The Altmann team designed and built a crane made entirely of stainless steel (V4A, 1.4571) without a chain hoist. However, implementing the project was challenging. molkerei-industrie asked Alpenhain about it.
The Altmann team designed and built a crane made entirely of stainless steel (V4A, 1.4571) without a chain hoist. However, implementing the project was challenging. molkerei-industrie asked Alpenhain about it.
"The crane system should serve our salt baths. Since we always plan sustainably for the future, the rails of the runway for the two hoists should not only be in the direct area of the salt baths, but right above the entire production hall, so that we can set up additional salt baths later, if necessary, without needing major structural measures additionally", explains Peter Hauder, technology project manager at Alpenhain. At the same time as the system dimensioned according to Alpenhain's requirements was in the planning stage, the structural analyses were being carried out, a procedure that took more than a year. The responsible structural engineer finally prohibited the transfer of vertical forces into the existing reinforced concrete ceiling in 2018, so that Altmann had to plan special brackets with conical washers to achieve a distribution of the reaction forces and a load transfer compatible with the building. The final official approval was given at the beginning of 2019, and in May 2019 the crane system was handed over to Alpenhain.
Automatic processes
The stainless-steel crane system with its two monorails serves two rows of salt bath basins. Since the supply and removal station of the cheese racks must also be covered by the crane, the total travel distance is 15 m each. The crane system is designed for a weight of 1,500 kg to be lifted. Each production batch comes into a salt bath in closed form, which was emptied of brine when the previous batch was retrieved, and which is then refilled with brine. The cranes grasp the cheese racks by using a support structure and set them down at the specified location in the salt bath. On the other hand, the racks are transferred to the removal station after the salting period. The system is operated via a radio remote control in "dairy version". All travel and hoist movements are regulated with frequency converters. Smooth and low-swing movements are made possible through individually adjustable braking and acceleration ramps in a large speed range. This is ensured by the controls that Altmann has not placed in the damp and corrosive environment of the salt bath zone, but above the hall ceiling in the attic. The operators can intervene at any time via a manual control, should this become necessary.
Altmann had to install the crane system above the already existing salt baths, so that scaffolding was necessary. Although the works were very complex, including numerous core drillings etc., the soft cheese production at Alpenhain was only marginally impaired.
Belt hoist made of stainless steel
In order to meet the hygiene standards of a soft cheese dairy, a belt hoist made of stainless steel 1.4571 was chosen. This hoist works almost wear-free and does not require any lubrication. All external surfaces made of stainless steel were ground smooth to Ra <1.6μm. The running wheels and deflection pulleys are made of plastic with FDA approval. The belt hoist has a low design and therefore a very good lifting height. The height conditions play an important role when whole cheese racks are to be lifted out of a salt bath. Martin Schaber, deputy head of the cheese dairy department at Alpenhain, particularly appreciates the belt hoist: "With the old system, we had to replace the chains every few months because they couldn't withstand the corrosive environment. The biggest problem, however, was that the chains had to be constantly lubricated, which implicated a permanent risk of product contamination".
A belt hoist made of stainless steel is no panacea either, the load belt at Alpenhain has already been changed once since the crane system was put into operation. However, it works with extremely low wear, which is a decisive advantage in the day-to-day routines of a cheese dairy. Alpenhain has charged Altmann with the maintenance of the crane system via a service contract. Once a year, two Altmann technicians come to the plant and usually finish their work after two hours. Peter Hauder is satisfied with the system, there have been no failures or malfunctions since it was put into operation.
Technical data of the salt bath crane system at Alpenhain:
o Lifting speed:0.5 - 5.0 m / min, converter-controlled
o Travel speed:5.0 - 30 m / min, converter-controlled
o Load capacity: 1,500 kg
o Classification: 3,200 full load hours
o Lifting height: 4,204 mm
o Pre and final shut off of cross travel at the end of the runway
o Pre and final shut off of hoist movement
o Radio remote control "dairy version"
Alpenhain
The family business Alpenhain is now in its 4th generation. Soft cheese and cheese specialties such as fresh cheese spreads ("Obazda", Camembert Cream), baked Camembert, breaded cheese and BBQ cheese make up an assortment that consists of around 300 individual items. With around 450 employees, including eleven apprentices, Alpenhain processes around 80 million litres of milk and generates sales of € 120 million. Approximately 19,000 t of finished products are produced every year.
Alpenhain added a new building to the Lehen location in 2020 (photo: mi)
