| 摘要 |
844,580. Dental handpieces. KALTENBACH, A., and HOFFMEISTER, E. Jan. 8, 1959 [Jan. 9, 1958], No. 774/59. Class 81(2). A handpiece for a dental drill has an air turbine interchangeably mounted adjacent the nose part of the handpiece. An axial flow turbine is used in the embodiments described and in one form the rotor 8 is mounted on a spindle 7 carried in bearings 5, 6 and having a friction grip chuck 33 at its outer end. Air is directed into the rotor through oblique holes 16 in a fixed plate 15, the air being admitted through radial holes 28, a central tube 23 and a connecting stub 26. After passing through the rotor the air passes out through a second perforated disc 13 and radial holes 29 to the annular space 18 and thence through the interior space 30 of the handpiece to discharge orifices 31. A spring- loaded push rod 35 passes centrally through the handpiece and is used to engage a short rod 43 to press a burr out of the chuck 33. If the end cap 24 is unscrewed, the turbine may be drawn out bodily through the rear of the casing. In the construction shown, the rear of the turbine casing is centred by the end of the air tube 23 engaging a conical recess in a collar 20 but in a modified form there is no collar but the end of the tube passes into the centre hole of the disc 15 to centre it. A further form is also described in which the turbine rotor and chuck are carried in a ball bearing at each end of the assembly. In this case the air is admitted through the outer annular chamber of the handle and the exhaust air passes out through the central tube. |
