Note: Descriptions are shown in the official language in which they were submitted.
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~ TITLE: LATHE FOR GENERATING ASPHERICAL SURFACES ON WORK PIECES
,. 1 FIELD OF THE INVENTION
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,~. Tnis inven~ion rela~es in general ~o a laL;le for generating
~ aspnerical surfaces on work pieces and in par~icular generating suci
,~ 5 surfaces of revolution on a fron~ surface of an optical lens blank.
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' BACKGROUND OF THE INVENTION
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i'~ Optical lenses designed for correcting vision deEiciencies of
'~ 10 persons ilave been developed and utilized for a long period of time.
, As is t;~e case Wi~il any optical lens, it is necessary to genera-e
,~ surfaces, bot;l front and rear, of predetermined configuraLion Lo effect
, a desired correction of a particul,ar patient's vision deficiency. It
~' is a common prac~ice ~o utilize an apparatus wilicn is of a maciline
,~ 15 lat'ne ~ype structure w;lerein t;le lens blank is mounted on a spir.dle
-,~ winici~ is revolved w;lile a cutting ~ool is applied to tile surface for
generating of a specific configuration. An example of sucil a prior
' art lati~e is disclosed in U. S; Paten~ No. 3,977,279 issued Augus~ 31,
1976 to Derrell C. Hooker. Tile latile disclosed in tHat paten~, in
general, comprises a spindle for suppor~ing tne lens blank and roLation
ti~ereof during surface forming opera~ions and a cu~ting tool carried
~, on a turret device ~i~at is rotatable about'an axis transverse to t;~e
axis of rotation of t;le lens supporting spindle. Control mecinanism is
provided ~o effect rela~ive displacement of tHe cut~ing tool in a
predetermined manner during ~;le surface generating operation. T;lis
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1 control mecilanism includes a concave cam surface against Wi~iC;l a spring-
biased tool support and cam follower cooperaLe in effecting Linis conLr
over t;le surface to be generaLed. Tile surfaces tilat can be generated
.~' by ~ile Hooker latile may be of not only an aspilerical configuration,
buL may also be spilerical. Tile parLicular configuraLion is dependen~
upon tile settings of t;le various components of tile appara~us and particularlyas Co Lile control elements.
SUMMARY OF THE INVENTION
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Tile present invention provides an improved laLile ilaving
superior capabilities of generating desired surfaces on work pieces
SUCil as contac~ lens blanks. Tile improved la~;~e includes tile general
basic components of a ro~atable spindle for supporting ~ile lens blank,
a turret assembly carrying Lile len3 cu~ting tool and a con~rol cam
assembly. Tne control cam assembly suppor~s a roller cam in a prede~ermined
position wit;l respect to t;le turret assembly. Mounted on tile turret
assembly is a cutting tool support tHat not only carries tile cutLing
~ool, but also carries a cam follower. Tine supporLs for tile cut~ing
tool and cam follower are spring-biased ~o maintain tile follower in
engagement wi~;l t;le roller cam as tile ~urret assembly is revolved in
~ effecting a cutting operation. In accordance Witil tilis invention, ~He
; cam follower i~as a V-silaped configura~ion including divergent side
A walls ~Hat extend at a prede~ermined angle Co eacil otiler and from an
- 25 apex tilat ilas a small radius curvature. In setting up tile latine, tile
roller cam is positioned at a predetermined point witH respect t-o ile
; axis of rotation of tite turret assembly. Tile cutting tool and cam
follower supports are relatively adjus~able and positionable on tile
urret assembly. Tiley are prepositioned witil respec~ to tHe axis of
rotation of ~ile ~urre~ assembly in accordance wiCil tile posi-ion of tile
roller cam and are set to develop or generaLe a predeLermined surface
on tile lens blank.
