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markus_rothtechnik Founding Pro, Partner Posts: 15 Handy
edited June 2016 in Applications
This discussion was created from comments split from: Applications, Integration or Programming : Where should I ask my question?.
okay i'll be the first and post a challenge i am trying to solve. since i am a newbie to robotics i don't have years of experience to draw from :-)
a potential customer asked me to automate the task of clipping these plastic strips onto various aluminum profiles. they have a snap on shape and at the moment they do this by hand. thousands per day.
the aluminum profiles vary in width, length and shape. the region where the plastic strip snaps on is of course always the same. some profiles need these strips on one side only, some on both.
so far i have concluded:
1. handling these plastic strips is not feasible when they are shipped "unordered" and mixed in a box.
2. so first i would need to make sure they come ordered. see picture where they are layered. i talked to the Injection Moulder and he might be willing to set a UR10 ontop of his IMM. the idea is to stack the parts into boxes where they could not move. the boxes themselfes would be stackable too. this way alot of storage volume would be saved and also transports too. Problem: the parts deform when they cool. i don't know if they are completely done deforming when they arrive in the box or only 50%.
i don't know if this will me a big problem causing jamming etc.
3. at the assembly company i would install a UR10 as well, and the idea is that on one side there is a pallet or similar with stacks of aluminum profiles, and on the other side there are the boxes with plastic strips. the robot picks a profile and places it in a "vice", some mechanism that will hold the aluminum profile in place while the robot clips on the plastic strips.
4. the robot then picks a plastic strip (or two) and the robot tool itself has a clamping mechanism that will perform the clipping onto the profile.
A) the robot needs to know how many clips he needs to put on a profile, depending on the length of the profile. numbers range from 1 to about 4 or 5, so lengths of profiles are 200mm to 1200mm. ideas are: measuring system at "vice", vision system, touch-probing the sides to determine length.
The robot needs to know if he needs to clip only one side of the profile or both. easiest would be to make two stacking places, or two seperate programs. other thoughts are with selector switches or sensors / markers at the stacks. i tend to make things simple and easy, so at the moment i lean towards two stacking places. this will result in low autonomy times since stacks cannot be very high. so no running overnight.
C) additionally, once the plastic strips are clipped onto the profile, the ends stick out since the profile lengths vary but the plastic strips are of course always the same. they need to be cut. it would be great to do this with the robot too. my idea is to integrate a pneumatic clipper into the robot tool and seek the end of the profile (or calculate it when measuring system on vice is implement it).
5. Robot then places finished profile on a seperat pallet.
i don't know if all pictures are visible, i added 4 but i only see two.
any ideas, thoughts, comments are welcome :-)
Your 3 first steps seems ok.
After that it is becoming a little more complex.
First to determine the length of the metal profile you may want to use proximity sensor at different distance. If the first sensor is ON, then you got 200mm, if the second sensor is ON then you have a 500mm profile... Use a PLC or maybe it can be integrated directly into the UR controller (not sure) .
So then when your part is in the vice and the length is determined, you will be able to grasp the plastic part and insert the first extremity into the metal profile. To do so it would be nice to have a video of how the workers are doing it right now. Mu thought is that you would need some kind of force feedback.
Anyways, when the first section of the plastic part is inserted you will probably need to 'clip' the entire plastic part using the same approach/grasp/force feedback.
For the second side of the metal profile, I have no clue of to solve this.
Finally for your pneumatic clipper, it can certainely be done. Make sure to make it safe if the robot is working around human operators.
Mathieu Bélanger-Barrette Jr. Eng. / ing. jr
Proximity sensors is a good idea. They could be hooked up to the digital input of the UR. And you can then use these digital inputs in your program logic to figure out the length of the profile.
I think that pressing the first end is the way to go also. Once this part is clip I would simply move the robot across while maintaining a constant pressure against the part to make sure the clip snaps into place. For this I thing you would need a custom made roller as a tool on your robot. The roller would allow you to roll across the profile while maintaining a constant force to press the clip into place. The roller would also have to somehow guide the profile into place. What I have in mind would look a bit like a pulley but shaped in a way that it would fit your plastic clip and therefore guide it into place. What do you think?
a great challenge there!
I would try to beak this down and eliminate certain constraints for now.
Here are few additional notes.
separating the cutting process from the rest is probably a good idea to make the eoat simpler, and the process safer.
sensing the lengths with proximity might be impossible since the profiles can have any length from 200 to 1400mm. i would need something that measures, not only detects. but this is doable.
not sure if a roller is better than clamping it on all in one. this will depend on how we determine the exact position. there shall be no gap between the strips, and this means we have to touch probe the end of the strip to the previous one.
i will work the concept out more detailed over the coming days/weeks and keep you updated on the progress...
Beside the proposals with the tool and rolling which may work, I'd recommend to consider using the robot just to load aluminum profiles and plastic clips in two opposite fixtures and let a pneumatic cylinder do the clipping. It will be more stable and easier to handle.
In case you use the robot to load aluminum profile into the jig, you could use the force mode while sliding it in to push it against a reference edge. A few sensor along the aluminum profile jig would give you the length easily, fast and reliable. Now load the plastic clips with force mode into the opposite jig. Using force mode would ensure you have no gaps.
When finished, activate the cylinder and let it handle the clipping. End position sensor would give you feedback about success.
Unload by robot or use a pusher.
Developing your tool for the robot and setting up the application will take time. Doing all sensor detection and other jobs in sequence will make the process slow.
However it depends on your aluminum profile condition ahead of the process.
The beauty of this is that you take complexity out of the process which will increase stability and you only need robotiq and a UR for the loading so that part is going to be simple as you may already have it.