In many cases, the handling of materials in sales and production handling still offers a considerable potential for rationalisation. In a typical example, rods and bars are usually unloaded from the delivery truck with a crane and placed in the stockroom. When an order is received, one or more rods are taken from stock by hand, moved to the machine tools (such as a power saw) and either placed in the magazine or clamped on the machine table.

Depending on the diameter, length and weight of the rods and bars, this may be a difficult task and two persons may be needed. In addition, the machine is stopped for a considerable time while this is being done, and the standstill times can, in the course of a day with many sawing operations, rapidly accumulate – a considerable cost factor. Furthermore, the manual handling of the rods or bars also incurs the risk of injuries to the operators. The responsible persons at Hydro Aluminium Alutubes GmbH, which produces aluminium tubes used mainly in the manufacture of axle supports and other structural elements in the automobile industry realised that this was the case in their factory.

Depending on the job, the aluminium tubes have to be taken from a storage rack and placed in the magazine of a power saw. Once the required length ash been cut off, the remainder is returned to stock, which means that it is quite possible that these short tubes will have to be handled again. Until recently, the rods and tubes were handled manually by two persons – an unproductive task with ergonomical drawbacks.

Taking advantage of potential rationalisation effects

For this reason, the management at Hydro Aluminium Alutubes GmbH decided to implement a more rational material-flow system and asked EFS-Handlingsysteme to develop, construct and install a flexible handling system for aluminium tubes with various lengths (max. 7,000 mm) and diameters (35 to 90 mm) and with a maximum weight to be handled of 160 kg.
This maximum weight results from the fact that up to seven tubes are handled together in order to achieve efficient loading of the machine magazine. After a technical examination, EFS decided to use a vacuum handling system, for which it obtained support from the vacuum specialists at J. Schmalz GmbH in 72293 Glatten. EFS was responsible for the complete handling device, the wall crane, the vacuum crossbeam and the project management, while Schmalz planed and manufactured the complete vacuum system.

This vacuum system had to meet the following requirements: safe handling of both long and short tubes of various diameters and weights; no bending of the tubes (even long ones); flexible and easy adjustment of the suction pads to match all tube diameters; universal use of the vacuum-gripper system to pick up complete layers of up to seven tubes or to pick up other configurations by the individual positioning of the vacuum beams or rows of suction pads; safe and efficient operation by a single person; suitable for use in multi-shift operation.

Thick or thin, long or short …

The handling solution implemented in close cooperation between EFS and Schmalz consists of a wall crane with chain hoist, which has a working area of X = 4,000 mm (up to 9,000 mm would be possible), Y = 6,000 mm and Z = 2,340 mm. The vacuum crossbeam is designed such that the distance between the rows of suction pads can be adjusted very quickly, with a single operator control, between 30 mm and 100 mm, permitting handling of tubes with diameters between 35 and 90 cm. In order to permit gripping of both short and long tubes, 240 individual suction pads are mounted at carefully selected intervals on the beam.

These suction pads of the type FSG have 2.5 corrugations, a diameter of 32 mm and a ¼“ vacuum connection. They thus adapt themselves well to tubes of varying diameters and their long stroke when vacuum is applied ensures that each layer of tubes is lifted from the layer below during the evacuation step.
The individual main beams of the vacuum-gripper system are connected to the vacuum generator by separate hoses in order to permit them to be traversed separately for handling different tube configurations. The crossbeams also act as vacuum distributors, thus considerably reducing the number of hoses needed.

Suction pads which become worn or damaged can be replaced quickly, without the need for tools: they are simply pulled off and a new pad is snapped into position. The vacuum is provided by a central vacuum pump.
The entire handling operation is now more efficient, flexible and safe. Even the longest tubes can be positioned precisely, without bending or sagging, the suction pads permit universal use of the system for all types of tubes and the crossbeams, which also act as vacuum reservoirs, hold the tubes securely, even in the case of a power failure, until they can be lowered safely (a non-return valve prevents inadvertent venting of the suction pads).

The experience with the vacuum handling devices has been so good that Hydro Aluminium Alutubes GmbH is now using three systems of this type and is thus working more productively and with considerably lower costs.