieces exhibiting the high cutting efficiency as described above. 
     In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of a cutting frame including a plurality of cutters for cutting two or more kinds of rectangular unit pieces having relatively small sizes from a rectangular base material at a predetermined inclination, the cutters being mounted or formed in the cutting frame such that the cutters correspond to the rectangular unit pieces, wherein the cutters are formed in the cutting frame in an array structure of the rectangular unit pieces in which largest-sized rectangular unit pieces are arranged at a central part of a base material based on the height of the base material in the longitudinal direction of the base material, and small-sized rectangular unit pieces are arranged above and below the largest-sized rectangular unit pieces. 
     The ‘largest-sized rectangular unit pieces’ mean the rectangular unit pieces having the largest area among a series of the rectangular unit pieces arranged at the rectangular base material. The ‘small-sized rectangular unit pieces’ mean the remaining rectangular unit pieces having a size less than that of the largest-sized rectangular unit pieces among a series of the rectangular unit pieces arranged at the rectangular base material. 
     Consequently, the largest-sized rectangular unit pieces are arranged at the central part of the base material based on the height of the base material in the longitudinal direction of the base material, and the small-sized rectangular unit pieces are arranged above and below the largest-sized rectangular unit pieces, thereby achieving high cutting efficiency. 
     The inventors of the present invention have prepared and examined various array structures of the rectangular unit pieces and found out that, when the largest-sized rectangular unit pieces are arranged at the central part of the base material, the cutting efficiency is improved, and this array structure of the rectangular unit pieces greatly reduces the number of cases produced when two or more kinds of the rectangular unit pieces are arranged in correspondence to the cutters mounted in the cutting frame, thereby greatly simplifying the manufacturing process of the cutting frame. 
     One of the reasons why the array structure of the rectangular unit pieces according to the present invention exhibits relatively high cutting efficiency is that the size of upper end and lower end cutout parts inevitably produced when the rectangular unit pieces are arranged at a predetermined inclination is minimized by arranging the relatively small-sized rectangular unit pieces at the uppermost row and the lowermost row of the array structure of the rectangular unit pieces. The upper end and lower end cutout parts are decided by the length of each side of the respective rectangular unit pieces and the inclination of the rectangular unit pieces. The upper end and lower end cutout parts are disposed of except in a special case. 
     According to circumstances, an assembly (‘combination’) of two small-sized rectangular unit pieces adjacent to each other at a long side of each rectangular unit piece such that the long sides of the respective rectangular unit pieces coincide with each other may be arranged at the central part of the base material when the combination has a size greater than that of each largest-sized rectangular unit piece. 
     That is, when the size of the combination of the two small-sized rectangular unit pieces is greater that that of each largest-sized rectangular unit piece, the combination is considered as another rectangular unit piece having a size greater than that of each largest-sized rectangular unit piece, and therefore, the combination may have a priority to be arranged at the central part of the base material. 
     When the cutting frame is constructed to cut three or more kinds of rectangular unit pieces, each rectangular unit piece constituting the combination may have a smallest size based on the above array structure of the rectangular unit pieces. 
     For example, when three or more kinds of rectangular unit pieces have similar sizes, a combination of two smallest-sized rectangular unit pieces adjacent to each other at a long side of each rectangular unit piece such that the long sides of the respective rectangular unit pieces coincide with each other may be a largest-sized rectangular unit piece. This combination is arranged at the central part of the base material, and other rectangular unit pieces are arranged above and below the combination, thereby improving cutting efficiency. 
     In a preferred embodiment, a large majority of the rectangular unit pieces arranged at the base material are arranged while being adjacent to other rectangular unit pieces at four sides of each rectangular unit piece. In the array structure of the rectangular unit pieces according to the conventional art, two sides of each rectangular unit piece, among four sides of each rectangular unit piece, are adjacent to two other rectangular unit pieces for each side, and the remaining two sides of each rectangular unit piece are adjacent to another rectangular unit piece for each side. According to the conventional art, therefore, the number of other rectangular unit pieces to which a large majority of the rectangular unit pieces each can be adjacent is six (see  FIG. 1 ) or five (see  FIG. 2 ). 
     In consideration of this matter, the rectangular unit pieces are somewhat offset from one another such that each side of any arbitrary rectangular unit piece is adjacent to only another rectangular unit piece in the preferred array structure of the rectangular unit pieces as described above. In this array structure of the rectangular unit pieces, at least some combinations of adjacent four rectangular unit pieces form an island-type residue in the center thereof. The ‘island-type residue’ means a residue having a relatively large size produced by the offset array structure of the rectangular unit pieces. This island-type residue is left at a scrap produced after cutting the base material in a small rectangular shape. 
