giago

starter

22/08/2018 at 12:51

@strangemetalcutting yes, I use the catalog to choose the dimension, it seems correct.

Before this version, i was thinking to use a similar method, double shaft to drive shredder and extrusion separately, with a special coupler, see photo. The problem when you drive simultaneously shredder and extrusion is that you have to raise up the temperature of extrusion to prevent clog of cold and stiff plastic inside. So I’ve designed a coupler to transmit or not the power at the extrusion, see photo. I was thinking also a coupler that transmit power only to shredder if turns in a way, and transmit to shredder and extrusion if turns on the other way. I don’t not if it can works, if you want i can try to design in cad to better understand what i told you 🙂

@anne-barbier hi, thanks for you seggestion 😉 5hp motor is very powerful, I hope i don’t need all this power. Now i’ve collected one 550w and 1.3kw, with two reducer they run at 35/40 rpm. In my first prototype i’ve used 550w motor and the shredder didn’t lock often. Using a vectorial inverter I can use max torque power also at 1rpm, so I think i can work, obviously at lower rpm.

Motor is a crucial part, i want to use the power i need, not more. According to you can work this setup? Motor 550w + vectorial inverter.

Maybe redesing the shredder to have the knife smaller so it can run with less power?

I will start to draw machine on CAD on 15 of september, more or less. Before i want to brainstorm all idea, and mostly i’ve to study 🙂 so share all your thoughts and contribute if you like this idea 😉 cheers

Hi,
just adding some more input to your idea. In the attachment you see a 5Hp motor (1500 RPM) which is just enough to shred most plastics flawlessly with no jamming (it can however) and do extrusion at the same time. The couplings are stupid simple and have a lock bolt(10mm screw) and have to be at least 70 mm diameter. The lock bolt however needs to be at least 10mm, anything below will bend badly.
The 5Hp however pushes you in the 800 – 1000 Euro range for the whole drive part (reducer = 600E, 20:1, inverter= 200E, motor = 100E). The required couplings (both sides) for that would actually cost up to 200 Euro but you can do them with a Lathe/CNC in a day for around 100 in fees (aluminum, your min. labour).

So as you see, the only real ‘modular’ thing here are the mount beams and the frame. I can imagine to run a bigger shredder or 2 (with certain plastics only) with the same motor but it rather looks like that 10Hp would be a better choice.
Btw. I’d love run a semi-automatic injection on the same setup.

There is another guy here (precious plastic USA) who made the same, but a bit more pretty (see second picture) but i have no feedback/data on this one.

So next steps would be : get the plastic from the shredder out back into the hopper for re-shredding, and also to the hopper of the extrusion/injection 🙂
g

strangemetalcutting

starter

15/08/2018 at 14:34

There actually is a coupler that is already available that should work for what you want, they are what I have known as spiders or jaw couplers. The nice thing is they are an intentional weak point that will fail before damage occurs to either the power side or the work side.

Generally I use these in higher speed (1000-3000RPM), but they should translate over to what you need for low speed high torque applications.
If that doesn’t suit, I can probably provide you a different solution.

strangemetalcutting

starter

24/08/2018 at 14:35

@giago
Other thought(s), if you are working with a low RPM output and torque issues, you need a more aggressive means of power transmission than a belt, swapping over to a chain drive system would be fairly cheap and would work neatly as you can pull it off a bicycle.

If you’re clever about it you can even keep the derailer system and have a range of gears to get more torque for the shredding or higher speed.

strangemetalcutting

starter

18/08/2018 at 01:16

@giago page 77-79 of that catalog have jaw couplers and the information for calculating which one you should select.

A further consideration I’ve had recently is to used a dual output gearbox to drive a shredder and extruder off one motor, you’d only be able to use one side at a time, but both would rotate when the unit was turned on.

strangemetalcutting

starter

08/09/2018 at 14:14

@giago
Regarding the the gearing, I’m suggesting you use the gearing off a 15 speed bicycle and the chain from the same to give you a solid range of gears to work from and means of power transmission that won’t slip. The gearing and associated bits, I would think, can be pulled off. I can’t see to locate a good example on youtube for you to take a look at.

For the flywheel I’m suggesting you place it on the motor output shaft before your gearbox to act as a kinetic energy reservoir. That way when you do have those unexpected high load moments on the shredder there will be a greater amount of kinetic energy when high friction happens. It’s a similar method of storing kinetic energy that you’d find in a mechanical press:

Ref: https://youtu.be/T8R2dcLY1IE?t=30s

strangemetalcutting

starter

24/08/2018 at 12:27

@giago
I had a thought regarding your concern about the shredder binding or bogging down, have you considered adding a flywheel to the motor end to store centripetal force? It’s the trick used in some cars and several motorcycles that have lower RPM idles.

giago

starter

17/08/2018 at 21:24

Hi everybody,
So…

@fathullah87 thank you for your quick reply, and for your support. Very important for me 😉 thanks

@morethantencents I’ve seen their work on Facebook page. I’ll send them a message as soon as possible 😉

@strangemetalcutting this is very good idea for the coupler, very elegant more than mine 😉 Looking on SKF catalogue I’ve found FRC coupler at page 73. I think I need a 150 size with appropriate taper bushing 2012. I’ve calculated assuming a service factor of 2.0, 1.5 Kw of motor power and 50 rpm. Right? I really like this idea.

Thank you all, bye 😉

morethantencents

helper

15/08/2018 at 10:13

HI Giuseppe,

Monash University in Melbourne Australia have been working on exactly this idea and launched their machine about a week ago. They are marked on the Precious Plastic map and I am sure they would be very helpful if you reached out to them.

🙂

giago

starter

07/09/2018 at 15:18

Hi,

@strangemetalcutting I think we’re going little bit off topic. The image represents an old idea, that I have realized some months ago, but it didn’t work properly, like you say caused by belt slipping. I have posted those images only to show my idea regarding the coupler to switch off/on the extruder.
Returning to the modular machine why you say to put a flywheel? it can substitute the inverter? but how we can control precisily the rpm for thw extruder for example?

In these days i’m very busy and is very difficult to find time to think about machine. I hope the next month I will more free to get my hands dirty ;). For now I’m searching a place where I can work in my town for free or almost nothing. I hope well.
For the moment is all 🙂 Cheers

fathullah87

starter

14/08/2018 at 10:25

you have a good idea of combining all machines into one. if the machine can be de attached and attach to another machine it also good. moreover if portable much more awesome. by the way keep up a good work. farid from malaysia