Patent GB-847331-A (GB)
Title: Improvements in or relating to high speed dental turbo-drills
IPC: A61C1/05
Filed: 1958-10-23
Abstract: 847,331. Dental engines. SANDRI, B. Oct. 23, 1958; (Feb. 5, 1958; June 28, 1958; Aug. 23, 1958], No. 34004/58. Class 81(2). A dental turbo-drill comprises a handpiece having at one end a head in which is mounted a compressed air turbine the rotor of which has its shaft at an angle to the handpiece axis and at the opposite end attachment means for the feed of compressed air and lubricating and cooling fluids, the rotor shaft having means for removably fastening thereto a rotatable tool with a stem, whereby the working part of the tool projects from the head at an angle to the handpiece axis. As shown, a turbine rotor 4, Fig. 2, retained by screw holding rings 6, 7 in the head, 3 of an angle handpiece, 1 has a hollow spindle 304 mounted on ball bearings 5 and compressed air, which may be mixed with an oily mist, is supplied from a nozzle 9 to the radially extending sides 104 of the turbine blades, Fig. 5, and is discharged through the bearings 5. The stem 102 of a drilling tool 2 is inserted in a sleeve 10 within the spindle 304, the sleeve having longitudinal slots 110, preferably extending of its length, to permit its being clamped around the stem 102 by means of a sleeve 12, the conical end 112 of which engages the conical end 210 of the sleeve 10 when the sleeve 12 is screwed into the spindle 304. A cooling jet of water is directed towards the drill bit 202 from a nozzle 13 and atomised by compressed air from a nozzle 15 encircling the nozzle 13. The nozzle 13 is supplied with water via a tube 14 from a tube 17 which passes through the interior of a flexible hose 16 supplying the handpiece 1 with compressed air, the hose 16 and tube 17 being connected to the handpiece 1 and tube 14 respectively by a joint 8, Figs. 6 and 7, constructed as follows. A partially threaded nipple 18, Fig. 7, is adapted to be inserted in the hose 16 and fastened therein by a bored cap nut 19. A gasket 26 placed between the nipple 18 and the handpiece 1, has a bore 226 co-operating with bores 21, 24 in discs 118 and 101 at the end of nipple 18 and handpiece 1 respectively and a ring of bores 126 co-operating with bores 20 and 23 in discs 118 and 101 respectively. A cap nut 25 retained by an end flange on the nipple 18 is screwed on to the threaded end of the handpiece 1 to tighten the joint 8. To prevent accidental unscrewing of the nut 25 a tooth 130 on a sleeve 30 is urged by a spring 31 along a groove 32 in the wall of the handpiece into engagement with ratchet teeth 33 on the nut. To allow the nut to be unscrewed, the sleeve is drawn back and turned so that the tooth 130 is held in an extension 132 of the groove 32. A pedal device for controlling the supply of air, lubricating oil and water to the turbo drill comprises a footplate 43, Fig. 11, hollow base 42 and a housing 41 closed by a stop 45 with a level gauge (not shown) and having bars (not shown) in the horizontal bores of which the lunge pivot 61 of a pair of pedals 60, 66 is mounted. A block 46 screwed to the base 42 and closing the bottom of the housing 41 has three adjoining chambers 50, 51, 52, each closed by a screw stopper 48 with a hose-joining nipple. Water supplied by a hose 49 passes from the chamber 50 through a valve 54 controlled by the pedal 60 through a chamber 55 and conduits 56, 57 to a tube 58 which connects with the tube 17. Compressed air supplied through a hose 53 to the chamber 52 passes through a valve 63, controlled by the pedal 66, to a rear chamber 64, Fig. 10, which communicates with the chamber 51 through a passage 80. A tube 69, Fig. 11, leads from the chamber 64 into the housing 41, ending above the level of oil contained therein, and the air jet issuing from the tube sucks up and atomises oil from a small tube 70 with its lower end below the oil level and its upper end curving over the tube 69. The air and oil mist passes through a vertical tube (not shown) into the chamber 51 where it mixes with compressed air the volume of which is controlled by a throttle cock 68 in the passage 80.