; Tbe improved s~ructure of tile cam and cam follower in tile
~ 35 latine of tiliS inven~ion are capable of effec~ing a precise surface
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: 1 configuracion wilicil, in Cile case of a conCacC lens, is of an opCic
design Cila~ i9 necessary Co effecC Cile appropriaCe correcLion for a
particular paCienC. AddiCionally, Cile improved cam and cam follower
mecilanism are capable of conCrolling tile generaCion of Cile surface Co
a desired silape WiCilouC disconCinuicies Cilrougi~ou~ e ex~enC of ~ile
opCically effecCive porCion and Cilereby avoid any disconCinuities in
: Cile area or region of tile lens CilaC effecCs Cile opCical correcLion.
One aspec~ of ~ili9 invenCion is a laC;le for generaCing surfaces
of revoluCion on a work piece comprising a base; a spindle assembly
-- mounced on said base and including an elongaCed, roCaCably suppor~ed
spindle ilaving a longiCudinal axis and an end for mounCing of a work
piece Cnereon and means for roCa~ing said spindle, said spindle axis
being disposed in a predeCermined plane; a CurreC assembly mounCed on
15 said base and including a ro~a~able base mounC for pivoCally suppor~ing
said CurreC assembly for revoluCion abouC a verCical axis of roCaCion
disposed cransversely ~o said spindle axis, a cam follower and cuCCing
Cool supporC assembly secured Co said base mounC for relaCive dis-
placemenC along an axis of displacemen~ in a plane disposed in Cransverse
relacionsilip Co said verCical axis of roCation of said CurreC assembly,
a cam follower ilaving an end porCion of V-silaped configuraCion ilaving
~ an apex and side walls divergenC from said apex, a cuCCing Cool and
-`~ resilienc biasing means for urging said cam follower and cutCing cool
supporC assembly in a predeCermined direcCion along said axis of dis-
;~ 25 placemenc; and a conCrol cam assembly mounCed on said base and including
` a cam ilaving a convexly arcuaCe camming surface disposed in radially
.. ` spaced relacionsilip Co a vertical axis of said cam and againsC wilici
said cam follower bears, and a supporC assembly for supporCing and
posiCioning said cam wi~il iCs verCical axis disposed parallel ~o i~e
axis of roCaCion of said Currec assembly.
T;lese and oCiler objecCs and advancages of Cilis invenCion will
be readily apparenC from Cile following deCailed descripCion of ile
- embodimenc Cilereof and Cile accompanying drawings.
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1 BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a side elevaLional Yiew of a lati~e embodying tilis
` invention
FIGURE 2 is a ~op plan view of ~ile la~i~c
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` FIGURE 3 is a fragmentary sectional view ~aken along line 3-3
j~ of FIGURE 1
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FIGURE 4 is a medial cross-sectional view of a conLacL lens
ilaving surfaces generated by tile la~ile apparatus
FIGURES 5 and 6 are sequen~ial diagramma~ic illus~rations of
, 15 LHe rela~ive posi~ioning of ~i~e cam and cam follower as results from
`~ revolution of ~ile turret assembly
~ DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT
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Having reference in par~icular ~o FIGURES 1 and 2 of tile drawings,
; ~ile latile appara~us i8 seen to include as ~ile basic component a base
10, spindle assembly 11, turre~ assembly 12 and control cam assembly
13 Eacil of t;le spindle, ~urret and control cam asscmblies 11, ]2
and 13 are moun~ed on ~i~e base 10
Tbe spindle assembly ll includes a moun~ing frame 14 carrying
a~ i~s upper side a spindle suppor~ drive 15 Lilat ilas an elongated
spindle 16 adapted ~o carry a work piece sucil as a lens blank L a~ iLs
free end As is conventional in a la~ile of ~ilis ~ype, ~ile spindle 16
is suppor~ed for ro~a~ion about a ilorizon~al axis Incorpora~ed in
Lile spindle support drive 15 buL noC specifically illustra~ed, is a
drive mecilanism of a ~ype generally u~ilized in lens cut~ing appara~us
of tilis na~ure and may include a gear mecilanism capable of ob~aining
differenL rotational speeds as between an elec~ric drive mo~or and tile
spindle 16 Sucil components are well-known Lo tilose skilled in tilis
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1 par~icular ar~ and ~i~us Liley are noL illus~raLed in furLiler de~ail.
