university project

[Reynolds vs. Grashof]

Bye to all,

we must realize this shovel (present in attachment) for foundry. Since the tolerances obtained in the foundry are very bad while the internal surfaces of the spoon and knife are functional we would like to work with the machine tools, milling the knife vertically and polishing the shells. according to you is correct this passage or should we mill the spoons and then polish them? Since we cannot use cnc machinery according to you it is possible to mill or polish such a surface with standard machinery? we are open to suggestions that simplify the project as much as possible, remaining the need to realize the piece for foundry and then work it with machines not electronically controlled.

thanks to all

 

[MassiVonWeizen]

object purpose?

the internal surfaces of the spoon and knife are functional

tolerance or roughness? It's two different things.

according to my operator experience without a control machine you don't.

 

[Reynolds vs. Grashof]

the purpose of the object is to be cast on a impeller to realize a hydraulic turbine, therefore the jet of water will hit the centre by affecting the surfaces we call functional.
from foundry we obtain both tolerances and bad roughness, but most of the blade is not affected by the jet of water and therefore we do not care to work it. we are interested only to work knife and conche for good tolerances and low roughness but we have no control machines available.
according to your experience is it really impossible to make them with a traditional machine?

 

[MassiVonWeizen]

tolerances only affect the knife, that is the rectangular part with the two holes, which will not be calettata but fixed with a bolting.
the concave part of the spoon do not think it has problems of tolerance, half a millimeter more or less (exaggerating) does not change its functionality; If not, motivate me the reason why I am a little ignorant about turbines, but the finish that I think will also suffer a treatment on the surface affected by the jet of water.
the knife works without problems with a traditional cutter and if necessary, but you will establish it, with a rectification.
the spoon does not need processing but only of the polishing process and treatment.

now it is up to you to propose solutions otherwise I will take the vote

 

[Reynolds vs. Grashof]

You are completely right, we did not consider the fact that the feet of the shovel should be calettati and therefore have to be worked, with addition of sorametal, because, assuming a 4% discard on the measure due to the foundry, it would not be insured coupling within the limits of the tolerances.
we thought that even the central foil, which is located between the two basins, can be milled vertically with a traditional machine and possibly rectified, according to you is right?
As far as polishing is concerned, we do not know so much since it was not treated in class and on books we do not find much. in what differs from rectification? needs overmetal? how can you polish an ellipsoid profile, like that of the conca, with a traditional machine? What do you mean by treatment (if you mean a treatment to make it stainless we already chose to use a stainless steel)?

 

[SHIREN]

http://www.cad3d.it/forum1/showthread.php?41231-creazione-angoli-di-sformoMore or less is the same discursion
read a moment
then if you have other questions......... .

 

[Reynolds vs. Grashof]

the project is the same because it is our classmate, our problem does not concern model 3d but our doubts concern the work to be done at the completed foundry and how to execute them

 

[SHIREN]

Hi.
The only "functional" zone is where the holes are
you have to work the faces that mate with the rotating body of the turbine
holes can also be obtained directly from chip removal
to make them in the foundry it takes a soul case with overmetal included
all with a traditional alesatrice-fresher-ecc machine
for the interior of the shovel
in foundry, tolerances are also obtained in the order of mm
based on the assumption that the max performance condition of the shovel is
when the liquid does not suffer shocks at the entrance of the shovel
the inside shovel should be finished with a manual operation of flex
with abrasive discs of various grains
then the molten body and all crude except the two blades with hole that must mate
with central body tolerance
Thank you very much

 

[Reynolds vs. Grashof]

So the two concavities, except for the central foil, remain crude of foundry? Should the grinder be used only on the central foil?

 

[SHIREN]

So the two concavities, except for the central foil, remain crude of foundry? Should the grinder be used only on the central foil?

