Integration to improve the efficiency of machines and plants.

Dicembre 2014

What does integration mean?

Perhaps simplification, or reduction of the unnecessary, or at least a different way to design the structure of machines and their way of functioning. The past 30 years have seen an extraordinary transformation of the servos used for the movement of machines and systems.

The application of screws and recirculating balls moved by servomotors with permanent magnets were the first step of the evolution in the late 1970s and early 1980s. An example of simplification that I like to remember was determined by the transformation of embroidery machines (multi-needles) . To simplify, they are a large vertical plotter that moves in X and Y positioning a series of needles that create the points and fills, the mechanical handling of the axes was achieved by a real processor equipped with a mechanical punched tape reader and a kinematic mechanism formed by 3,800 mechanical details! All wrapped up in the "head" of the machine that was lubricated daily with a "mist" of oil!

In 1982 with a customer, we made the first CNC machine, two servo motors coupled with rack and pinion replacing 3,800 mechanical parts!

30 years ago this integration was the first step towards a horizon that, at that time, was only a dream.

Today, the ever more pressing need to reduce costs while simultaneously increasing performance and productivity of machines and systems requires a new way of interpreting the concept of systems integration of motion control.

Thirty years of technological progress have introduced new drive and control techniques, so precision screws and racks often give way to motors with direct load coupling, either linear, rotary or torque. Technology that is not entirely new as it was already available on the industrial market in the early 1990s, but experience in its use was consolidated gradually.

The first performances that improved immediately were speed and acceleration, supplied for the most part in frameless versions, which immediately required structural changes in the support structures and in the entire configuration of the machine.

On many occasions they have allowed brave and alert manufacturers to sign important contracts that provided a different and better positioning of their machines in their markets.

The diffusion of these motors is now very advanced, it is a reliable route today that is chosen not only to obtain the best speed and acceleration but also to improve efficiency or reduce the noise level of the machine, with current needs to find "green" approaches. Plant design and equipment should consume less, it is imperative, therefore, to reduce the kinematic and motion conversions, create simplified structures within which coils and magnets can be installed, to orient the forces in the desired direction to move the mass or implement pre-loads, and obtain rigid but light structures. The guidelines for the design of efficient plants (green):

• Light on mechanics but well designed (calculated and not improvised), possibly modular and with the control electronics mounted on board.

• Little wiring and reduction or elimination of electric cabin . It is the mechatronics approach, which of course requires up to date skills and advanced technologies including electronics.

The servo drives of the present generation are well suited to being integrated in the structure of the machine or inside the servomotor. The electronic components in large-scale integration (FPGA) and field effect transistors (FET AND IGBT) are getting smaller and more powerful. This increases efficiency and reduces heat dissipation, the structure of the machine is used as the radiating element to dissipate the residual energy. The IP 65 versions are in increasing demand and servo drives have become black boxes with Ethernet port connected in field BUS.

Ethernet-based field buses have greatly contributed to accelerating the trend towards integration and modularity, today the most widely used in the automation market are EtherCAT, Sercos 3, Profinet, Ethernet IP. The BUS transmits commands and receives the status of the servo drives (servo drive network) at high frequency so as to ensure synchronisations and interpolations in real time. The servo is in effect an intelligent peripheral connected to a network and has high computing power. The control loops (Position, speed, current, torque) are controlled by complex algorithms capable of reading the behaviour of the load and auto-regulating gains. Dynamic performance is optimal in respect of the structure of the machine and its efficiency.

Servotecnica, always focused on research of advanced solutions, has consolidated more than 25 years of experience in motor applications in direct collaboration with industry leaders, now it offers a wide range of solutions that are characterised by technological excellence and services based on years of experience .

Emilio Bistoletti

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Lingua: IT - EN