Micro-hole machining EDM injector nozzle technology
With the increasdrill edming demand for diesel engine emissions， fuel injector nozzle to the small aperture， the number of the development of porous， spray hole drilling process will be difficult to adapt to the smaller diameter nozzle requirements。 The EDM injector nozzle is a machinable diameter， high precision and glitch-free characteristics of the pressure chamber， and on the heat treatment process。

1 processing principle

The principle is based on the EDM electrode and the workpiece (positive， negative electrode) spark discharge between the pulses of electrical corrosion， galvanic corrosion of excess metal， to achieve the purpose of processing hole。 Processing is the use of nozzle electrode wire rod 300mm long (often used in electrical wire brass， tungsten carbide， electric wire， copper electrical wire and silver electrical wire， but according to its quality and processing efficiency and cost， in most cases selection of tungsten carbide electric wire electric wire and silver)。 This wire is centerless grinding machine， wire roundness to ensure the following in the 3μm， 3μm straightness ensure the following。

EDM now there are two main ways: one is the processing nozzle when the electrode wire as axial feed， the other is the processing nozzle when the electrode wire as axial feed and rotation。 In the process， always according to the processing of different parts (material， diameter and hole depth， etc。) to determine the discharge parameters (pulse frequency， pulse width and the discharge gap， etc。)。

(2) processing equipment and process parameters

Suzhou Changfeng Electromechanical Technology Co。， Ltd。 production of CF-007 micro-EDM CNC machine tools， micro below 0。2mm can be processed。 The machine has three axes and three rotational displacement axis， is automatically controlled six-axis machine tools； with single and double clamping system clamping system two processing methods。 Processing to the nozzle hole and Seat positioning， two pin holes fixed circumferential direction， and by clamping claw body， loading and unloading very easy。
Axial wire feed in three steps: wire rod working electrode dressing → (electrical erosion) → workpiece finishing the entire nozzle (remove inverted cone)。 Each step of the process feed rate should be based on the hole depth to determine the hole， the electrode wire can automatically feed， automatic compensation。 After batch processing test， the nozzle of the precision machining line for the prime parallel 6μm， diameter tolerance of 6μm， roughness Ra0。6； orifice can be observed rounded， circular micro-precision machining is generally in the range of ¢ 0。08 ~ ¢ 2mm， hole depth generally less than 1 ~ 3mm nozzle。 Nozzle of the precision is better than drilling precision。