If you don't have or can't use or are not expected to use a numerically controlled cn work center is the only solution
all the inside shovel should be grinned
in the specific case
for the construction of the model you could remain 1-2 mm of overmetal in the concave part
that you will delete with the flex
so it would be appropriate to build you some control templates or templates
that you will use during the emery
if you want you can also work the top of the shovel (the edge)
always with traditional machine tools
Thank you very much

 

[Reynolds vs. Grashof]

Meanwhile we thank you infinitely for the help you're giving us, you said it's best to grind everything, but it's correct to straighten out the crude without having it before roughed (for example, by fresandolo)?

 

[SHIREN]

Meanwhile we thank you infinitely for the help you're giving us, you said it's best to grind everything, but it's correct to straighten out the crude without having it before roughed (for example, by fresandolo)?

with a traditional machine you do not have the possibility to perform such processing
you do with a cad-cam process
you can also use widia fresettes with swivel laces to have always manual work and then brush and polish the surfaces
p.s. maybe the ultimate goal of the school exercise is to make you realize what you can do with traditional machines
or vice versa with c.n. milling machines with cad-cam
thanks to you

 

[Reynolds vs. Grashof]

I know that dye we're killing with the questions but you don't know what help you're giving us!
by means of the single rules, given the size of the central foil, we have calculated to apply 5 mm of overmetal. Is it right, before moving to semi-finishing with grinder and polishing finishing, to pass through a roughing through traditional milling, since the profile of the lamina is still flat (bypass the angle of which the suerficie is inclined by recording the piece with the same angle)?

 

[marcof]

did you say that it is better to grind everything, but it is correct to directly finish the crude without having it first roughed (for example by fresandolo)?

look that with manual grinding you make both roughing and finishing and final polishing, both for the knife and for the spoons.
only to rub the faces of that knife with a traditional stain while you have turned it and worked a good operator with a grinder and related cutters, abrasive rollers, brushes etc. you finished knife and mirror spoons. if the fusion is done well, with some shaped template, 800-1000 heuri between axial and angle grinder, cutters, brushes etc. an operator who knows how to do his work gets results that could embalm those of the methylological room:smile:
that then to produce industrially pelton turbine blades you should naturally use cnc machines is obvious, but I don't think your case, so...

 

[Reynolds vs. Grashof]

Unfortunately in lesson we treated only work at the counter (torn, milling,...) but not with manual tools. we must take into account parameters such as strength and cutting power, processing times, tool selection. in case of manual processing how do these parameters vary?

 

[SHIREN]

look that with manual grinding you make both roughing and finishing and final polishing, both for the knife and for the spoons.
only to rub the faces of that knife with a traditional stain while you have turned it and worked a good operator with a grinder and related cutters, abrasive rollers, brushes etc. you finished knife and mirror spoons. if the fusion is done well, with some shaped template, 800-1000 heuri between axial and angle grinder, cutters, brushes etc. an operator who knows how to do his work gets results that could embalm those of the methylological room:smile:
that then to produce industrially pelton turbine blades you should naturally use cnc machines is obvious, but I don't think your case, so...

:36_1_11::36_1_11:

 

[marcof]

Unfortunately in lesson we treated only work at the counter (torn, milling,...) but not with manual tools. we must take into account parameters such as strength and cutting power, processing times, tool selection.

I would say that of the two or you have (you or the professor) wrong in choosing the piece to work or wrong in choosing the usable machines.
the spoons of that shovel can not work with traditional machines, therefore cutting strength, power, times etc. become purely theoretical disquisitions unless you reconsider the whole working cycle on a numerical control machine.

in case of manual processing how do these parameters vary?

Good question... I believe that the only one able to respond to the times and choice of tools is that famous operator able to work as a rule of art those surfaces with an axial and angle grinder.
I don't want to discourage you, but since I don't think you're dealing with artisanal production processes (in the true sense of the word) and you'll have to provide technical documentation with charts, tables, time evaluation, powers, costs, work cycles etc., I'm afraid you'll have to review the project (machine change or piece change), and it will be another step towards the disappearance of certain manual skills and their study, even academic.

