One company's radical new design—a non-reciprocating table— demonstrates a fundamental rethink of grinding-machine technology.
An upper-mounted carrier/wheelhead executes X-axis movement for both creep-feed and reciprocating operations on a Dominator surface grinder.
Because of its nonreciprocating table, a Dominator surface grinder is rigid, compact, and a perfect candidate for automated part loading/unloading.
Jones & Shipman, Leicester, U.K., wasn't thinking conventional surface grinder while developing its new machine with a non-reciprocating table. Eliminating the usual back-and-forth table keeping parts still, a more compact size, enhances structural rigidity, and, most creates a dual-grinder.
Called the Dominator, it performs both creep-feed and reciprocating operations. A carrier/wheel-head executes the main X-axis movement for either operation. Mounted top of the bed, a saddle the entire carrier/ assembly and traverses front to back for Z-this also puts motor at the which dissipates heat more readily. The machine's table lower along the Y axis, but that is its only movement.
Relative to a compact geometry, Dominator's work envelope measures 600 3 300 3 400 mm, and a 7.5-kW motor (18 kW optional) drives the 355 3 50-mm (400 3 50 3 127 mm optional) grinding wheel. A substantial cubed bed sustains the work table on widely spaced, preloaded slides.
Contrary to standard designs, Dominator's moving-mass size is virtually constant, varying only due to relatively small losses from wheel diameter reductions. This fixed-minimum than that of a reciprocating workpiece. In addition,
J&S engineers have achieved a virtually zero coupling at the carrier-V by keeping the wheelhead light but stiff.
Dominators feature a Windows-based man-machine interface (mmi) that presents straightforward routines for both grinding and wheel dressing. Operators, using a pendant-mounted panel or remote handset, can select manual override feedrates, and movement for emergencies. Fanuc Series 180-MB controls grinding system via a PC included is a J&S-developed graphics user interface, color screens, and spreadsheet-style programming.
A compact machine enclosure surrounds the grinder's frame and packages it as a one-piece unit that includes the temperature-controlled electrical cabinet. A great advantage of the system is that coolant does not slosh around, as on a conventional reciprocating table, and its effect is more predictable. In addition, because there are no horizontal slide-ways below the wet grind zone, operators needn't worry about way contamination.
The machine is designed lower than technology previously permitted, making heavy part loading easier. Working height doesn't change, regardless of short or tall parts, and the wheel/work-piece interface is readily visible at all times. "Since the workpiece is stationary, inexpensive pick-and-place robots mesh perfectly with a Dominator for loading/unloading parts," says company president Nelson Beaulieu.
In response to strong comments from the field, he goes on to say, J&S is currently building a smaller version of the Dominator. Beaulieu foresees the greatest interest from electronics and aerospace industries and facilities housing 'banks' of surface grinders.
Typically, aerospace companies manufacturing small turbine blades are forced to grind them on large creep-feed machines. This, he says, can add high hourly labor to a part that doesn't have enough built-in profit to justify using a $500,000 creep-feed grinder.
In situations where a line of surface grinders does sequential part operations, a single smaller Dominator has the potential to replace up to four or five machines. One operator, taking advantage of indexing units, multipositioned fixtures, and the Windows-based controller, can set up a Dominator for several different grinding operations. Consequently, using both creep-feed and reciprocating modes, companies can reduce the number of necessary grinders in a production line and eliminate a lot of part handling between machines.