A/B Rotary Head Turns Heads

The A/B rotary head module on Cincinnati Lamb’s new HyperMach rail-type plate mill might not be the first thing to catch the attention of aerospace shops. Perhaps it will be. This head is designed to be compact and powerful, yet exceptionally stiff at high feed rates in heavy cuts. Such performance is the key to productivity when milling aluminum plate to make large monolithic aircraft components.

What these shops might notice first about the HyperMach family of vertical machining systems is that they are big, fast and powerful. For example, the first production unit of the plate mill model, which will be shipped from the company’s new Hebron, Kentucky, production facility in late spring 2004, has X-axis travel of 70 feet (21,336 mm) and Y-axis travel of more than 10 feet (3,250 mm). Linear motors on both axes provide maximum feed rates of 2,400 ipm (60.96 m/min.) The standard spindle from Fischer on the A/B head has a continuous rating of 130 hp (100 kW) for speeds as high as 18,000 rpm. It takes HSK100-A toolholders. The digital controller/servo system is a Siemens 840D; the linear motor systems are also from Siemens.

What sets Cincinnati Lamb’s machine apart appears to be the A/B rotary head module. According to Randy Von Moll, manager of product development, the twin ballscrew design makes this head reliable yet simple. Because it is more compact and has less mass than an A/C gimbal head mounted on a tall Z-axis ram (the style of most high speed aerospace profilers and routers from Europe and Canada), the A/B head is proving to be exceptionally stiff, he says. The HSK100-A tool interface tolerates higher radial forces and is less susceptible to damage in a minor collision than the smaller, HSK63-A interface that is more common for this class of machine.

Although the A/B head provides the tilt and swivel for simultaneous five-axis machining, rotary motion is limited to ±40 degrees in these axes. This feature helps minimize the size and mass of the head, yet allows machining of aerospace geometry, where pocket walls and similar features rarely exceed 30 degrees from normal. Inexpensive right-angle attachments allow the machine to drill or mill features outside of this range for single-setup machining.

According to Mr. VonMoll, the overall design objective for the HyperMach family was to produce high performance machines that would 1) require a lower capital investment than comparable machines from overseas; 2) account for lower annual operating costs; and 3) be less expensive to install and maintain for reduced life cycle costs. The company has been able to meet these objectives, he says, because of the extensive computer simulation used in the line’s development. This effort involved developing a computer model of the exact characteristics of the control unit and feedback system. In other words, the simulation reflected the influence of position loop performance, servo gains and so on, upon on the dynamic stiffness of the machine.

The modular design of the HyperMach family also helps keep manufacturing costs down. By mixing and matching modular components, various configurations of HyperMach models can be constructed with a streamlined engineering cycle. For example, the A/B head can be replaced with an A/C gimbal head for milling of aluminum and cured composites on five sides or for drilling and routing operations. Along with the rail-type traveling gantry models, bridge-type moving table models can also be specified. Other configurations include bridge-type twin-table plate mills and twin-spindle gantry models.

The introduction of these machines marks a turning point for Cincinnati Lamb. The company has largely completed the move of its Cincinnati Operations to new production facilities in Northern Kentucky. Sales and marketing efforts between the Cincinnati and Lamb brands have been coordinated. Efforts to re-establish brand identity are also well underway. The HyperMach embodies the company’s renewed commitment to advanced technology in the aerospace field.