Design Of The Replacement System Of Spindle Head For EDM

The development of the hot section materials and cooling structure of theaero-engine, new materials and new technology has been widely used in themanufacturing, higher demands and new challenges of which are put forward to themanufacturing technology. Such as the manufacture of the high-temperature alloys(nickel-based alloys) film cooling holes, composite structural materials (ceramic coatings)film cooling holes and high aspect ratio holes. A method of electrode replacement byreplacing the spindle head used iron-hand is put forward in this paper, in order to adapt tothe aperture change of the film cooling holes (Φ0.2~0.8mm) in the gas turbine blade ofthe aero-engine and to solve the electrode loss during processing, which makes it becomepossible to process the multiple types of the film cooling holes in a single setup and bebeneficial to the composite processing.Switching can be achieved EDM electrode technology is mainly concentrated in themolding machine recently, most of which are developed and researched based onhigh-speed small hole machine, which is found through the research status of theswitching technology of electrode at home and abroad. A principle is used of the structureof the electrode automatic replacement bodies and guide which is similar to the CNCmachining center with a knife library. The replacement of the electrode is achievedthrough the movement of the spindle to a fixed tool change position, while thereplacement of guider is realized by the transverse or circumferential array layout. It isdifficult to improve the quality and accuracy of the hole further in the electric dischargemachining using this structure, in which the very high accuracy to the machining andassemble of the machine is required. A method is proposed in the paper to replace theelectrode by replacing the spindle head with an iron-hand which is driven by air cylinderin order to solve these problems.The fast modular fixture is used as the interface between the spindle head and themachine tool spindle in order to ensure the spindle head can be replaced smoothly. Aniron-hand is used as the exchanged tool in order to ensure the spindle head can be replaced smoothly and accurately. A storage device is designed on the spindle head and a spindlehead library is designed in the system, which are used as the storage of the different or thesame wire electrodes in order to realize the replacement of the same or the different wireelectrodes. Six guide posts are designed in the iron-hand that are matched with the sixguide holes in the spindle head in order to ensure the iron-hand can grab the spindle headstable and reliable. A locking mechanism for the pulling nail of the spindle head isdesigned in order to realize the positioning installation of the spindle head in the spindlehead library.PMAC motion control card is used to achieve the control of spindle head’s movementreplacement accurately. A one-dimensional horizontal movement platform and360degreerotating platform which driven by stepping motor driver with20segments are used toensure the iron-hand’s horizontal and rotational movement. A360degree rotating platformwhich driven by stepping motor driver with20segments is used and a method which withthe way of order choose knife as the choice of the spindle head is used in order to ensurethe selection of spindle head in the library smoothly. Limited position switches areinstalled in one-dimensional platform and rotating platform in order to ensure the safety inthe process of movement.The designed strength and rigidity of the parts and overall structure are ensured tomeet the operating requirements by the force analysis and the finite element analysis of thewhole system and the key parts of that. The cylinder is used as the power source of theiron-hand’s movement to insure the sufficient clamping force and buffer of the iron-hand.The error may be generated between various actions is analyzed in order to ensure thesystem has the smallest movement motion error, using the exact installation position, areasonable chamfer design, accurate relative position. Zero position switches are installedin the one-dimensional platform and rotating platforms to reduce the accumulated errorcaused by movement, then the program executes resetting operation by motion controlprogram.