     Consequently, the number of the combinations of every adjacent four rectangular unit pieces forming the island-type residue in the center thereof while being arranged in the specific array structure as described above is preferably not less than 50%, more preferably not less than 90%, of the number of the remaining rectangular unit pieces excluding the uppermost row rectangular unit pieces and the lowermost row rectangular unit pieces, although it may vary depending upon the kind and number of the rectangular unit pieces. 
     Also, when two kinds of the rectangular unit pieces are cut or when the sizes of the rectangular unit pieces are not in direct proportion although three or more kinds of the rectangular unit pieces are cut, island-type residues are produced for most combinations of the rectangular unit pieces. The island-type residues may have the same size or different sizes. 
     That is, the cutting frame with the above-stated construction is characterized in that, although the rectangular unit pieces are arranged while being adjacent to one another as shown in  FIGS. 1 and 2 , one side of one rectangular unit piece does not completely coincide with, but is somewhat offset from, the corresponding side of another rectangular unit piece. This array structure of the rectangular unit pieces is not the structure that can be generally easily considered when the cutters are arranged in the cutting frame to cut inclined rectangular unit pieces. However, it was confirmed that this unique array structure of the rectangular unit pieces provides higher cutting efficiency than the conventional cutting frame to our surprise. 
     The cutting frame exhibits higher cutting efficiency than the conventional cutting frame by the unique array structure of the rectangular unit pieces including the island-type residues as defined above because the unit pieces are constructed in a rectangular structure, and the rectangular unit pieces are cut while being inclined at a predetermined angle to the longitudinal direction of the base material. 
     The inventors of the present invention confirmed that, when the unit pieces are constructed in a square structure or the unit pieces are cut while not being inclined, the cutting efficiency is further improved by an array structure in which the unit pieces are arranged while being adjacent to one another such that the opposite sides coincide with one another. Consequently, the cutting frame with the above-stated construction is preferably used to cut the rectangular unit pieces while the rectangular unit pieces are inclined at a predetermined angle. 
     In the present invention, the base material may be a separate single material on which one-time or several-time cutting processes can be carried out or a continuous material having a predetermined width and a relatively very long length. The latter may be a long base material sheet. In this case, the base material sheet may be unwound from a roller, and the unwound base material sheet is sequentially cut by the cutting frame. In consideration of the manufacturing production efficiency and economical efficiency of the rectangular unit pieces, the base material is preferably a continuous material. 
     As previously described, all the rectangular unit pieces are cut from the base material while being inclined at a predetermined angle to the longitudinal direction of the base material. The rectangular unit pieces may be cut while being inclined at the predetermined angle to the base material, for example, when inherent physical properties of the base material in the longitudinal direction or in the lateral direction must be expressed by a predetermined angle with respect to the rectangular unit pieces. For example, the rectangular unit pieces may be inclined at an angle of 20 to 70 degrees. 
     In a preferred embodiment, the base material is a film including layers (‘absorption layers or transmission layers’) that absorb or transmit only a specific-direction wave motion of light or an electromagnetic wave in the longitudinal direction or in the lateral direction, and the rectangular unit pieces cut from the base material is a relatively small-sized film of which the absorption layers or the transmission layers are inclined at an angle of 45 degrees. 
     In the present invention, the array structure of the rectangular unit pieces substantially coincide with the cutters of the cutting frame or the array structure of the cutters. Consequently, it is interpreted that the array structure of the rectangular unit pieces means the cutters or the array structure of the cutters, so long as an additional description is not given. 
     The kind of the cutters is not particularly restricted so long as the cutters exhibit the structure or properties to cut the rectangular unit pieces from the base material. Typically, each of the cutters may be a knife for cutting, such as a metal knife or a jet water knife, or a light source for cutting, such as laser. 
     Meanwhile, when small-sized rectangular unit pieces having a size sufficient to be included in the upper end and lower end cutout parts of the base material are to be cut together, the array structure of the rectangular unit pieces is designed in consideration of only the relatively large-sized rectangular unit pieces, and then the small-sized rectangular unit pieces are located at the upper end and lower end cutout parts of the base material. This array structure of the rectangular unit pieces is preferred in the aspect of designing the cutting frame because the cutting efficiency is further improved by the array structure of the rectangular unit pieces. 
