Patent GB-712038-A (GB)
Title: Improvements in or relating to gear generating machines
Inventor: DEAKIN THOMAS MEYRICK
IPC: B23F5/06
Filed: 1951-01-31
Abstract: 712,038. Gauging toothed gears. DEAKIN GEARS, Ltd. Jan. 24, 1952 [Jan. 31, 1951], No. 2456/51. Class 106 (2). [Also in Group XXII] A gear generating machine for forming or measuring gear tooth profiles comprises a pair of rectilinear slides mounted in respective guideways on a common subframe assembly supporting the workhead 1 and angularly displaceable about an axis AV normal to the generating plane at the cone apex of the work, the first slide being coupled to a rotary member 3 whose rotation is proportional to the rotation of the work about its axis whilst the second slide is coupled to an arcuate surface 13 concentric with said normal axis and the two slides being interconnected by at least one pair of elements capable of relative motion in a plane normal to the generating plane and substantially parallel to the work axis. The workhead 1 has its axis AW adjustable through 90 degrees in a plane normal to the horizontal generating plane GG. The point A represents a fixed point in the machine and generally represents the apex of a bevel gear and lies in the plane GG. The work-head 1 and the tool cradle 11 are relatively adjustable in the direction OV. The work-head 1 carries the disc 3 connected to a slide 4 by a non-slip coupling such as flexible bands. The slide 4 is also connected in iike manner to a disc 5 on a shaft 6, which is carried on a saddle 7 which may also carry the driving means (not shown): Journalled on the shaft 6 is a housing 10 in which slides a member 9 connected at one end in non-slipping relationship to a disc 8 on the shaft 6 and at the other end to a block 17 by means of a pivot 18. The block 17 slides in a bracket 15 adjustably mounted on a slide 14 connected in non- slipping relationship to a disc 13 on the toolhead spindle 12. The block 17 may, however, be secured to the bracket 15 by micrometric adjusting means. The tool, shown as a grinding wheel t, is reciprocable along a mean line T-T and is adjustable with its cradle 11 in the direction D2. To adjust the relationship between the rotation of the work and of the tool cradle, the housing 10 is adjusted angularly on the spindle 6 and the bracket 15 adjusted to centre the block 17 in the slideway 16. The reciprocative movements of the slides 4 and 14 and the rotational movements of the work and cradle are then proportional to the cosine of the angle at which the housing 10 is set. If the discs 3, 5, 8 and 13 each have the same radius, if the slides 9, 14 are parallel to one another, and if the axes OV, AW are coincident, the machine is set to cut a crown wheel. For cutting spur gears, the axis AW is set horizontal, the cradle 11 is locked in its bearings, but is allowed to float transversely in the direction 19 parallel to the plane GG, and the housing 10 is set according to the base circle diameter. The horizontal position of the housing 10 corresponds to the spur gear having the maximum base circle diameter. For generating skew or hypoid bevel gears the cradle 11 and the slide 14 are adjusted in the direction D2 according to the offset required. The tooth shape may be modified by providing an adjustable cam 14a on the bottom of the slide 14 to co-operate with a follower 14b fixed on the machine frame. In a modification, the slide 9 is omitted and change-speed or infinitely variable gearing is interposed between the discs 5 and 8. In a further modification, the slide 4, Fig. 3, moves on the saddle 7 which is carried on an arcuate guideway 28 centred at A on a frame 29 rotatably mounted about the axis OV. The slides 4 and 14 are reciprocated by adjustable cranks 22, 32, rotated by synchronized motors 26, 36 or by the motor 26 and an interconnecting drive represented at 38. The crank adjustments allow variation for, say, tooth depth and pitch angles. In a similar modification, the frame 29, Fig. 5, swings on vertical pivots as at 30a and carries a sector plate 45 on arcuate guideways 44 centred on the axis HH. The work-head 1 encloses bevel gears on the shafts carrying the work B and the disc 8. The housing guiding the slide 9 is not shown but is similar to that of Fig. 1. The work is rolled by the movements of a hydraulic piston 46, the disc 13 being stationary. The tool-head is supported on trunnions 48 which permit adjustment according to the tooth profile required. The tool t is adjustable vertically on a slide 51 which is reciprocated in the direction D6. The proportionality of movement of the slides 9, 14 is automatically maintained during angular adjustment of the work axis AW, the slide 9 being at right angles to the plane containing the axis AW and the axis of the shaft 6. In another modification, a disc on the work-spindle is connected directly in non-slipping relationship to the slide 9, either the disc 13 or the spindle 2 being fixed relatively to the machine frame. In an embodiment of this modification, the work-head 1, Fig. 8, is adjustable according to cone angle on a slide 44 on the frame 29. A slide 14 connected in non-slipping relationship with the fixed disc 13 is formed with arcuate guideways carrying a slide 62 on which the bracket 15 is mounted. The slide 9 is supported as before in the housing 10 which is adjustable angularly by means 59, 60. A disc 52 on the work-spindle is in non-slipping relationship with the slide 9. The drive is preferably applied to the spindle 2 while the tool t is reciprocated. The non-slipping connections may all take the form shown in Fig. 10 in which four bands 65, 66 are tensioned by a screw 75 or a rack-and-pinion device. The machines described may generate spherical involute or octoid tooth forms and tip relief may be imparted by mounting the housing 10 in such a way that its angle may be altered by a cam driven, say, by the shaft 6. In each machine it is immaterial which parts are regarded as fixed relatively to the machine frame and the drive may be applied at any convenient point. The machines described may generate straight and helical spur gears and straight, spiral, and skew bevel's. It is stated, however, that machines may be built which do not make provision for all these types.