Design of a modular test fixture for hinges

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Hi all

I don' t know what  would allow me to put this post here, but every day we can  find the information in any  place (forum).

 

Well, I will share with you this post about the design and manufacture of hinge mounting tools suitable for a tensile machine in order to perform the required characterization tests.

First of all, these tests are the tensile and shear tests of the hinges, so axial loading, radial loading, and 90° stressing as shown below:

The problem where the requirement is to design a tooling that adapts to a hundred models and simultaneously performs the three types of tests! Let me explain, this means that the trials will be separated, in other words; On the same tool, we will do test 1, then test 2, then test 3 for each of the hinge models.
Well, I'll give you a few examples of the hinges for the test:

It turns out that there are two types of fastening, either by screws or by welding (3).

First, I took a look at the current tooling and found an example of tools that have split into two sub-tools, one directly related to the hinge and the other adaptable to each of all sub-tools.
To fully understand what I said, here are 2 minutes and more:

https://www.youtube.com/watch?v=xgWxiYc-yB8

So the reasoning is directed towards how to design modular tooling for all hinge references.
The problem is therefore with this tool, which contains the configuration of the different tests. Thus, it must also be a single "modular" tool and not 3 tools (depending on the type of test). In short, the problem is with the 90-degree test!

I want to know or think about how to think or how to examine this challenge.

I wish everyone a great day:)

Kind regards 

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Good evening @firasschafai 

Your problem is not simple because as we can see very well in the video, the tools must be 20 or a hundred times more robust than the part being tested. In addition, the spacing of the fixing holes (for hinges mounted with screws) is never the same.
Another difficulty is that the possible deformation of the tools must not lead to an error in the results of the part test.
In addition , there are different types of solicitation that change depending on the size of the object being tested.
So apart from very strong tools like the one in video, I don't see it.

We could use simulation, but the parts created in PART are not precise enough and do not take into account the stresses suffered by the hinge (e.g. hinges made of bent sheet metal. Also, the simulation remains in the elastic domain and will say nothing about the deformations in the plastic field or the permanent deformations that prevent the hinge from rotating.

Sorry but I don't see any other solution than those in the video which is still quite classic breakup tests.

Kind regards

PS: good the new profile  picture ;-)

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Good evening @Zozo_mp 

A good return with you. Always you are the first time to take the first shot ! 
 

Good for the choice of material concerning the tooling is after. 

Precisely, the different spacing complicates this tooling, but by the sub-tools so I'm talking about the part that must be connected to the hinge and the "mother" tooling it will be a little relaxed.

Yes, absolutely, the tooling must be extremely robust to transmit the test effort without "imperfections".

Good for the simulation, it's a bit deep now, because you first have to know the law of damage and then real tests to exploit the results like inputs etc...

Yes, this case is very close, especially when we are talking about a single tool that performs the 3 tests  for each hinge and with a 90° test  it will be "Mission Impossible" (a little laugh).
 

Kind regards 

PS: Thank you very kind;-)

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Hello

There would certainly be the possibility of separating the tool into several parts.  This limits the number of tools and greatly reduces the costs of manufacturing these tools.
By using guide shafts (as in injection molding machine tools or tracking tools for sheet metal parts).
I use this principle for the assembly of truck chassis, it is heavy but very effective.

However, it is utopian to want to vary the spacing infinitely for the screw holes. The same goes for  the distance between the fixing holes and the hinge axis of rotation.
I assume that this is still a subject in your studies.
In which case you could limit yourself to a dozen cases just to show that you are able to offer clever and reliable assemblies.

In real life;-)  a manufacturer like Pinet to name but one has more than 2000 references and they are dedicated teams for the certification of production.

Kind regards

 

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Hello @Zozo_mp

Well frankly, I lost a bit when you suggested that I make the guidance system that separates the tool into several parts.

But still the problem with the 90° test that will be forced to rotate the tool at this angle, so I think it is difficult for the system you proposed to do this function
(it's every day in my opinion).

"Make it as simple as possible, but no more so." Albert Einstein

Kind regards

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Good evening firasschafai

It is sufficient that the axis of the hinge and the tool is collinear. I don't see where the difficulty lies.

