Spaceform series: bus door handles with Siemens NX

Portfolio Description

Product: Bus door handles
Software used: SIEMENS NX
Project: Design of a new line of bus, industrial and special vehicle door handles

The client

PRIMA INDUSTRIES is a leading company for the design and manufacturing of automotive products and accessories.

The software

For the whole duration of design and engineering, each handle model was checked with structural calculations by means of the NX SIEMENS integrated module together with the SolidWorks Simulation module.
NX SIEMENS is ideal for 3D modelling and easily enables generating parametric design surfaces that can effortlessly re-adjust to dimensional changes. We can produce 2D drawings that are automatically updated based on 3D changes.
SolidWorks Simulation is the best software platform to calculate movements, deformations and stresses of the components subject to internal and external loads.

The project

The customer wanted to place a new line on the market of handles suitable for buses, industrial and special vehicles, starting from an already defined innovative design.
The project was so aimed at making the initial idea functional through a study and engineering process always taking into account the client’s needs.

The challenge

A draft was submitted to Project by Prima Industries, i.e. a pre-set visual to start with and design the whole Platform series. That represented an important aesthetic constraint that should be taken into account by the whole engineering process, to combine with structural constraints.
The handles should be fabricated with a UV-resisting material, capable of withstanding low temperatures and with a high breakup load.
The threshold for breakup is important not only for the handle’s operation, but also in case of tampering (vandalism or theft), as the pressure can cause internal elements to get broken, preventing the opening by the driver.

The solution

We have kept the original design, while working on different functions and positions of the handle. The shell is the same and as such that the number of moulds is reduced, but each model has its own technical particular features for the operation.
Moreover, as requested by the customer, the P600 has been manufactured in three different versions: manual, pneumatic and electric. It can be supplied with or without reflector and integrated LED light. We succeeded in keeping the physical characteristics identical, by reducing costs and maintaining the same product quality and safety.

Our action

We began with a prefeasibilty study of the original idea.
In particular, we focused on the structural mechanics optimization by studying and analysing the static deformations and state of stress of load-bearing handles, while considering the whole set of moving components.
For the P600 model, besides those studies, several use simulations were necessary, to verify the handle compatibility with the three matching locks.
Regarding the breakup load, as the case had already been defined and was therefore “blocked”, we decided to act on the type of material to use and consulted Mr. Enea Negri of Nevicolor in Luzzara, a plastic materials specialist firm. The company provided us with several samples of reinforced material with glass fibres that could have suited our needs. However, as the moulds were already in production, we chose to use the pre-set plastic material and work on the ribs. Rib overlapping is a process that requires a lot of monitoring, as in the cooling phase external depression sections may develop due to uneven shrinkage of the material. Therefore, we decided to start a structural double checking for which two types of software are used, to compare results and be more confident about the seal of internal spaces.

The result

We managed the entire design process with a simultaneous overlapping to check that the line maintained the same design and a perfect optimization of the production processes for the components interchange.
The engineering process allowed us to obtain a safe, resistant and versatile product, while complying with the customer’s costs, times and constraints. With rendering, we made visible the work done.
We also drew up a component list for an easy estimate of bills of materials, and production cycles and times.