GB502176A - Improvements in and relating to milling-machines for copying or profiling - Google Patents

Abstract

502,176. Copying milling - machines. ATKINS, H. F. Aug. 11, 1937, No. 22061. [Class 83 (iii)] In a profile-milling &c. machine of the kind in which the cutter and tracer are rigidly coupled together to co-operate with the work and pattern which are rigidly mounted together on a carrier, the carrier being automatically given linear, circular or combined linear and circular movements to effect the copying, the work and pattern are automatically given independent swivelling movements additional to the carrier movements for the purpose of enabling the tracer to surmount abrupt portions of the pattern. The machine comprises a circular table 2 adapted to be rotated intermittently through half a revolution, as deter. mined by indexing dogs 10, 11 on the table and a pivoted stop 49, by a worm drive 4 and a friction coupling. The work to be machined, e.g. a connecting rod 18, is secured by clamps 30, 31 to a template 19 which is secured by a nut on a spindle 15 rotatably mounted on ball bearings 16 in a block 13 attached to a slide 12 movable in a diametrical guide 8 in the table 2. Movement of the slide is produced by two pinions 42 freely pivoted on hydraulic plungers 41 operating in cylinders 39 within the table, the pinions rolling on fixed racks 45 on the table and engaging racks 44 on the slide to traverse it at twice the speed of the plungers. The cutter 33 and tracer 34 are coaxial and are rigidly connected to. gether on a slide which is capable of rectilinear motisn only, transverse to the slide 12, and pressed towards the work and template. In operation, the slide 12 is traversed towards the right in Fig. 1 by the plungers 41 whilst the tracer and cutter follow the straight shank of the work, the table 2 being stationary. On reaching the curved shoulder in the work, as shown in Fig. 1, an arm 35 attached to the spindle 15 engages a spring plunger 37 which is backed by a stationary surface on the support 1 of the table, thereby rocking the work and template in a counterclockwise direction so that the tracer will be able to surmount the curved portion- 50 of the template. During this rocking movement a cam 20 attached to the spindle 15 coacts with a spring-pressed plunger 25 on the slide 12 to exert a restraint on the rocking motion. When the tracer has reached the point x in the teinplate the slide 12 is at the end of its stroke and the stop 49 is automatically released to permit the friction drive of the table 2 to operate. The table then makes half a revolution, being stopped when the dog 10 engages the stop 49, the tracer following an idle arcuate portion 32 of the template, and the cutter thereby being held out of contact with the work. During this rotation the plunger 37 acts on the cam 20 to restore the work to its position on the centre' line of the slide 12, and a a second lever 36 secured to the spindle 15 then engages a fixed abutment 7 on the frame 1 to oscillate the work and pattern and enable the tracer to follow the curve 51 on the template. When rotation of the table 2 has ceased, the hydraulic plungers 41 are brought opposite a supply port 48 and the return of the slide 12 across the table takes place. As the lever 36 leaves the abutment 7 on motion of the slide 12, the plunger 25 restores the work in line with the slide. On reaching this end of the traverse, the stop 49 is again released, whereby the table is rotated through another half revolution whilst the tracer follows the cylindrical end y of the template and the cutter completes the work. During rotation of the table the port 48 is cut off from the hydraulic plungers and the fluid in the cylinders locks the slide against movement. In a modified construction the table 2, Fig. 15, is not provided with a diametrical slide and rotates slowly and continuously in a clockwise direction whilst the tracer 33 follows a template 52, and in order to allow the abrupt shoulder 53 thereon to be surmounted the template and work are oscillated about a centre 55 to the position shown by the dotted line 54 duriag the table rotation. The work and template may be mounted on a hydraulic or mechanical slide instead of the table 2, when it is desired to operate on one side only of the work, the spindle 15, cam 20 &c. being carried by the slide.