| 摘要 |
PROBLEM TO BE SOLVED: To supply a machining material by opening and closing a collet chuck while rotating a main spindle motor in an automatic lathe for gripping the machining material (a bar) by the collet chuck for machining. SOLUTION: A magnetostrictive element 36 and an exciting coil 37 for surrounding this element are embedded inside the collet chuck. An exciting power source between a main spindle frame body 1b and a hollow main spindle 6b is supplied in a noncontact state by a rotary transformer. Output of a hollow main spindle 6b side secondary winding 40 is rectified and smoothed to be converted into DC exciting voltage. The hollow main spindle 6b and the collet chuck 3b are mutually connected by respectively arranged exciting voltage electrodes 45 and 46 and wiring. A magnetic field is generated by impressing the DC exciting voltage on the exciting coil 37. Shaft directional elongation of the magnetostrictive element 36 by impression of this magnetic field is amplified and converted into the action force in the work 2 central direction of the collet chuck 3b. A work can be supplied by opening and closing the collet chuck without adding an exclusive opening-closing motor.
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