GB956081A - Improved power feed drill - Google Patents

Abstract

956,081. Drilling and boring. DESOUTTER BROS Ltd. April 9, 1963 [June 13, 1962], No. 22710/62. Heading B3C. A pneumatic power feed drill comprises a central valve portion 1 attached to an outer casing 3 and a two-port inner casing 9, longitudinally slidable within the outer casing, housing a pneumatic motor 4 and gearing 5. The inner casing 9 constitutes a piston which effects the tool feed, the motor 4 rotatably driving the output shaft 6 by way of the gearing 5. Air under pressure is admitted to the tool through connector 21 and the feed movement produced is controlled by a shuttle valve 19. As the feed movement continues, radial bores 23 in coaxial tube 20 are uncovered and air present in the annular space 22 around the tube 20 enters the bores 23 to start the motor 4. To stop the feed at the required depth there is provided on the tube 20 a crosshead 56 which carries a threaded rod 58 which is adjustable and is adapted to co-operate with a valve 60. The operation of valve 60 permits air to by-pass the piston only and stops the feed, the piston then being returned under the action of spring 14. The feed rate at which the tool approaches the work is controlled by an adjustable needle valve within the valve portion 1. To control the feed stroke the rate of penetration of the tool into the workpiece to allow for tool size and nature of material of the workpiece a dash-pot 66 may be provided which contains a piston with an extension 62 which is engageable with a threaded rod 63 on the crosshead 56. The position of contact between the rod and piston extension are adjustable and can be locked by nut 64. The dash-pot may therefore be used in conjunction with the needle valve to control the feed rate throughout the whole drilling operation.