     Consequently, in a cutting frame including a plurality of cutters for cutting two or more kinds of rectangular unit pieces from the rectangular base material at a predetermined inclination, the cutters being mounted or formed in the cutting frame such that the cutters correspond to the rectangular unit pieces, the cutters may be arranged such that smallest-sized rectangular unit pieces Y are located only on the upper end and/or lower end cutout parts of the base material in an array of the remaining rectangular unit pieces excluding the smallest-sized rectangular unit pieces Y. 
     The ‘upper end and/or lower end cutout parts’ mean residues produced at the upper end and/or the lower end regions of the rectangular base material after cutting the rectangular unit pieces having sizes greater than that of the smallest-sized rectangular unit pieces Y from the base material by the cutters. 
     The cutout parts are included in a scrap, which will be disposed of after the cutting. Consequently, when the rectangular unit pieces are cut from the base material, the smallest-sized rectangular unit pieces Y are also cut from the cutout parts of the base material, whereby further improving the cutting efficiency. 
     Also, the number of cases may be reduced when two or more kinds of the rectangular unit pieces are arranged, and therefore, it is possible to greatly simplify the manufacturing process of the cutting frame. That is, the array structure of the remaining rectangular unit pieces excluding the smallest-sized rectangular unit pieces Y is constructed, and then the smallest-sized rectangular unit pieces Y are appropriately located at the cutout parts of the base material, thereby achieving a desired array structure of the rectangular unit pieces. 
     Consequently, the above-described array structure of the rectangular unit pieces is constructed by a process, for example, including arranging the remaining rectangular unit pieces excluding the rectangular unit pieces Y at a maximum cutting area ratio and arranging the rectangular unit pieces Y on the upper end and/or lower end cutout parts of the base material. 
     The ‘cutting area ratio’ means percentage of a value obtained by dividing the areas of the rectangular unit pieces arranged on the base material by the total area of the base material. In this specification, the cutting area ratio is used as a meaning similar to the cutting efficiency. 
     Preferably, each of the rectangular unit pieces Y satisfies conditions of Equation (1) below with respect to each rectangular unit piece X having a size greater than that of each rectangular unit piece Y. 
         D≦Ls× sin θ  (1)
 
     Where, D is a diagonal length of each rectangular unit piece Y, Ls is a length of a short side of each rectangular unit piece X, and θ is an inclination angle of the respective rectangular unit pieces. 
     In Equation (1) above, Ls×sin θ corresponds to the height of a short side of each rectangular unit piece X. Consequently, when the diagonal length D of each rectangular unit piece Y is less than or equal to the height of the short side of each rectangular unit piece X, the above-described array structure of the rectangular unit pieces is constructed. The above conditions are preferred in an aspect in which the manufacturing production efficiency is improved by a cutting margin, which will be described hereinafter. 
     The inclination angle θ may vary depending upon inherent physical properties of the base material in the longitudinal direction or in the lateral direction, as previously described. For example, the inclination angle θ may be 45 degrees. 
     In accordance with another aspect of the present invention, there is provided a scrap obtained after cutting two or more kinds of rectangular unit pieces from a base material at a predetermined inclination. 
     Specifically, the scrap according to the present invention is characterized in that a plurality of bores corresponding to the rectangular unit pieces are continuously connected to one another by a cutting margin, the largest-sized rectangular unit piece bores are arranged at the central part of the scrap based on the height of the scrap in the longitudinal direction of the scrap, and the small-sized rectangular unit piece bores are arranged above and below the largest-sized rectangular unit pieces. 
     The shape of the rectangular unit piece bores of the scrap reflects the cutters of the cutting frame or the array shape of the cutters. Consequently, in the cutting frame corresponding to the scrap, the cutters are spaced apart from each other between the rectangular unit pieces by a cutting margin, and the cutters are arranged such that the largest-sized rectangular unit piece bores are arranged at the central part of the scrap, and the small-sized rectangular unit piece bores are arranged above and below the largest-sized rectangular unit pieces. 
