Patent GB-683417-A (GB)
Title: Improvements in automatic drilling, tapping and like machine tools
IPC: B23B39/00
Filed: 1950-04-11
Abstract: 683,417. Drilling and tapping machines. MARCHANT, L. E., FARR, C. P., and ROE CANADA, Ltd., A. V. March 30, 1951 [April 11, 1950], No. 8947/60. Class 83 (iii). An automatic drilling, tapping, &c. machine having a rotatable worktable driven by a reversible motor in two senses in relation to an automatic tool head, is characterised in that the reversible motor is controlled by a control having a displaceable element normally urged to a position at which the control is conditioned to cause the motor to turn in one sense, the element if displaced from the said position conditioning the control to stop the motor and the element if further displaced from the said neutral position conditioning the control to cause the motor to turn in the opposite sense, the element being displaced by an abutment on an interchangeable index member carried by a mounting rotated in synchronism with the worktable to bring the latter to rest at a position where a machining operation is to be performed by the automatic tool head, means being provided to disengage the displaceable element from the abutment on completion of the machining operation. The machine comprises a base 1, Fig. 1, supporting vertical columns 8 connected at the top by a bridge 9. The columns constitute slideways for a cross-piece 10 which is raised and lowered automatically by motor-driven screws (this drive is not described). On the cross-piece a number of tool-heads are adjustably mounted which may be fed towards and away from an indexable work-table 2. A work-centre 13 is also arranged on the cross-piece. The toolheads may carry drilling, milling, or tapping tools. An index plate 16 is mounted on the table 2 by a spigot 17 and is driven around with the table through a key 18. Pins 19 are arranged at intervals in circularly-spaced holes around the plate, the pins coming into contact with an abutment 27 to stop the table for a working operation by the tool-heads, workpieces being clamped on the index plate 16. The abutment 27 forms part of a fluid control valve 21, Fig. 6, interposed between a pump 27 and a fluid motor 7, Fig. 2, for rotating the table. Slight deviations from a neutral position of abutment 27 give forward and reverse rotation of the motor while the neutral position shuts off fluid supply to stop the motor. Contact between a pin 19 and abutment 27 thus causes a brief " hunting " motion of the table, after which it is brought to rest for the working operation in the required indexed position. The abutment 27 and valve is tilted downwardly by a solenoid energized automatically by switches connected to the tool spindles so that the table starts rotating again and moves to bring the next workpiece into operating position. The upper ends of the pins 19 strike limit switches 34, 36, to start up the rotation and feed of the tool spindles immediately the table stops. The control valve 21 may be adjusted downwardly and inwardly to contact a further set of index pins 20 when the series of operations controlled by pins 19 has been completed. An electric motor and electric control system may be used in lieu of the hydraulic motor and control. U.S.A. Specification 2,130,109 is referred to in the Provisional Specification.