FE Simulation of Ball Screws

Source: http://www.bs-wiki.de

The Ball Screw - The Drive Element

Ball screws are among the most frequently used drive elements. With the advancing electrification of products, they are also opening up new areas of application in which mostly hydraulic systems have been used so far. Prominent examples include actuators for presses and power steering systems as well as aircraft landing flaps and helicopter rotors.

Due to the new areas of application, new types of strains arise and thus ever greater demands on the precise torque force transducer. In the past, ball screws had to absorb purely axial forces, but nowadays they have to absorb large radial forces and tilting moments. In some cases, the loads exceed the yield strength of the material.

The classical methods of interpretation, such as i.e. the DIN Standards, are no longer sufficient because they assume an even distribution of forces on the individual balls and presuppose generous safety factors.

Whoever wants to save time and money in the design of heavy-duty ball screws and at the same time achieve high quality results for their customers, relies on the simulation of ball screws.

Simulation of Ball Screws

Correctly used, the simulation of ball screws allows an optimal design with very low safety factors. This is typically demanded by the aircraft industry for weight-saving reasons. Due to the precise calculation of ball forces and pressures, service life calculations can be carried out more reliably. Combined load cases are also not problematic - something that is otherwise only possible to a very limited extent in DIN-based design. In most cases, simulation can replace test benches, prototypes and tests. Furthermore, the influence of the surrounding construction (i.e. rolling bearing of the spindle etc.) can be taken into account in the simulation. The computer-aided engineering of ball screws ultimately allows automated parameter studies to select the best design from a wide range of possibilities. The most important achievement of the ball screw simulation is the adaptive optimization of the ball preload. The aim of adaptive ball pre-tensioning is to adapt the geometry of the ball track or balls in the individual ball chains according to the load so that all balls in contact with each other bear the same load as far as possible.

Pioneer Work in the Simulation of Ball Screws

We at Meshparts have a wealth of experience in the behaviour of ball screws and the most modern methods for efficient simulation of them. The "Simulation of Ball Screws" division has been being developed in our research environment since 2011 and is based on preliminary work that was carried out a few years before. Since then, we have continued the pioneer work of the simulation of ball screws with maximum efficiency. Maximum efficiency means high accuracy of results with minimal effort. This claim concerns the modelling of ball screws, their calculation and evaluation of results.

In the course of time there were many moments when we thought we had finalized the development of the simulation of ball screws. However, new ideas arose within the scope of customer projects and practical applications, which then improved our products beyond all previous efficiency limits. We are always wondering what else might be possible. We now know that development is never-ending. We do all this because of an internal driving force, that lays in the conviction that the manufacturers of ball screws need a simulation solution that was created in practice for practical use. We simply know that good software and services do not have to be expensive if the processes are optimized and specialized.

Two Solutions for the Simulation of Ball Screws

What can we offer you to simulate and optimize your ball screws? Our offer is structured as follows:

In both cases, the ball screws are calculated using Finite Element Analysis. Below you can learn more about these two solutions.

Simulations-App for Ball Screws

The web app for the simulation of ball screws allows you to configure a ball screw interactively. You can enter parameter values in the corresponding input fields and see in real time what the model to be calculated will look like. Afterwards, you can determine the boundary values (where what is held or clamped) and loads (where, which forces act on the ball screw drive). Finally, you can use the web app to order the simulation of your ball screw from us with the help of our software. Here you may choose the option:

  • Single Simulation
  • Parametric Study
  • Parameter Optimization

We will then send you a simulation report in HTML format within 24 hours. You can view the results in your browser and easily share them with your team. The simulation report typically contains the following results:

  • Animations of deformations separated from the ball screw (nut and spindle), spindle and nut.
  • Deformation curves representing the radial and axial expansion of the nut and spindle.
  • Displacements of the two spindle ends directly at the nut flange and at the flange side of the nut.
  • CSV file with ball forces, pressures, contact ellipses (length, width) and contact angle for each ball.

Software for the simulation of ball screws

Our software related to Ball Screw Model Library will be installed locally. You have the possibility to calculate any number of design variants of ball screws. The software is available as an annual rental license. We provide choice standard support (up to 8 hours per year) or intensive maintenance and support (8 hours per month). For this we recommend a four-day training, which you can flexibly divide over the course of a year.

Simulation App vs. Software

Whether the simulation app or the software for the simulation of ball screws makes more sense for you depends on several factors. The following is a comparison of the most important features within both products.

Simulation App

  • No license costs
  • No training
  • Simulation report is delivered by MESHPARTS within 24 hours
  • Plausibility check by MESHPARTS
  • Affordable (1000 EUR / simulation report)
  • Only one load case per job (forces and torques around all three axes)
  • Attractive packages for multiple applications and parameter studies or /-optimizations

Software and Ball Screw Library

  • License costs MP Software (10000 EUR / year)
  • License costs Ball Screw Library (3000 EUR / year)
  • Workshop (2-4 days of training)
  • Optional: Startup Package (4000 EUR/year for 40 hours of support including customer visits, training and education)
  • Unlimited number load cases
  • Free configuration of the simulation report
  • Any add-on parts can be added to the simulation.
  • Special nut geometry can be imported from CAD.

Personalised advice

Our ball screw specialists will gladly answer all your questions and show you which solution suits you best.

Just contact us.