TWO AXIS LENS LATHE SERIES III/2 Features Description Operation Operator Machine Interaction Control System Tooling Automation Option Specifications

This DAC machine is a computer numerically controlled two-axis, multi-tool, high precision, diamond turning lathe for the generation of contact or intraocular lenses as well as the precision machining of small non-ferrous metal parts.

The machine base is a granite surface plate for accuracy and stability. The surface plate is mounted with vibration isolators on a welded frame. The complete machine and electronics are housed in a single cabinet.

The X axis is mounted directly to the granite and carries the spindle. The Y slide is also mounted on the granite and precisely positioned at 90 degrees to the X slide.

The tooling and front surface gaging system are mounted on top of the Y slide.

This machine geometry assures that the machining loaded are well centered within the travel of the slides and that the spindle mounting is stiff and stable.

All axes are D.C. servo driven with position feedback provided by optical encoders.

The lathe "head" is a carefully balanced, air bearing, high frequency spindle with programmable speeds of 6,000 to 18,000 RPM. Either an automatic mechanical collet or a vacuum chuck may be used to hold the work piece. 

The part to be turned may be directly mounted in the spindle collet for posterior surface contouring or may be "blocked" on an arbor. Vacuum colleting may also be used for either side of the lens with special tooling.

The roughing tool is used to remove the bulk of the material. As the finishing tool removes only a minimal amount of material, its edge (and life) are preserved. The requirement for tool changes is greatly reduced. As all cuts are made by X or Y motion, or by X-Y interpolation, junction problems are eliminated. Any number of spheric and aspheric surfaces (front or back) can be generated by the system. Because of the fine resolution of the slides (0.07 micron) the surface requires cloth polishing for cosmetic purposes only.

Edge radiusing is accomplished by utilizing a left hand tool mounted at 90 degrees to the spindle center line and interpolating the X and Y axes to produce the desired contour.

Typical contact lens base curves can be produced in 30 to 60 seconds. 

"Menu" type of queries, on the color monitor screen, guide the used quickly through machine set-up, calibration, alignment and tool replacement. DAC Script Language (DSL), which employs a subset of RS274D machine language, is a high level programming language that is easily understood by the used and is included in each lathe.

If all lens design parameters are known, the used simply enters the appropriate numbers by use of the keyboard or Touch Screen Monitor. The machine will calculate variables, such as junction thickness, after the entry of the basic design factors. A display of a lens cross section aids the user in the design process by graphically presenting the actual design. The machine's computer automatically converts the lens design specifications into the machine language program necessary to machine the desired part.

Programs may be stored on either the floppy or hard disk system. New lens specifications may be entered during the time that the machine is turning a previously entered part. 

The DAC Digital Motion Control system is at the "heart" of all Series III DAC Lathes. It is housed in the on-board computer, mounted, with the servo amplifiers, in the base of the machine behind a removable panel for easy access.

Each axis is driven by a servo motor with rotary encoder feedback and is controlled by the Digital Motion Control (DMC).

Auxiliary functions such as actuating lights, vacuums, air, etc. can be added by the user by utilizing the several available "M" functions. 

Both the roughing and finishing tool holders are of the simple, accurate "flexure" type conceived by DAC. Dial indicator gages to show both the vertical and lateral adjustment of the finishing tool are provided as standard equipment. Either 1/4" or 5/16" shank tools may be used. Air nozzles are furnished for both tools and may be programmed to operate only while each tool is actually cutting. 

Autoloading systems can be supplied to automate loading and unloading of buttons and blocked parts.

Slides:

Linear slides are D.C. servo motor/zero backlash ball screw driven with rotary encoder feedback.

 

Type: Travel: Resolution:

X Dovetail 8" (204mm) 3 micro-inches (0.07 micron)

Y Dovetail 4" (102mm) 3 micro-inches (0.07 micron)

Accuracy (incremental):

Center Thickness Diameter Radius of Curvature

+ 0.0002" (5 microns) + 0.0004" (10 microns) +  0.0002" (5 microns)

Traverse Rates:

200 I.P.M. (5 meters/min)

 

Spindles:

6,000 to 18,000 RPM air bearing, liquid cooled, high frequency synchronous motor. May be equipped with automatic collet or vacuum check. 1/2" x 1/4" step collet is standard.

 

Installation Data

Power:	208, 220, 230, 240 VAC, 1 phase, 50/60 Hz, 20 Amps
Air:	2.75 CFM @ 80 PSIG (4.7m3/Hr. @ 5.6 Kg/cm2)
Temperature:	68 to 74 Degrees Fahrenheit (20 to 23.3 degrees C)
Vacuum:	User Furnished 1.25" (3.2 cm) Diameter Manifold
Spindle Cooling:	Air - Supplied by User
Floor Space:	30" X 44" X 60" high (762mm X 1118mm X 1524mm)
Floor Weight:	1600# (726Kg). Shipping - 2000# (908 Kg)