 

[SHIREN]

I know that dye we're killing with questions but you don't know

no prob
We're here for this.
I hope that your visit to the forum will enrich you again

I know that dye we're killing with questions but you don't know

no prob
We're here for this.
I hope that your visit to the forum will enrich you again

then in the processed areas (the big piece is 600 mm long
is in stainless steel or aisi 304 and similar things
you need to apply 10 mm of machining plus sform angles
the holes do them from the full in the sense that they do not revenues from the fusion
you can get the two sunshades on the tip of the spoon with traditional milling operation is simple feasibility
then close the concave part
this is good for you because to make those two sunshades you have to create a false flow so a hairstyle
with relative formation of excessive bays
on the wedge inside the spoon you have to add 2-3 mm of overmetal which is then eliminated with manual operation
as already placed before and with the construction of a series of silhouettes or dimes that revenues from the mathematical model
the important thing is the construction of the model x foundry the secret of all "work" is right there
a good model made to rule of art uni h1-h2
It solves your prob
no parameters exist for manual adjustment operations
indeed in telling you the truth for an adder (with moustache white hair reading glasses and cigarette between the lips) time does not exist
For the knife you don't care, it's raw, for the size of the piece, it's always been rough.

I add
to melt that piece the foundry in addition to the model with metal-static rectires (inox 2%) must add in particular areas
of machined areas -jobs that are of the relays of material that must be inserted on the model that serve in case the molten metal embroidery

all must be eliminated in the foundry by grinding then at the delivery of the piece you will already have a rough and granigliato piece

p.s.
I guarantee that it's easier to do the job than to transcribe everything.
Thank you very much

 

[Reynolds vs. Grashof]

We thank you for the very detailed answer. from what we have read you have thought of a traditional foundry with wooden model; we had thought instead of 4 models (there are only 4 of palettes required) to lose to realize in polystyrene to avoid souls, angles of disform,plans of separation, not too high staffes (the size of the piece is 211x165x45 mm). What do you think is a plausible road to go?

 

[meccanicamg]

that bad thing does not make a minimum of experience at machine tools and not get your hands dirty. Maybe it's even worse to see teachers inventing strange things, for the sake of not doing the same things, but then... ..quantita ignorance on their part.

I don't know how lucky they were to get into a workshop that overhauls the pelton turbines and creates new ones. I assure you, it's like getting into a urinal.

turbines are made from the cast of the central wheel that is pre-finished to accommodate bearings and palettes.
The palettes that come from the foundry and are pre-worked for the blade attachment zone on the central impeller.

I remember that there are alternatives where they are obtained all from full conores of blades (but it happens in these years with multi-axis machine tools).

The shovel is then processed internally and externally through numerical control machines where it is possible to impose a series of 2d working planes where to slide by interpolation the ball mill to model coarsely the shovel.

I remember that by coarse, in this sector I would say that there are steps of 0.5/0.2 mm approximately.

Once you have done all this beautiful thing on all the palettes, inside and out, you have that the impeller is ready to be removed from the cnc milling machine and carried in polishing department.

in this department there are welder tools, molators, polishers that do everything by hand. have available a series of blades for dimensional control of the palettes in the area of the spoon they use to verify which side molar and which side to add material.

this department is the same as that of repairs though those who repair undoubtedly need more welding and more skill than those who already have the coarse shape that is only polished.

It is really unthinkable to calculate the cutting forces of a spherical mill on an ellipsoidal path that is then translated ellipsoidally in the orthogonal direction. each pèassata has a different cutting force. with a machine tredizionaòe of milling you do not make a cran that because manually you have to be a great genius in order to be able to interpolate dua axes with the handleettini turning them by hand to make an ellipsoid.

It's a bit like making the shifts with the manual parallel lathe....if small you can do them by hand interpolation but if they are larger than 2x45° you must have the tilted tool or still the turret rotated at 45° etc... this as a traditional example/cnc.