GB792884A - Improvements in or relating to machine tools, for example milling machines - Google Patents

Abstract

792,884. Milling. WERNER AKT.-GES., F. March 7, 1956, No. 7167/56. Class 83 (3). A milling-machine, or other machine-tool, comprises first and second limit-switches 2, 3 having contact-pairs which are in a circuit for controlling relative movement of tool and workholders in opposite directions, and which are actuated by dogs 8-13 when movement takes place, the first of the contact-pairs 2b in the first switch 2 acting to change the movement from rapid to feed-speed in one direction and the second of the pairs 2a acting to stop the movement, similar contact-pairs 3b, 3a in the second switch acting in the same manner for movement in the other direction, a third pair of contacts 2c in the first switch 2, actuated when the movement is in said other direction to change the movement from feed to rapid speed, a similar contact-pair 3c in the second switch acting in the same way for movement in the said one direction, and a single actuating-member 7b for both switches, which is displaced by the dogs so that either only one of the first and second pairs, or both of them, or all three pairs of one switch are actuated, the control-circuit being such that the operation of the first and second pairs in the latter case has no effect on the movement. In a milling-machine having a vertically-movable knee carrying a table transversely movable on a slide, the table-movements are controlled by electric, or electromagnetically-operated friction-clutches controlling right-and-left movement, rapid traverse and feed. If movement of the table 4 is desired to the left, a move-left press-button is actuated to cause the rapidtraverse and left-movement clutches to be energized. The dog 11 then opens the contacts 3b to de-energize the rapid-traverse, and energize the feed-clutch. Feed continues until the dog 13 opens the contacts 3a to cause both direction-clutches to be energized and lock the slide. However, if the swinging dog 12 is in the position shown, it actuates the other switch (2) to cause rapid traverse to the left before the dog 13 brings it finally to rest. A series of dogs 11, 12 may provide a series of intermittent feedmovements interspersed by rapid movements. To return the table, a move-right button is pressed and the table traverses rapidly to the right until stopped by the abutment 10. If the initial movement of the table is required to be to the right, the move-right button is first pressed and the swinging dog 9 can be used for intermittent feed.