Abstract:
A recycling process for cutting tools for machining printed circuit boards aims at recycling and reclaiming worn cutting tools. The process includes: grinding off the edge section of the worn cutting tools, complementing one end of the worn cutting tool to achieve a desired length, and forming a new edge section at the other end thereof. The worn cutting tools may thereby be effectively recycled and reclaimed to reduce production cost.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a recycling process for cutting tools used in machining of printed circuit boards and particularly a process for recycling and reclaiming worn cutting tools.  
         BACKGROUND OF THE INVENTION  
         [0002]    The printed circuit board is an essential component for nearly all electronic devices nowadays. With increasing development and popularity of various types of electronic products, the demand for printed circuit boards is also growing. As a result, the consumption of cutting tools used for fabricating the printed circuit board is rapidly increasing as well. Commonly used cutting tools for printed circuit boards are drills and routers for drilling holes or shaping the desired forms. Because of the need for high precision, the machining rotation speed is very fast, usually ranging between 40,000 and 120,000 RPM or higher. Hence, the cutting tools wear out very fast (for instance, a drill is usually discarded after about 10,000 drilling operations).  
           [0003]    This type of cutting tool is generally made of material consisting of cobalt-contained tungsten carbide constructed by extra fine grains for attaining both strength and durability. As tungsten carbide is quite expensive, large amounts are required and it is quickly worn down, to recycle the worn cutting tools becomes an important issue. However, the presently available recycling methods still have many drawbacks and are not very practical, thus are not widely accepted. Hence, most manufacturers simply throw away the worn cutting tools, or give them to waste collectors for recycling to make lower grade products. This is a waste of expensive resources.  
         SUMMARY OF THE INVENTION  
         [0004]    The primary object of this invention is to resolve the aforesaid disadvantages by providing a recycling process for cutting tools used in machining of printed circuit boards, to recycle and reclaim worn cutting tools for reducing production cost.  
           [0005]    The recycling process for cutting tools according to the invention includes: grinding off the edge section of a worn cutting tool (including the screw portion and front edge section), then supplementing one end thereof to attain the total desired length by bonding a pad rod to the bottom end of the shank or coupling the edge section with a sleeve, and forming a new edge section at the other end, to thereby effectively recycle and reclaim the worn cutting tool and reduce production cost.  
           [0006]    The foregoing and additional objects, features and advantages of the present invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a process flow of a first embodiment of this invention.  
         [0008]    FIGS.  2 A- 2 F are schematic views of the first embodiment of this invention.  
         [0009]    [0009]FIG. 3 is a process flow of a second embodiment of this invention.  
         [0010]    FIGS.  4 A- 4 C are schematic views of the second embodiment of this invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0011]    Referring to FIG. 1 for a first embodiment of the recycling process of the invention, the first step is to remove the edge section  301  of a worn cutting tool  30  by grinding (step  101 ), including the screw portion and the front end of the edge section  301 . The worn cutting tool  30  originally has an edge section  301  and a shank  302  (shown in FIG. 2A). After the edge is ground off, a round rod of a smaller diameter thereof is formed (shown in FIG. 2B), then a pad rod  40  is bonded to the bottom end of the shank  302  to attain a total desired length (step  103 ), as shown in FIG. 2C. Then the round rod is machined to produce a new edge section of a smaller size (step  102 ), as shown in FIG. 2D.  
         [0012]    The cutting tools for machining the printed circuit boards are mainly routers and drills. The edge section of the routers usually has a thicker center portion (viewed from the end; not shown in the drawings). The rod section that remains after the edge has been ground (as shown in FIG. 2B) may be fabricated to form a new edge of a smaller size (shown in FIG. 2D). On the other hand, the edge section of drills generally has a relatively thin center portion, and after the edge is ground, the remaining portion becomes too small and is not suitable for fabricating to form a new edge. Hence, this embodiment is suitable only for routers.  