When I say in several parts, you have to consider what would be the main block on which the adapted fastener is attached. Look at the EV and counter VEV on a CNC bending machine.
After that, it is enough that the main support can be adjusted mainly according to the Y and Z axes and a little according to X, mainly for the thickness of the hinge.

Tell us what you've already imagined and I'll tell you what I'm thinking about.
This is a challenge for you ;-)  ;-)

"He has no genius without a grain of madness". Aristotle

Kind regards

PS: you did a great job to find the video "Testing tensile strength on hinges" because it's part of the trade secrets that we don't publish on the net.

 

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Hello @Zozo_mp 

Well sorry for this delay in answering.

Well, if I understood correctly and my imagination in the right place, the tool should be mainly in 2 parts; one fixed (I'll detail it later) and the other mobile (which is 90°).

For the fixed part, it consists of two sub-parts or we can make a single part (we will come back later) and at this point we find half of the hinge fixed with screws, it is good because the center distance as you have already said "infinitely" we can place a piece between the tool and the hinge.

For the second part where the mobile assembly is rotated 90°, it's almost like the first part but we add another part with a groove in this part to rotate the whole thing and a stop pin . 

I hope  I've worked or imagined  common sense, in the meantime I'm installing SolidWokrs 2k21 ;-)

PS: I forgot to make the link with this tool and the jaw of the machine the traction machine!

"There is always something absent that torments me." Camille Claude 

Kind regards 

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Hello@firasschafai

Keep the old versions of SW. Personally, I'm in V 2019 so I won't be able to read your creations anymore.

Notice that with images it is enough to understand what you are going to design.

The stop pin is not a good solution, you have to put ball or roller bearings depending on the maximum power possible on the largest hinge known to date from the manufacturer.
It must not be forgotten that the moving part of the system must be able to do the combined pulls according to XYZ and also according to Y in simultaneous rotation to the XetZ pulls

I look forward to your first images of the system you have imagined.

Kind regards

PS: when will you finish your studies. You should be in the last year if my calculations are correct! Tell us a little more about your training in Monastir (engineering or other ??? courses).

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Hello @Zozo_mp

Unfortunately, every day with my tardiness...

I think  I've  noticed things  now about the tooling, but I 'm not  a great designer, but  I think  I've managed to make sure after your intervention or to convey the  imagination of this tool.

So attached you can find the explosion of the tool's sketches.

Kind regards 

PS: Well, I 'll take a look  at my university curriculum ;  so after getting   my bachelor's degree in technical sciences with honors , I got my bachelor's degree in mechanical engineering , that I was in those three years the Major,  for this reason I took advantage of the engineering training that I participated in the competition for the engineering training , so I admitted with rank 1/5 in the ENIMonastir in mechanical engineering every day. (5 people who are admitted by the specific competition and not the preparatory one , because there are about  50 students of preparatory class  in the ENIM so the sum is 55)

Well, in Tunisia, you can enter the engineering training in two ways, either through the national competition with the preparatory (2 years), or through the specific competition with a bachelor's degree (3 years), each has its advantages and disadvantages, but frankly I chose to study at the beginning at ISETNabeul, It's a great training with a higher technician diploma / bachelor's degree, because it's more practical than the preparatory course which is similar to "a machine"... I forgot that I chose the CFM specialty (mechanical design and manufacturing) ... the famous story with the Design of the Shredder, Cardboard Mandrels with Screw Conveyor is my PFE (end of studies project)... (a little laughter).

And now, I'm in my final year of high school, so I'm in my last year for my engineering training and I went into simulation, so I chose the numerical mechanics option this year to enhance my knowledge of mechanics and also it's the right choice for me.

So it's time to talk with the PFE, that's why I'm engaged with the subject of our discussion as a proposal from my professor in collaboration with the industrialist that you are already marked but in Tunisia. So I have to work on taking charge of this project and I have to work autonomously as you know (a little laughter).

Yes, it's too much, but you have to explode the load...

Last word, for the pivoting part of the tool, I noticed in the gym a nice way to do this function .... yes sometimes there are in the river that there are none in the sea .... it happens.

 


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Hello @firasschafai 

Thank you for sharing your career with us and it is very good to have chosen this field which is sorely lacking in qualified engineers, especially in Tunisia.

Very well the best answer ;-)

Kind regards