Looking for an effective and efficient means to grind complex workpieces? One way to handle tasks like this is a modular multi-surface grinding machine from Bryant Grinder, a division of Vermont Machine Tool Corp. The LL2U-MS can be configured as a chucker, shoe-type centerless, roll-type centerless, or center-type grinder, depending on your specific application. Which certainly means that this machine is flexible in operation.
The grinder has 10-in. of Z, X, and optional U-axis travel. The linear axes use the Bryant round hydrostatic way system that provides 300° of bearing wrap to assure accurate tracking. There are linear glass scales that provide position feedback with a resolution of 0.000004 in. on all linear axes. Axes moves are powered by liquid-cooled Fanuc linear motors that provide thrust of 6,000 N. The rotary axis for the workhead is powered by a Fanuc servo motor or by a Fanuc synchronous built-in DiS servo torque motor with a high-accuracy rotary encoder. (The "S" in the latter stands for "Strong" in that it is said to provide significant torque through the use of neodymium-iron magnets.) In the case of either workhead motor, it is a direct-drive setup to help assure that there is geometric accuracy during grinding, particularly in non-round applications.
When the machine is setup as a chucker, the swing diameter over the table is 14 in. When deployed as a center-type grinder, with a hydraulic tailstock and live centers, the maximum diameter is 4 in. and length 10 in. The center-type configuration can also be used with a chuck and a C-axis that permit O.D. grinding of non-round workpieces. When fitted with shoes, diameters up to 6 in. can be accommodated (hydrostatic shoes are available). Setup in a standard mode, the machine provides ±5° of taper. If the optional B-axis is used, ±45° can be attained.
The machine base is a cast granite epoxy. It features a thermal stability system that uses strategically located thermocouples to monitor temperature. An optional thermal control system uses the information from the thermocouples to allow the Fanuc 30 control and the Bryant Revelations software to make required thermal adjustments.
It is possible to swap out the standard bridge with an extended bridge and workhead option that permits the grinding of long, awkward parts that feature either bore depths or O.D. surfaces of up to 11 in. The aforementioned optional U-axis, stacked X- and Y-axes, and multiple wheelhead configuration, the machine can be used as a bore, face, and seat grinder for fuel management applications. Among the products available for the LL2U-MS grinder are high-torque wheelheads from 5,000 to 165,000 rpm.