         [0013]    When forming a new edge section  303  of a smaller dimension by grinding (as shown in FIG. 2D), a larger cutting tool made according to the standard size will have a longer edge section, while a smaller cutting tool will have a relatively short edge section. Hence, after machining by grinding (for forming various types of cutting tools, such as drills or routers), the length of the edge section  303  will be reduced. Deducting the edge which has been removed by grinding (step  101 ), the total length will become smaller. In order to attain the standard length (according to the specifications suggested in IPC-DR-570A, 1994, the length of the cutting tool shall be 1.5 −0 015   +0 005  inches), a pad rod  40  may be bonded to the bottom end of the shank  302  to complement the total length (referring to FIG. 2C). The length of the pad rod  40  is determined by the size of the recycled cutting tool, bonded so as to achieve the standard length.  
         [0014]    The pad rod  40  may be bonded to the bottom end of the shank  302  by soldering. Although the bonding strength is not great, the chucking position when in use is located at the shank  302 . That is, the bonding portion of the pad rod  40  and shank  302  is located in the chuck, thus the chucking strength is enough so as not to result in breaking off when in use. When the pad rod  40  is relatively long, and the resulting recycled dimension is quite different from the original dimension, the chucking portion is partly the shank  302  and partly the pad rod  40  (not shown in the drawings). As the shank  302  is made of tungsten carbide, it is still strong enough.  
         [0015]    Of course, the bottom end of the shank  302  may be formed into various shapes for bonding to the pad rods  40 . The bottom end of shank  302  is formed a fastening section  306  with a smaller dimension. And the fastening section  306  is engaged with a sleeve  60  by welding or forced coupling through a bonding section  601  formed in the sleeve  60 . The pad rod  40  may be made of cheaper material such as stainless steel for saving material cost (of course, tungsten carbide may also be used).  
         [0016]    [0016]FIG. 3 illustrates a second embodiment. The first step is similar to that described above; remove the edge section  301  of a worn cutting tool  30  by grinding (step  201 ), including the screw portion and the front end of the edge section  301 , to form a fastening section  304  (shown in FIG. 4A). Then couple the fastening section  304  to a sleeve  50  which has a bonding section  501  (step  202 ) to achieve a desired length (shown in FIG. 4B). The shank  302  may be fabricated by machining to form a new edge section  305  (step  203 ).  
         [0017]    Similarly, the edge section of the routers usually has a thicker center portion (viewed from the end; not shown in the drawings). The resulting fastening section  304  formed after grinding the edge (shown in FIG. 4A) may be coupled with a sleeve  50  (shown in FIG. 4B). However, the edge section of drills generally has a relatively thin center portion after the edge is ground, and the remaining portion becomes relatively small in size. The fastening section  304  for coupling the sleeve  50  also has a smaller size (with a small rod diameter). After coupling with the sleeve and put into use, the fastening section  304  is prone to fracturing or becoming loose. Hence, although this embodiment is not limited to use with routers, it is preferable for use with routers. When the remaining portion is too large (i.e. the rod diameter of the fastening section  304  is too large), the wall of the mating sleeve  50  will be too thin and might result in fracturing when in use. Hence, when the rod diameter of the fastening section  304  is too large, it must be ground to a smaller size before coupling with the sleeve  50 .  
         [0018]    The length of the sleeve  50  is determined by the length of the cutting tool after the edge has been ground and removed (i.e. the combined length of the fastening section  304  and shank  302 ) to achieve the standard length (as suggested in IPC-DR-570A, 1994).  
         [0019]    As the new edge section  305  is formed by grinding the shank  302 , there is no limitation for the machining dimensions. In other words, any size smaller than the outside diameter of the shank  302  will be acceptable. When in use, the chucking portion is the bonding portion of the sleeve  40  and shank  302 , hence it has sufficient chucking strength for adapting to various types of cutting tools, such as routers or dills.  
         [0020]    As described above, the fastening section  304  may also be formed into various shapes before bonding. However, this will increase machining cost. The sleeve  50  may also be made of cheaper material such as stainless steel for saving material cost (of course, tungsten carbide may also be used).  
         [0021]    In summary, the recycling fabrication process of the invention is capable of recycling and reclaiming worn cutting tools for productive use, and eliminates the wasteful practice of discarding worn cutting tools that might otherwise occur. It also conforms to environmental protection regulations, and can reduce production cost.  
         [0022]    While the preferred embodiments of the invention have been set forth for purposes of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments that do not depart from the spirit and scope of the invention.