Patent GB-1497129-A (GB)
Title: Ultrasonic lapping apparatus for drawing dies
IPC: B24B37/00
Filed: 1975-11-19
Abstract: 1497129 Ultrasonic machining NISSIN DIAMOND CO Ltd 19 Nov 1975 [21 Aug 1975] 47677/75 Heading B3D Ultrasonic lapping apparatus for finishing or reconditioning holes in drawing dies D comprises an ultrasonic generator 9 for exciting a transducer 5 to produce mechanical oscillations of a lapping needle 25, a turntable 8 for supporting a die and normally axially aligned with the needle, drive means for rotating the turntable, an arm 27 carrying the turntable and pivotally supported at one end for swinging motion about an axis passing through the die on the turntable, and means arranged adjacent the other end of the arm for causing swinging movement of the arm. As described, the apparatus has a pair of lapping units 1, each having a transducer 5 connected to a respective generator 9. Each transducer is mounted on a respective column 3 of a common pedestal 2 and can be clamped in position on its column by a lever 24, fine adjustment being provided by a rack-and-pinion mechanism and a knob 22. The pedestal has a pair of forwardly projecting legs 10, one of which mounts a grinder 11 for reconditioning the lapping needles of the apparatus. Each transducer has a tool holder 5<SP>1</SP> for a lapping needle 25 and is associated with a turntable 8 rotatably supported in a bearing 81, a spring 42, adjustable by a screw 40, acting to resiliently urge the turntable upwardly to engage a die D mounted thereon with the needle 25. Each turntable is formed with a pulley 811 engaged by a belt 16<SP>1</SP>, 18<SP>1</SP> entrained around a respective pulley 16, 18 on a common drive shaft rotated by a belt drive 20 from a motor. Each bearing 8<SP>11</SP> is mounted in a housing 8<SP>111</SP> supported by leaf spring 37 from the swing arm 27. A bracket 38 is fastened at one end to the housing and has an adjusting screw 38 st its other end whereby the turntable is adjustable in an X direction relative to the lapping needle. The swing arm is mounted on a pivot 28 on a supporting frame 26, the axis of the pivot passing through a die mounted on the turntable. The frame is carried by leaf springs 35 from the pedestal 2 and a thumb screw 36 in a bracket 34 mounted on the pedestal provides for adjustment of the turntable in the Y direction. Each frame mounts a shaft 31 having a pulley 32 driven by a bell 33 from respective pulley 15, 17 on the common shaft. A disc 30 is secured to each shaft 31 and has a radially adjustable cam 30d in the form of a rubber engaging a follower 27<SP>1</SP> formed by an extension of the swing arm 27. As the turntables are rotated about their axes by the belt drives 16<SP>1</SP>, 18<SP>1</SP> from the drive shaft 7, the belt drives 33 rotate the shafts 31 and hence the discs 30 so that the cams 30d engaging the followers 27<SP>1</SP> cause swinging of the arms 27 and thus the turntables about the pivots 28 so that the needles 25 lap the holes in the dies; the dies may be of diamond or other hard material and the holes have a cylindrical position between two tapered portions. In another embodiment, the turntable of each lapping unit is mounted in a shaft axiably, but not rotatably, movable in a sleeve formed with a pulley driven by a belt from the common drive shaft, a spring in the sleeve acting on the shaft to urge the turntable and die mounted thereon towards the lapping needle.