     Generally, the cutting frame independently cuts a plurality of small-sized rectangular unit pieces from a large-sized rectangular base material through the use of the cutters. Consequently, when the rectangular unit pieces are in full contact with one another, i.e., facing sides of the adjacent rectangular unit pieces are simultaneously formed by a single cutter, it is difficult to handle the rectangular unit pieces as independent unit pieces at a cutting process and subsequent processes. For this reason, it is more preferred to arrange the rectangular unit pieces such that a small cutting margin is provided between the respective rectangular unit pieces. Consequently, the region where the rectangular unit pieces are adjacent to one another is constructed in a structure having a narrow and long cutting margin. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIGS. 1 and 2  are typical views illustrating a conventional cutting frame in which rectangular unit pieces are located on a base material to construct cutters corresponding to the rectangular unit pieces; 
         FIG. 3  is a typical view illustrating a cutting frame according to a preferred embodiment of the present invention in which two kinds of rectangular unit pieces are located on a base material to construct cutters corresponding to the rectangular unit pieces; 
         FIG. 4  is a typical view partially illustrating two kinds of rectangular unit pieces according to another preferred embodiment of the present invention located on a base material; 
         FIG. 5  is a typical view partially illustrating three kinds of rectangular unit pieces according to another preferred embodiment of the present invention located on a base material; 
         FIG. 6  is a typical view partially illustrating an array structure of rectangular unit pieces according to another preferred embodiment of the present invention when two kinds of the rectangular unit pieces are arranged; and 
         FIG. 7  is a typical view partially illustrating the shape of a scrap according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted, however, that the scope of the present invention is not limited by the illustrated embodiments. 
       FIG. 3  is a typical view illustrating a cutting frame according to a preferred embodiment of the present invention in which two kinds of rectangular unit pieces are located on a base material to construct cutters corresponding to the rectangular unit pieces. 
     Referring to  FIG. 3 , relatively large-sized rectangular unit pieces A are arranged at a central part, including a center line C, of a base material within an effective width W of the base material in the longitudinal direction L of the base material, and relatively small-sized rectangular unit pieces B are arranged above and below the relatively large-sized rectangular unit pieces A such that a cutting margin  120  is defined between the rectangular unit pieces B and the corresponding rectangular unit pieces A. 
     Also, the rectangular unit pieces are arranged such that one rectangular unit piece  200  is adjacent to other rectangular unit pieces (only rectangular unit pieces  210  and  230  are illustrated in  FIG. 3 ) at four sides thereof but is not adjacent to one rectangular unit piece  220 . In comparison with this array structure, one rectangular unit piece is in contact with six other rectangular unit pieces in the array structure of the rectangular unit pieces as shown in  FIG. 1 , and one rectangular unit piece is in contact with five other rectangular unit pieces in the array structure of the rectangular unit pieces as shown in  FIG. 2 . Consequently, some sides of the rectangular unit pieces are simultaneously in contact with two other rectangular unit pieces in the array structures of the rectangular unit pieces as shown in  FIGS. 1 and 2 . For reference,  FIG. 3  illustrates only two rectangular unit pieces  210  and  230  adjacent to the rectangular unit piece  200  but not two other rectangular unit pieces for simplicity of illustration. 
     Also, the rectangular unit pieces are arranged such that an island-type residue  110  is formed among the adjacent four rectangular unit pieces  200 ,  210 ,  220 , and  230  (see a circle drawn by an alternated long and short dash line). The island-type residue  110  is an approximately rectangular residue defined by the respective sides of the rectangular unit pieces  200 ,  210 ,  220 , and  230 . This structure is not seen from the array structures of  FIGS. 1 and 2  at all. 
     In the array structure of the rectangular unit pieces as described above, the utilization of the base material sheet  10  is greater than that in  FIG. 1 . Preferably, the effective width W of the base material sheet  10  is substantially almost equal to the cutting width D (see  FIG. 1  or  2 ). 
     Also, a cutting margin  120  having a size less than that of the island-type residue  110  is located between the rectangular unit pieces  200  and  210 , which are adjacent to each other at one side of each rectangular unit piece. Consequently, when the rectangular unit pieces  200 ,  210 ,  220 , and  230  are cut from the base material sheet  10 , the respective rectangular unit pieces are effectively cut as independent unit pieces by the cutters of the cutting frame. 
       FIG. 4  is a typical view partially illustrating two kinds of rectangular unit pieces according to another preferred embodiment of the present invention located on a base material. 
     Referring to  FIG. 4 , a combination  2 B includes two relatively small-sized rectangular unit pieces adjacent to each other at a long side  130  of each rectangular unit piece such that the long sides  130  of the respective rectangular unit pieces coincide with each other. The combination  2 B has a size greater than that of each relatively large-sized rectangular unit piece A. The combination  2 B is located at the central part of the base material. 
