Patent GB-527205-A (GB)
Title: Improvements in tracer controlled machine tools
IPC: B23Q35/12
Filed: 1939-04-04
Abstract: 527,205. Milling machines. TRIGGS, W. W. (Niles-Bement-Pond Co.). April 4, 1939, No. 10456. [Class 83 (iii)] In a copy milling machine having a tracer movable relatively to a model with poweractuated mechanism individual to the tracer to move the tracer to and from the work, the tracer movement also controls the rotation cf a rotary member by which power-actuated mechanism for moving the tool to and from the work is controlled. As applied to copying in a manner similar to that described in Specification 233,747, [Class 83 (iii)], two machines are provided, one a tracing machine and the other a cutting machine of similar construction which may of necessity be located some distance from the tracing machine. In the cutting machine the milling cutter 11 driven by a motor 16 is carried in a spindle movable axially to and from the fixed work W in slides 15 on a head which is movable vertically in guides on a column 12 which has a horizontal traversing movement in guides on the base 10. The axial cutter movement is effected by a screw 17 rotatable in opposite directions through electro-magnetic clutches 19 from a motor 19b controlled as described in Specification 233,747, [Class 83 (iii)]. The screws for the vertical movement and the horizontal column movement are actuated in a similar manner. The tracing machine, Fig. 3, similarly comprises a horizontally movable column 22 carrying a vertically movable head 23 in which the tracer slide 24 is movable to and from the fixed model M. The electro-magnetic drives 26, 26a, 26b, for the feed screws 25, 25a, 25b. are similar to those for the cutting machine. The tracer may be as described in Fig. 16 or Fig. 27 of the abovementioned Specification according to whether die sinking or profiling operations are to be performed. The slides 22-24 of the tracer machine are connected through racks such as 31 and pinions to the individual generators 27-29 of self-synchronizer sets, each of these generators being coupled to the corresponding motor 33-35 on the cutting machine. Each motor carries on its shaft an arm 40, Fig. 6, between contactcarrying levers 41, 42 on a member 43 so that when a motor shaft, for instance 33, is moved one of these contacts will be closed to energize through a relay A<SP>1</SP> or B<SP>1</SP> one of the magnetic clutches A or B to rotate screw 17a and actuate column 12 of the milling machine in unison with the tracer movement. This movement of the column 12 actuates a rack 36 on the column connected through gearing to the member 43 through a combined electro-magnetic clutch so that when the column movement corresponding to the tracer movement has been completed the contact between arm 40 and one of the levers will be broken and the column movement then stops. The gear ratios between the rack 36 and plate 43 and between the rack 30 and generator 27 determine the relative movements of the tracer and cutter and thus the scale of the reproduction. In a modification, Figs. 7 and 8, the rotor of motor 33 is connected to a shaft 58 of differential gearing, the final shaft 60 of which is geared to the rack 36. The housing 59 has an arm extending between contact levers 63, 64. After the contacts have been closed by movement of the shaft 58 the column 12 is moved as before and the shaft 60 is driven oppositely from the shaft 58 so that the casing remains stationary and the contacts remain closed. When the rotation of the shaft 58 stops the continued rotation of shaft 60 rotates the casing and separates the contacts, thus stopping the column movement. A switch 52 between the generator 27 and motor 33 determines whether the motor movement is in the same or the opposite direction to the generating movement. In order to prevent overrunning, the speed of the tracing machine column 22 is normally greater than that of the milling column so that motor 33 moves the arm 40 beyond the normal contact position and opens one of the normally-closed supplementary contacts controlled by levers 48, 49. This causes one of the relays C, D to open the circuit of corresponding magnet 130 or 131 on the tracing machine and stop the motion of the tracer until the plate 43 has moved sufficiently for the contacts 48, 49 to close, whereupon relay C or D is energized and the tracing 'movement continues. Runaway relays are also provided for the other motions of the tracing machine. Similar supplementary contacts on levers 63, 64, control the runaway relays in the modification shown in Fig. 8. U.S.A. Specification 1,683,581 also is referred to.