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453,119. Turning or milling profiled articles. MOSSDORF, R., 58, Dresdner Strasse, Chemnitz, Germany. Jan. 1, 1935, No. 73. [Class 83 (iii)] [See also Group XXIII] Congruent non-circular external and internal profiles, e.g. for fitting together a shaft and its corresponding hub, are produced by grinding, milling or turning, by moving according to one and the same kinematic law of cyclic curves, the point of action of an outer tool working on the shaft portion and an inner tool working on the hub portion, and maintaining the position of the tools relative to the curve to be produced, and therefore the cutting angle, constant by the feature that the edge-cutting tool, or the line joining the centre of the grinding or like tool to the point of contact with the curve is always normal to the tangent to the curve at this point and the tools are fed along this normal. Figs. 1, 2 are diagrams of the principle involved. In Fig. 1, the work 5 to be produced is stationary and its centre 8 corresponds with the centre of a circle 2 inside which rolls a circle 1 from the centre 7 of which extends a link 4 the extremity 3 of which forms the cutting point. As the normal to the curve traced by 3 always passes through the point of contact of the circles 1, 2, it can be represented by a slotted link 6, the radius of the circle 2 serving as the length of the crank arm 10. As the circle 1 and therefore the arm 10 rotate about centre 8, the point 3 traces out the profile 5 the form of which can be varied by varying the ratios of the gearing. Other links of this gearing may be fixed, and, in Fig. 2, a form is shown in which the slotted link 6 and the cutting point 3 are fixed, the work 5 rotating, and oscillating on each side of the link 6. The angle of rotation alpha, between crank 10 and link 4 bears the same relation to the angle #, between crank 10 and the profile centre line 8, 17, as the diameter of circle 2 bears to diameter of circle 1. A grinding machine producing movements equivalent to those of Fig. 2 is shown in Figs. 3, 4. A grinding wheel 36 is mounted in a bracket 37 adapted to be adjusted on a bed 38 by a screwed spindle 39 and wheel 41. A headstock 43, Figs. 3, 4 is mounted on a tranversely reciprocable table 35. A shaft 46 is driven through a pulley 45 and, through gearing 20 21, 22, imparts a corresponding rotation to a shaft 47. The shaft 46 with axis 9 has an eccentric portion 46a with axis 7 and two eccentric outer parts 46b with axis 8. The references 9, 7, 8 correspond to those in Fig. 2. The shaft 47 with axis 48 has two eccentric outer parts 47a with axis 53. The shafts 46, 47 are mounted in blocks 49, 50 adapted to slide in guides 51, 52 so that the axes 9, 48 and the axis 12 of the grinding wheel 36 are always on the same straight line. The eccentric outer parts 46b, 47a are journalled in a common oscillatable body 54 carrying a clamping spindle 55 for the work-piece 34, the axis 18 of this spindle and the axes 8, 53 being thus maintained on the same straight line and describe similar paths. The middle eccentric part 46a of shaft 46 forms a bearing for a link 56 pivoted at 3 to a fixed bracket 43a in the headstock 43, the axis 3 being always on the straight line 9, 48, 12. A gear wheel 23 is rigid with part 46a and drives a wheel 24 rigid with a wheel 25 both running freely on a stud 27 in link 56. Wheel 25 drives a wheel 26 loose on 46a said wheel rotating the shaft 55 and work piece through discs 57, 28 and wheels 29, 30, 31. The gearing 23 .. 26 is selected to give the same ratio of angles of rotation as in Fig. 2, one revolution of wheel 23 being necessary to obtain one section of the cyclical profile, so that in order to produce the whole curve the wheel 23 must describe as many revolutions as the curve has sections. An inner grinding wheel is described with reference to Fig. 5 (not shown). The link 4, Fig. 1, might be fixed. The cyclical curves may be formed on conical parts.
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