Tile mounting frame 14 in tilis lat;~e apparaLus is of a ~ype Lilat permiLs
selecLive adjus~ment of its position on tile base along an axis Lila~
parallels tile spindle. Ti~is adjusting mecilanism includes coopera~ing
guide ways 17 fixed on t;le Lop sur~ace of Llle base 10 ancl formed in
~ile lower porLion of ~ile mounting frame 14. A screw ~ilread adjus~ing
device 18 is provided and manually operable Lilrougi~ a band wbeel 19 ~o
effecL positioning of ~ile spindle assembly 11 a~ a desired poin~.
Displaced from ~ile spindle assembly 11 is ~ile ~urreL a.s.sembly
12 and i~ is posi~ioned along tile longiLudinal axis of Lile spindle.
Tilis turre~ assembly 12 includes a roLa~able base mount 20 ilaving a
vertical pivoL axis designaLed as 21. Tilis roLaLable base moun~ 20
includes a bo~om por~ion 22 WiliCil iS adapLed Lo be fixed ~o L;le upper
- 15 surface of ~ile base and an upper secLion L;la~ is relatively roLaLable
wiLil respec~ ~o L;le bo~tom. Secured Lo Lile upper sec~ion 23 is an
elongated mounLing pla~e 24. MounLed on Cile plaLe 24 is a cam follower
and cuL~ing Lool support assembly 25. Tilis suppor~ assembly 25 includes
a cam follower mecilanism 26 WiliCil i9 disposed nexL above ~ile moun~ing
plaLe 24 and a cu~ing tool nolder 27.
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Tile cam follower mecilanism 26 comprises a cam follower 28 Li~at
includes as iLs basic componenL a flaL plaLe ilaving an end porLion
formed wiLi1 side walls 29 LilaL converge Loward an apex 30 as can be
besL seen in FIGURE 3. Tnese side walls 29 are intercohnecLed by tile
generally circularly-silaped apex 30 WiliCil ilas a relaLively small
radius. Also included in Lile cam follower mecnanism 26 are guide way
plaLes 32 WiliCil mecilanically inLerengage wiLil ~i~e cam follower and
permit its axial reciproca~ion. A screw Lilread adjusLmen~ mecilanism
33 is provided to posi~ion tile cam follower Wi~ll respec~ to Lile mounting
pla~e and Lo main~ain Lile follower in ~ile selecced posiCion. Tile
` cu~ing ~ool ilolder includes an inLerconnec~ing mecilanism ~o permi~
rela~ive adjustmen~ of Lile ilolder wi~il respec~ Lo Lile cam follower
mecilanism. Tilis cut~ing ~ool nolder also includes a ~ransverse slide
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supporL 34 tilal: ;las a t:ool clamp 35 and carries ~;le cutLing Lool 36
adjustable Witil respec~ Lo C;le CurreC assembly 12. A spring biasing
mecnanism 37 is provided and mecilanically incerconnecced as be~ween
C;le mounCing plal:e 24 and Cile cam follower and cuCt:inR cool supporC
assembly 25. Tilis biasing mecilanism includes a resilicnC spring
device 38 W;liC;I is operal:ional t:o urge cile cam follower and associaced
componenLs in a direcCion Cilal: i9 Reneraliy Coward ~ile spindle.
Operal:ion of Lile ~urre~ assembly essen~ially consisLs of roCaLing Lile
CurreC assembly abouC iCs vercical axis 21. Tilis causes tile cuCLin~
point of Clle Cool 36 Co swing across Cile forward face of cile lens
blank L and Co Cilereby cul: cile desired surface. Manual operaCion of
Cile CurreC assembly is facilit:at:ed by means of a ;landle 39.
