Hi All,
I'm working on designing an automatic machine / tester that will open
and close a water tap for about 200,000 cycles (to ensure that the tap
complies with BS5412 (1996)Clause 12).
The requirement of the standard is to open the obturator in the tap to 90% of its maximum opening and then to close it with a torque of 1.5 N.m. These are the normal half inch diameter household taps.
Currently I am looking for ideas on how to close the tap with a torque of 1.5 N.m and then to open it automatically. I am familiar with PLCs and electronics with a bit of mechanical knowledge. I am thinking DC motor connected to gearbox conected to a 'breaking torque' device. The DC motor can be reversed for opening / closing and the breaking torque set to 1.5 N.m.
However I am not too sure how accurate and repeatable a breaking torque device can be. I also have this problem where the torque required to reopen the tap (after it has been closed) is higher than the closing torque. Do breaking torque devices work in one direction only or both? The tap would probably not open again if they work in both directions.
Other Questions: 1. Am I on the right path? 2. If you were going to design the system that opens and closes the obturator, how would you do it? 3. Any recommendations on what to use for the torque control? 4.How do you interface the torque device to the PLC so that the PLC can tell that the tap has been closed?
Thanks Manvinder S. Bhullar
The requirement of the standard is to open the obturator in the tap to 90% of its maximum opening and then to close it with a torque of 1.5 N.m. These are the normal half inch diameter household taps.
Currently I am looking for ideas on how to close the tap with a torque of 1.5 N.m and then to open it automatically. I am familiar with PLCs and electronics with a bit of mechanical knowledge. I am thinking DC motor connected to gearbox conected to a 'breaking torque' device. The DC motor can be reversed for opening / closing and the breaking torque set to 1.5 N.m.
However I am not too sure how accurate and repeatable a breaking torque device can be. I also have this problem where the torque required to reopen the tap (after it has been closed) is higher than the closing torque. Do breaking torque devices work in one direction only or both? The tap would probably not open again if they work in both directions.
Other Questions: 1. Am I on the right path? 2. If you were going to design the system that opens and closes the obturator, how would you do it? 3. Any recommendations on what to use for the torque control? 4.How do you interface the torque device to the PLC so that the PLC can tell that the tap has been closed?
Thanks Manvinder S. Bhullar