xxi
Guest
You have to apologize I made a gaffe, I can't read!!!! ahahah.. thanks always mechanicm that helps me even in the banality. . .
Ste_d
Guest
my drawing prof said that it is "the dog who bites the tail"... try to make a course of constructions of machines or elements without knowing how to read an overall. I see it hard. try to correctly quote a particular with relative tolerances without knowing the technology and cycles of processing. I see her even harder. I remember that the design prof dedicated a couple of hours to explain how the lathe and the milling machine worked to make us understand a bit the "functional" quota speech. It is clear that it is not enough 2 hours to learn how to quote.
However for the design the design part should not interest, usually you start drawing something already quoted, for example a particular taken from an overall scale (I always did so). if the prof leaves you freedom on the measurements so that the piece is well proportioned, what you will be evaluated is only the part of drawing and quotation... no one will check the resistance go quiet, so you will have time at the 3rd and 4th year!
xxi
Guest
Is it okay with the right teeth wheel on page 7?
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Ste_d
Guest
the important in the drawing of the toothed wheels is to make the table where you indicate all the parameters... in the true design in fact it is enough to draw the outer diameter and to mark the lines of the primitive diameter.
then you do a partial section where you also see the circumference of foot. In your case, since you have to do it a little bit if I understand, you don't have to do the hole! In fact the toothed wheel and the tree are all a piece of fusion.
edit: I read the text better... the pinion is of piece ok, on the other wheel instead you have to make us the hole and the quarry for the tab reminding you to tolerate it as manual.
then you do a partial section where you also see the circumference of foot. In your case, since you have to do it a little bit if I understand, you don't have to do the hole! In fact the toothed wheel and the tree are all a piece of fusion.
edit: I read the text better... the pinion is of piece ok, on the other wheel instead you have to make us the hole and the quarry for the tab reminding you to tolerate it as manual.
Snow32
Guest
I write in this topic because this week's problem is always a reducer, always for the same design course of topic initiator machines.
on the input shaft I had foreseen two oblique ball bearings arranged precisely to x. on the exit shaft, since the presence of a double-acting brace is required, I predicted the use of two additional radial bearings. if I do not err these last must be a locked both in place and on the tree, one stuck only on the tree and with game in place. I then calculated with the appropriate formulas the rays, the angles of primitive cone etc.. for the wheels... There are no calculations required for efforts and stresses. then the module and everything is chosen arbitrarily.
I have great doubts as to the area where you go to place the piece pinnacle of the input shaft. there are those who say that it must be a special case that must be sampled, being it a real box, not like the rest of the body of the reducer that instead should not be sampled, but drawn normally since the reducer is actually divided in that way into two pieces. How should this case be placed? how do I enclose the pinion while also considering the other wheel?
second big question... how can I keep the scanned coupling in place? Are they good spacers on both sides?
Last thing, can I use a spacer to keep the oblique input shaft bearings away from each other? placing this spacer on the horse of a part of tree with marginal narrowing of diameter of the tree (obviously realized avoiding double lines of the spacer itself and having the diameter of the two parts on the right and left larger)? theoretically it does not compromise the assembly.
Thank you very much for your patience and for sure stupid questions
on the input shaft I had foreseen two oblique ball bearings arranged precisely to x. on the exit shaft, since the presence of a double-acting brace is required, I predicted the use of two additional radial bearings. if I do not err these last must be a locked both in place and on the tree, one stuck only on the tree and with game in place. I then calculated with the appropriate formulas the rays, the angles of primitive cone etc.. for the wheels... There are no calculations required for efforts and stresses. then the module and everything is chosen arbitrarily.
I have great doubts as to the area where you go to place the piece pinnacle of the input shaft. there are those who say that it must be a special case that must be sampled, being it a real box, not like the rest of the body of the reducer that instead should not be sampled, but drawn normally since the reducer is actually divided in that way into two pieces. How should this case be placed? how do I enclose the pinion while also considering the other wheel?
second big question... how can I keep the scanned coupling in place? Are they good spacers on both sides?