T;le conCrol cam assembly 13 includes as it:s primary componenC
.~ 15 a cam ;laving a convexly arcua~:e camming surface and WiliCil, in L;lis
illusl:racive embodimenc, is a roller cam 40 ;laving a cylindrical cam
surface t:;~a~ is circular. T;lis roller cam is mounCed on a supporC
assembly 41 wi~ s axis of rotaCion vercically orienCed l:o be
parallel ~o L;~e axis of roCaCion of C;le t:urrel: assembly. Included in
C;le supporC assembly 41 is a frame strucCure w;lic;l is of an adjuscable
Cype l:o permiC boc;l longil:udinal and Cransverse posil:ioning of C;le
roller cam 40. Forming ~:ne adjusl:able sCrucCure is a base member 42
secured Co ~;le base 10 ~;lroug;l a guide way 43. T;le base member 42 is
adjuscable longi~udinally of t:ile base and parallel Co ~ile spindle 16
Cilrougil a screw ~ilread adjusting mecnanism 44. Secured Co C;le base
member 42 is an elongaLed support: arm 45 Co W;liCil C;le roller cam 40 is
journalled aC iCS one end. Tile arm iCself is slLdeably secured in a
guide way formed in t:;le base member 42 and is cransversely adjusCable
,k` Co a desired posil:ion WiCil respect: Lo t:;~e base member. T;lis adjusCmenC
mec;lanism permits L;le roller cam 40 Co be relacively posit:ioned as o
L;le axis 21 of ~ile l:urret: assembly l:o enable t:;le lac;le Co be ucilized
in forming of any particular and desired surface configural:ion on t:ile
lens blank. T;lis adjusLmen~ is in cooperaLion wit:;l C;le posiCioning of
Cile cam follower 28 and enables Cile operaLor Lo obCain cile desired
lens curvat:ure. RelaCive positioning of tile axes 21 of L;le CurreC
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1 assembly and tilaL of ~;le roller cam WiliCil iS designated as 46 in FIGURES
5 and 6 can be seen ~o be rela~ively adiusLable bo~;l in a longitudinal
direc~ion as well as a ~ransverse direc~ion
FIGURES 5 and 6 diagramma~ically illus~raLe ~ilc funcLioning of
~i)e cam follower 28 wi~i~ respec~ to ti~e cam roller 40 In ~ilis diagrammaLic
illus~raLion, i~ will be noLed ~i~a~ ~ile axis 46 of ~ile cam roller i9
loca~ed along Ll~e longi~udinal axis of ~ile laLile and wilicil longitudinal
axis is excending ~i~rougn ~ile ver~ical axis 21 of ~ile ~urre~ assembly,
bUL i9 spaced wi~in re~pect to ~i~e Lurre~ axis 21. Tile Lurre~
assembly is opera~ed ~o swing ~ile cu~ing ~ool 36 along a prede~ermined
patil wiLi~ ti~at pa~i~ being determined by ~ile cooperative action of ~ile
forward end of a cam follower 28 rela~ive ~o ~ile circular surface of
~ ~ile cam roller 40 Tilis s~ructure comprising primarily ~ile cam follower
; 15 and roller cam enables ~ile la~ilc of ~ilis inven~ion to perform a unique
function in ~ile forming of a lens surface and specifically, ~i~e fron~
surface of a lens A silape tila~ can be developed for a con~acL lens
is diagramma~ically illustra~ed in FIGURE 4 In Lila~ illus~ra~ion
wilic;l is a medial sec~ional view of a formed lens, tile lens is seen ~o
ilave a rear spilerical surface designated by t;le le~ter S ilaving a
- radius R and a fron~ surface designa~ed by ~ile le~er F A lens
- configura~ion ~ina~ can be developed by tile latile of tiliS invention is
~ a fron~ surface F ilaving a configuration w;lic;l, t;lroug;~out ~ile ex-cn-
-` of effective optical operating range, w;lic;l range is generally indicaLed
by an arc A, results in a lens L;~at inas a cons~an~ ~ilickness T ~;~rougi~ouL
~;le extent of i~s operating range Variations in ~ile t;lickness T
result in different optical cinaracteristics as determined in accordance
wit;~ ti~e particular patient's requirements
