problem quickly biting

[leosci]

Hello boys, I am a student of the course chemical engineering and not mechanical engineering. I'll still have to take a look at your course of study as we have it planned. matter is computer-assisted design by autocad software. in practice the examination consists in the theory and subsequently in the design of mechanical components, supports, semi supports connected via screws etc. I'm studying from the chirone backincasa both the first and the second volume but I can't overcome some obstacles. what is more frequently recurred is caused by the bite vines. today I had to connect two thick plates 11mm each with 2 bite screws m6 and after doing all the counts for the length of the screws through the tables of the size contained in the vol.2 the screws are longer than 4 mm and exit from the plate. I have done the accounts 100 times and in theory I don't touch anything you do to my case!!! I went three times to reception from the teacher for other things and if I return he kicks me all the university!!! Do you have any advice to give me before he goes crazy?? ? Thank you.

 

[MassiVonWeizen]

the lengths of the screws are standardized as they are produced in series of thousands of pieces and therefore standardize the most common lengths. download one of the many catalogs of viteria and see what lengths are for the type of screw you are using.
or consult a site, like swallows, and do the same verification.
two 11mm plates means a thickness of 22mm. screws from m6x22 exist http://www.gandini.it/www/vitidadi/...uageid=it&idfam_articoli=5c1&idcat_articoli=1

 

[cacciatorino]

Hello boys, I am a student of the course chemical engineering and not mechanical engineering. I'll still have to take a look at your course of study as we have it planned. matter is computer-assisted design by autocad software. in practice the examination consists in the theory and subsequently in the design of mechanical components, supports, semi supports connected via screws etc. I'm studying from the chirone backincasa both the first and the second volume but I can't overcome some obstacles. what is more frequently recurred is caused by the bite vines. today I had to connect two thick plates 11mm each with 2 bite screws m6 and after doing all the counts for the length of the screws through the tables of the size contained in the vol.2 the screws are longer than 4 mm and exit from the plate. I have done the accounts 100 times and in theory I don't touch anything you do to my case!!! I went three times to reception from the teacher for other things and if I return he kicks me all the university!!! Do you have any advice to give me before he goes crazy?? ? Thank you.

Take a 20mm long screw, so it won't protrude from below (11 mm in the hole and 9 mm in the threaded hole, if you don't put the washer). What are you doing? Are they sticking to thread resistance?

 

[leosci]

no unfortunately I cannot arbitrarily take the measure of the vine. we must respect the values imposed by the norm step by step. then the screw part over the hole passing to understand all the piece that screws in the second plate excluding the piece that passes from the first plate must be: the first piece once the diameter of the thread, the second three times the step and the third is a y value which is tabled as well. the step for a screw m6 is 0.75, the value y instead is 4.7. then in the second plate of 11 mm must enter 0.75x3 plus 4.7 plus the diameter which is obviously 6... for a total 12.95mm.. then 1.95 mm longer. this if you use the values for the fine step because with the values of the big step I do completely tombola!!! I don't know what to do. .

 

[MassiVonWeizen]

a design would make everything easier than reading an explanation with deficit punctuation.
I don't know about these calculations, but if you have a 11mm plate, they're gonna take 11mm of thread, all that's protruding doesn't need anything.
if the calculations for construction purposes do not increase the thickness of the plates or decrease the diameter of the screw increasing the quantity

 

[leosci]

you are right about writing. I had a lesson until 13:00 and I realize I've written very approximate. detail in pdf. unfortunately some detail is lost. Thanks again View attachment Esercitazione 13.pdf

 

[MBT]

I'm sorry, I'm gonna be stunned from Friday. .
But I don't see the vine protruding!
In addition... how are the "plants" solicited (which actually look like the masks of a rigid joint) and consequently the screws?

 

[MassiVonWeizen]

bhé, it is definitely a design that lets you want:
-File on the bottom plate that is not passing (you can put a screw as long as you want, but beyond that point you do not go. indeed if it is too long it does not block anything at all)
- tip, you don't know what, which protrudes
-Leave a rosette

But at this point I would go through holes and tighten with a nut.

 

[leosci]

Unfortunately exporting pdf lost thin lines and sampling. I can't change anything about this support. all sizes are provided in the delivery of the exercise. the regulation for the size of the bite screws is what I told you earlier. I cannot arbitrarily decide the length of the screws. ah and what is fundamental I can not add in rosettes or even less cracked washers because in that case the word "add spontaneous antisvitation device" appears. I believe to apply incorrectly the formula

 

[MassiVonWeizen]

in pdf you have not lost nu,lla, there are really incomprehensible things. I wrote them in orange in pdf and I repeat to you:
- termination of the thread instead of doing it for all the thickness of the plate
-design of an incomprehensible tip

I think the exercise is something that's in the air. I don't want to insist on the matter and I can't unbalance on the calculations I have no competence and I don't even have the volume to check what it says, but I do a logical analysis of the situation
subscribed that the total is 22mm
any length you compute over 22 protrudes and does not take on the thread. Ergo doesn't need anything. But let's say the calculations need a 26-screw, if the screw sticks out 4mm what changes you?
if the calculation tells you that the screw is less than 22 and then you would have a light between the bottom screw and wire plate what prevents you to put one from 22 to prevent that in that empty space go to deposit dirt (dust+fat/oil, weld sketches, blablabla) creating a predisposition to the grip?