     The respective rectangular unit pieces B of the combination  2 B may be arranged such that the long sides  130  of the respective rectangular unit pieces B are adjacent to each other with a cutting margin  120  or such that the long sides  130  of the respective rectangular unit pieces B are in contact with each other without the cutting margin  120 . 
       FIG. 5  is a typical view partially illustrating three kinds of rectangular unit pieces according to another preferred embodiment of the present invention located on a base material. 
     Referring to  FIG. 5 , an inclination θ is an angle between the upper end line  12  of the base material and a rectangular unit piece X. Consequently, the maximum height  150  of a short side of the rectangular unit piece X from the upper end line  12  of the base material is calculated by the production of the length Ls of the short side of the rectangular unit piece X and a sine function value of the inclination θ. 
     In an array structure  104  of rectangular unit pieces in which rectangular unit pieces X constitute the uppermost row, therefore, smallest-sized rectangular unit pieces Y have a diagonal length  140  less than or equal to the maximum height  150  of the short side of each rectangular unit piece X from the upper end line  12  of the base material such that each smallest-sized rectangular unit piece Y is located in each upper end cutout part  160  of the base material. Of course, even when this condition is not satisfied, i.e., the diagonal length  140  of each rectangular unit piece X is greater than the maximum height  150  of the short side of each rectangular unit piece X from the upper end line  12  of the base material, each rectangular unit piece X may be located in the corresponding upper end cutout part  160  of the base material. However, productivity is improved, when a predetermined cutting margin is secured between the corresponding rectangular unit pieces X and Y, and therefore, the array structure of the rectangular unit pieces satisfying the above condition is more preferred. 
       FIG. 6  is a typical view partially illustrating an array structure of rectangular unit pieces according to another preferred embodiment of the present invention when two kinds of the rectangular unit pieces are arranged. 
     Referring to  FIG. 6 , there is partially illustrated an exemplary array structure  105  of rectangular unit pieces in which relatively small-sized rectangular unit pieces  203  and  204  and relatively large-sized rectangular unit pieces  205  and  206  having a size ratio of 30:34 are arranged in a number ratio of 2:3. Here, the size ratio is set based on the diagonal lengths of the respective rectangular unit pieces  203 ,  204 ,  205 , and  206 . 
     An island-type residue  114  is included in the array structure of the rectangular unit pieces including the relatively small-sized rectangular unit pieces  203  and  204  and the relatively large-sized rectangular unit pieces  205  and  206 . Consequently, this array structure of rectangular unit pieces is different from the conventional array structure of rectangular unit pieces. 
     According to the array structure of the rectangular unit pieces, no island-type residue  114  may be formed at a specific region E at which some rectangular unit pieces  204 ,  205 , and  206  are in contact with one another. In the array structure of the rectangular unit pieces according to this embodiment, however, the island-type residue  114  is necessarily included in the combination of at least some rectangular unit pieces. 
       FIG. 7  is a typical view partially illustrating the shape of a scrap according to a preferred embodiment of the present invention. 
     Referring to  FIG. 7 , the scrap  102   a  is obtained after cutting a plurality of rectangular unit pieces from a base material according to the array structure of the rectangular unit pieces as shown in  FIG. 3 . Specifically, when the base material is sequentially cut by a cutting frame including the array structure of the rectangular unit pieces as shown in  FIG. 3 , it is possible to obtain the scrap  102   a  in which a plurality of bores A′ and B′ corresponding to the rectangular unit pieces are continuously connected to one another by a cutting margin  120   a,  the relatively large-sized rectangular unit piece bores A′ are arranged at the central part of the base material (not shown) based on the height of the base material in the longitudinal direction of the base material, and the relatively small-sized rectangular unit piece bores B′ are arranged above and below the relatively large-sized rectangular unit pieces A′. 
     Also, an island-type residue  110   a  having a size greater than that of the cutting margin  120   a  is formed among the adjacent four rectangular unit piece bores A′ and B′ of the scrap  102   a.    
     INDUSTRIAL APPLICABILITY 
     As apparent from the above description, the cutting frame according to the present invention exhibits high cutting efficiency through a unique and regular array structure of rectangular unit pieces when the rectangular unit pieces, of which the direction particularity is required according to the properties of a material, are to be cut from a base material while the rectangular unit pieces are inclined to the base material. In particular, when a large amount of rectangular unit pieces are produced through mass production, it is possible to greatly reduce the total manufacturing costs of the rectangular unit pieces based on the high cutting efficiency. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.