1 year ago

MDA Technologies 2/2014

MDA Technologies 2/2014

Machine elements

Machine elements Benefits of lubricant-free linear drives in special stackers The Jungheinrich factory in Lüneburg is solely relevant for special stackers and modified serial devices. It produces many industrial trucks. Learn why lubrication-free linear drives are used in the special constructions. Jungheinrich AG from Hamburg is the number three in the world among the manufacturers of forklift trucks. The company’s six factories produced about 73,200 forklifts and other vehicles for material flow in 2012. The Lüneburg factory is responsible for special stackers and small series in the production association. Partially, present devices from the large series are modified according to customer wishes there as well. Many devices are newly developed from scratch, with the engineers being able to make use of the complete construction kit of serial production. that the stacker only transports ten carts, the front of the clamping device has a triangular sheet that limits the number of carts that can be taken along. However, there are also other destinations where more carts can and should be transported. The wings can be turned out for this.” The constructor therefore faces the task of moving the triangular sheet up and down “The pair of aluminium guide and plain bearing elements warrants smooth running” A special forklift truck The special low-lifting vehicle that Jungheinrich recently built in Lüneburg and delivered to a big Scandinavian dairy company seems rather confusing at first glance. Where any normal load handling device has a double fork for taking up pallets, there is only a single fork and a single caster here. Looking at the chassis, this is a kind of “reversed” three-wheel stacker. The missing second fork is compensated for by an additional book-like load handling equipment in the third dimension. The reason behind this construction becomes clear as constructor Dipl.-Ing. Aimo Helbach explains the purpose: “The vehicle collects rolling carts throughout the dairy operation, pushes them together and takes them to the infeed position of an automated washing system.” This task requires only a single fork that the driver moves between the rolls of the carts. When operating the lifting function, he clamps the carts against the upper, fixed load handling device, and can drive even longer distances safely without losing any carts. Linear system extends its “wings” Jungheinrich has already built several such special stackers for various dairy companies. In the current project, the persons responsible were looking for an additional function. Aimo Helbach: “The washing system takes up ten rolling carts. To ensure by a motor. This is done with a linear axis from Igus’ Drylin SHT range with trapezoid thread and 60 mm movement path. The ball-bearing lubricant-free spindle linear table was delivered by Igus ready for installation with compact DC motor and end-position query. A wedge of wear-proof plastic translates the linear to a swivelling movement and ensures that the wing-shaped sheets swivel down by 30°. The corresponding command is issued by the operator at the jet pilot. If the wing pair is to swivel upwards, the Drylin system will turn in the opposite 18 MDA Technologies 2/2014

Machine elements 01 The Drylin SHT linear axis works wear and lubricant-freely 02 Aimo Helbach (left) explains the surrounding construction of the linear drive to Igus sales consultant Christian Wille 03 The linear system is shown in the installed condition here 04 A trapezoid thread with hand-wheel ensures quick adjustment of the jet pilot in the vertical axis direction, the wedge will clear the movement and a spring warrants retraction of the wings to the “top” position. The ideal sliding pair of aluminium guide and plain bearing elements from the high-performance polymer Iglidur J warrants calm and quiet running; the spindle as such is made of steel. The system is controlled by a multifunction micro controller Jungheinrich developed specifically for the special vehicles. High demands to ergonomics This drive constructed by Aimo Helbach translates one movement into another in two locations — from the rotating motor to the linear movement of the linear system, and then on to a swivelling movement. The system has proven its worth in all test runs. It is not the only one that uses a linear axis by Igus either. An individual solution was constructed when designing the operator’s workplace as well. Aimo Helbach on this: “Conventional low-lifting vehicles are operated via a tow bar and have a folding driver’s platform. Since this special device passes very long distances, however, the drivers desire a standing platform that they can lean onto.” Operating unit can be comfortably adjusted In this case, the stacker functions can be moved better with the multifunctional Jet-Pilot steering wheel than with a tow bar for reasons of ergonomics. To give stacker drivers of different size and build the perfect driving and working positions, the Jet-Pilot can be moved in the longitudinal direction, i.e. in its distance from the driver, by 50 mm. This linear movement is also performed by a Drylin axis. Here, Jungheinrich chose a Drylin SHT-Ssystem with a steep thread that is moved via a rotary wheel. This axis is, like the electromotor drive in the fork, characterised by maintenance-free dry running. The good sliding properties of the linear system are particularly important for this. When the operator adjusts the position of the jet pilot, he will apply leverage that is not perfect according to the law of physics. The Drylin unit, in contrast, is slidingcapable and puts the jet pilot into the desired position without shaking. Right after the driving and function test that every special stacker is subjected to and acceptance by the customer, the device went on its way North from Lüneburg. Now it completes the stacker fleet of the large dairy company, which includes many other Jungheinrich stackers as well, with a true specialist among the forklift trucks. About Company name: Igus Established: 1964 Headquarters: Cologne, Germany Turnover: approx. € 400 million Employees: 2,200 worldwide Products: : plastics for longer life - e-chains, plain bearings, linear bearings, piston rings, low-cost automation MDA Technologies 2/2014 19


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