Marginal Column

System with perfect proportions

High productivity in a small package. SMI satisfies this demand, put forth by the solar collector industry, with an automation concept devised by Rexroth and incorporating a number of different technologies.

 
Photo | SMI s.r.l.

The back absorber plate and the flow tubes are joined in this welding line.
Photo: SMI s.r.l.

The welding line is the heart of the manufacturing process for thermal collector panels. This is the line where the two main components – the absorber plate and the tube assembly – are joined one with the other. This is a complex procedure and a request for bids issued by Buderus, a Bosch Thermotechnik brand, made special demands. The 13 processing stations involved here were to occupy no more than 80 square meters of floor space. The Italian tube machining specialists at Sistemi Meccanici Industriali (SMI) took up the challenge and soon identified the correct approach to the solution: Saving space by automating.

The answer: automation

When implementing this concept, SMI called on the automation specialists at Bosch Rexroth to serve as their project partners. From the very outset cooperation went far beyond the simple delivery of components. Developers from both companies worked out construction drawings right down to the last detail and carefully selected the appropriate components. Thus it was possible to make all the processes within the system fully automatic – from deep-drawing the sheet metal through to welding work. Combined systems comprising electromechanical axes, pneu­matic actuators and vacuum clamps are the “prime movers” for every step in manufacture.

The pneumatic system from Rexroth, using the serial Drive & Diagnostic Links (DDL), makes it possible to control the entire unit with just a few field bus couplers. Over and above that, a number of different valve systems and pneumatic cylinders are used. Rexroth delivered the MKR modules to power linear motion, complemented by both ball and roller guide tracks.

“We especially appreciate the ruggedness of the axes,” emphasizes SMI general manager Sergio Campeotto. “This feature was decisive for maintaining the strict tolerances specified for the project.” The deep drawing process was planned by Fluidotecnica Impianti, an authorized Bosch Rexroth sales partner. That company’s engineers solved two problems. A pump with screw-type rotors keeps down noise while careful regulation of valve actuation times prevents annoying pressure surges.

One operator, many formats

When planning the very few steps that the operator has to execute by hand, the developers paid attention to avoiding typical sources of error. The Japanese “poka-yoke” principle, for in­stance, precludes inserting the wrong parts. And changing between more than twenty potential product formats is facilitated using machine handles and automatic clamps. Thus only a single operator is needed to run the entire line. For SMI this is the icing on the cake and achieves the major objective of maximum automation.