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[giulia94]

Good morning, everyone.
I'm designing a plastic injection mold with screwing.
the element material is a pa6 loaded 30 % glass.
I should unscrew a thread diameter 85 step 5 with 5 ridges.
I wanted to use the system with gears and racks.
Some of you can help me understand how many dense wheels and how many you have to use.
I forgot I have a module 2.
thanks in advance to all

 

[Fabietto]

Bye.
depends on how much space you have in the mold, and in the press. .
the complete execution of the thread is about 1335mm
You need to get on the road with the cylinder. .
so to nose you must have at least 1/4 ratio between the 2 wheels. .
ps.
vague memories of when I made tanks before 2000
pss.
I used at least 3-3,5. .

 

[giulia94]

Bye.
depends on how much space you have in the mold, and in the press. .
the complete execution of the thread is about 1335mm
You need to get on the road with the cylinder. .
so to nose you must have at least 1/4 ratio between the 2 wheels. .
ps.
vague memories of when I made tanks before 2000
pss.
I used at least 3-3,5. .

Thank you! but excuse ignorance, if I put a wheel toothed by 80 teeth at the rack and one from 25 to my screw-up thread, shouldn't I shorten the rack race?
I don't know the calculation to do to understand how to reduce the length of the rack and make it work.

 

[giulia94]

Thank you! but excuse ignorance, if I put a wheel toothed by 80 teeth at the rack and one from 25 to my screw-up thread, shouldn't I shorten the rack race?
I don't know the calculation to do to understand how to reduce the length of the rack and make it work.

per se stampo ho un 296 x 246

 

[Fabietto]

Sorry, I didn't get it. .
Maybe to understand it is better if you put a pattern of unscrewing.

 

[giulia94]

Sorry you're right. This is a fast pattern. with three dense wheels and a rack.
the rack will be connected to the toothed wheel you see in green. the thread that must turn is that block in dark green. the red mushroom instead will be screwed into the bottom plate and will remain firm. I don't know if these gears can work. Thank you very much

 

[Fabietto]

Okay.
from what I remember also the pattern used by us in the tanks was equal.
our module was 2.5.
You need a lot of cylinder racing, but it should work. .

 

[giulia94]

Okay.
from what I remember also the pattern used by us in the tanks was equal.
our module was 2.5.
You need a lot of cylinder racing, but it should work. .

Thank you very much, I ask you one last thing. will my rack be 1400 mm long or can I reduce it somehow? Thank you.

 

[Fabietto]

No, it'll be shorter. .
from the thread you need to unscrew:
5 thread ridges=5 turns of dark green block=5 turns of pink wheel
5 turns wheel pink=2.5 turns wheel yellow=2.5 turns wheel green
2.5 turns green wheel * dp50 * 3.14= 392.5mm cylinder stroke. . .

That's when you count on the fly, of course you have to keep some margin.
I hope I didn't do anything wrong.. It's been years. .

If I can give you an opinion, I don't like the third plate driven by springs that pushes on the piece while you screw up.. it gives me the idea that it can ruin the thread, especially towards end of unscrewing.
Clearly that if the system already tested it in other cases, then you already have experience on it.

Hi.

 

[giulia94]

No, it'll be shorter. .
from the thread you need to unscrew:
5 thread ridges=5 turns of dark green block=5 turns of pink wheel
5 turns wheel pink=2.5 turns wheel yellow=2.5 turns wheel green
2.5 turns green wheel * dp50 * 3.14= 392.5mm cylinder stroke. . .

That's when you count on the fly, of course you have to keep some margin.
I hope I didn't do anything wrong.. It's been years. .

If I can give you an opinion, I don't like the third plate driven by springs that pushes on the piece while you screw up.. it gives me the idea that it can ruin the thread, especially towards end of unscrewing.
Clearly that if the system already tested it in other cases, then you already have experience on it.

Hi.

Thank you so much! I'll update you at the end of the project. However, I also thought about that problem, and I thought I'd change it and carry out the parade as if it were the extraction table.
Thanks again

 

[@ndreaR]

Thank you! but excuse ignorance, if I put a wheel toothed by 80 teeth at the rack and one from 25 to my screw-up thread, shouldn't I shorten the rack race?
I don't know the calculation to do to understand how to reduce the length of the rack and make it work.

