Linear technology solves aerospace stress
New precision linear technology has helped a specialist UK motion control company address a critically important issue for one of the world's leading aerospace companies.
When this aerospace company needed to ensure the stress state of aluminium arriving at its production site, it turned to Henlow-based Ansell Motion Control for a test rig. In turn, Ansell turned to Hampshire-based Oriental Motor to deliver the precision needed for the application.
Oriental Motor's 'EZLimo' linear actuator range combines advanced stepping motor functionality and sophisticated motion control features and houses them in an easy-to-use linear motion solution. The range uses an Oriental Motor stepping motor with built-in feedback system and closed-loop control to ensure stable operation. The motor, ball screw and feedback system are all housed in a compact body.
In this application, the EZLimo units and drivers are used to control the position of aluminium test billets - representative of material destined to become wing spars - throughout a milling operation that is used to determine the residual stress in the material. The 'Wide Slot Stress Analysis' rig machines a slot, to a depth of up to 60% of the depth of the test billet, at a variety of increments between 0.1 and 1mm.
The manufacturer measures the deflection of the far end of the 12-inch long aluminium billet after each pass of the cutting tool, the stress levels within the material can be determined.
The calculations, performed by software developed by a UK university, use figures supplied by Ansell's test rig, including depth of cut, step number and the amount of deflection - measured by LVDTs. These figures are used to generate a stress value for the particular batch being tested. According to Andrew Sell of Ansell Motion control: "The deflection is not always uniform, a bar could bend downwards during the first cuts and upwards towards the end of the process. It is the LVDT figures we are interested in, in relation to the cutting schedule.
"I chose the EZ Limo unit because it cuts a huge chunk out of my design and development time. Because the actuator is all self-contained, it is simply a case of mounting the actuator and marrying the end of the rod with the component that needs to be moved - I do not have to worry about the alignment because it is already there."
