Machine-tool trends II

Last week, the focus of this column was on developments in machining centres, as well as drilling, milling and turning machines. In this second contribution of emerging machine-tool industry trends I home in on some of the opinions expressed by those experts who compiled the ‘closing report' for VDW (the Association of the German Machine Tool Manufacturers) for at the EMO Hannover 2007 concerning grinders, as well as metal-forming machines and sheet-metal machining centres.

GRINDERS
In years past, machine tool manufacturers focussed on optimising the actual machining process, namely on reducing peak times. For this reason, there are not expected to be great leaps forward expected, unless, that is, significant progress is made by component manufacturers.

Therefore, in order to minimise this dependency and achieve a competitive edge, a few machine-tool manufacturers have developed methods for specifically reducing nonproductive time.

In fact, one grinder manufacturer has implemented the objectives mentioned in a new CNC grinding centre by integrating a grinding disk changer and a pick-up loading unit into the working area, thus achieving a high degree of automation, which, in turn, raised both productivity and repeat accuracy.

A particularly efficient solution for reducing nonproductive time unveiled at EMO Hannover 2007 was the incorporation of nozzle elements for injection pumps, used by motor-vehicle manufacturers, into a new grinding machine. The machine has been so constructed that the required cooling jet does not just fulfil its actual function, but is also used for transporting the work pieces. In this way, the time taken for changing work pieces has been reduced by over 50%, to 0,9 s. Since the grinding process for these nozzle elements only takes a few seconds, the whole machining process duration was considerably reduced.

METAL-FORMING AND SHEET-METAL MACHINING
For metal forming machines and sheet-metal machining centres, too, the trend towards shortening nonproductive time is a major theme, with technical challenges arising in this area being solved by EMO Hannover 2007 exhibitors in very different ways.

A further and very important topic for manufacturers and users of metal-forming machines and sheet-metal machining centres is the reduction of manufacturing costs.

In order to meet both requirements, manufacturers showed the results of their optimisation attempts and of their machines that had been improved in terms of construction details.

In sheet-metal machining, the requirement for laser-welding equipment is increasing, since the demand for accuracy, particularly for tailored blanks and profile sections, is increasing. In previous years, great progress had been made in this area, and these tasks had in the meantime been converted into standard procedures in the machining units.

In order now to reduce costs, it appears that laser machining and machining centres will now become more compact and flexible. Over and above this, they will be offered with integrated automation. For example, a directly-linked loading and unloading unit, making the hitherto employed pallet-changer superfluous. This should reduce the footprint, which in turn will be able to be used to best advantage for tasks to be carried out.

The operating speed for the latest laser-machining devices is limited by the mass of the work piece to be moved. Here, the so-called flying optic (laser head) is the optimisation device, which is moved using highly dynamic motion sequences at speeds of up to 200 m/min and acceleration of up to 20 m/s. In order to achieve this mass reduction by lighter and more stable structures, various types of lightweight construction are employed in these machines.

Cold massive forming was likewise exhibited at the trade fair and focussed on shorter processing times. Through innovation, high-tensile materials can be rolled, using optimised thread rolling machines, economically and with maximum precision, even for short runs.

Along with thread making, gear cogs, worm gears and other profile sections are also cold-rolled. For instance, a machine concept was presented, which is able to complete gear cogs within 46 s.