Patent GB-474950-A (GB)
Title: Improvements in or relating to pattern-controlled milling machines or the like
IPC: B23Q35/10
Filed: 1937-02-06
Abstract: 474,950. Pattern - controlled milling machines. STEVENS, A. H. (Sundstrand Machine Tool Co.) Feb. 6, 1937, No. 3611. [Class 83 (iii)] In a pattern-controlled milling- machine, particularly for milling aircraft propeller blades, the blade and pattern are carried by parallel spindles rotatably mounted on a table which is traversed in a direction parallel to the spindles and the cutter and tracer are carried by arms linked together and pivoted on parallel axes on a head which is vertically adjustable on a pillar, the distance apart of the tracer and cutter being adjustable. The machine comprises a base 8, Fig. 1, supporting a vertical column 9 on which a cutter head 10 is slidable, and horizontal ways 14 for the work table 13. Pivots 54, 55, Fig. 3, on the head 10 carry arms 52, 53 on which are rotatably mounted a milling cutter 50 and a tracer roller 51 respectively, both being of the same size and the former being driven by a number of parallel belts 75 and a grooved pulley 74, concentric with the pivot 54, and rotated through bevel gearing and a splined shaft 70 from a motor in the machine base. A jockey pulley 82, adjustable on the arm 52 by known means, maintains the belt tension. The cutter spindle 77 is mounted in conical roller bearings and the tracer 51 is freely rotatable in ball bearings. The arms 52, 53 are linked together by a pivoted link 56 and are partly balanced by a spring 85 attached at 86 to a bracket on the head 10, the unbalanced weight maintaining the tracer and cutter in contact with the pattern P and work W. The tracer bearings are carried by a slide 60 which is vertically adjustable on the arm 53 by means of a screw and hand wheel 66 in order to position the tracer at exactly the same distance from the cutter as the distance between the pivots 54, 55. A pillar 13<1> on the table 13 rotatably supports a pattern spindle 18 and a work spindle 19, each carrying a worm wheel 24, Fig. 2, driven by worms on a vertical shaft which is connected by pick-off gears with a short vertical shaft within the pillar and driven through bevel gears from a motor 30. Removal of a cover-plate 47 and a bracket 31 supporting the motor gives access to the worm gearing. The spindles may be rotated by hand for setting-up through a horizontal shaft 461 connected by bevel gears to the worm shaft. An extension 9<1> of the column 9 carries a guide 911, Fig. 3, which coacts with bearing surfaces 101,102 on the pillar 13<1> to support the upper end thereof. In operation, whilst the pattern and work are being mounted on the spindles 18, 19, the arms 52, 53 are raised by means of a screw 90, rotated by bevel gearing and a hand wheel 94, and co-operating with a nut 95 on a bar 96 slidable in a slot in the head 10 and carrying a projection 98 engageable with the arm 52. The work and pattern are then rotated slowly by the motor 30, the table 13 traversed slowly by means of a feed screw 17, and the tracer is lowered into contact with a cylindrical surface on the boss of the pattern. The machine then operates to produce the root portion of the pattern on the work and when the desired length of work has been machined, the arms 52, 53 are raised and the table 13 returned by a rapid traverse. The traversing movements of the table are controlled by a hand lever 15 or by dogs 16 on the table engaging plungers 15<1> connected to the handle. The screw - 17 mav be rotated by hand for setting-up. The thin outer end of the work is subsequently finished in another machine. Chucks ; lathe &c. centres.-The cylindrical bosses of the pattern P and work W are held in chucks 18<11>, 19<11>, Fig. 2, by means of hooked bolts 23 which are rotatable into recesses 23 Figs. 1 and 3, in the chucks to allow insertion of the bosses. Positioning pins 103 in the chucks, against which the bosses are clamped, locate them in the same vertical plane. Plungers 19<1> in the hollow spindles 18, 19 are pressed forward by springs 21 to engage conical recesses in the pattern and work, and may be withdrawn by nuts 22 when the pattern and work are changed.