GB1099085A - Rotary positive displacement units - Google Patents

Abstract

1,099,085. Grinding; milling; planing. E. WILDHABER. Feb. 21, 1966, No. 7513/66. Headings B3D, B3K and B3L. [Also in Division F1] In a rotary pump or motor comprising a pair of rotors 34, 35, Fig. 14, journalled in a housing with the rotary axis 31 of one inclined with respect to the rotary axis 30 of the other and formed with lobes meshing around their whole peripheries with one rotor having one more lobe than the other (see Division F1), the rotors are produced by continuously rotating a blank about its axis and imparting motion to a tool to effect relative feed between the tool and blank about an axis which intersects the blank axis, so that the tool moves from the top to the bottom of a tooth and then from the bottom to the top of a tooth. To produce large size rotors, a milling cutter or grinding wheel 62, Fig. 9, is disposed so that its axis 63 intersects the axis 30 of a blank 34a at 0. The cutter 62 rotates about its own axis for stock removal whilst the blank turns slowly on its axis 30 with the cutter fed about apex 0. Another position of cutter 62 is shown dotted at 62<SP>1</SP>. The feed motion is a slow oscillating motion between two end positions timed to the turning motion of the blank. The mating rotor 35 may be produced by the same cutter using a different timing between the turning motion of the blank and the angular feed motion between the cutter and the blank. The rotors can also be produced by tool reciprocation. An edged tool 64 or grinding wheel 64<SP>1</SP>, Figs. 10, 11, having a convex arcuate cutting edge 65 centred at 67 reciprocates lengthwise towards and away from the apex 0 along line 70 to produce the concave bottom of the rotor lobe. The side surfaces of the lobes are produced by feeding the blank 34 angularly about an axis 59 passing through the apex 0 and perpendicular to the drawing plane (Fig. 10). Dotted lines 34<SP>1</SP> show blank in tilted position where a straight-line element of lobe side is produced. To cut or grind all the time along a fixed line 70, the tool or wheel is fed in a circular path 72 about an axis coincident with line 70 at a rate so that the inclination of tool coincides with the profile inclination of the workpiece. Spiral teeth may be cut by adding a continuous turning motion to the blank and timing the reciprocations with the added motion. In another embodiment the reciprocating tool or wheel can oscillate about an axis (77), Fig. 13, (not shown) which lies in a plane perpendicular to the line (70). Additional tool motion is in this plane such that the tool profile (73) always passes through a point where line (70) intersects the plane.