Last thing, can I use a spacer to keep the oblique input shaft bearings away from each other? placing this spacer on the horse of a part of tree with marginal narrowing of diameter of the tree (obviously realized avoiding double lines of the spacer itself and having the diameter of the two parts on the right and left larger)? theoretically it does not compromise the assembly.
Thank you very much for your patience and for sure stupid questions
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meccanicamg
Guest
I'll look at you tonight and I'll tell you tomorrow:I write in this topic because this week's problem is always a reducer, always for the same design course of topic initiator machines.
http://dmmf.mec.uniroma2.it/docs/dm1_2011/eser-7_2011.pdfon the input shaft I had foreseen two oblique ball bearings arranged precisely to x. on the exit shaft, since the presence of a double-acting brace is required, I predicted the use of two additional radial bearings. if I do not err these last must be a locked both in place and on the tree, one stuck only on the tree and with game in place. I then calculated with the appropriate formulas the rays, the angles of primitive cone etc.. for the wheels... There are no calculations required for efforts and stresses. then the module and everything is chosen arbitrarily.
I have great doubts as to the area where you go to place the piece pinnacle of the input shaft. there are those who say that it must be a special case that must be sampled, being it a real box, not like the rest of the body of the reducer that instead should not be sampled, but drawn normally since the reducer is actually divided in that way into two pieces. How should this case be placed? how do I enclose the pinion while also considering the other wheel?
second big question... how can I keep the scanned coupling in place? Are they good spacers on both sides?
Last thing, can I use a spacer to keep the oblique input shaft bearings away from each other? placing this spacer on the horse of a part of tree with marginal narrowing of diameter of the tree (obviously realized avoiding double lines of the spacer itself and having the diameter of the two parts on the right and left larger)? theoretically it does not compromise the assembly.
Thank you very much for your patience and for sure stupid questions
meccanicamg
Guest
Here we are... then we have:
- input shaft ball bearings arranged by x --> ok
- shaft output a double effect bearing + 2 radial ball bearings --> ok
- special case --> if you can make merge only ok, otherwise 2 mergers
- as the rest of the reducer should not be sampled --> if not sampled does not exist... What is the theory? ?
- spacers on both sides --> ok
- marginal narrowing of diameter --> posting drawing that you do not understand. advice: Spacers must touch either the outer ring or the inner ring of the bearings. not both.
- place draft scheme (you do not look at formal inaccuracies... is a drawing made in bed at 4:00 in the morning). It's an idea of how to develop things.
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Snow32
Guest
Thank you so much for your always precious help and especially the time you spent for your sketch. Thank you very much. Now I'll put my version in the morning.
I leave you two questions:
because in zone 1 often in the examples the book makes a reduction in the diameter of the tree under the spacer (without getting to the extremes) as I misdesigned you with paint?
surely the answer to this question is seen that the sketch was made by an expert designer like you, but the groove on the tree is possible to do it even on a stretch with a uniform diameter? in the sense is it not necessary that the groove on the tree begin where there is a change of diameter? can also start and finish on a stretch with the same diameter? I apologize for the scrumptical question, but on the book all examples of grooves are made at the beginning of a change of diameter... .
Thank you very much again! ! !
I have annexed the areas concerning my questions
I leave you two questions:
because in zone 1 often in the examples the book makes a reduction in the diameter of the tree under the spacer (without getting to the extremes) as I misdesigned you with paint?
surely the answer to this question is seen that the sketch was made by an expert designer like you, but the groove on the tree is possible to do it even on a stretch with a uniform diameter? in the sense is it not necessary that the groove on the tree begin where there is a change of diameter? can also start and finish on a stretch with the same diameter? I apologize for the scrumptical question, but on the book all examples of grooves are made at the beginning of a change of diameter... .
Thank you very much again! ! !
