News

AMS Offers High Speed Video Capture Service: See What You Are Missing

7/6/2010 7:55:32 AM

As strange as it may seem for a controls developer, we spend much of our time trying to help customers troubleshoot mechanical problems. Often this relates to simple things such as encoder wheel alignment. In some cases, however, we are trying to solve problems involving high-speed presses, linear actuators or part handling systems. Our technicians are accustomed to using digital oscilloscopes to capture and view high speed electrical events and in some cases we can use this tool to measure mechanical events using accelerometers or other sensors/switches. We have recently added a high-speed video camera to our toolbox to help with particularly challenging problems.

At a max speed of 1200 frames/second (0.83 milliseconds per frame) we are now able to "see" things happen that would have been a blur at normal speeds. We filmed an air press at various frame rates to demonstrate the camera's abilities (click on link to view).

As you can see from the video, as the frame rate gets faster, the image gets smaller and a bit darker. To get good results at the highest speeds, it is necessary to really bathe the mechanism being recorded with a lot of light.

So what can you do with a high speed camera on a roll forming machine? Here are a few ideas:

Directly measure press dwell times

Directly measure press reaction times rather than using empirical methods (very handy!)

Accurately adjust die boost pressure and timing

Capture material crashes

See material movement and machine vibrations

In one situation, we were trying to determine the source of "ringing" in the line encoder signal on a servo flying shear application. We watched the closed loop diagnostic screen and saw the material speed oscillate wildly immediately following the shear hit. We suspected the vibration from the shear was affecting the encoder mount. It was easy to mount a dial indicator on the encoder mount, but the vibration was happening so fast, it was impossible to tell what the magnitude of movement was. By looking at the face of the dial indicator with the high speed video camera, we were able to see that the encoder mount was indeed vibrating in the X axis (direction of material flow) and this caused the "ringing".

Another great feature of this type of video camera is the ability to see backwards in time. If you need to capture a machine crash, you can put the video camera in a mode where it will continuously record until you hit a button. At that time, it keeps the last 5 seconds of video and starts recording normally. As long as you can start recording within 5 seconds of a crash occurring, you can capture the entire event in high speed.

We have also found the camera to be quite helpful for R&D. This video shows the improved performance provided by the 5840 "Slammer" module (click on link to view).

The 5840 was designed to improve the performance of air and hydraulic valves by initially hitting the coil with a high energy spike to get the valve moving faster and more consistently. This is important for high performance flying open loop applications. The selection of voltage (switch setting on the 5840) is based on the size of the valve. Larger valves need higher voltages. Smaller valves can "bounce" if too high of a voltage is selected which leads to less-than-optimal results. Although there are empirical methods for measuring press reaction times, it is so much easier to simply count the frames on the video to see exactly the effects of different voltages.

The next time you run into a tough roll forming control problem, give AMS a call. For a reasonable daily premium, our experienced technician can come to your location equipped with a high-speed video camera to aid with troubleshooting. Please contact your salesperson for details and availability.