I'd like to point out that the fabietto account comes back to me, from what I see if you want to change the rack race you have to act on the wheel transmission reports. However, you have to understand that constraints on the problem, such as the whole of the tree in the sky and the red rod if it must be of those 67.08 that are marked.

 

[giulia94]

I'd like to point out that the fabietto account comes back to me, from what I see if you want to change the rack race you have to act on the wheel transmission reports. However, you have to understand that constraints on the problem, such as the whole of the tree in the sky and the red rod if it must be of those 67.08 that are marked.

Hi! I have no constraint for size, but I would not like to create a huge mold. to reduce the footprints in your opinion, could I go direct or, rack and only one wheel attached to the thread? as the situation in the 2d with pink wheel and green male. if you which toothed wheel should I use? Thank you.
I hope I've explained well

 

[Fabietto]

Bye.
if you attack the pink wheel rack:
5 thread ridges=5 turns of dark green block=5 turns of pink wheel
5 turns pink wheel * dp60 * 3.14= 942mm cylinder stroke. . .

the cylinder of course you have to protrude it from the mold (296x246), but not knowing the press planes, it goes wrong to evaluate everything.
Surely it will not be a big press, 100-150ton, and then you will have clutters to respect (columns, hatchons etc.) so it is likely that the cylinder will have to put it up or down mold. .
to save some space the rack can put it in parallel to the cylinder, instead of in a stem axle.
But you have to see all the mold assemblies to make these evaluations. .

Consider that, in my experiences, tanks with 4 threaded ridges, and transmission ratios similar to yours, we had 320mm rush cylinders. .

2 questions. .
Do you already have experiences on similar movements, applied to such small molds?
Have you already evaluated alternative movements?

 

[giulia94]

hello thank you so much for being so helpful.
Unfortunately I have never had experience with screwing molds.
as alternative methods, I have not evaluated as the customer demands the rack.
I would exclude the solution of a single gear, and continue the design with the solution seen yesterday of the 3 toothed wheels and the rack.
I would only reduce the size of the plates, and then approach the gears.
should work right?
I can also ask you how I could move the parade plate (yellow plate, but you'll know better than me) ? I peeled the springs, to avoid tearing the thread. I thought I'd put another external piston to move the parade.

 

[Fabietto]

the parade plate, to fulfill the task you hypothesized, you have to move in sync with the unscrewing, so I see it hard to move it with a further cylinder. .
the unscrewings that I designed, the thread was always fixed in part mold, and therefore the unscrewing happened to closed mold.
I don't think anything about your case right now. .
other thing.. how do you ensure that the piece does not roar during the unscrewing? Does the upper part (red tag) have a shape that prevents you from turning? or are there ribs in that upper area?

 

[giulia94]

I'll attach you a picture, I have two turrets that brake me. in the photo see the element on the mold. I thought to print so: the mold opens, the unscrewing begins (and the element unscrewing progress), then I start the parade plate with a second cylinder.

 

[Fabietto]

Okay, but...
or parade plate let you leave when the thread is completely unscrewed, and therefore it only helps you to extract the piece from the green male (I think at this point I go by fall from the mold),
and then you have to do at least the plate race equal to the height of the green male.

or it does not serve anything, because the piece will already be detached from the walls, thanks to the deformed, and the 2 semicircular ribs at the top will already be extracted thanks to the advancement of the piece in do of unscrewing. .

 

[Fabietto]

and just for..
Where do you inject the detail?
I hope in the top, in 2 opposite points, with a channel that goes normal to the section you did. . .

Last question. .
How much is the annual production of the particular?

 

[Giogo]

Sorry you're right. This is a fast pattern. with three dense wheels and a rack.
the rack will be connected to the toothed wheel you see in green. the thread that must turn is that block in dark green. the red mushroom instead will be screwed into the bottom plate and will remain firm. I don't know if these gears can work. Thank you very much

hi from this design I don't understand when you do the unscrewing, which part of the print prevents the rest from turning while the unscrewing takes place.
if you do the closed-cast screw you also need a screw that allows the threaded compass to retract

 

[TETRASTORE]

the principle of operation of cinematism @ giulia94 with three gears, it is similar to that depicted in 3d in the first image of the jpg I attach.
another simplified scheme you can see in this old discussion su cad 3d.