The industrial production of wooden houses and prefabricated houses with timber frameworks is today highly automated. For the efficient assembly of the variously-sized elements for such houses, including connecting the various layers together, the manufacturing specialists Weinmann Holzbausystemtechnik GmbH in 72813 St. Johann-Lonsingen offer powerful so-called multifunctional bridges. In these, all necessary machining and connections can be carried out automatically on the parts and elements placed on the machine table.

Multifunctional bridges rationalise
the production of house elements

However, a multifunctional bridge can offer its full benefits only if the material-flow and material-handling periphery around it is also designed optimally. And this is where the specialist for the vacuum handling of all sorts of workpieces, Messrs. J. Schmalz GmbH in 72293 Glatten, comes into the picture. With two modular systems, namely the vacuum-tube lifter Jumbo and vacuum lifting device VacuMaster, Schmalz offer a wide range of vacuum handling systems which can be composed from standard components to meet almost every requirement. In close cooperation with Messrs. Weinmann, a complete production system with matched material-flow and material-handling system was built for a large company which produces prefabricated houses. This involved more than simply handling sheets of wood: the sheets to be handled varied widely in their composition (air-tight to porous) and dimensions (between 3,200 x 1,250 mm and 1,200 x 400 mm) with a maximum thickness of 22 mm and weights of up to 110 kg. In addition, cycle times are defined for each step and working station in the industrial production of house elements, which meant that the sheets had to be picked up quickly and safely and that the distance between the storage location and the machine table had to be taken into account. Since the elements of prefabricated houses are large, the multifunctional bridge is also very large, and the working areas of the two vacuum lifting devices installed in the system were 13 x 5 and 10 x 5 metres, respectively. The necessary aluminium crane was also planned by Schmalz.

Vacuum handling systems
improve efficiency

In the course of the various production steps. Sheets made of differing materials have to be loaded onto the multifunctional bridge. For this reason, two vacuum-tube lifters of the type Jumbo 110 are used, in covering part of the total area. They are suspended from easily moved aluminium crane systems to permit simple and fast movement and positioning of the sheets. The vacuum for the fast and safe gripping of the sheets is provided by powerful vacuum blowers mounted at the ends of the crane rails and connected to the vacuum-tube lifters by spiral hoses running along these rails. The vacuum-tube lifters pick up the sheets from a storage stack on the floor and place them on the machine table, which is about 70 cm above floor level.. For the ergonomical handling of the sheets, the vacuum-tube lifters have longer (1,250 mm) tubular operator handles of the type Ergo and a maximum lifting distance of 1,700 mm. In order to ensure that the sheets, of varying sizes and weights, are handled quickly, safely and without damage, the vacuum-tube lifters are equipped with dual vacuum heads. Each such head consists of a crossbeam with a length of 1,600 mm on which two suction pads can be moved to any desired position. Depending on the size of the sheet to be lifted, the dual head can be adjusted quickly and flexibly without the need for tools. A further special feature is the wireless remote control of the blower which permits the blower to be switched on and off from any position of the vacuum-tube lifter, with the aid of a radio transmitter mounted on the operator handle.

Vacuum handling leaves the user's hands free for
other work and saves personnel costs

The advantages of vacuum handling are so convincing that the house company also uses a further special vacuum lifting device of the type VacuMaster Window from Schmalz for lifting and inserting windows into walls on a production line designed especially for fitting windows and doors. In contrast to the vacuum-tube lifters on the Weinmann multifunctional bridge, these are crane-mounted vacuum lifting devices which grip the windows with suction pads and move them to the installation position. The worker thus has both hands free for the actual insertion task.
Vacuum handling equipment thus not only increases productivity and quality, but also makes the process more efficient by reducing the number of persons needed for the work. With conventional handling, at least two persons are needed to position the sheets efficiently; with the vacuum handling system, one person is sufficient while still achieving the desired cycle times. Since the flexibility of the multifunctional bridges from Weinmann means that they are also ideal for medium-sized woodworking and prefabricated house companies, the combination of automated production and materials handling with vacuum will become m more and more important in this sector, where firms also need to reduce their personnel costs and, at the same time, increase their productivity.