Patent GB-1424272-A (GB)
Title: Copying machine tools
IPC: B24B21/00
Filed: 1973-02-08
Abstract: 1424272 Abrasive belt machines CENTRAX Ltd 8 Feb 1974 [8 Feb 1973] 6256/73 Heading B3D  A copying machine tool comprises means 8, 11 for mounting a cam 9 and workpiece for rotary movement in synchronism, a movable member 16 carrying a follower 17 for engagement with the cam and further mounting means 41 for means 19 for removing material from the workpiece, the further mounting means being connected to the movable member by yielding means 43 which permits the further mounting means to move relative to the movable member when the material-removing means encounters resistance from the workpiece. As described the machine is used for polishing the blades of turbines or compressors by means of an abrasive belt. The machine has a headstock 2 which is reciprocatable along guideways 3 on a bed 1 by an hydraulic device 4 and carries an hydraulic motor 7 for rotating a pair of face plates 8, 11 in synchronism. The face plate 8 has a clamp for the cam 9 having the desired shape of the workpiece, and the plate 11 carries the workpiece. The spindle carrying the face plate 11 also carries a cam 12 which co-operates with a follower 13 controlling a valve which varies the instantaneous speed of rotation of the face plates. A belt drive assembly 16 is mounted for pivotal movement about an axis 20 on a block 15 fixed to the bed 1, the assembly being rocked about the axis by a pneumatic device 21 to engage a follower wheel 17, carried by a mount 18 on the assembly, with the cam 9. The abrasive belt 19 is entrained about a drive pulley 23, driven by an hydraulic motor having a shaft coincident with the pivot axis 20, idler pulleys 25, 26, 27, a contact wheel 28 and a further idler 29. Pulley 27 is mounted for adjustment along a slot 31, and pulley 26 is mounted on an arm 32 which is adjustable along a slot 34 and acted on by a tensioning cylinder device 35. Movement of the arm 32 in the event of breakage of the abrasive belt actuates a limit switch 37 to stop the operation of the machine. The contact wheel 28 is mounted on an arm 41 which is pivotable about the axis 20 and is biased towards the workpiece by a spring-pressed plunger assembly 43 mounted on the belt-drive assembly 16. The upper end of the arm 41 abuts one end of a finger 46 mounted on a pivot 50 perpendicular to the pivot axis 20. The other end of the finger abuts an adjustable stop 47 on the assembly and has a cam surface 52 for actuating a micro switch 54. In operation, the cam 9 and workpiece are rotated at the speed determined by cam 12 as the headstock is reciprocated by the device 4. The pneumatic cylinder 21 pivots the assembly 16 at a controlled rate to engage the follower wheel 17 with the cam 9. Full pressure is then applied. If the workpiece is oversize, the spring assembly 43 between the contact wheel arm 41 and assembly 16 permits the contact wheel to yield relative to the assembly 16 and follower wheel. Material is removed from the workpiece until the finger 46 is rocked by the contact arm and actuates the switch 54, the axes of the follower wheel, contact wheel and pivot 20 then being in line. A pneumatic circuit is described for automatically controlling the operation of the machine.