I am trying to find out precisely the force required of a cylinder on an assembly.
The answers to this question refer to calculators but they are not useful to me because the part to be lifted is not linear and homogeneous. It is a rather complex structure with a "basket" of several tens of kilos assembled by a pivot at a specific location.
Some people talk about the motion analysis tool but I have trouble using the function and can't find any tutorial.
If your system is mechanically 2D modelable, a simple sketch that deals with the problem graphically may be sufficient, without the need for other modules or applications. Otherwise, you have to use a mechanical simulation tool...
Can you at least give a diagram of your mechanism, to assess the problem?
I'm posting images of the construction. That's all I have at hand for now. The cylinder would come at the left end of the beam to allow the assembly to rise.
Making a 2D model is quite possible if it is the best solution for you.
At first glance, even with a 2D model, you have to use the motion analysis tool . Is there any interest in remodeling in 2D rather than performing the analysis in 3D?
In my opinion, an equation of force as a function of angle would be easier and faster than an iterative simulation since the movement is rather smooth (without sudden variation or shock...).
I'm doing some research, it's progressing and it shouldn't be complicated, it's just that it will be with the complement "solidworks motion" and (or) "design study", so if you don't have this module better use an equation,
Where is the cylinder placed? Does he shoot and where?
If the mass to be lifted is only the grey parallelepiped, it is easy to know the position of the CG. After that, if I understand correctly, it's just a basic lever arm calculation.
For the cylinder, what counts is the maximum effort for sizing.
Specify if it is an electric actuator (it is the easiest) or pneumatic or hydraulic but it all depends on the speed which I assume here to be very low.
It is a cylinder to help the movement, made by an operator, via the handle at the right end of the jib crane.
It can be placed elsewhere or otherwise, without any worries. Correct me if I'm wrong but the cylinder must be placed with its direction of force, tangent to the rotation of the jib at the moment when the force is greatest. In other words, the cylinder must be perpendicular to the jib crane when it has to lift the most weight.
I have Solidworks motion so I can do a proper motion analysis but I don't know the tool and don't see how to do this calculation.
If doing it by hand is simple, I'll go for it, but again, it's not linear. The gray parallelepiped has a center of gravity that is not always under the pivot throughout the rotary movement. Indeed, at approximately half of the rotation, the bell comes into contact with the double post, just under the main ball joint and then starts to follow the movement of the stem. I don't know if it has an impact on the calculation.
Since it is a lifting aid and not an "autonomous" jack. The calculation seems more demanding to me! The lift must be easy for the operator, therefore just below the weight of the assembly to be lifted , but if the force of the cylinder is calculated too strong, it may not hold in the low position.
Thank you for looking into this with me. It's really cool!
Obviously, your lifting system is mechanically flat. As a result, a 2D mechanical study based on sketches can be based on the existing 3D geometric model . It involves constructing a sketch in the assembly in such a way as to simply identify the key elements of the mechanism: connecting centers, directions, forces. Then to apply the few basic rules of "graph" statics.
Details of a possible study in the attached zip, in the form of a Word document and a template made with SW 2018.
I have come to read your last remarks on the fact that the cylinder must assist an operator. This changes the objective of the problem a little since it is a question of limiting the effort it must exert to ensure openness. To the static study should be added the effort of the operator (constant?) to deduce the law of the assistance that the actuator (or why not a simple spring) should provide. The framework of your study should be more fully defined...
That being said, the principles of using a sketch remain valid.
Two remarks following an intense reflection ;o) - a gas spring works by pushing, which is not compatible with the diagram I have proposed, in which the cylinder must act by pulling to lift the fairing. The geometric layout would have to be reviewed to make it work by pushing; - still on the basis of my diagram, the action of the cylinder should decrease by about 30% during the lifting, in an approximately linear way. However, the force of a gas spring varies little over the course of its travel...
Two reasons that make the gas spring unsuitable a priori. It might be a good idea to think about using a simple spring for support: - or a coil tension spring to replace the cylinder. He works by pulling, and his effort is reduced when lifting; - or a torsion spring installed at the pivot link between the frame and the tonearm.
A trick that we often see in foundries where the conditions are very or too harsh for the cylinders, they are replaced by stacked wafer weights.
This system also has the advantage of being modular if you change operator.
The fact that the effort is not linear is not a problem since you can have stops that limit the travel of some pancakes.
I did a comparable system but with springs where I can have a little variation throughout an important race. But in my opinion, the counterweight system is simpler to implement and above all less expensive.
@lynk thank you! I'm going to do this again with a motion. I admit it sounds deadly. Solaris is an aluminum mold oven for plastic chair shells.
This allows you to bring the mold on wheels and lower the oven from the top.
@Zozo I agree with you. I wanted to put weight weights first. It allowed me to manage to within 500g. But it's not cheap! It was cheaper to get a gas spring from our suppliers, hence the addition of this spring to the model.