I have annexed the areas concerning my questions
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meccanicamg
Guest
Please:wink: Then I come to answer:
- the spacers between two bearings can be found with a corresponding diameter reduction on the shaft because it would actually be better to rectify (on the shaft) only the part that goes in coupling with the two bearings. to achieve these two adjustments, instead of making a double rectification gorge in between, a downturn is made, but it has the same function. Furthermore, the spacer remains lawfully centered on 0.5 mm per part on the rectified parts (clearly with game 0.05/0.1 or higher depending on ø). the solutions for rectified traits that can be both equal to name value (ø20) can have equal or better different tolerances, so as to realize on the first a slightly lower diameter (cuscinet with axial scrolling style trolley) while the second blocked (hinge style clamp). at the following link you can see the 3rd pulley to dx that has a central rib, so as to rectify only at the beginning and at the end, decreasing the distortions and guaranteeing a better cylindricalness and coaxiality
- the scanned trees normally if long, you take the grooved tree from trade along the whole tree and you go back the smaller diameters to accommodate the bearings and the rest (as I did in the sketch). on the trees where the coupling with a grooved tree is planned for a very lower length, it must be realized directly on the tree itself by means of a special disc brake, therefore depending on the encumbrance it is not possible to have gorges close to high diameters (see drawing to this link). for scanned trees partially it is not possible to get in line with the grooved hub because there is the milled bottom radius (you see it in the axieme at the link before)
Snow32
Guest
with regard to the second part of the exercise, that concerning geometric and dimensional tolerances with relative quotation only of the input shaft.. It's okay if I act like this:
1) for dimensional tolerances pongo on the seat of the two oblique bearings a dimensional tolerance j5 (loads and average speed). I also put on the quarry for tongue a special tolerance
2) with regard to quotations this time I have to write (as in the previous exercise) those both functional (in series) and technological/working (looking at "scale), or are the latter not explicit?
3) with regard to the piece sprocket is right if I affix the quotation table of the conical wheel, even if it is a piece sprocket?
4) regarding roughness is it right to put on the pinion a 2.5 in the external part of the teeth and 1.2 on the internal cavities of the teeth? Is there any roughness on the bearings?
5) regarding the second oblique bearing that touches me on the shouldering I have often seen the professor tend to put a thin line "similgolaf"... Is it really enough that the shoulder connection radius is less than the bearing connection radius?
6)as regards the geometric tolerances pongo as a plane out of the tree axis on the shoulder exactly before the pinion, then placing on the tooth an oscillation toll of 0.05.
Is it necessary that I then define another plane b from the other head of the tree and then put a total oscillation on the bearing seats? and if you like to indicate the tolerance of oscillation on your teeth instead of as mentioned before? Thank you so much for your patience!
1) for dimensional tolerances pongo on the seat of the two oblique bearings a dimensional tolerance j5 (loads and average speed). I also put on the quarry for tongue a special tolerance
2) with regard to quotations this time I have to write (as in the previous exercise) those both functional (in series) and technological/working (looking at "scale), or are the latter not explicit?
3) with regard to the piece sprocket is right if I affix the quotation table of the conical wheel, even if it is a piece sprocket?
4) regarding roughness is it right to put on the pinion a 2.5 in the external part of the teeth and 1.2 on the internal cavities of the teeth? Is there any roughness on the bearings?
5) regarding the second oblique bearing that touches me on the shouldering I have often seen the professor tend to put a thin line "similgolaf"... Is it really enough that the shoulder connection radius is less than the bearing connection radius?
6)as regards the geometric tolerances pongo as a plane out of the tree axis on the shoulder exactly before the pinion, then placing on the tooth an oscillation toll of 0.05.
Is it necessary that I then define another plane b from the other head of the tree and then put a total oscillation on the bearing seats? and if you like to indicate the tolerance of oscillation on your teeth instead of as mentioned before? Thank you so much for your patience!
meccanicamg
Guest
how much I love these 40 lines or more to have to read 20 times because I lose the thread of the speech. Wasn't posting a drawing easier?
