APPLIED TECHNOLOGY SOFTWARE
SOFTWARE SUPPORTS THE MANUFACTURE OF GEARBOXES
Almost one in four new cars in western Europe are made by Volkswagen. The Group, in fact, comprises 12 brands from seven European countries: Volkswagen Passenger Cars, Audi, SEAT, ŠKODA, Bentley, Bugatti, Lamborghini, Porsche, Ducati, Volkswagen Commercial Vehicles, Scania and MAN. The company’s primary transmission site at Kassel supplies almost four million manual and automatic transmissions every year, and includes a light-alloy foundry to produce aluminium and magnesium housing components. The plant also reconditions old engines and gearboxes, and manufactures 3.5 million exhaust systems each year. Here, the engineers use RomaxDESIGNER
software on a range of standard and non-standard investigations to support the effective production of manufactured gearboxes. Juri Kniss, calculations engineer, said:
“We’ve used RomaxDESIGNER for more than four years. As a factory site, our focus is not to design gear sets, it’s to ensure the gearboxes we manufacture are consistently of the required quality. Using it, we can assess the effects of gear manufacturing variability within
a fast and accurate simulation.” The engineers use RomaxDESIGNER to
analyse existing designs and assess how the tolerance variability of gear microgeometry will impact on the NVH of the finished gearbox. Kniss added: “Romax allows us to do this
by integrating rapid modelling and analysis of gears, shafts, bearings and housings within a single gearbox model to predict how components interact with each other.” It is also being used to predict bearing
preloads required for a new EV gearbox, which was achieved by calculating the interaction between three shafts and the electric motor, and to look at which rings to mount in the factory. “The housing hasn’t a great degree of
stiffness, leading to complex interactions,” explained Kniss. “So we want to change the bearing preloads and see the effects, to identify the correct settings to use when manufacturing the gearbox. To validate the methodology we set up a test rig to compare results and were able to see that Romax provided a good validation.” RomaxDESIGNER was also used to
analyse the fit between the motor stator and the gearbox housing, to predict any
housing deformations and the resulting effects on the gears and bearings. During the gearbox assembly the stator
is fitted into the housing, resulting in an interference fit and a degree of deformation of the housing, which causes some displacement of the gearbox bearings. The interference fit was modelled externally and the bearing displacements then applied as preloads to the Romax model. In this case the company had a highly detailed model that it could apply to all of the bearings, to examine the effects of the interference fit, with different shaft misalignment predictions being evident along with different contact patterns for most of the gear sets. The Romax misalignment predictions were then passed to colleagues in Wolfsburg to support optimisation of the gears, enabling them to apply this to calculate new micro geometry, to reduce noise and improve durability, etc.
Romax Technology
www.romaxtech.com Enter 200
MODELLING AND SIMULATION HELPS TARGET TRACKING
When developing a controller for servo-actuators on a target-tracking radar gimbal, Blue Joule Corporation turned to Maplesoft Engineering Solutions for assistance. A gimbal is a platform that can rotate about an axis – by combining two, an object on the platform can be pointed in any direction, which is useful when you want the gimballed object to continuously point at a moving target. For example, a tracking radar on an aircraft is mounted on a gimbal mechanism, allowing it to maintain a fixed lock on a ground position as the airplane changes altitude, direction and orientation. A target-tracking radar uses a gimballed antenna along with
controllers and servo-actuators to lock onto a target and maintain this lock as the target moves. A servo compares the commanded position from the controller to the actual measured position and rotates to correct the output angle accordingly. Should either the measured or desired angles change, then the motor rotates to compensate. A well-designed, well-tuned tracking radar quickly turns to the
desired angles and tracks the target as it moves. Blue Joule needed to create a controller that could determine the angle each motor should be in order to maintain a lock on the target, in a way that is fast enough to keep up as the target moves. Determining the angles using traditional modelling tools is slow and requires several iterations as the process
6 MAY 2015 | DESIGN SOLUTIONS
is typically based on numeric computation techniques. Using a symbolic approach makes the process faster and presents
the ability to be treated as an inverse kinematics problem - a term to describe problems where the desired end position is known, and the problem is to determine the angles needed in the mechanism to achieve the motion that will get there. As a solution, the team used Maplesoft’s MapleSim, an advanced
system-level modelling and simulation tool built on the Maple symbolic computation engine, to create a model of the aircraft, the gimbal mechanism and the target. MapleSim’s multibody analysis tools can be used to generate the dynamic and kinematic equations of motion. These constraint equations, when incorporated back into the model, can be used to quickly calculate the desired azimuth and elevation angles during the simulation. The values are the set-point values for the servo motors on the gimbal. Once testing is completed, code to calculate these values can be automatically generated from the formula so that it could be executed on the controller itself, in real time. As a result, a controller that keeps the tracking radar gimbal in the correct position can be developed.
Maplesoft
www.maplesoft.com Enter 201 / DESIGNSOLUTIONS
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