Press Release Summary:
Used for internal and external grinding of small workpieces, such as fuel injector nozzles, Precision Spindle workhead utilizes hydrostatic bearings that provide radial and axial stiffness of 2,200,000 and 1,995,000 lb/in., respectively. Unit comes with precision variable speed AC motor operating at up to 6,000 rpm, and hollow spindle shaft for power actuated workholding devices. Measuring 14.5 x 6.3 x 7.7 in., unit employs non-contact air seals to prevent oil contamination.
Original Press Release:
Random Axial and Radial Motion Error under 10 Millionths Guaranteed!!
Design Integrates a Precision Variable Speed AC Motor
Gros-Ite Precision Spindle of Farmington, Connecticut, a division of EDAC Technologies, has introduced an extremely accurate, high speed, base mounted, direct driven, motorized workhead spindle for critical grinding applications. This design utilizes our hydrostatic bearing internal construction to eliminate the non-repetitive errors associated with rolling element bearings. Further, this concept integrates a precision, variable speed permanent magnet spindle motor to eliminate errors induced by the varying forces of typical belt drive systems. A hollow spindle shaft is included for power actuated workholding devices. These compact workheads are only 6.3" wide by 7.7" high by 14.5" long.
The Gros-Ite Precision Spindle workhead was developed specifically to improve productivity, surface finish, and workpiece quality simultaneously. These workheads are generally used for internal and external grinding of relatively small workpieces, such as fuel injector nozzles, requiring a high degree of repetitive accuracy in terms of concentricity, roundness, and surface finish.
The selection of materials and the execution of precision in processing the fabricated internal components result in the final guaranteed accuracy. In addition to the inherent accuracy, the hydrostatic bearings in this workhead provide a radial and axial stiffness of 2,200,000 pounds per inch and 1,995,000 pounds per inch respectively, as measured at the spindle nose face and axis correspondingly. The temperature controlled oil input for the hydrostatic bearings is 900 PSI for the radial bearings and 340 PSI for the axial bearings. The total oil flow is 1.8 GPM. Specially designed, non-contact air seals are employed to keep the oil in the spindle and to prevent the ingress of coolant and other contaminants such as grinding swarf from getting into the spindle.
The integral liquid cooled variable speed permanent magnet AC motor is capable of operating up to speeds of 6,000 RPM. This totally enclosed motor has a continuous power rating in excess of 9 HP, a peak torque rating of nearly 20.7 lb-ft, and a continuous stall torque rating of over 12 lb-ft. An encoder is incorporated for speed control feedback. The motor requires liquid cooling using 70°F water base oil coolant at the rate of 5.6 GPM. The liquid cooling also provides the added benefit of stabilizing the base to centerline dimension.
All Gros-Ite Precision Spindles, including our hydrostatic bearing spindles, are thoroughly tested in our test facility. The tests are run in the actual operating position or attitude as the spindle is utilized on the machine. During the testing cycle, vibration characteristics and temperature rise are monitored and recorded. The test proceeds sufficiently long enough to establish an acceptable stabilized maximum temperature at eh maximum speed.
Upon successful completion of the basic dynamic testing, accuracy measurements are taken and recorded using non-contact gaging instrumentation and computer software to provide assurance of compliance to the standards set forth by the Gros-Ite Precision Spindle Engineering. Final static dimensional measurements are then recorded. Copies of all final quality control data are included with the shipment.
Gros-Ite Precision Engineered Spindles:
A Division of EDAC Technologies
1798 New Britain Ave.,
Farmington, CT. 06032
Tel: (860) 677-2603, 800-851-2654
Fax: (860) 677-7344
Gros-Ite Precision Spindle
Tel: (860) 679-7474