Metal working – Method of mechanical manufacture – Shaping one-piece blank by removing material
Patent
1987-03-12
1988-05-24
Echols, P. W.
Metal working
Method of mechanical manufacture
Shaping one-piece blank by removing material
29407, B23P 1304
Patent
active
047456728
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of, and apparatus for manufacturing contact lenses.
The most commercially important method of manufacturing contact lenses at present is by machining from suitably sized lens blanks. Although the lens blanks are commonly machined on automatic or semi-automatic lathes, the manufacturing process is necessarily somewhat laborious, since the lens blanks have to be loaded by hand into the lathe collet, and unloaded by hand after the sequence of machining operations has been completed. A typical machining method and lens manufacturing apparatus are described in British Patent Specification No. 1,488,001. There is consequently a need for a method of automatically loading workpieces, such as contact lens blanks to a machine tool, and for apparatus suitable for this operation
Furthermore the manufacture of contact lenses involves a series of operations in which the lens surfaces are polished after lathe cutting steps in which the base and power curves are formed and the finished lenses are then inspected for quality and reference to specification. These operations are difficult to carry out accurately and repetitively since, according to conventional procedures, each lens is handled individually.
According to one aspect of the present invention, there is provided a method of machining workpieces, especially contact lens blanks, the method comprising the steps of feeding the workpieces sequentially from a magazine to a loading station, at which each workpiece is positioned accurately in a predetermined location with respect to a machine tool collet, transferring each of the workpieces from the loading station to the collet, and machining a surface on each of the workpieces.
The invention also provides apparatus for feeding workpieces to a machine tool collet, the apparatus comprising a loading device and a magazine for containing a plurality of workpieces, the magazine having an opening at one end through which the workpieces are sequentially removable, the loading device being arranged to accept workpieces sequentially from the magazine at loading station and to feed them to the collet of a machine tool, the loading device having means for holding a workpiece removed from the magazine and means for positioning said workpiece at the loading station in a predetermined position with respect to the collet, and the loading device having a mechanism for moving the holding means so as to carry said workpiece from the loading station to the machine tool collet.
By designing a magazine for the lens blanks and providing similar loading and unloading devices on each of the machines employed for the different stages of lens manufacture, the magazines containing lens blanks or partly worked blanks can readily be taken from one machine to the next, with the minimum of handling. Higher productivity with greater accuracy and repeatability can thereby be achieved.
Thus, although the loading and unloading devices using a magazine will be described in greater detail as applied to the automatic feeding of lens blanks to a lens lathe, and for removing the machined workpieces after the machining operation, the loading and unloading system described herein is applicable to other operations in the manufacture of lenses for example, feeding lenses or partly-worked blanks to a polishing machine. However, in the case of feeding blanks to a lathe there is normally a need for precise determination of the position of a work-piece with respect to the collet, while feeding of lenses to polishing machines does not require the same degree of accurate positioning of the lenses.
Advantageously, the loading device has a carriage which supports the holding means, and the carriage is movable by at least one piston-and-cylinder device. Preferably, the carriage is movable by first and second piston-and-cylinder devices, the first and second piston-and-cylinder devices being jointly effective to move the holding means from the loading station into a position in which said workpiece is in alignment with the collet, the fir
REFERENCES:
patent: 1862042 (1932-06-01), Stevens
patent: 3064531 (1962-11-01), Bullock
patent: 3301105 (1967-01-01), Morris
patent: 3360100 (1967-12-01), Seragnoli
patent: 3423886 (1969-01-01), Schpak et al.
patent: 3507403 (1970-04-01), Moore
patent: 3630111 (1971-12-01), Hartford et al.
patent: 3738204 (1973-06-01), Spriggs
patent: 3763597 (1973-10-01), Schlotfeldt
patent: 3914853 (1975-10-01), Jauch
patent: 4002247 (1977-01-01), Dixon
patent: 4035904 (1977-07-01), Ishizaka et al.
patent: 4072476 (1978-02-01), Kulson
patent: 4084458 (1978-04-01), Galley
patent: 4090287 (1978-05-01), Selander
patent: 4210038 (1980-07-01), Hill
patent: 4541762 (1985-09-01), Tischler et al.
patent: 4677729 (1987-07-01), Morland et al.
Walker, "Loading on the Fly Speeds Internal Grinding", Machinery, vol. 72, No. 5, (Jan. 1966), p. 137.
Walker, H., "Magazine und Zubringe-Einrichtungen fur Einspindel-Drehotomaten", Werkstattstechnik, vol. 56, No. 10, Oct. 1966, pp. 481-486.
Morland Albert H.
Sealey Michael J.
Echols P. W.
Gorski Joseph M.
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