design of an eccentric press

[Mattymecc]

hi mechanicalmg I threw down just two considerations:regarding the law of motion frankly I have some difficulty as well as for the clutch as it would be necessary the maximum couple that you have on the tree to which the eccentric is connected....
but of biella-eccentric systems I know little or nothing... If you have any formula or document to recommend I see if I can help you...

 

[meccanicamg]

hi mechanicalmg I threw down just two considerations:View attachment 67273View attachment 67274regarding the law of motion frankly I have some difficulty as well as for the clutch as it would be necessary the maximum couple that you have on the tree to which the eccentric is connected....
but of biella-eccentric systems I know little or nothing... If you have any formula or document to recommend I see if I can help you...

Thank you. from your considerations I understood how to calculate the engine for charging fly.
I have to understand how to properly transform the energy of the flywheel into final force and calculate the residual angle speed...but with the formulas indicated by you I should have everything.
I will certainly have to be able to divide the cycle at discreet intervals to see the times: brake, descent and climb. already so I can check the number of cycles with the charging time.
the maximum torque is to be evaluated between the inertial ones and the actual cutting one.
In the next few weeks I hope to be able to devote the appropriate time to study the phenomenon because in the next few months there is a machine.

 

[PIETRO2002]

If it can be useful, I'll attach you a pdf with copies of an old tech book.

 

[TETRASTORE]

ti indico this document that could be useful to you for brake-friction, but you wouldn't want to start examining and proposing to the customer a more current system as that proposed by siemens? in this case you would have their full assistance with their software even in the calculation.
of course it is to be evaluated with them if it is applicable to the type of shears you have to build.

 

[biz]

hi mechanicalmg I threw down just two considerations:View attachment 67273View attachment 67274regarding the law of motion frankly I have some difficulty as well as for the clutch as it would be necessary the maximum couple that you have on the tree to which the eccentric is connected....
but of biella-eccentric systems I know little or nothing... If you have any formula or document to recommend I see if I can help you...

your considerations for a maximum sizing are right. regarding the performance of couples in practice are complex, but also can be greatly simplified with linear traits, at least first approximation. A fluctuation coefficient or degree of irregularity is generally defined.
In these cases, the fluctuation coefficient "medium" is around 4%.
to explain everything comes a little long. I recommend shigley if you have a chance to consult him.

 

[biz]

Thank you. from your considerations I understood how to calculate the engine for charging fly.
I have to understand how to properly transform the energy of the flywheel into final force and calculate the residual angle speed...but with the formulas indicated by you I should have everything.
I will certainly have to be able to divide the cycle at discreet intervals to see the times: brake, descent and climb. already so I can check the number of cycles with the charging time.
the maximum torque is to be evaluated between the inertial ones and the actual cutting one.
In the next few weeks I hope to be able to devote the appropriate time to study the phenomenon because in the next few months there is a machine.

force depends on the eccentric biella system. that is, hypothesizes the length of the biella and net of the race, backwards, revenues the necessary force.

 

[Mattymecc]

Thanks to the biz board, the shigley I own it, I will take a look... I do not agree that the force depends on the tactical, in my opinion it is defined by the cutting tension of the sheet. will instead be dependent on the maneuvering the law of motion...
so at least I understood from the lessons of mechanics and machines of the 5th year itis.

 

[biz]

Thanks to the biz board, the shigley I own it, I will take a look... I do not agree that the force depends on the tactical, in my opinion it is defined by the cutting tension of the sheet. will instead be dependent on the maneuvering the law of motion...
so at least I understood from the lessons of mechanics and machines of the 5th year itis.

Let us understand, the force depends on the cutting of the sheet, but also on the maneuver. Think about it, if the biella is very long (we pass through the inertia of the biella), you will employ less strength, if the biella is very short, you will employ more strength. You know? therefore it depends also on the biella. Let us say that it is a fact that could be negligible in this case, but if you think for extremes the thing will be clearer to you.

 

[Mattymecc]

Sure. the force on the crank button whose tangential component determines the moment on the shaft is certainly function of the geometry, but also of the force applied by the biella on the blade that performs the cutting.. .
I explained badly at first, not saying what strength I meant.. .

 

[meccanicamg]

then, analyzing the question, I must start with the pulling/cutting force and that I must guarantee it generating with the press.

definitely this force passes on the biella and depending on the angle I get an effective couple to the eccentric tree.

clearly if I start cutting in square I have the maximum expression of press force. clearly the cut will last for a rotation arc of several degrees on the eccentric tree because cutting a broad sheet I will get a long blade engagement time. so as I work on an effective arm that regrets and therefore to ensure a cutting force greater or equal to the necessary one I will discharge a lot the flywheel because it will have to give me more torque.... because of the arm that decreases.
certainly it will be an important thing to return the rotation in a corner where at least too much with the fly. then it will be a compromise between blade angle, flywheel, biella geometry/handle.
If I can parameterize everything in excel then I worry about optimizing, even at attempts..... but first I have to make the model live....and that's where I'm concentrating.

 

[PIETRO2002]

ti indico this document that could be useful to you for brake-friction, but you wouldn't want to start examining and proposing to the customer a more current system as that proposed by siemens? in this case you would have their full assistance with their software even in the calculation.
of course it is to be evaluated with them if it is applicable to the type of shears you have to build.

very interesting the system siemens, where the mechanical system is removed fly / brake / clutch, replaced by a kind of electric "fly". definitely to deepen.

 

[meccanicamg]

ti indico this document that could be useful to you for brake-friction, but you wouldn't want to start examining and proposing to the customer a more current system as that proposed by siemens? in this case you would have their full assistance with their software even in the calculation.
of course it is to be evaluated with them if it is applicable to the type of shears you have to build.

the explanation document of the clutches is what I am already using and is done well to start.

the siemens system would like to deepen it to understand well what it is. it seems to me to understand that with the sevonotor you define the electronic cam and he produces the bike.
I hope I don't come across a rubber wall.
Thank you tetrator.

 

[meccanicamg]

If it can be useful, I'll attach you a pdf with copies of an old tech book.

thank you pietro, I love the explanations of the books "antichi" because they go on the practical and explained well.

 

[TETRASTORE]

for more information about servopresses see qui e qui.
Obviously it is a solution that the client should carefully consider as it would also affect his production system, so it would be necessary a cost-benefit assessment, even in the perspective that a traditional press / shears with flywheel can be used for decades and long go, with the current evolution of technology, could not be more competitive in a much shorter period than initially estimated.

 

[biz]

Clearly if I start cutting in square I have the maximum expression of press force

I don't think it's a good idea to start the cut in the square, because you'd need a big pair.
here to understand well it is necessary to prepare a nice spreadsheet and to prametrize everything, which, I suppose, you are already doing.

 

[meccanicamg]

I don't think it's a good idea to start the cut in the square, because you'd need a big pair.
here to understand well it is necessary to prepare a nice spreadsheet and to prametrize everything, which, I suppose, you are already doing.

In fact, I am already doing this and I will have some good problems because the force is really very high, that of cutting and it is a problem to keep it constant throughout the width.

 

[meccanicamg]

As I am trying to implement my spreadsheet, I put the link to the discussion on the flywheel, where there is important information and formulas.fly