- Surely the bearing seats have tolerance. where there are the sleeves ...the trees have tolerance (in letters or in breaks)
- functional odds don't mean in series. Technological quotas does not mean parallel. if not specified you must quote according to the criteria of good design thinking about how you would realize the piece and what errors you could make. support tolerances to functional quotas and technologically reason
- piece sprocket: tabellina with toothing data, module, angles etc. the rest must be quoted on the tree
- bearing shouldering: provided with radius on the shaft below the bearing radius. if tree area made of grinding apply throat and or f depending if you want to rectify or not even shouldering
- roughness: already said several times that we have to use the standard values 0.8 internal toothing, 3.2 or 1.6 on the outer diameter wheel cone, 0.8 rectification for seat bearings, decoys and long gorges ... i.e. discharge downs also 3.2
- for geometric tolerances could be a solution even if there are others. If you look at the drawing book there should be some examples. then you can get rid of:biggrin:
Don't make me sweat like that, guys. I have a certain age....
Snow32
Guest
thank you very much for your precious mechanical helpmg, I put you the last (spero) question. for the arrangement of the quotas on the tree is fine this sketch (I do not see any other dimensional tolerances to put beyond the j5 of the bearing seats and the p9 of the hollow tab):
http://nobody32.interfree.it/p10.jpglack geometric oscillation tolerances that you have to tell me if they're okay like this:
1) reference axes to where there is the quarry tongue and b on the left shoulder of the pinion
2) total oscillation on the two bearing seats (of course a-b)
3) partial oscillation of the tooth of the pinion with respect to the only plane b.
for roughness I thought instead 0.8 on the two bearing seats (on the one with the throat f also on the rectification wall), 1.6 on the outside tooth, 0.8 on the inside tooth.
Thank you so much again and sorry to bother you!
http://nobody32.interfree.it/p10.jpglack geometric oscillation tolerances that you have to tell me if they're okay like this:
1) reference axes to where there is the quarry tongue and b on the left shoulder of the pinion
2) total oscillation on the two bearing seats (of course a-b)
3) partial oscillation of the tooth of the pinion with respect to the only plane b.
for roughness I thought instead 0.8 on the two bearing seats (on the one with the throat f also on the rectification wall), 1.6 on the outside tooth, 0.8 on the inside tooth.
Thank you so much again and sorry to bother you!
meccanicamg
Guest
- I'd say there's already a quota. substantially quoted so does not make sense. then for so long we put zero in the head and we put all quotas second axis x without having to ask the problem, all tolerances will be referred to uni en iso 2768-x but then if something is not found there is not to complain.
- for the oscillation could be feasible (but as always if you post a sketch I don't have to interpret what the... the diameter of...
- roughness 0.8 on the two bearings and inside tooth, 1.6 external tooth ok
- please post the images by uploading them to the server of the website cad3d.it. has been requested several times by moderators in various sections. please cooperate :finger:
meccanicamg
Guest
for all of exercise 7: in the text it is written to use mixed bearings in the input shaft. who used the same type of bearing would be good if he thought he'd change one of them. I had escaped this detail at 4:00 in the morning, so much so that I would not even use oblique contact bearings on the input shaft and even the biaxial bearing and at least the two radials ... I would have done as normal spindles... two conical roller bearings if ever of proper type but only that (view that work axial and radial and are recordable with a needle)
meccanicamg
Guest
I was asked to do a small seminar on how to quote trees. on drawing books, to say the truth there are many ideas of drawings already made, so I will see to you something that is not your alber of the reducer neither exercise 6 nor exercise 7, because looking I found the drawings already made and finished (I always have the same exercises that you do).
quotating the details is not simple and depends much on the production needs rather than a more functional approach.
if you are not imposed a specific way, act according to the criterion of good design: the design must be clear and logical (i.e. use quotas geometric, functional e technological innovation). It is not enough that all geometry is quoted so pedestally that i.e. if I need a length to be precise the indic specifies otherwise the rendo derived from other quotas by difference.
