| 摘要 |
637,226. Turning parabolic &c. surfaces. NEWTON, E. P. (Baker & Co., Inc.). March 28, 1946, No. 9691. [Class 83 (iii)] Relates to means for maintaining a forming tool 145, Fig. 6, at a predetermined aspect angle relative to the work 57, in apparatus for generating conic surfaces of revolution which includes mechanism for traversing the tool so that a point C-P thereon moves along a conic section line. According to the invention, the means comprises first and second links 33, 51 whose longitudinal axes lie in the lines joining the said point to the section foci co, F-2, means including a third link 41 whose longitudinal axis bisects the angle between the first-mentioned axes, and means for connecting the tool to the third link 41 to move in unison therewith. P-2 denotes a paraboloid to be turned, a pin 157 being fixed at its focus F-2 on a fixed platen 87. V designates the vertex of a similar parallel parabola along which a pin 13 travels as the tool is moved. The tool 145 is carried on the tool-block 41 which slides in a curved slot 143, Fig. 9, on a tool-holder 33, the slot having its centre at C-P, the cutting-point. The toolholder 33, Fig. 6, is carried in dovetail guides on a slide-block 31 which slides along a guide 29 in the fixed platen 87. In a guide 27 at right angles to the guide 29 is carried a slide-block 25 carrying a shoe 131 on a pivot 127. The shoe 131 and the pivot 127 connect to the slide-block 25 one end of a link 19 which is pivoted at its other end on a pin 173 which is situated at the vertex V. The link 19 is slidably connected to the tool-holder 33 by a rotary sliding member 15, Fig. 9, pivoted on the pin 13. The slideblocks 25 and 31 are moved at proportional speeds by levers 125, 137 pivoted on a bellcrank 121, rotated by a shaft 115, and thus control the longitudinal and lateral movements of the tool respectively. The linkage system for moving the slides 25, 31 may be replaced by two screws working in nuts in the slides. The tool is maintained at right-angles to the work by means of bisecting links 57, 59, Figs. 4 and 9, joined by a pin 167 which slides in a slot 63 in the tool-block 41. Link 57, Fig. 6, is pivoted to the tool-holder 33 and link 59 to the slotted drag-link 51. The slotted link slides at one end on the pin 157 and at the other end in a curved slot 159 formed on the tool-block 41 and concentric with the slot 143. The platen 87, Fig. 4, is mounted on a support 88 which is adjustably mounted on the saddle 65 of the lathe. The shaft 115 is driven from the lead screw 63 of the lathe via a belt 79 and gearing. The work 57 is mounted on a face-plate 55 by clamps 169 and is rotated by the headstock 53. Lubrication.-A pump 185, Fig. 4, is beltdriven from the headstock and supplies lubricant to the tool at 191. Gauging.-For setting-up (Fig. 11) the tooldriving mechanism is removed and a gauge-bar 103 is fitted over two pins situated at the points F-2 and V. The tip 109 of the gauge-bar represents the vertex of the paraboloid to be cut and is thus set at the centre of the headstock by adjusting the support 88 carrying the platen 87. The other tip 107 is set at the tailstock centre. |