 

[MassiVonWeizen]

but so much to understand what the rules tell you, that I didn't understand anything:

the first piece once the thread diameter

What? What measure do you refer to? in the first piece the hole is passing

the second three times the step

idem as before. What do you mean?

the third is a y value which is tabled as well. the step for a screw m6 is 0.75, the value y instead is 4.7. then in the second plate of 11 mm must enter 0.75x3 plus 4.7 plus the diameter which is obviously 6... for a total 12.95mm..

third what? piece? But if there's only two to block? What is it? where does that 3 multiply the step?
If you have to respect the rules where you think you find a 23.95mm long screw?

try to be clear if you bring back formulas and data.

 

[MBT]

dictated in a dark and perhaps vulgar manner. . .
If I were to be in my hands the drawing of a sheet of 11 that must be drilled m6 for 9.5 mm (case number), I take the drafter to kick the ass until the geox writing appears on the contrary on the ass!
If he comes to tell me that he has to buy 19 long m6 screws, I repeat the treatment to football on the other side, until the above geox writing disappears
Besides, I want to see the comment of the shop office and the shop chief when they must respectively buy and drill/short screws m6 at a fine pace.. .

 

[Focus]

dictated in a dark and perhaps vulgar manner. . .
If I were to be in my hands the drawing of a sheet of 11 that must be drilled m6 for 9.5 mm (case number), I take the drafter to kick the ass until the geox writing appears on the contrary on the ass!
If he comes to tell me that he has to buy 19 long m6 screws, I repeat the treatment to football on the other side, until the above geox writing disappears
Besides, I want to see the comment of the shop office and the shop chief when they must respectively buy and drill/short screws m6 at a fine pace.. .

Unfortunately, and I repeat unfortunately, it seems to me that university exercises are all of this level... and in this case the fault is not students.

Hi.

 

[MBT]

Unfortunately, and I repeat unfortunately, it seems to me that university exercises are all of this level... and in this case the fault is not students.

Hi.

I didn't say it was his fault.
I simply explained to him what could happen to him tomorrow, when he will deal with something that is not "academic"

 

[MassiVonWeizen]

Unfortunately, and I repeat unfortunately, it seems to me that university exercises are all of this level... and in this case the fault is not students.

it will also be true, but just think about it above to realize that beyond what they say calculations if your maximum thickness is defined and not editable the best screw is that covering all thickness. if you were shorter in your calculations, if you were longer in your performance, you have to lean and good peace to all.
then if I don't say shit, it would be necessary to consider that there is a decrease in functionality with the progress of threads; type that the first thread works at 80%, the second at 60% and away to decrease (they are randomly shot percentages to make the idea), so it could be that in a case similar between a 22mm screw and one from 18mm almost nothing changes for the purposes of tightening with so much greetings to the chirone

 

[meccanicamg]

As said several times, some people would be better off going to the factory... so they'd know what they're doing.
the norm that existed was withdrawn and it seems to me still without replacement because the regulatory body has not yet decided whether it makes sense or not that table that indicates whether the plate is iron, aluminum etc. where 1.5 times the thread is indicated....2 times and things like that.
Unfortunately, they say and have long said that that rule is a nonsense for several reasons:
If the material of the plate with clamping thread has very low yielding load is not enough neither 2....4...10...20....50 times the thread
- in all threaded couplings it is necessary to evaluate the resistance of the screw and the plate as from countless posts where we talk about thread lengths
- in a photo threaded even 10 times the diameter only work the first 4/6 threads and the rest does not collaborate
for these and other reasons has been withdrawn the rule that in many have always considered truth (I never...I have always made short threads equal to the diameter on tempered plates. ... plate 15 mm fon hole m8 threaded 8 mm and 12 mm hole)....just calculate right

So I'd say that in everything you've posted, there's little to it.
or we ran away something... .

 

[leosci]

Meanwhile thank you for the quick answers. then the screw should not protrude beyond the second support. the threaded hole should not cross aside the support seeds so there is no risk of deposits in when in the doors where now it protrudes the screw there will be nothing. I have checked the formula from which the length of the screw is visible and it is getting longer and longer. I will obviously make a mistake somewhere in the calculation of the length because apparently the correct text and someone managed to find a system to return to the 22mm. Thanks again for the help.
p.s do not see pdf with corrections

 

[MassiVonWeizen]

you have written

thanks for the answers byfrettate

?
Are we crazy?

 

[leosci]

Did you really write?
Are we crazy?

Forgive me my writing error. Forgive me!!! I always write running. I mean timely! !
- - - updated - - - -He uploaded me after the message with the correction. then summarize it better. the first piece of the screw (the one that crosses the upper support) is not considered.
the second piece of the screw (the one that crosses the bottom bracket) must be decomposed into three parts to get the length and you should do so:
point 1)It adds once the diameter then 6mm
point 2)3 times the value of the step that according to table is 0.75
point 3) add a y value which is tabled
then the final length is 11mm(which corresponds to the length of the first support) + 6mm(as from point 1) + 0.75x3(as from point 2) + 4.7 (value y as from point 3)=23,95mm.
are beyond the length of 1,95mm. I should have a maximum length of 20/21 mm to perform a correct computer. I have used the minimum step value that I have the table to get to this measure because with a larger step value it increases in proportion also y and thus making arrival over 26mm. I would like to know if there is a different way to find the correct length of the screw to be used because so doing I never return to acceptable values. thanks again

 

[MBT]

Mah, a sizing so I never saw it.
Of course if the formula is that and you can't derogate... You're a cat!
or use m5 screws or tell the teacher that the problem has no solution