It would be good that you knew how a lathe works, a milling machine and a grinding to understand how to quote a piece. but also here I can tell you the infinite of the lathe but the minimum necessary for not making big mistakes is:
- all parts can be taken to the lathe with one of the following solutions: self-centering spindles, independent griffe spindle, between tips, spindle and quilt
- depending on the type of socket (see previous point) and type of tool I can make the piece in a single socket or on several occasions (at each shooting I read the piece, turn it and put in the car)
- if I have to rectify it I need (not indispensable) the center holes because the rule wants me to turn the piece between tips and rectification between tips so as not to have very accentuated oscillations and to maintain the concentricity of the work
- if I do to the resumption of the piece I will have a "unworked" trait that will be given by the difference of the length of the piece minus the stretch worked in the first phase. So if I work after the shooting I will have a trait that will be able to suffer immancably of a certain axial error (imponable with tolerance if I need it or what comes and then should not be quoted).
as you can see qui the quotas 74 90 and 98 are referred to the extreme right because they are processes that are passed starting from the origin to the right of the piece (for technological reasons)
There is no quotation in series or in parallel, but both are used in a cone manner according to what I am listing. as you can see there is also the share of the total in parentheses that means that its length is not subject to tolerances because its true value will be given by the tolerances of individual listed jobs. However, that quota is convenient if of sixteen starting from a sawed crude or bar because, considering the due overmetal in length, I have the indicative value of the finished piece.
as you can see qui the tree is worked on several occasions both on the lathe and then successivemetne on the milling machine and possibly on the grinding. clearly you have the right and left origin on the piece.
how to quote your tree with conical wheel made of piece (exercise 7)?
quotating the details is not simple and depends much on the production needs rather than a more functional approach.
if you are not imposed a specific way, act according to the criterion of good design: the design must be clear and logical (i.e. use quotas geometric, functional e technological innovation). It is not enough that all geometry is quoted so pedestally that i.e. if I need a length to be precise the indic specifies otherwise the rendo derived from other quotas by difference.
It would be good that you knew how a lathe works, a milling machine and a grinding to understand how to quote a piece. but also here I can tell you the infinite of the lathe but the minimum necessary for not making big mistakes is:
- all parts can be taken to the lathe with one of the following solutions: self-centering spindles, independent griffe spindle, between tips, spindle and quilt
- depending on the type of socket (see previous point) and type of tool I can make the piece in a single socket or on several occasions (at each shooting I read the piece, turn it and put in the car)
- if I have to rectify it I need (not indispensable) the center holes because the rule wants me to turn the piece between tips and rectification between tips so as not to have very accentuated oscillations and to maintain the concentricity of the work
- if I do to the resumption of the piece I will have a "unworked" trait that will be given by the difference of the length of the piece minus the stretch worked in the first phase. So if I work after the shooting I will have a trait that will be able to suffer immancably of a certain axial error (imponable with tolerance if I need it or what comes and then should not be quoted).
as you can see qui the quotas 74 90 and 98 are referred to the extreme right because they are processes that are passed starting from the origin to the right of the piece (for technological reasons)
There is no quotation in series or in parallel, but both are used in a cone manner according to what I am listing. as you can see there is also the share of the total in parentheses that means that its length is not subject to tolerances because its true value will be given by the tolerances of individual listed jobs. However, that quota is convenient if of sixteen starting from a sawed crude or bar because, considering the due overmetal in length, I have the indicative value of the finished piece.
as you can see qui the tree is worked on several occasions both on the lathe and then successivemetne on the milling machine and possibly on the grinding. clearly you have the right and left origin on the piece.
how to quote your tree with conical wheel made of piece (exercise 7)?
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xxi
Guest
Mechanicalmg make me understand better.. Ball bearings hold only radial loads, only axial rods; ball bearings, double crown, tapered rollers bear both radial and axial loads for the alpha angle?
MBT
Guest
ball bearings hold both radial and axial loads.
to spans, it can be said that the accepted axial load is equal to half the radial load.
It is clear that if there are both loads, these must be combined and verified if they are lower than the limit load of the bearing.
for the remaining bearings, there are special coefficients that allow to determine the resulting load given by the combination of radial and axial load
meccanicamg
Guest
It's like mbt said. However, radial ball bearings or roller bearings are usually used for predominantly radial loads, axles for thrusts mainly in the direction of the axle and angled ones such as conical roller bearings for heavy loads in axial/radial direction.
about all bearings have a resistance capacity in the non-main direction, but it is very low and prematurely dies the bearing.
xxi
Guest
then as mixed I can put great on tapered rollers.thanks for the answers.