Patent GB-537792-A (GB)
Title: Attachment for milling machines to facilitate precision reproduction or duplication of articles or templates
IPC: B23Q35/32
Filed: 1940-01-30
Abstract: 537,792. Copy-milling machines. RIEPER, C. D. Jan. 30, 1940, No. 1827. Convention date, Feb. 4, 1939. [Class 83 (iii)] A precision copying attachment for templet reproduction on a milling-machine comprises a tracer 12 arranged on the machine adjacent the cutter 6, the templet 13 being mounted on the movable table beside the work 8, and the tracer having a group of electrical limit switches in circuit with electromagnetic clutches interposed in each manuallyoperated feed shaft to terminate the manual movement of the latter in any direction in response to deflections of the tracer resulting from contact with the templet. The table has three manual feed shafts 9, 10, 11, controlling respectively the longitudinal, lateral and vertical table movements. The tracer comprises a rod 14 enclosed in a sleeve 15 and grooved to receive a spring ring 20b which bears on the edge of a ring 18 to form a continuous fulcrum for horizontal tracer movements, the rod 14 having the necessary clearance in the ring 18. At the upper end the sleeve 15 is flanged to support the base 22 of a switchsupporting bracket which is fitted with diagonallyopposed columns 25, of square section. The switches for the horizontal movements are adjustably secured in pairs, Fig. 10, to these columns, the two opposed switches 28, 30 controlling one horizontal movement and the other opposed switches 27, 29 controlling the other. The operative buttons of the switches, which are normally open, contact the tracer rod as shown in Fig. 10. The columns carry an upper switch-supporting bracket 41 carrying the upper limit switch 42 the button of which lies above the tracer rod, for operation by vertical tracer movements which are limited by a stop disc 36. The tracer-head is completely enclosed by side plates 50. The usual hand wheels on the feed shafts are replaced by manually operable casings 53 ...5311 enclosing the electromagnetic clutch mechanism, Fig. 11. The two parts of each casing have inter-fitting flanged portions defining an outer annular space 83 and an inner space in which opposed electromagnets 69, 70 are mounted. The armatures of these magnets operate parts 73, 74, Fig. 12, coacting with oppositely-facing ratchet wheels 75, 76 mounted on the feed shaft. Thus while the electromagnets are de-energized the feed shaft may be moved in either direction from the handle 55 through one of the pawls and its coacting ratchet wheel. If however one of the electromagnets is energized to raise the " forward " drive pawl rotation of the handle 55 will produce no further motion in the forward direction though reverse motion may still be effected through the reverse drive pawl. An insulated sheath 84 carries spaced slip rings 83, 87 engaging wiping contacts 88, 90 on a base plate 91, secured to an external cover band 93 and provided with rollers engaging annular tracks 96, 97. The contacts are supplied from a cable 101 connected to the tracer switches the action being such that closure of a tracer switch by contact with the templet energizes the corresponding electromagnet to disengage its pawl and stop further hand feed, although the handle 55 may still be idly turned. The two casings 53, 531 are similar but the casing 5311 controlling the vertical motion includes only a single electromagnet and ratchet mechanism which is responsive to actuation of switch 42 to stop the vertical feed movement.