精微超硬研削工具線上開發與應用

Abstract

本研究旨在開發超硬微型研磨工具，提供微型模具的線上精研加工，並以低成本及陣列式開發，專用於脆性材料如細胞檢測之載玻片微溝加工、陶瓷光纖接頭的去角加工或模具材料如NAK80模具鋼的微溝加工等。研究中，提出一種複合製造技術，結合『精密複合沉積』與『微型線切割放電加工』，將粒徑0-2µm的鑽石或立方晶氮化硼(CBN)顆粒以電化學複合沉積方式沉積於基材上，而成特定形狀的微細鑽石(或立方晶氮化硼)工具。微細工具粗胚以高速主軸夾持，再以線切割放電加工方式，將之線上削正成型，完成的精微研削工具不拆卸，直接透由CNC刀具路徑移位至工件處，進行微細研削加工。由於本技術採線上複合式製造，故刀具沒有定位問題，可獲致製程之高同心度與高定位精度。刀具具『精微』與『超硬』外，製程所需費用低、環保、成型速度快、加工精度高，加工的工件更能獲致『精密快速』效果。The major aim of the thesis is to develop the micro cubic boron nitride (CBN) wheel tool array and rod-shaped diamond grinding tool for generating the micro grooves array on the optical glass and mould steel of NAK80, and chamfering at the edge of micro ceramic ferrule, respectively. A hybrid fabrication technique combining precise co-deposition with micro w-EDT is used to the process development. The tool blank is first fabricated through micro EDM and composite electroforming process so that the super abrasives, which includes cubic boron nitride (CBN) and diamonds with grain size of 0-2 µm, are uniform deposited onto the cylindrical substrate that made of aluminum alloy or tungsten carbide for producing a miniature multilayered grinding tool. Nickel, diamond and CBN play the role of binder and cutter, respectively. Some fabrication strategies including the partition plate for improving the convection in the electroforming solution, a miniature funnel mould enables the abrasives to converge toward the cathode to increase their deposition probability on the substrate, are designed and proposed. The dispersion of abrasive grains and displacement of nickel ions are noticeably made better. A non-continuous substrate design is proved that the current crowding effect is able to be restricted validly, thereby improving their distribution on the substrate surface. The finished wheel tool blank is clamped on a high speed spindle and formed into disk-shaped tool array with 10-µm for the thickness of each piece by means of micro w-EDT process. The miniature diamond grinding tool usable with the outside diameter of 100-µm for the precise micro grinding of miniature parts is also presented. They are individually directly used in grinding the workpiece using the ‘high-speed and fast-shallow grinding’ technique, with which a very high grinding velocity and very shallow grinding depth are employed, is used for precisely machining the microgrooves. The microgrooves with a checkerboard-like layout on optical glass and NAK80 mould steel are successfully fabricated for the application of cells counter. Also, a micro ZrO2 ceramic ferrule is finely chamfered at the edge of the inner hole by the developed tapered grinding tool so that the fiber easily passes through it. High dimensional and geometrical accuracy can be achieved with this hybrid technique. Further, the proposed technique is rapid, cost effective, environment friendly and easily controllable.