Page 15 - MetalForming September 2019

Modern Technologies for Metal Spinning
This article, the third of a three-part series on metal spinning processes and their tools, focuses on modern technolo- gies in metal spinning.
An automatic metal spinning machine in its most basic form consists of a headstock, tailstock and two-axis slide compound with a spinning roller attached. The numerical controls supplied enable the tool path to be CNC programmed off-line or at the spinning machine using teach-and- playback mode—sometimes referred to as programmable numeric control.
Early automatic machines utilized a template and single roller attached to a hydraulically actuated slide for form- ing, which also helped eliminate phys- ical wear on the spinner. Today, most machines have automatic tool change devices or a multistation turret with dif- ferent forming rollers, and cutting or trimming tooling ready to employ.
The first programmable technolo- gies were teach-and-playback control systems. An experienced metal hand spinner could create repeatable, pro- duction-ready spin programs in a rel- atively short period of time. This made spinners more efficient and adaptable to changes in the marketplace (e.g., lower volumes, more shapes, improved quality) and able to produce consistent parts over an entire production run. Software was intuitive and easy to use, even for those spinners with little or no CNC programming experience.
Peter Ulintz has worked in the metal stamping and tool and die industry since 1978. His background includes tool and die making, tool engineering, process design, engineering management and advanced product development. As an educator and technical presenter, Peter speaks at PMA national seminars, regional roundtables, interna- tional conferences, and college and university pro- grams. He also provides onsite training and consul- tations to the metalforming industry.
Peter Ulintz
Technical Director, PMA pulintz@pma.org
Software Transformation
The biggest trans-
formation in metal
spinning has been the
development of user-
friendly CNC pro-
gramming software to
generate tool paths
on a computer. Point-
and-click menus make
quick programming
possible. The use of
software embedded
G-code generators
eliminated the need
to know or learn G-
code programming
commands. Today,
user-interface software packages can be configured for specific types of spin- ning machines. Such packages provide enhanced machine safety, program- mable tailstock positions, axis-force control, secondary-operations posi- tioning, and in-process and production control functions. For long production runs and heavy or awkward shape parts, robots can be incorporated to handle repetitive machine-tending tasks.
Another transformative technology: live internet connections to the machine controls to provide machine manufacturers with immediate cus- tomer service feedback and trou- bleshooting in a matter of minutes.
Automatic metal spinning machines can replicate most everything a hand spinner does, only faster, longer and with greater repeatability. The greatest challenge with CNC programming: The metal spinning process takes years to learn and requires an expert to create the tool-path programs, and then refine them to make the machines produc- tion-ready, which may be the reason why older teach-and-playback pro-
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MetalForming/September 2019 13
Tooling by Design
In 2017 Abacus Maschinenbau introduced its vertical spinning machines to the North American market with polymer cast frames for better vibration dampening and a vertically mounted main-spindle that provides increased stability. Servo drives on all axes provide for high positioning accuracy and precise part reproducibility. Servo power eliminates warm-up time and the high service costs common to hydraulic machines.
By Peter Ulintz
gramming techniques remain popular. Like many metal forming profes- sions, metal spinning has met with little enthusiasm among younger genera- tions. This translates to a lack of skilled workers in this area for the foreseeable future. As a result, research continues in smart-programming methods that take a CAD model of the final part and automatically calculate a starting blank diameter, blank thickness and the num- ber of spin passes required, and gen- erate optimum tool paths. Although software applications can perform sim- ilar calculations for deep drawing and stamping applications, metal spinning requires the blank (workpiece) to rotate and to apply tangential forming forces. The complex kinematics and numerical models required to simulate, coupled with the current lack of scientific under- standing, means that the artisan portion of the spinning process will not be reduced to a fully computerized activity any time soon. MF The author thanks Dave Grupen- hagen, DG Associates, and other mem- bers of PMA’s Metal Spinning Division
for their contributions.