Patent Publication Number: US-8113917-B2

Title: Grinding structure having micro ball

Description:
FIELD OF THE INVENTION 
     The present invention relates to a grinding structure; more particularly, relates to melting a peak point of a micro device shaft into a micro ball with grinding particles deposited through composite electroplating. 
     DESCRIPTION OF THE RELATED ARTS 
     Technologies are advancing. Micro-molds and micro-machining are much more requested day by day. 
     Take micro-devices in micro electro-mechanical systems (MEMS) as examples. They include micro-shafts, micro-pores, micro-channels, etc.; and are obtained through micro machining. Thus, micro-machining becomes important. 
     Technologies for micro-machining includes laser machining, electro beam machining (EBM), ultrasonic machining (USM), ion beam machining (IBM), etching, electrical discharge machining (EDM), etc. Among them, the EDM is a low-cost machining for any hard and stretching conductive material, and can be used with other machining technology, like high-frequency magnetic grinding, electro-chemical machining (ECM), magnetic abrasive grinding, etc. 
     For forming a micro-tool, most researches are aiming at circular pillars, triangle pillars, tetragonal pillars, pin tools, etc., where tool with micro-ball in front is rare. A prior art of a punch is obtained from a pin electrode to form a micro ball through EDM. Another prior art uses EDM to fabricate a shaft with a micro ball at a front end of a micro pure tungsten electrode. For the micro ball has a diameter of 40 mm and the shaft has a diameter of 30 mm with a length of 300 mm, the prior art is merely used as a probe owing to the big aspect ratio. 
     A general ball cutter is fabricated through milling with a diamond grinder to be processed through a coating for obtaining the cutter. Besides, for a general diamond grinding tool, a diamond film is grown on a surface of the high-quality tool through a chemical vapor deposition (CVD). Although the diamond film obtained through the CVD is good in strength, uniformity and density, its fabricating cost is high. Hence, the prior arts do not fulfill all users&#39; requests on actual use. 
     SUMMARY OF THE INVENTION 
     The main purpose of the present invention is to obtain a grinding structure having a micro ball for precise machining through micro-milling and micro-paring. 
     To achieve the above purpose, the present invention is a grinding structure having a micro ball, where a micro device shaft is selected to be machined to obtain a peak point at an end surface; then a high-density power is inputted to melt the peak point to obtain a micro ball having a core material; and then the micro device shaft is processed through composite electroplating to deposit grinding particles on a surface of the micro device shaft in a base material. Accordingly, a novel grinding structure having a micro ball is obtained. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       The present invention will be better understood from the following detailed description of the preferred, embodiment according to the present invention, taken in conjunction with the accompanying drawings, in which 
         FIG. 1  is the flow view showing the preferred embodiment according to the present invention; 
         FIG. 2  is the view showing the micro device shaft having the peak point; 
         FIG. 3  is the view showing the micro device shaft having the micro ball; 
         FIG. 4  is the view showing the electroplating trough; and 
         FIG. 5  is the view showing the composite electroplating. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description of the preferred embodiment is provided to understand the features and the structures of the present invention. 
     Please refer to  FIG. 1  to  FIG. 5 , which are a flow view showing the preferred embodiment according to the present invention; views showing a micro device shaft having a peak point and one having a micro ball; a view showing an electroplating trough; and a view showing composite electroplating. As shown in the figures, the present invention is a grinding structure having a micro ball, comprising the following steps: 
     (a) Selecting a micro device shaft and machining a peak point  11 : As shown in  FIG. 2 , a machining handle  2  has a micro device shaft  3  selected at an end to be machined to a required size and to obtain a peak point  31  at center of a front end of the micro device shaft  3 . 
     (b) Melting the peak point to obtain a micro ball  12 : As shown in  FIG. 3 , a high-density power is inputted to melt the peak point  31  of the micro device shaft  3  to form a micro ball  32 . Thus, a micro device shaft  3  having a micro ball  32  and a micro handle  33  is formed, where the micro ball  32  has a core material of tungsten, tungsten carbide, high speed steel or tungsten steel; the micro ball  32  has a diameter between and 300 millimeters (mm); and diameter of the micro handle  33  is smaller or equal to that of the micro ball  32 . 
     (c) Obtaining an electroplating trough  13 : As shown in  FIG. 4 , an electroplating trough  4  is obtained to contain an electroplating solution  43  having an amount of grinding particles uniformly distributed, where the grinding particle  42  is made of diamond, SiC, polycrystalline cubic boron nitride (PCBN) or Al 2 O 3 ; and the grinding particle  42  has a diameter between 0.1 to 10 mm. 
     (d) Processing composite electroplating  14 : As shown in  FIG. 5 , a composite electroplating is processed to deposit the grinding particles  42  together with a base material to form a composite electroplated metal layer on a surface of the micro device shaft  3 , where the base material is Ni, Cr, Cu, Al, Ag, Zn or an alloy of any of the above metals. 
     After the composite electroplating, the micro device shaft can be further cleansed to remove the electroplating solution  43  left on the surface, where the cleansing is an ultrasonic cleansing or an electrolysis. 
     Through the above steps, the grinding structure  5  having the micro ball is obtained. The present invention has advantages on a mass-production, a simple process, a low cost and a high quality; and is used to form micro molds, to remove burr, to micro-mill, micro-pare or to micro-grind a surface, like micro-machining a concave ball mold, a printed circuit board (PCB), a micro-channel for bio-medical diagnosis, a micro electro-mechanical system (MEMS), etc., so that a surface obtained after machining is smooth and requires not second machining. Besides, the present invention can be operated on a surface having an arc degree more than 180 degrees, bigger than the arc degree of surface of a normal grinding device. 
     On using the present invention, a micro device shaft  3  obtains a required shape and a required size through a machining, like electrical discharge machining (EDM), electro-chemical machining (ECM), etching, laser machining or electro beam machining (EBM), etc. An end surface of the micro device shaft  3  is refined through EDM to be flat and smooth. The micro device shaft  3  is processed with a rough machining to roughly obtain the required diameter. Then the micro device shaft  3  is finely machined to exactly obtain the required diameter. At last, a peak point  31  is formed at center of the end surface of the micro device shaft  3 . 
     The EDM is then continued on processing to the micro device shaft  3 . A discharging with a high-density power is generated at the peak point until the peak point  31  is melted at a high temperature and a micro ball  32  is obtained before stopping the EDM. Then, the micro ball  32  can be further machined to obtain a micro-furrow on a surface to contain odds and ends and to remove them. During the discharging, the peak point  31  is positioned at center of the end surface of the micro device shaft  3  so that a core of the micro ball  32  is not deviated since the discharging happens where the distance is the shortest between the corresponding electrodes. 
     Then an electroplating trough  4  is obtained, where the electroplating trough  4  has a surrounding anode  41  and the micro device shaft  3  is sunk in the electroplating solution  43 . Under various parameters for machining, grinding particles  42  having diameters between 2 and 4 mm are used for electroplating. Two stirrers  44  are provided separately at two sides of the electroplating trough to keep the grinding particles  42  floating in the electroplating solution  43 ; and a surfactant is added in the electroplating solution  43  to improve a distribution and a deposition of the grinding particles  42 . After the deposition by the composite electroplating is finished, the electroplating solution  43  left on the surface of the micro device shaft  3  is removed by cleansing. Thus, a novel grinding structure  5  having a micro ball is obtained. 
     To sum up, the present invention is a grinding structure having a micro ball, where micro-milling and micro-paring are processed with the present invention to obtain a smooth surface; and the present invention has advantages on a mass-production, a simple process, a low cost and a high quality. 
     The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.