Production Machining - EMO 2004
       
 


More and more manufacturers are requiring their precision machined parts suppliers to enter into just-in-time (JIT) relationships in which smaller order quantities are supplied at more frequent intervals.
That trend would suggest reduced use of rotary transfer machines. However, Italian machine tool manufacturer Buffoli Transfer S.p.A. has introduced the Trans-Bar 55+, a CNC rotary transfer machine that adds flexibility and fast set-up capability to the productivity for which such machines are noted. The new model is a 12-station transfer machine with an indexing table (turret) that rotates on a horizontal rather than vertical axis.
A Hirth coupling ensures indexing accuracy and repeatability.
The slug is secured in a self-centering chuck or collet on the turret, and the turret indexes to present the part to each machining station in turn. The basic version of the machine is equipped with ten machining spindles, but up to 27 spindles can be installed on the right, left, top and bottom, machining the part from every direction in as many as 40 separate operations.
One version of the machine accepts two bars for simultaneous machining. The machine can also be equipped with three-axis CNC machining units and attachments that increase its flexibility.
For example, a CNC profiling head, which rotates about the stationary slug, permits such operations as facing, turning, recessing, contouring, grooving and single-point threading, all with low-cost standard inserts.
“The user can program our CNC profiling head to generate anything from complex OD contours to single-point threading. The profiling head can be reprogrammed to provide simple change-over between part profiles and can be moved from one station to another as required by the job.
Buffoli also offers an indexing milling attachment that uses straddle milling cutters to generate hexes, squares, octagons and other shapes at a single station. Buffoli three-spindle turret head is still another attachment that accepts up to three tools so that it can, for example, center drill, drill and tap the part at one station if cycle time considerations permit”.
The attachments can be moved from station to station as required and installed in a left, right or radial position
. As many as seven contouring and multi-process attachments can be installed in the machine at one time (two left, two right and three radially).
They provide the level of flexibility that the user needs to support JIT manufacturing. Set-ups for completely different parts typically run from 30 to 90 minutes.
The machine's CNC control also helps incorporate a diagnostic program that helps plant personnel identify and fix problems fast to keep downtime to a minimum. The program not only provides an alarm, but it also displays a digital image on the screen identifying the problem.
The software provides some 2,000 error messages that identify the problem and the fix needed to get the machine up and running again.

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