Patent GB-1439393-A (GB)
Title: Machine for producing surfaces of optical lenses for example toric surfaces
IPC: B24B13/04
Filed: 1973-10-26
Abstract: 1439393 Grinding E LOH and K LOH [trading as WILHELM LOH KG OPTIKMASCHINFABRIK] 26 Oct 1973 [26 Oct 1972] 49997/73 Heading B3D A machine for producing a surface, such as a toric surface on an optical lens 15, the surface being defined by a base curve and a transverse curve which is moved lengthwise of the base curve, comprises a first holder 62 for a rotatable cup-shaped tool 1, the lip 2 of which determines the form of the transverse curve, a second holder 61 for the workpiece 15, and a co-ordinating mechanism for producing a predetermined relative movement between the holders, the mechanism having a control mechanism which controls one or both holders in such a way that the workpiece axis and tool axis remain always in the same or parallel planes and the relative movement between the holders consists of a swinging movement about an axis 3 and a movement along axes which are perpendicular to one another. The tool 1 is carried by a spindle 4 in a head 5 on a carriage laterally adjustable along guides on a pivotally mounted arm 8 to position the cutting lip 2 on the swivel axis 3 of the arm, the axis being provided by a shaft 9 which is secured to the arm and formed with a gear 12 engaged by a rack 14 on a piston 13 movable by hydraulic fluid under the control of a servo valve 50. The workpiece is adhesively secured to a holder 16 on a quill 17 having a piston 18 slidable in a cylinder 34 in a table 19 movable along guideways 21 perpendicular to the movement of the quill by an hydraulic cylinder 23. The table 19 is formed with holders 26, 36 for control cams 25, 35. Cam 25 controls the base curve and co-operates with a scanning arm 27 during movement of the table, the arm 27 having a further guide arm 29 parallel to the guideways 21 for the table 19 and engaged by a pin 32 spring urged against the arm and carried by a feeler 31 secured to the quill. The pin produces a control voltage which is fed through an amplifier to a servo valve 33 controlling the hydraulic supply to the cylinder 34 so that the quill, and hence the workpiece, follows the movement of the pin as the scanning arm 27 is moved by the cam 25 during movement of the table 19. The cam 35 controls the swinging movement of the arm 8 and tool 1 and engages one end of a rocking lever 37 pivotable about a shaft 38. An adjusting piece 39, which determines the initial angular position of the arm and tool is disposed at the other end of the lever and co-operates with a pin 41 spring urged against the adjusting piece and carried by a feeler secured to the shaft 38. A disc 44 is secured to shaft 38 and connected by a tape 45, maintained under tension by a weight 47, with a disc on the pivot shaft 9 of the arm 8. The pin 41, like pin 32, produces a control voltage during movement of the table 19, the voltage, after amplification, being fed to the servo valve 50 to control the movement of the piston 13 and hence the swinging movement of the arm and tool. In other embodiments, the movements are controlled by digital apparatus and the movements may be effected by electrical and/or hydraulic mechanisms. Also, all the movements may be imparted to one of the holders, the other being stationary.