CAD-to-Motion Tool Seals Curtain Bags

Seamless Operation: Automated gluing process operates directly from CAD drawings of airbags provided by auto manufacturers.

A new tool that generates motion control paths directly from CAD drawings is helping airbag manufacturer Automotive Safety Components International (www.safetycomponents.com) ramp up production for the fast-growing curtain-bag market.

To protect automobile occupants in rollovers, curtain bags that cover the side window areas must stay inflated for longer than a standard airbag, a requirement achieved by adding glue to the seam stitching. With demand for curtain safety accessories escalating, ASCI initiated a development project to automate the gluing process. In addition to developing an applicator mechanism, the machine would need to operate directly from CAD drawings of airbags provided by auto manufacturers.

Motion system solution

Motion control supplier Baldor (www.baldor.com) provided a PC-based solution using its MintNC toolkit, which imports information in industry-standard CAD formats including G-code, HPGL, and DXF, and then generates the required real-time motion commands. After importing an airbag drawing, the software executes an optimization script to turn drawing lines into a time- and movement-efficient path and streams the resulting motion commands to the motion controller.

The motion system that controls the gluing process consists of a motion controller card plugged into the expansion bus of the host PC, connected to three FlexDrives and BSM servo motors that control X-Y-Z axis movement. During operation, an airbag is cut into two halves by a laser, and moves into the machine one-half on top of the other. The Z-axis vacuum lifts one-half into the air, and a glue gun mounted on the X-Y axes moves in and deposits a 4-mm wide bead of glue around the edge of the bottom half. The Z axis drops back down and compresses the pieces together to create the join, and the glued bag moves along to the sewing stage of the process.

The new machine is a prototype that allows curtain bags to be produced automatically from a design drawing, and also provides a service that allows ASCI's automobile customers to evaluate and rapidly optimize their designs. The system speeds production by allowing the gluing process for these very large airbags to be performed in typically seven minutes. ASCI's goal is to develop the machine concept to provide production sites around the world with automation for mass-volume production.

Baldor provided the motion control subsystem used in the machine, and worked on-site to develop and optimize the control software. The software was simplified by using multi-tasking facilities built into the MintMT motion language that allow the control program to be broken down into a number of small individual tasks, such as homing the axes, controlling Z-axis movement, controlling the glue-laying X-Y axes, collision-detection algorithms, and other machine safety tasks. Some tasks run in the background, while others are called as required by the software's event-driven scripting environment. The motion control subsystem was implemented in one month, and the overall machine was developed and commissioned in just over four months.

The software toolkit allowed us to create a custom automation solution quickly and economically," says Eddie Hood, the development engineer at ASCI responsible for the machine. Hood says they could have been faced with a major custom software project that would have added additional cost and months to the project.

Tony Collins of Baldor says that if an application requires unusual contouring or profiling, manufacturers are often forced to adapt their process to use a standard machine or build a custom automation solution from scratch. By leveraging the toolkit, ASCI implemented software building blocks that helped rapidly assemble motion machinery to precisely meet production needs.

From CAD to Motion: After importing a drawing, software turns drawing lines into an efficient path and streams resulting motion commands to the motion controller.