Help required - solving electro-mechanical quagmire

[Denniswho]

I'm researching a problem. I need to control the position and leveling of a 5 foot long roller. A hydraulic cylinder raises and lowers the left end through two standard push-button energized 115 vac solenoid valves. As the left end moves, a 10 turn 5K helipot tracks the position. A reference voltage is used with a LM311N Dual op amp comparator chip which in turn, triggers a H11J3 Opto Isolator coupled to a SC141B Triac. The Triac energizes the respective solenoid valve causing a second hydraulic cylinder to raise the right end to the same level as the left end. The right end also utilizes a 10 turn 5K helipot to confirm the correct travel. There is also another triac controlled solenoid valve - used to lower the right end as necessary. This is all controlled through a printed circuit board. The board contains regulated power supply, two triacs, two opto-isolators, two dual op amp comparator chips etc. I was wondering if there is a different way of performing this task - without reinventing the wheel. Any input would be much appreciated. No pun intended

 

[bryan1]

Hiya Dennis,
The easiest way would be simply connect the 2 hydraulic cylinders via a levelling valve as used on farm tractors on the front end loaders no electronics needed apart from a few push button travel switch's.

 

[Denniswho]

Ref: electro-mechanical quagmire

Thanks for the noteworthy advice Bryan. That is definately a good way to go about solving my problem. However, This is an existing, piece of manufacturing equipment. The printed circuit board is obsolete and no-longer available, but all of the hydraulic plumbing and solenoid operated valving is in good order and must be utilized. A hydraulic leveling valve and plumbing changes would most certainly be cost-prohibitive at this point. I attempted to rebuild the circuit board myself - replacing the triacs, comparator chips and opto isolator chips. After repairs the board appeared to function properly on the bench - but failed to work properly when installed in the machine. I'm convinced that the problem is isolated to that printed circuit board. I'm no expert but I took all precautions against ESD while handling and was careful to solder effectively and quickly so as not to overheat any components. I am seeking advice for an electronic solution. Perhaps a simplified Forest Mims style board design or the purchase of a manufactured control module. I am appealing to the many electronics experts who frequent this forum for advice along these lines. Thanks

 

[Klaus]

I am wondering if there is a compelling reason to level BOTH ends of the rod.
If I were to design this I would fit one end to a swivel mount and raise/lower the other to get it level.

Perhaps you can disable one side mid range and see if its still possible to level that thing.
Of course, not having this device in front of me makes the above just guesswork.
Klaus

 

[Denniswho]

Thanks for your interest Klaus. The roller is used in forming sheet metal. Therefore, it is imperative that both ends are adjustable. In practice, the left end is adjusted up or down as required for a variety of thicknesses and bend radii. This up or down adjustment is constantly measured electrically with a 10 turn potentiometer mounted on the left end. The right end follows at a slight delay - according to the potentiometer reading on the left. An identical potentiometer is also mounted on the right end. Right end adjustment is confirmed and matched by the resultant measurement. So the lefthand pot senses direction and amount of movement first. The circuit then uses that information to instruct the direction of movement on the right end. The reading obtained from the righthand pot is used to measure and confirm stopping point. In a sense, the system actually does the leveling on the right end by moving to the appropriate level to match the left. When this operates properly, the balance and level is maintained.

 

[Klaus]

Thanks for your interest Klaus. The roller is used in forming sheet metal. Therefore, it is imperative that both ends are adjustable. In practice, the left end is adjusted up or down as required for a variety of thicknesses and bend radii. This up or down adjustment is constantly measured electrically with a 10 turn potentiometer mounted on the left end. The right end follows at a slight delay - according to the potentiometer reading on the left. An identical potentiometer is also mounted on the right end. Right end adjustment is confirmed and matched by the resultant measurement. So the lefthand pot senses direction and amount of movement first. The circuit then uses that information to instruct the direction of movement on the right end. The reading obtained from the righthand pot is used to measure and confirm stopping point. In a sense, the system actually does the leveling on the right end by moving to the appropriate level to match the left. When this operates properly, the balance and level is maintained.

Thanks Dennis, you see now how important it is to provide relevant detail in your post. It could have saved me typing my post :lol: as while I'm familiar with manually adjustable sheet metal rollers I have never come across an automatic one. Therefore I'm not qualified to comment :wink:.
Klaus